TS 102 252 V1.1.1
Contents
1. SOURCE QPSK QAM OFDM aiae 0x73 0x71 1 0x72 1 0x74 Head End Modules unique SID for the same address OUTPUT MODULATION QPSK QAM 1 QAM QAM Analogue COMBINER QAM STB STB Set Top Boxes STB STB unique Master ID within network STB STB STB STB STB STB QPSK STB STB Example of network configuration and use HEM output Frequency Bandwidth Control Channel used QAM 47 MHz to 862 MHz 8 MHz RF see clause A 2 in 1 QPSK 47 MHz to 2150 MHz 40 MHz 22 kHz RF see clause A 2 in 1 Table A 1 taken from 1 gives the values for the Address byte ETSI 29 ETSI TR 102 252 V1 1 1 2003 10 Table A 1 Values for the Address byte Address type Value All SMATV Head end devices 0x70 QPSK QAM transmodulator 0x71 QAM QAM frequency converter 0x72 QPSK QPSK IF IF converter 0x73 OFDM QAM transmodulator 0x74 Reserved 0x75 0x7E Reserved for future expansion 0x7F A 1 2 PIN code allocation The eight bits of the SID in the range 0x00 to 0x07 are reserved for installation purposes Already installed HEDs can not be allocated an SID in this range HEDs identified by the same Address byte i e QPSK QAM transmodulator must have different SID HEDs not capable of automatic installation must have a pre set SID higher than 07F HEDs capable of automatic installation will be assigned an SID in the range 0x08 to Ox7F All user termi2. Amplitude dB 20 30 Frequency MHz Figure 8 Amplitude response of typical SMATV installations with inductive directional taps 60 to 80 users ETSI 15 ETSI TR 102 252 V1 1 1 2003 10 D c coupled inductive taps as described in figure 5 could be theoretically implemented to provide a flat response from d c to 2 150 MHz like resistive couplers However in some industrial developments of the 22 kHz bus solution aiming at reducing costs and space of the taps the tap attenuation below 47 MHz is increased while keeping adequate performance in the frequency range around 22 kHz smaller choke coils needed with respect to ones providing d c coupling 6 Control Channel protocol 6 1 Basic features The Control Channel protocol is based on messages sent by the user terminal to the corresponding Head end device via the 22 kHz bus or the RF bus carrying commands in order to perform specific actions at the Head end side e g installation set up tuning reset etc the Head end device sends messages to the user terminal as answers to the received commands if required In the communication between the user terminal and the Head end device a master slave approach is used where the user terminal is the master For this reason an Head end device can transmit a message only after a request from the user terminal The list of relevant Control Channel commands so far specified is given in
3. ACKnowledge Cyclic Redundancy Check Direct Current Digital Satellite Equipment Control Digital Video Broadcasting Transport Stream Frequency Division Multiple Access Forward Error Correction Frequency Shift Keying Head End Head end Control Device Head End Device High Priority InDoor Unit Intermediate Frequency Low Noise Block Low Priority Master Antenna TV Master IDentifier Man Machine Interface OutDoor Unit Orthogonal Frequency Division Multiplexing Personal Identification Number Pulse Width Keying Quadrature Amplitude Modulation Quaternary Phase Shift Keying Radio Frequency Slave IDentifier Satellite Master Antenna TV Set Top Box Time Division Multiple Access ETSI 8 ETSI TR 102 252 V1 1 1 2003 10 UHF Ultra High Frequency VHF Very High Frequency 4 Reference model The reference model representing the Control Channel solution adopted by SMATV MAT V distribution systems and specified in TS 101 964 1 is shown in figure 1 i L Local bus In building 1 Module 1 Head end unit e g QPSK to i i QAM IF to IF eee ere eee r H TEE 1 HeCD SMATV MATV Cable Network Broadcast Channel User allocated RF Channel e g 8 MHz Control Channel Narrow band carrier SetTopBox gt Control Channel Interface Figure 1 Simplified functional block diagram of the in building SMATV MATV System using a Control Channel The system approach is based on the allocati
4. e g clearing a block of memory and could delay the reply for say up to 100 ms if it needed to assuming the master has asked for a reply If not all the subsequent blocks are to be replied to then the LAST block could then have a reply of the form E4 OK or Ex nn nn Please repeat block number s nn All subsequent continuation blocks would be of the form Ax dd dd dd dd dd dd pp where A is A B or C indicating the high nibble of the block count x is the low nibble of the block count d are data nibbles and pp is a simple optional checksum of the 6 bytes in the block t b d AO will be reserved as a wildcard block number for applications where it is unnecessary to update the block identifier byte for each block The last block contains data or stuffed bytes if appropriate AND the 16 bit CRC The reason for this is mainly that the CRC is processed in exactly the same way as the data bits and then if the result is 0000 the data is valid In this way with 6 bytes per data block this fits 256 data bytes CRC neatly into exactly 43 blocks plus the initial header block which would be carried in the range of OxA1 to OxCB The structure is shown below F Framing byte P Parity bit A Address byte C Command byte L Length of message R Reserved byte for reply strategy etc B Block identifier D Data byte S checkSum optional V Verification CRC as described in clause 7 3 7 Control
5. 88 8 Figure 13 Example of timing for a multiaccess SMATV system The way in which the different sets of anticollision times t1 and t2 are allocated to the STBs by the head end may follow several methods e g fixed t1 t2 to every STB installed or change of t1 and t2 randomly for every STB after several or all installed STBs have been switched on and off again at least once etc ETSI 23 ETSI TR 102 252 V1 1 1 2003 10 8 2 RF Control Channel bus 8 2 1 System description Because of the directional characteristics of the inductive network components the messages sent by one terminal to the head end are not detected by the other terminals The access system is then based on an Aloha scheme randomly exploiting the channel transmission resources in a time division mode i e whenever a terminal has an information to be sent transmission is started without checking if the channel is free or busy This implies a non null probability of message collision on the channel However the receiving device Head end and user s terminal is able to detect the correctness of the message thanks to the CRC An automatic mechanism of acknowledge and command repetition may be adopted 8 2 2 Traffic hypothesis N different users terminals need to communicate to associated head end modules via the same physical channel The command messages are corrupted when collisions occur The behaviour of the multiaccess collision scheme is analysed within a define
6. Channel bus 7 1 Implementation of the 22 kHz bus The communication between the STB and the head end based on a 22 kHz PWK Pulse Width Keying signal is defined by the DiSEqC specification 2 The impedance of the bus at 22 kHz shall be 15 Q A parallel inductor of 270 uH can be used to support a d c power supply current In this case a capacitor to ground should be supplied to shape the 22 kHz signal The d c feeding point is grounded for 22 kHz with a capacitor If a d c is not needed for powering peripheral devices then in order to maintain correct operation of the DiSEqC bus there should be a minimum of 10 V bias applied but the inductor and capacitor can be omitted ETSI 18 ETSI TR 102 252 V1 1 1 2003 10 The nominal communication signal from every device on the bus is produced by a 43 mA current shunt producing a 650 mV signal which is monitored from every device This amplitude of the DiSEqC carrier tone on the bus is normally too small to detect directly on a TTL or CMOS compatible pin on a microcontroller so usually a comparator input or a simple external one transistor amplifier is required In any case it is important not to make the input too sensitive to small amplitude signals which may be noise or interference It is recommended that the smallest amplitude normally detected is about 200 mV peak peak This can be achieved either with hysteresis positive feedback applied around the comparator amplifier or wi
7. Device HED Head End Device HED Figure D 1 Structure of the RS485 common us Table D 1 Electrical specification of RS485 bus Signal name Description A Non inverted data B Inverted data Half full duplex Half Baud rate 19 200 bps 3 Max number of transceivers on bus 20 HeCD terminating impedance R1 Max 150 Q Min 100 Q HED terminating impedance R2 Min 2 kQ Differential voltage A B when bus is idle Max 0 5 V Min 0 2 V Driver common mode voltage A B 2 Max 7V Min 7 V Driver differential voltage A B Max 5V Min 1V To ensure the non zero differential voltage when the bus is idle the following bias network should be used in the head end control device ETSI 41 ETSI TR 102 252 V1 1 1 2003 10 Figure D 2 Example termination for a non zero differential voltage when the bus is idle D 3 Message structure The common bus simply retransmits the control channel information so its message structure is very similar As shown in the next figure the head end control device should strip out the RUN IN and CRC bytes and append a 3 byte end of message EOM sequence This is needed since the message length is not fixed For transmission via the RS485 common bus a start bit and a stop bit must be added to every byte of the message FSK message structure RS 485 message structure FRAMING ADDRESS E OMMAND DATA EOM 3 bytes RS 485 data fo
8. ETSI TR 102 252 V1 1 1 2003 10 A 2 4 Operations A255 re TT te AOS ed Barents DA TT 34 Annex B DiSEqC Commands allowing compatibility with existing systems 35 B SMATV Installation ses aaa ie ne nn aoe eh Te sevens leech eds 35 B 2 Headend_Call_Out_of_Standby sise 35 B 3 Headend Tunings Parameters sifflet D EE ENRE EE EEEE E EERE Ei 35 B4 Master Switch to Standby icre GE Na sha senses EE TES EI EEEE EST EEEE TENORE 36 Bi SMATY 5 TETE S 1 51 LT 36 B 6 Headend_Call_Out_of_Standby_ reply sienne 37 Bal General CaA for Sd BCS ar RS oot cased ede A nm HE 37 B 8 Service Commands Tor the Head end sss sss 37 B 9 Head end installation tuning etc procedure 37 Annex C Subset of commands that FLEXIMATV recommends for implementation of the control Channel protocoles vga Eng RESSORT SREE 30 L Framing a 1 TT 39 C2 Commands st mn gee e eases ans ae se hissy A a eee 39 Annex D Common bus implementation ss 40 DeL TES Tre OS ER ES PR PR RS PO ES H 40 D 2 Physicallayer z is ses sstents tannins rites unes ten a tee quest tee LUS 40 D3 Messase structure sus fun nn nt mettre Lutte etes tee le al faite een rate inst 41 D4 Bus protocol vais Monte au nine Rte Ar nt her Aude AE ete 41 Annex E informative Bibliography e seesessoesessoesocesesocssesoossessosseseossosssesseseoesossossosssesooseessossessossosssssoesos 44 ISE THT 45 ETSI 5 ETSI TR 102 252 V1 1 1 2003 10 Intellectual Propert
9. V1 1 1 2003 10 STB Headend 1 Installation Request for new ID Number E2 73 5A Installation reply Returns next available ID Number and new timing parameters and user frequency E4 nn tt tt uu uu 2 Coming out of Standby Send Current ID number E2 73 5B nn Returns new timing parameters and user frequency E4 nn tt tt uu uu 3 Tuning Sends new tuning parameters E2 73 5C nn pp ff ff Tuni 1 or E0 73 5C nn pp ff ff ning TED Acknowledgement E4 NOTE No reply if Tuning master message starts EO 4 Switch to Standby ee Release current user frequency E2 73 5D nn Acknowledgement E4 Note must be received by STB BEFORE it goes to standby Figure B 1 Typical message dialogue in a multiaccess SMATV situation ETSI 39 ETSI TR 102 252 V1 1 1 2003 10 Annex C Subset of commands that FLEXIMATV recommends for implementation of the control channel protocol The following is a recommended minimum subset of commands and framing bytes that the HED and STB should recognize and use for the implementation of the command channel protocol The use of other commands and framing bytes can extend the system functionality but those listed below are sufficient for the implementation of a two way protocol C 1 Framing bytes The only error reply included is for when a command is not executable by the slave If the slave detects a corrupted message it should not send an error reply because the pin code may also
10. Wide band amplifiers may also be used at the user s premises in order to extend the in house distribution network Head End 2 way Splitter 4 way Splitter 4 way Splitter to the distribution to the distribution network network Figure 6a Typical location of the intermediate amplifiers in large installations 5 4 Performance of typical SMATV MATV installations in the Control Channel frequency range Figure 7 shows the frequency amplitude response of some typical SMATV MATYV installations using resistive components clause 5 3 1 measured between the input and a user outlet These installations do not currently provide adequate performance for the distribution of the 22 kHz bus ETSI 14 ETSI TR 102 252 V1 1 1 2003 10 Networks A B E floor 1 outlet 1 amplitude responses Amplitude dB 20 30 Frequency MHz Figure 7 Amplitude response of typical SMATV installations with resistive taps 10 users Figure 8 shows the frequency amplitude response measured on some typical SMATV MATYV installations using inductive components clause 5 3 2 For these installations the Control Channel approach based on the 22 kHz bus can not be adopted because of the high level of signal attenuation at low frequency particularly at 22 kHz The RF bus in a frequency range above 10 MHz provides a suitable solution Networks C D F G H floor 1 outlet 1 amplitude responses
11. and 8 2 8 1 kHz Control Channel bus To avoid collision problems a suitable access control scheme is adopted in TS 101 964 1 capable to ensure a maximum access time of about 1 5 s in the case all users up to 12 are switching at the same time ETSI 22 ETSI TR 102 252 V1 1 1 2003 10 To hold the anti collision preambles as short as possible for a given number of STBs the following rules are recommended see also table 4 1 Begin with the shortest time intervals 2 Use all possible combinations of t1 and t2 for the shortest possible sum of t1 and t2 Table 4 Timing parameters for different number of STBs Number of STBs t1 ms t2 ms t1 t2 ms 1 4 4 8 2 4 8 12 3 8 4 12 4 4 12 16 5 8 8 16 6 12 4 16 7 4 16 20 8 8 12 20 9 12 8 20 10 16 4 20 11 4 20 24 12 8 16 24 13 12 12 24 14 16 8 24 15 20 4 24 Priority An STB which is to be installed for the first time i e MID 0 see annex A always has the highest priority The corresponding command has therefore the parameters tl 40 ms t b c and t2 0 t b c In normal operation zapping by the users the box with the longest t1 and shortest t2 always has the highest priority So in the following example figure 13 with four STBs STB No 2 has the highest priority t0 tl t2 Message P 8888888888 8 first priority 3 _____ sy seen 1 8 R R N NB RB N NB EH III 1 E 8 8 8 8 8 8
12. i while the output of each remaining xor adder is connected to the input of z i 1 with i 0 4 8 and 11 Refer to the figure 6 Bytes are received at the input of the CRC decoder Each byte is shifted into the CRC decoder one bit at a time with the left most bit MSB first For example if the input is byte 0x01 the seven 0 s enter the CRC decoder first followed by the one 1 Before the CRC processing of the data of a section the output of each delay element z i is set to its initial value 0 After this initialisation each byte of the section is provided to the input of the CRC decoder including the two CRC_16 bytes After shifting the last bit of the last CRC_16 byte into the decoder i e into z 0 after the addition with the output of z 15 the output of all delay elements z i is read In the case where there are no errors each of the outputs of z i shall be zero At the CRC encoder the CRC_16 field is encoded with a value such that this is ensured Received data and CRC_16 bis MSB first 2 5 A 2 6 d 2 7 208 Big gt z 9 z 10 d z 11 gt 2 12 gt 2 13 d z 14 gt 2 15 Figure 10 CRC decoder model ETSI 17 ETSI TR 102 252 V1 1 1 2003 10 6 3 Extension of the message length In case of communication between the STB and
13. performance because of the impedance mismatching and the low isolation among the output ports The number of users in these installations is limited to ten to twelve Networks using resistive taps are also very sensitive to the matching condition of the outlet termination Figure 4 shows a typical resistive tap supplying the signal from the main cable line to the user outlets Table 1 reports the values of the attenuation among its ports Theoretically the frequency response of the resistive tap is frequency independent O1 O2 Figure 4 Circuit of a typical resistive tap Table 1 Theoretical attenuations of the resistive tap of figure 4 Through Loss I O 0 dB Tap Loss I gt 01 02 21 7 dB Directional Loss 01 02 1 21 7 dB Mutual Isolation 01 02 46 3 dB ETSI 12 ETSI TR 102 252 V1 1 1 2003 10 5 3 2 SMATV MATV installations with inductive directional taps Inductive directional taps are currently used in recent installations These devices have different electrical characteristics according to the signal propagation direction directional couplers and show a low transit attenuation and a high isolation between the output and the user outlet ensuring good matching conditions The low value of the transit attenuation allows the insertion of a great number of cascaded taps to implement distribution networks with a high number of users 100 to 200 The high isolation level between the line output and
14. selected service The solution presented in clause A 1 of TS 101 964 1 which is based on the use of a 22 kHz bus is suitable for the case of small SMATV MATYV installations using d c coupled elements The solution presented in clause A 2 of TS 101 964 1 which is based on the use of an RF bus in a frequency range above 10 MHz provides the capability to pass through community installations using inductive components So this second solution potentially allows for a transparent introduction of the Control Channel in most existing SMATV MATYV systems The present document gives details on the technical parameters and guidelines for system implementation and provides an evaluation of the performance of the multiaccess schemes adopted for the 22 kHz bus and the RF Control Channel bus as well as a better knowledge of the features and possibilities offered by the Control Channel protocol FLEXIMATV Project IST 2000 28695 has been devoted to develop technological solutions based on the DVB control channel specification aiming at consolidating that European standard introducing any necessary enhancements and producing clear guidelines on the best practices for implementing DVB control channel systems These contributions have been included in the present document Consequently FLEXIMATV has been aimed at the consolidation of a mature standard supported and endorsed by the analysis and studies development of industrial solutions confirmation of su
15. 2 26 Physical Layer based on a 22 kHz bus Carrier frequency Bus load impedance R DC supply Bus load inductance LB Bus load capacitance CB Current source Source impedance Bit definition Timing base Bit length ng 1 22 kHz 20 1595 270 uH 5 470 nF typically gt 10 KQ 0 5 ms 0 1 ms 1 5 ms 1 0 ms burst 0 5 ms pause 0 5 ms burst 1 0 ms pause Physical Layer based on a RF bus Frequency Modulation Bit definition Bit length ng q Tx max power level STB Head end unit Rx min power level STB Head end unit f 10 7 MHz 7 kHz t b c or and fy 18 MHz 7 kHz t b c or and f 70 MHz 7 kHz t b c 2 FSK Af 67 kHz 1 kHz t b c 10 us 50 ns t b c fy Af fy Af 98 dB LV 75 Q 108 dB uV 75 Q 53 dB uV 75 Q 43 dB uV 75 Q ETSI ETSI TR 102 252 V1 1 1 2003 10 27 ETSI TR 102 252 V1 1 1 2003 10 The transmit power level may be ramped up during the 40 ms immediately prior to the start of the first message byte The 40 ms immediately following the end of the final message byte may be used to ramp down the transmit power level Care must be taken in the design of the baseband section of the FSK modem when using an NRZ coding scheme because of its non zero DC component The use of high pass baseband filters may distort the signal especially when a long sequence of 0 s or 1 s is transmitted The designer must be aw
16. ATYV installations with inductive directional taps sees sese sees 12 5 3 3 SMATV MATYV installations with d c coupled inductive taps esse ee eee eee 12 5 3 4 Multiswitches equipped SMATV installations 13 5 3 5 Intermediate amplification ris Rela da est Bi AE Ge ein Re ae nie 13 5 4 Performance of typical SMATV MATY installations in the Control Channel frequency range 13 6 Control Channel Protocol siioni ei e hile eats se Liane ides Get fin dete eS 15 6 1 IST TT 15 6 2 CRE decoding implementations s csnconaicseneren tied eeul ener Td tbe ere ahi eee tienes 16 6 3 Extension of the message TT 17 7 Control Channel BS assos ant mit NM en sn tr ct cde bac Zaz E RE EE Taza ete 17 7 1 Implementation of the 22 KHZ DUS sente nine es teteine EEE EEE EE Ee SEEE REEE ES ee 17 7 1 1 Example for a 22 kHz bus interface circuit seen 19 7 2 Implementation of the RF control channel bus ss 20 7 2 1 ACK and answer to command sisi 20 7 2 2 Control channel frequencies in networks with intermediate amplification 20 8 Performance evaluation of the multiaccess system 21 8 1 kHz Control Channel DUS eisisto eesse eserine esei ere scoussdeaaensbeasveussdeusse sess Ea etes ion I SEAP ERS ETTR 21 8 2 RE Control Channel Dhs ss aes ea seta ie ea eh ae eG ae iad 23 8 2 1 System description sine rte ee ha tt eA I ed tae he eh deed te era ede 23 8 2 2 TAT hypothesis sinistre eG he ee ee he eh i ee i eee en 23 8 2 3 Theoretical analysis ist ass Ae
17. ETSI TR 102 252 V1 1 1 2003 10 Technical Report Digital Video Broadcasting DVB Guidelines for implementation and use of the control channel for SMATV MATV distribution systems European Broadcasting Union Union Europ enne de Radio T l vision EBU UER Cy 2 ETSI TR 102 252 V1 1 1 2003 10 Reference DTR JTC DVB 152 Keywords broadcasting control digital DVB SMATV video ETSI 650 Route des Lucioles F 06921 Sophia Antipolis Cedex FRANCE Tel 33 4 92 94 42 00 Fax 33 4 93 65 47 16 Siret N 348 623 562 00017 NAF 742 C Association but non lucratif enregistr e la Sous Pr fecture de Grasse 06 N 7803 88 Important notice Individual copies of the present document can be downloaded from http www etsi org The present document may be made available in more than one electronic version or in print In any case of existing or perceived difference in contents between such versions the reference version is the Portable Document Format PDF In case of dispute the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat Users of the present document should be aware that the document may be subject to revision or change of status Information on the current status of this and other ETSI documents is available at http portal etsi org tb status status asp If you find errors in the present document send your comment to ed
18. Np defined as in the previous section where N is the number of users and Np is the number of transmissions per user per minute The message length is extended to 5 ms so the result must be considered as a worst case Below are the results of simulations carried out with a constant delay of 10 ms followed by a random delay which has a maximum of between 0 ms and 50 ms wait tub 0 01 0 0 05 o E D packet loss ratio x100 S P 0 2 0 L 1 L L L L L 1 L J 0 0 005 0 01 0 015 0 02 0 025 0 03 0 035 0 04 0 045 0 05 Figure 15a It can be seen that with a maximum random delay of 50 ms the collision probability has been reduced to around 0 2 as compared to 2 for a single transmission The retransmission strategy can provide a good level of performance even when a unidirectional approach is required due to network and or cost constraints However it must be noted that the lack of any information from the head end makes all of the extended CC functionality automatic installation monitoring unavailable 9 Receiver and Head end implementation aspects The implementation of the Physical Layer for both the STB and the Head end devices must cope with the technical characteristics given in annex A of TS 101 964 1 for the two Control Channel solutions i e Physical Layer based on a 22 kHz bus and Physical Layer based on a RF bus The main characteristics are reported in the following ETSI 9 1 9
19. are of this potential problem and take the appropriate precautions depending on the implementation ETSI 28 ETSI TR 102 252 V1 1 1 2003 10 Annex A Installation and operation routines A 1 Introduction The following procedures give a basic approach for installation of the Head End to Set Top Box connection through the use of the Control Channel These procedures can be generally applied to both cases i e use of the RF bus and of the 22 kHz bus The installation procedures are described through a flow chart summarising the main steps of the logical path Reference is made to the relevant commands described in clause 3 of the Control Channel Specification see TS 101 964 1 i e for automatic installation Installation_status_request Installation_status_reply Configuration Configuration_reply The PIN code is used to identify the couple Head End Device Slave and user terminal Master It is made of two bytes the MSB is an 8 bit Master Identifier MID and the LSB is an 8 bit Slave Identifier SID Use of these two bytes for installation purposes is described A 1 1 Network diagram The following figure shows a typical SMATV MATV network configuration where the Head End Devices HED and the user terminals STB are all connected to the same coaxial cable
20. as ACK Unless differently stated the HED answering time to a command should not be longer than 50 ms 7 2 2 Control channel frequencies in networks with intermediate amplification In conventional SMATV MATV systems broadcast services are delivered from the Head end to the user s terminal However the SMATV Control Channel requires a bi directional communication link to allow the information exchange also in the reverse direction from the user s terminal to the Head end In SMATV MATYV installations where intermediate amplifiers see clause 5 3 5 are not used a single frequency is used in both directions In SMATV MATYV installations where intermediate amplifiers are present the wide band intermediate amplifiers have to be replaced by new bi directional amplifying devices as shown in figure 12a in order to allow the propagation of the Control Channel signals Solution A uses low pass and high pass filters while solution B uses band pass and band stop filters In order to avoid positive feedback in the amplifiers it is necessary to use different frequencies for the forward and reverse Control Channel paths Moreover a high degree of isolation between the two branches has to be guaranteed The choice of frequencies suggested in table 5 fulfils these requirements and allows the filtering of the forward Control Channel signal together with the broadcast channels If the filters have low insertion losses less than 1dB and the network i
21. atibility with the single master mode All controller outputs for switching purposes are assumed as open collector ports values of R3 and R4 depend on the output currents of the controller applied At the STB side L1 C1 and R1 are switched off by T1 and T2 in the case of 22 kHz multimaster bus application The DiSEqC transmitter with T4 is the current source with the external pull up impedance bus impedance of 15 Q The DiSEqC transmitter driver R4 R8 R9 T4 and receiver amplifier C2 R6 R7 R9 D1 T3 circuits are already described in the existing DiSEqC bus specification 4 2 2 and additional manufacturer recommendations made by Eutelsat In the single master DiSEqC mode R1 L1 and C1 are switched on the bus impedance of 15 Q is now realized in the STB with additional power supply capability coil L1 for external LNB or multiswitch ETSI 20 ETSI TR 102 252 V1 1 1 2003 10 At the Head end side L1 R1 and C1 are always switched on because the bus impedance is represented by these two elements Generally in the case of extension it may be possible to cascade several identical Head end components In this case only one Head end component is allowed to switch on the bus termination L1 R1 and C1 in order to avoid bus mismatch see also figure 12 An enhancement MOSFET transistor S1940DY in this example for the switch T1 is suitable for this application especially for the case of high d c current supplying external componen
22. bytes which carry the access parameters timing data which is used after the installation N ff ff two bytes which carry the allocated user frequency in Binary Coded Decimal BCD ETSI 37 ETSI TR 102 252 V1 1 1 2003 10 B 6 Headend_Call_ Out_of_Standby_reply This command is used in response to the SMATV_Headend_Call_Out_of_Standby command from the master device when it is switched on by the user i e comes out of standby mode The Head end updates the access parameters and allocates a new user frequency Syntax No of bits Content Headend_Call_Out_of_Standby_reply DiSEqC_framing 8 E4 DiSEqC_Master_Identifier required 8 nn DiSEqC_timing data 16 tttt DiSEqC_user_frequency 16 uuuu B 7 General Call for STB s This command will be used for service purposes e g maintenance By this command the installer can stimulate every STB in the network from a central point for example with a special measurement tool measurement receiver This measurement tool is connected to the 22 kHz bus in the same way as the STB s or the Head end B 8 Service Commande for the Head end For these commands the commands can be used which are already defined for the new DiSEqC bus specification B 9 Head end installation tuning etc procedure Dedicated DiSEqC commands for low cost QPSK QPSK SMATV head ends using the low data rate communication have been introduced Commands data bytes for other kinds of head ends f
23. ctive tap For signal distribution in the network d c coupled splitters are preferred because the realisation is quite simple in P Bas Out 1 Out 2 Figure 6 d c coupled splitter ETSI 13 ETSI TR 102 252 V1 1 1 2003 10 5 3 4 Multiswitches equipped SMATV installations Two main types of multiswitch components are used for these installations with and without built in 5 MHz 65 MHz return path Some of the multiswitches available on the market can be controlled by means of DiSEqC commands 2 at 22 kHz some only by means of 13 18 V d c levels polarisation selection and 0 22 kHz tones band selection The LNB is fed with a d c by the multiswitch if at least one of the user terminals supplies it to the multiswitch The cable carrying the terrestrial channels is not affected by the DiSEqC commands sent by the user terminals 5 3 5 Intermediate amplification In the majority of the SMATV MATYV installations the active devices are located in the Head end and the distribution network only contains passive devices However in some cases in order to meet the signal level requirements at the user s terminals intermediate amplification may be used according to the following topologies N Large installations may require intermediate wide band amplification in this case the amplifier is located after the branching points of the distribution network in order to serve different sections in the building as shown in figure 6a N
24. d time interval T assuming a great number of messages sent from the user devices as for the case of zapping after the end of a trigger event e g a football match The protocol is assumed without access control i e it is based on Aloha without retransmission The analysed time intervals are T 1 min and T 5 min Two cases with different numbers of user terminals are considered N 10 and N 40 and the number of messages Np transmitted by each terminal is 10 in 1 minute or 30 in 5 minutes Parameters of the system are N User number N Message duration T e Incoming flux A in messages per second Np 60 e Traffic G TA 8 2 3 Theoretical analysis As no retransmission is allowed global traffic is the same as for the basic user terminal G At The following formulae apply Global traffic G At with A NpN T N Throughput S Ge 2G N Collision probability pe 1 e2G The system performance has been evaluated in two configurations 1 Collision probability as function of message duration T in four different situations see figure 14 a T 1 min Np 10 N 10 b T 1 min Np 10 N 40 c T 5 min Np 30 N 40 d T 5 min Np 30 N 10 ETSI 24 ETSI TR 102 252 V1 1 1 2003 10 Collision versus message duration N N a O a oO a gt 2 6 c 2 2 O 3 85 4 5 7 5 10 15 20 Message duration ms Figure 14 From this figure it is clear that the w
25. ding used for remote controlling the Head end of the SMATV MATV distribution system The specification covers both the approaches adopted for the delivery of satellite signals as identified in EN 300 473 3 i e transmodulation from QPSK to QAM System A and direct distribution in QPSK after frequency conversion System B as well as the remote control of other head end devices for broadcast services The specification also takes into account the requirements from EN 301 790 4 in order to achieve the best commonality and ensure the minimum functionality required for operating via the SMATV systems the satellite interactive terminals Although primarily focused on SMATV systems for delivery of satellite DVB services the Control Channel shall also be applicable to MATV systems currently used for terrestrial broadcasting services via VHF UHF and microwave The Physical layers of the Control Channel system described in clauses A 1 and A 2 of TS 101 964 1 allow for a general use of the Control Channel in the whole range of SMATV MATYV distribution systems having different topologies and characteristics The transmission protocol providing the communication link between the user s terminal and the head end device makes use of the same commands and coding for both physical layers Furthermore since the Control Channel capacity is shared among all the user terminals a multiaccess approach is adopted in order to guarantee adequate access time to the
26. e FSK and RS485 buses ETSI 43 ETSI TR 102 252 V1 1 1 2003 10 Table D 3 Timing definitions for messages on the FSK and RS485 buses Message length on FSK bus lt 3ms t2__ Message length on RS485 bus lt 20 ms t3__ Delay between reception of FSK message and transmission on RS485 bus lt 10 ms t4 Timeout for response from HED gt 30 ms lt 50 ms t5 Delay between reception of R8485 message and transmission on FSK bus lt 10 ms ETSI 44 ETSI TR 102 252 V1 1 1 2003 10 Annex E informative Bibliography DVB CM 216 DVB TM 2342 Commercial Requirements for the addition of a Control Channel to the SMATV MATYV distribution system ETSI 45 ETSI TR 102 252 V1 1 1 2003 10 History Document history ETSI
27. e of the communication protocol one or two way and reply mechanism required The user terminal is called Master and the corresponding device at the Head end is called Slave Details are given in table 1 of TS 101 964 1 The ADDRESS byte used to identify the different device types for the Head end units slave See table 2 of TS 101 964 1 The COMMAND bytes are specified in table 3 above The DATA bytes carry the encoded information relevant to the specific command or answer and are described in clause 3 of 1 The control channel message excluding the RUN IN bytes is protected against transmission errors by CRC Cyclic Redundancy Check whose field is 2 bytes long and is based on the following polynomial generator CRC X64 X12 X 4 X59 4X41 The maximum length of the message is 32 bytes excluding RUN IN and CRC Messages longer than 32 bytes are fragmented into blocks of 32 bytes each using the Message Fragmentation command If the message length is less than 32 bytes the CRC will be calculated as if the missing bytes were all set to 0x00 6 2 CRC decoding implementation The Cyclic Redundancy Check CRC field is 2 bytes long The 16 bit CRC decoder operates at bit level of 16 delay elements z i The input of the CRC decoder is xor added to the output of z 15 and the result is provided to the input Z 0 and to one of the inputs of each remaining xor adder The other input of each remaining xor adder is the output of Z
28. ends a message to the selected HED indicating the next available MID and SID and other relevant parameters frequency modulation Symbol rate FEC constellation etc if needed 0 indicates no value The interrogated HED configures on the valid parameters received and through the Configuration Reply command sends to the STB the assigned MID and SID all the HED output settings frequency modulation Symbol rate FEC constellation etc as set by the installer or proposed by STB In case of not compatible parameter value or 0 sent by the STB the HED answers with the old settings 6 If no conflict data is detected by the STB the installation process for the selected HED is completed and the couple STB HED is identified Another HED can be installed starting from point 5 The sequential steps 1 to 7 described above describe the complete installation procedure allowing the STB to access the wanted service Transport Stream through suitable commands ETSI Select another HED 31 ETSI TR 102 252 V1 1 1 2003 10 Preset Verify Control Channel compatibility Set Control Channel frequency RF bus Assign installation SID Set RF channel central frequency Searching for available HEDs Polling for any Address and SID from 0x00 to 0x07 Installation Status Request from STB Installation Status Reply from HED Searching for already allocated HEDs Polling for any Address and SID from 0x08 Installation Status Reque
29. from the Head end to the specific user taking into account the RF constraints on the cable network e g existing analogue channels existing HEDs etc The pre set of this parameter may be done at the HED 3 Manually assign to the HEDs for any Address all the information relevant to the network configuration MIDs and SIDs used etc The choice of the SIDs has to be made in the range 0x80 to OxFF see table A 2 Use of SID byte as shown in table A 3 SID value These SID value are calculated using the following formula as described in DE09 1 MID see note 1 SID INT 1016 Fout 8 128 see note 2 for OFDM QAM QPSK QAM 2 MID see note 3 SID INT 4016 Fout 32 128 see note 4 for QPSK QPSK NOTE 1 Having assumed that MID SID for simplicity NOTE 2 MSB of the SID byte always set to 1 NOTE 3 Having assumed that MID SID for simplicity NOTE 4 MSB of the SID byte always set to 1 Table A 3 SID value for QAM SID Value RF centre frequency MHz 226 fic 234 225 Tau 242 224 f3c 250 198 fogc 450 197 fogc 458 196 Tanez 466 Add a similar table for IF IF ETSI 33 ETSI TR 102 252 V1 1 1 2003 10 A 2 3 Installation Routine 1 The installer selects the manual option by using OSD of the IRD see User Manual 2 He selects the family type of TDT to be install and sets the input frequency according to the formulas 1 and 2 At the end of the process described in poin
30. have been corrupted No extended commands are included because none of the commands require a message length longer than the maximum 32 bytes Framing byte function Value Command from master OxE0 No reply required first transmission Command from master OxE1 No reply required repeated transmission Command from master OxE2 Reply required first transmission Command from master OxE3 Reply required second transmission OK reply from slave OxE4 No errors detected Error reply from slave repeat of message is not required OxE5 Command not executable by slave not supported C 2 Commands Command Command byte hex Reset 0x00 Stand by 0x02 Tuning 0x73 Installation status request 0x74 Configuration 0x78 Resource enquiry Ox7A ETSI 40 ETSI TR 102 252 V1 1 1 2003 10 Annex D Common bus implementation D 1 Introduction The control channel needs to address a head end with different devices These devices need a common bus to receive the commands from the control channel and answer its requests This annex describes the physical layer except the connector message structure and bus protocol D 2 Physical layer The common bus is based on the RS485 standard It is a point to multipoint half duplex communication via a two wire interface The structure of the bus is shown in the diagram below along with the electrical specifications of the bus Head End
31. he Head end device are equipped with a suitable Control Channel interface implementing physical layer and protocol management This interface at the STB is implemented using a modem which receives the commands from the STB and sends them to the head end The user s head end device then selects the appropriate service DVB TS The decision of whether to include the modem in the STB is up to the STB manufacturer and therefore outside the scope of these guidelines ETSI 9 ETSI TR 102 252 V1 1 1 2003 10 The Control Channel Interface at the head end can be implemented in two different ways N Embedding the modem in the head end devices Adding a new device Head End Control Device HeCD which receives the commands coming from every STB in the network and sends them to the appropriate associated devices which are linked to the HeCD by means of the local bus Both solutions are compatible and can be used simultaneously 5 Configurations of SMATV MATV distribution systems The present document considers the introduction of the Control Channel solution in the two SMATV satellite distribution systems A and B identified by DVB EN 300 473 3 as well in MATV terrestrial installations The basic architecture is shown in figure 2 Three main functional blocks are identified parabolic or and terrestrial antenna s head end in building cable network 4 Te QPSK QAM Head End Unit Trans
32. her at the HED or by the STB ETSI 30 ETSI TR 102 252 V1 1 1 2003 10 A 1 4 3 Installation Routine 1 2 3 The STB through the Installation Status Request command interrogates the Head End unit to detect new HEDs polling trough each address type 0x71 to 0x74 with SID starting from 0x00 to 0x07 In this case the STB uses the MID 0x00 The HED through the Installation Status Reply command answers the STB indicating channel frequency 0 if none other settings The STB through the Installation Status Request command interrogates the Head End unit to detect already allocated HEDs polling trough each address type 0x71 to 0x74 with SID starting from 0x08 The SID is incremented every time an answer is received and the relevant information stored When there is no answer a new address type is set and the searching process is re initialized The STB uses the MID 0x00 The HED through the Installation Status Reply command answers the STB indicating allocated MID by other STBs 0 if none allocated frequency 0 if none At the end of the process described in points 1 to 4 the STB knows 4 5 which type of HED it will be connected to the next available SID in any address type all the used MIDs in the network associated to HEDs having answer capability the settings of all HEDs the RF channels used by installed HEDs having answer capability The STB through the Configuration command s
33. itable performances through appropriate tests in laboratory and in real installations ETSI 2 7 ETSI TR 102 252 V1 1 1 2003 10 References For the purposes of this Technical Report TR the following references apply 3 ETSITS 101 964 Digital Video Broadcasting DVB Control Channel for SMATV MATV distribution systems Baseline Specification Eutelsat DiSEqC Bus Functional Specification version 4 2 February 25 1998 ETSI EN 300 473 Digital Video Broadcasting DVB Satellite Master Antenna Television SMATYV distribution systems ETSI EN 301 790 Digital Video Broadcasting DVB Interaction channel for satellite distribution systems IEC 60728 1 Cabled distribution system for sound and television signals Part 1 Methods of measurement and system performance ETSI EN 300 421 Digital Video Broadcasting DVB Framing structure channel coding and modulation for 11 12 GHz satellite services ETSI EN 300 429 Digital Video Broadcasting DVB Framing structure channel coding and modulation for cable systems ETSI EN 300 744 Digital Video Broadcasting DVB Framing structure channel coding and modulation for digital terrestrial television Abbreviations For the purposes of the present document the following abbreviations apply ACK CRC DC DiSEqC DVB TS FDMA FEC FSK HE HeCD HED HP IDU IF LNB LP MATV MID MMI ODU OFDM PIN PWK QAM QPSK RF SID SMATV STB TDMA
34. itor etsi org Copyright Notification No part may be reproduced except as authorized by written permission The copyright and the foregoing restriction extend to reproduction in all media European Telecommunications Standards Institute 2003 European Broadcasting Union 2003 All rights reserved DECT PLUGTESTS and UMTS are Trade Marks of ETSI registered for the benefit of its Members TIPHON and the TIPHON logo are Trade Marks currently being registered by ETSI for the benefit of its Members 3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners ETSI 3 ETSI TR 102 252 V1 1 1 2003 10 Contents Intellectual Property Rights s su rene ent Manet tee cael toh Rene een Ed 5 FOWO ren Inn te te de NY eae E no te Te Ont ln adn st ls 5 1 L0 o E Mn alt nt ad ead E A AL RAT case A D sl SAd ss 6 2 References NS nn ER enr AS cule eG te A A E iets Nes 7 3 ADbIeVIatlons states tete nn ETENEE E E nt t ant sin nn liens devin wie entre 7 4 Reference models wh ia Sa stew ele eae Rad hae dain te EE ERS 8 5 Configurations of SMATV MATY distribution systems 9 5 1 Current SMATV MATY implementation eee Za Tessa ss 9 5 2 SMATV MATV implementation based on the control channel 10 5 3 Typical SMATV MATV topologies ste cy ZSS oren ZTE RRR TR EREEREER OADET att 11 5 3 1 SMATV MATY installations with resistive taps 11 5 3 2 SMATV M
35. l allows each single user of the building to autonomously decide on the possibility of receiving digital broadcasting services through the community installation without the need of authorisation from the other users So the user connected via the in building cable network can access the broadcast services satellite and terrestrial as in the case of individual reception The Control Channel protocol is based on DiSEqC 2 to maintain compatibility with existing products and has the further advantage of being sufficiently flexible to allow for future extensions if and when needed The structure of the Control Channel message ensures a robust transmission mechanism SMATV MATYV distribution systems as described in EN 300 473 3 represent a solution widely adopted for in building delivery of DVB signals both satellite and terrestrial through collective installations The adoption of the Control Channel specification which has been defined in accordance with the commercial requirements given in DVB TM 2342 see bibliography offers an alternative cost effective solution to the current implementation of SMATV MATV systems especially for the case of small and medium size installations allowing the delivery of DVB TSs multiplexes without the constraints of the limited bandwidth available in the installation The technical specification of the Control Channel system see TS 101 964 1 describes the message structure and the set of commands and co
36. modulators QPSK QPSK Frequency Converters a Line Splitter ae User Tap Cable distribution network p DO DO HO OO OO OO O ter OO DO O 4 OO OO Goes Figure 2 Typical architecture of in building SMATV MATV distribution systems 5 1 Current SMATV MATV implementation The distribution of satellite digital signals via SMATV systems is currently carried out adopting the two basic approaches identified by DVB EN 300 473 3 1 SMATV System A This approach consists of the transmodulation at the Head end from satellite Quaternary Phase Shift Keying QPSK signals as defined in EN 300 421 6 to a Quadrature Amplitude Modulation QAM scheme 2 SMATV System B This approach consists of distribution of QPSK satellite signals as defined in EN 300 421 6 after frequency conversion of the received satellite signal into a frequency band appropriate to the characteristics of the distribution network e g satellite 1st IF and or extended S band The use of the System A or System B approaches depends on the technical performance and cost trade offs required in each particular situation ETSI 10 ETSI TR 102 252 V1 1 1 2003 10 Figure 3 shows a possible channel allocation for the delivery of DVB services and terrestrial TV through in building cable distribution networks based on the following approach e For SMATV System A use of the available frequency channels e g 7 MHz 8 MHz in existing in building cable sy
37. more in case the number of users in the building willing to access the new services is limited e g in small and medium size installations the implementation cost can not be equally shared among the total number of users with significant penalty for those interested The adoption of the Control Channel solution allows each single user of the building to autonomously decide on the possibility of receiving digital broadcasting services through the community installation without the other users authorisation In addition it allows the delivery of DVB TSs multiplexes without the constraints of the limited bandwidth available in the single cable installations For the case of satellite reception with reference to figure 3 in the Control Channel solution the frequency resources of the extended S band 230 MHz 470 MHz and or of the 18 IF band 950 MHz 2 150 MHz can be exploited for the delivery to the individual users on a single cable of all the DVB TSs multiplexes provided by the satellite transponders made available at the Head end up to 30 user terminals for each frequency range ETSI 11 ETSI TR 102 252 V1 1 1 2003 10 5 3 Typical SMATV MATV topologies The Control Channel baseline specification adopts two Physical Layers see clauses A 1 and A 2 of TS 101 964 1 in order to cover the whole range of SMATV MATYV distribution systems having different topologies and characteristics i e available frequency bandwidth type of ne
38. nals STB of the network must be identified by a different MID Table A 2 reports the range of the SID byte used to control identify the HEDs Table A 2 Use of the SID byte SID range Use 0x00 0x07 Installation phase 0x08 0x7F Automatically installed 0x80 0xFF Not capable of automatic installation A 1 3 Assumptions As some information is not automatically available at the beginning of the installation phase e g frequency band not occupied by the broadcast channels on the cable network the installer must provide the required information manually This information may be given to the HED or to the STB via adequate Man Machine Interface MMI A 1 4 Installation operation A 1 4 1 Automatic Installation A 1 4 2 Pre setting The installer shall 1 Verify the compatibility of the Control Channel physical layer adopted 22 kHz bus or RF bus on the network with the HEDs to be installed 2 Inthe case of the RF bus set the centre frequency of the Control Channel 3 Assign to the HEDs for any Address different SIDs in the range 0x00 to 0x07 4 Set the value of the centre frequency of the RF channel e g 8 MHz if address 0x71 0x72 or 0x74 40 MHz if address 0x73 allocated to the delivery of the DVB signals from the Head End to the specific user taking into account the RF constraints on the cable network e g existing analogue channels existing HEDs etc The pre set of this parameter may be done eit
39. oe het a teed etek te aed ed eR oe eel eee ee ee tape ee 23 8 2 4 Collision scenario for repeated transmissions 25 9 Receiver and Head end implementation aspects 25 9 1 Physical Layer Based ona 22 KHZ US entente nn E AE den rer E diet situ 26 9 2 Physical Layer Based ona RE DUS rss sn SR nn tn en NE 26 Annex A Installation and operation routines scccsscssssscssssccsssccssssssssccssssscssssessesssssssscsssssssssssssessseses 28 Ack Introduction ess Rss a CRE a sted A Rd ts nn A eee chee hh EA RE 28 A 1 1 Network dia gram seereis ani mere ire EA EE A EE EEr EE EEE EE EEEE cheeses 28 A 1 2 PIN codeallocatio Me neee eiei AE E ET AEA AEA DARE aes eee 29 A 1 3 ASSUMPTIONS si ee e e a e O i E o E E EEE OT EE EEEE EED S EEEE 29 A 1 4 Installation op rations dessein hotte mien tte a E A men tn ROT E E E E tite lists 29 A 1 4 1 Automatic Installation essieu sieste EOS TET et EE etant rss nette en en une etes 29 A 1 4 2 Pre s ttin t sienne dise E eh Sauk ane cn Hitler ge tent ere Maa E ehhh as tee en tte arenes 29 A 1 4 3 Installation ROUNE setes sers t 552 KZ a Era sees rE TORT sen ele ns est RATRE STEK cna 30 A2 Operations re ennemie ne ee woh eee tee veto tatu see eed eats na te 200 32 A 2 1 Manual Installation ire an Rs RIRE MERE ER RER NI Rat O RME NU Mt hasten oy 32 A 2 2 PHE SELEMING ss x ee cacy sonne rabat S aa en nr des Nr A nr ne RE el ardro 32 A 2 3 Installation ROUNE saien eee nn nent anne ruse ne EESE ES 33 ETSI 4
40. on of two independent logical channels to each user terminal N Broadcast Channel a unidirectional broadband delivery channel for video audio and data services N Control Channel a bi directional narrow band channel established between the head end device and the user s terminal for control and signalling purposes This logical functionality is performed by allocating to each user terminal STB an individual RF channel on the in building cable network for the delivery of the DVB services Each service DVB Transport Stream is remotely selected by the user s terminal controlling the head end device installed in the building e g QPSK QAM transmodulator QPSK QPSK frequency converter via a suitable set of commands provided by the Control Channel which is unique for all the users of the network All the equipment which are operated via the Control Channel i e the head end devices and the user s terminals are connected through the same coaxial SMATV MATYV installation The RF channel can make use of any available frequency slots within the in building cable network in the frequency range between about 30 MHz and 2150 MHz in accordance with IEC 60728 1 5 The bandwidth of the RF channel depends on the characteristics of the delivery solution i e typically 33 MHz in case of QPSK satellite signals 7 MHz or 8 MHz in case of QAM satellite and OFDM terrestrial signals In order to provide remote control of the Head end both the user terminal and t
41. or example QPSK QAM Converter may be possible The DiSEqC bus is defined as a single master bus but by following the multiaccess scheme reported in the Baseline Specification it is possible for multiple masters e g set top boxes to co exist on the same bus cable however any slaves including the Head end can only respond as slaves i e they are NOT allowed to initiate a message they can only reply to a message from a master which is by definition ignored by all other masters It must be understood that all slaves will respond to any master command and it is not foreseen to co ordinate the allocation of individual addresses to slaves as described in the existing DiSEqC specification with more than one master This multiaccess scheme is primarily intended for the SMATV environment where all the masters are effectively talking to an intelligent slave the head end In this case in order to allow one one communication between an individual master STB and the intelligent head end slave some new DiSEqC commands are required and in particular the allocation by the Head end of a unique Identifier ID to each master device This Master ID MID once allocated is stored in both the Master and the Head end to allow specific request and actions to be performed by the Head end The flow diagram reported below shows an example of the procedure adopted for performing some typical functions Installation Tuning etc ETSI 38 ETSI TR 102 252
42. orst case is T 1 min Np 10 N 40 this is considered in more detail below 2 Collision probability as function of number of user terminals in four different situations see figure 15 a T 1ms Np 10 T 1 min b t 2 5 ms Np 10 T 1 min c T 5ms Np 10 T 1 min d t 10 ms Np 10 T 1 min Collision versus number of user terminals Time Interval T 1 min Nr of transmitted messages per terminal Np 10 pe Oo Message duration O1 1 e 1ms a 2 5 ms b amp z 5ms c X 10 ms d Collision probability 1 2 5 7 10 15 20 25 30 35 40 50 Number of user terminals Figure 15 The results achieved by computer simulations are in good accordance with the theoretical evaluations Given the maximum message length of 32 bytes at 100 kbit s which corresponds to the maximum message duration around 2 5 ms the results above indicate an acceptable performance about 97 probability of success up to around 40 user terminals ETSI 25 ETSI TR 102 252 V1 1 1 2003 10 8 2 4 Collision scenario for repeated transmissions In order to reduce the collision probability a retransmission strategy can be adopted This analysis assumes a retransmission strategy that consists of sending a new packet with the same information after a time t with an added random delay that has a maximum value of tp The basic traffic analysis is N 10 and N 6 with N and
43. qC Commands allowing compatibility with existing systems B 1 SMATV_ Installation This command is used when an STB is installed for the first time in the SMATV network The slave Head end reply is SMATV_Installation_Reply as defined in the following Syntax No of bits Content SMATV_Installation DiSEqC_framing 8 OxE2 DiSEqC_address 8 0x73 DiSEqC_command 8 Ox5A B 2 Headend Call Out of Standby This command is sent when an existing STB is brought out of standby mode by the user The slave Head end reply is Headend_Call_Out_of_Standby_ reply as defined in the following Syntax No of bits Content Headend_Call_Out_of_StandbyQ DiSEqC_framing 8 OxE2 DiSEqC_address 8 0x73 DiSEqC_command 8 0x5B DiSEqC_Master_Identifier 8 nn Where N nn One byte to indicate the value for the Master Identifier stored in the STB s memory B 3 Headend Tuning Parameters This command is used when the user changes the programme on the STB Zaps and the tuning parameters at the head end need to be changed i e when the required programme is not in the same DVB transport stream Syntax No of bits Content Headend_Tuning_Parameters DiSEqC_framing 8 OxEO or OxE2 DiSEqC_address 8 0x73 DiSEqC_command 8 0x5C DiSEqC_Master_Identifier 8 nn DiSEqC_data byte 8 pp DiSEqC_data bytes 16 ff ETSI 36 ETSI TR 102 252 V1 1 1 2003 10 Where N pp One data byte which carries
44. rmat NEXT START BIT Figure D 3 Control channel FSK and common bus RS485 message structure Table D 2 Sequence definition RUN IN 0x55550D END OF MESSAGE EOM 0x55550D START BIT 0 STOP BIT 1 D 4 Bus protocol The bus master is the Head End Control Device HeCD To avoid collisions the HeCD must wait for a response from the Head End Device HED after it has transmitted a message if required by the message Framing byte during which time it cannot send any other message The HED must respond within a defined timeout period after which the HeCD will continue to transmit on the bus The protocol is described in figure C 4 ETSI 42 ETSI TR 102 252 V1 1 1 2003 10 Wait for new message on FSK bus Transmit message on FSK bus Generate and add CRC Format message for transmission on RS485 bus Format message for transmission on PSK bus Transmit message on RS485 bus Does message require a response check framing byte Listen for message on RS485 bus Figure D 4 Flow chart of RS485 common bus protocol The timing of messages on the FSK and RS 485 buses is shown in the following figure for messages that do and do not require an acknowledge from the HED With these timings the maximum delay between the HeCD receiving a message form the FSK bus and the same HeCD sending the response on the FSK bus is 100 ms FSK Without acknowledge 3 D t4 Figure D 5 Timing of messages on th
45. s properly designed no other adjustments are required The amplifier for the Control Channel in the reverse direction see figure 12a may not be necessary because of the lower attenuation of the cables in the Control Channel frequency ranges ETSI 21 ETSI TR 102 252 V1 1 1 2003 10 x 2 A K ae N De A B Figure 12a Structure of the bi directional amplifiers Table 3 Frequencies for the Control Channel in networks with intermediate amplification Direction Frequency Forward from Head end to user terminal 70 MHz Reverse from user terminal to Head end 10 7 MHz or 18 MHz depending on network characteristics Table y gives some indications of the characteristics required for the amplifiers Table 3b Characteristics of the intermediate amplifiers RF bus of the Control Channel Maximum output level Control Channel signal upwards 98 dB uV downwards 108 dB uV 8 Performance evaluation of the multiaccess system In all in building cable installations the Control Channel functions are performed on a single communication path whose transmission capability is shared among the user terminals via a multiaccess system which has been specifically designed for the two physical layers i e 22 kHz bus and RF bus Both systems should provide reduced access time to the wanted DVB channel TS for all the terminals connected to the cable network The performance of both solutions are evaluated in clauses 8 1
46. ssional association of broadcasting organizations whose work includes the co ordination of its members activities in the technical legal programme making and programme exchange domains The EBU has active members in about 60 countries in the European broadcasting area its headquarters is in Geneva European Broadcasting Union CH 1218 GRAND SACONNEX Geneva Switzerland Tel 41 22717 21 11 Fax 41 22717 2481 Founded in September 1993 the DVB Project is a market led consortium of public and private sector organizations in the television industry Its aim is to establish the framework for the introduction of MPEG 2 based digital television services Now comprising over 200 organizations from more than 25 countries around the world DVB fosters market led systems which meet the real needs and economic circumstances of the consumer electronics and the broadcast industry ETSI 6 ETSI TR 102 252 V1 1 1 2003 10 1 Scope The present document provides the first guidance to manufacturers network operators and service providers on equipment design for the use of the Control Channel for SMATV MATV systems whose baseline specification is given in TS 101 964 1 The Control Channel for SMATV MATYV distribution systems is intended to provide remote control of the head end device from the user s terminal through a set of commands in a closed in building environment for the delivery of broadcast services Furthermore the Control Channe
47. st from STB Installation Status Reply from HED Configuration of the selected HED STB sends parameters to HED MID SID etc Configuration from STB Confirmation of HED configuration HED sends its configuration parameters to STB MID SID etc Configuration Reply from HED Is HED answer OK NO YES Other HED to be configured YES NO Installation completed Figure A 1 ETSI 32 ETSI TR 102 252 V1 1 1 2003 10 A 2 Operation During normal operation the STB will use the tuning command to control the HED In order to avoid any potential confusion with multiple masters accessing the Control Channel bus and to avoid any contention schemes other than a random back off the command and reply if required will use the address and pin_code to fully identify the slave and master However it is probably better NOT to request a reply to minimize bus activity and let the STB monitor the lock of its own tuner if there is no change within a given time out it can repeat the tuning request automatically until the tuner detects a change A 2 1 Manual Installation A 2 2 Pre setting The installershall 1 Verify the compatibility of the Control Channel physical layer adopted 22 kHz bus or RF bus on the network with the HEDs to be installed 2 Set the value of the centre frequency of the RF channel e g 8 MHz if address 0x71 0x72 or 0x74 40 MHz if address 0x73 allocated to the delivery of the DVB signals
48. stems in the frequency range between about 30 MHz and 862 MHz e For SMATV System B use of the 15 IF 950 MHz 2 150 MHz in new in building cable systems for the delivery of up to 30 DVB S channels in QPSK 33 MHz channel need to rebuild the existing in building system using network components suitable for high frequency operation taps cable outlets etc potential use of the extended S band in existing installations allowing the delivery of up to 6 DVB S channels e For Terrestrial analogue and DVB T signals use of the VHF UHF bands TERRESTRIAL SATELLITE TERRESTRIAL SATELLITE CHANNELS CHANNELS CHANNELS CHANNELS VHF UHF band I band III extended bands IV V satellite 1 IF superband 47 68 174 230 470 862 950 2 150 f MHz Figure 3 Possible channel allocation for the delivery of DVB services in SMATV MATV installations 5 2 SMATV MATV implementation based on the control channel In both SMATV Systems A and B the number of devices at the Head end unit frequency converters and transmodulators is proportional to the number of satellite channels multiplexes i e DVB Transport Streams It means that the delivery of each DVB TS requires the allocation of a corresponding RF channel on the cable with the penalty of the need of increased bandwidth availability when new services TSs are delivered through the network and with the constraints on the maximum number of services which can be delivered via a single cable network Further
49. table 3 taken from TS 101 964 1 Provision for further extension is made if needed Table 3 List of the SMATV MATV Control Channel Commands Command Command Byte Direction hex STB lt gt Head End device Reset 0x00 gt Stand by 0x02 gt reserved 0x70 0x72 Tuning 0x73 gt Installation Status Request 0x74 gt reserved 0x75 0x77 Configuration 0x78 gt Maintenance 0x79 gt Resource Inquiry 0x7A gt reserved 0x7B 0x7E Message Fragmentation 0x7F Command Reply ACK lt Installation Status Reply lt Configuration Reply lt Maintenance Reply lt Resource Reply lt The commands in the range 0x01 and 0x03 to Ox6F which are standard DiSEqC commands and are used in solutions adopting the 22 kHz bus are not reported in table 3 for sake of simplicity and can be found in 2 and annex B of the present document These commands may also be used with the RF bus The structure of the Control Channel messages is shown in figure 9 Figure 9 Message structure The Most Significant Bits and Most Significant Bytes are always transmitted first The RUN IN bytes are used to provide a reliable reception of messages with large variation in signal level The value of this 3 byte field is 55 55 OD hex notation ETSI 16 ETSI TR 102 252 V1 1 1 2003 10 The FRAMING byte is used to define the natur
50. th a d c bias offset equivalent to about 100 mV applied to the input of the amplifier comparator Hysteresis if symmetrical can maintain a reasonably constant 50 duty cycle for the detected carrier tone whilst the d c offset method may generate a less desirable asymmetric pulse waveform when the carrier amplitude approaches the lower limit All devices are connected in parallel on the bus and therefore shall have a high impedance 3mA i RITES Bias Voltage gt 10 V gt 10 000 Q thd Lz 270uH yess ib Cs 470 nF i i i typicall Oi R t b d os Headend 3 mA gt 10 000 Q lt tbd Uno R t b d STB Figure 11 Principle of the 22 kHz bus ETSI 19 ETSI TR 102 252 V1 1 1 2003 10 7 1 1 Example for a 22 kHz bus interface circuit C1 470 nF 18 V Supply i Switch LNB power on off STB Pullup on off Headend 7 30 V R2 147 kQ 5v Controller R3 t b d Out Port N ve T2 R8 147 Q 5V T4 Controller Out Port DiSEqC R7 147kQ gt a R9 82 Q R6 2 kQ Controller In Port DiSEqC T3 lt R10 10kQ C2 2 2 nF Figure 12 Implementation example for a 22 kHz bus interface An example of a 22 kHz bus interface circuit as shown in figure 12 implementing the multiaccess system may be applied to both the STB and the Head end unit This implementation provides also downward comp
51. the Head end based on a 22 kHz in order to maintain backward compatibility with existing DiSEqC processors typically 8 bit microprocessors it is not possible to have more than 8 bytes of continuous code without the risk of potentially crashing existing devices Therefore to allow for the transmission of much longer messages these will be subdivided into blocks of 8 bytes Between each block there must be a short pause of 5 ms to allow existing microprocessors and systems with small hardware buffers to process each block without a data overflow The structure of the first block will always be a standard DiSEqC message which has a framing address and command byte and does NOT contain any of the subsequent data which is to be error protected e g CRC verified This block will identify that the subsequent blocks are mostly data and will have a different structure namely the first byte will be a block identifier which increments in each block and the last byte will again be reserved for error protection The framing byte OxE0 E2 of the first block defines whether a reply is required to THIS initial block before the data is transmitted Also within the first block it will be possible to define if replies are required to all subsequent blocks and or just the final one as well as the how many blocks there are in total An advantage of the optional reply here is that the slave can be given some time to prepare itself for the main data processing task
52. the band polarity position and option status identical to the DiSEqC write port data byte that follows command 0x38 committed switches N ff ff two bytes which carry the required satellite frequency in Binary Coded Decimal BCD as per the DiSEqC data bytes that follow the write channel frequency command 0x58 B 4 Master Switch to Standby This command is used when the STB is switched to standby to indicate to the head end that the allocated users frequency in the network is no longer required and is released for other another user Syntax No of bits Content Master_Switch_to_Standby DiSEqC_framing 8 OxE2 DiSEqC_address 8 0x73 DiSEqC_command 8 Ox5D DiSEqC_Master_Identifier 8 nn NOTE STB must wait for the acknowledgement from the Head end 0xE4 BEFORE it switches to standby in case the message was lost and needs to be repeated B 5 SMATV_Installation_reply This command is used in response to the DiSEqC_SMATV_Installation command from the master device when it is first installed on the network the Head end allocates the next available MID resets the access priority from the default parameters set high if no MID stored in the STB i e STB is not yet installed and allocates the user frequency Syntax No of bits Content SMATV_Installation_replyQ DiSEqC_framing 8 E4 DiSEqC_Master_Identifier 8 nn DiSEqC_timing data 16 tttt DiSEqC_user_frequency 16 uuuu Where N tt tt Two data
53. the user outlet limits the effects of mismatching and possible disturbances on the user side New installations and installations upgraded for satellite reception are currently equipped with inductive components splitter and tap off and cables working up to 2 150 MHz These components typically show a high signal attenuation gt 60 dB in the frequency range below about 10 MHz see clause 5 4 so in these installations the Control Channel must adopt the RF bus solution clause A 2 of TS 101 964 1 Table 2 reports the typical attenuation values of an inductive directional coupler in band I Table 2 Typical attenuation of an inductive directional coupler in band I Through Loss 1 dB 2 5 dB Tap Loss 12 dB 29 dB Directional Loss 35 dB 48 dB Mutual Isolation 40 dB 60 dB 5 3 3 SMATV MATV installations with d c coupled inductive taps For the 22 kHz user outlets are realized as shown in figure 5 These kind of taps principally have the same RF performance of the inductive directional taps described in clause 5 3 2 at least in the frequency area between 47 MHz and 2 150 MHz d c and 22 kHz bus signal are decoupled from and coupled to the signal path by choke coils This kind of tap is also suited for the 22 kHz bus Loop Through Output terrestrial 47 MHz to 862 MHz SX AN SAT 950 MHz to 2 150 MHz TV Output VHF UHF Radio Output UKW Sat 22 KHz Figure 5 d c coupled indu
54. ts The voltage of 30 V is necessary for suitable switching performance and is usually available in the STB and the Head end as well tuning voltage for sat tuner In this example the diode D2 is a schottky type DIFS4 In the case of Head end application the use of a bipolar transistor for T1 with separate short circuit protection instead of the MOSFET transistor may be more cost effective because the total bus current given by the d c input impedance of the STBs does not exceed 100 mA practical value for the case of 15 STBs connected to the cable network All bipolar transistors shown in the example are standard type BC847B Additional grounding capacitors should be provided for the 18 V and 30 V supply voltage connections 7 2 Implementation of the RF control channel bus The RF Control Channel bus is necessary for use on typical SMATV MATYV installations using inductive components where the user terminals and the Head end are not d c coupled This type of installations are currently used in most countries to be completed 7 2 1 ACK and answer to a command In case the confirmation of correct reception is adopted the ACK message must be sent not later then 50 ms after reception of the command To be noted that ACK guarantees that the command has been correctly received although not necessarily executed In case the HED answer to a command from a STB is sent within the ACK receiving time out this answer is to be considered also
55. ts 1 and 2 the STB knows N which type of HED it will be connected to N the SID of the TDT installed the own MID having assumed that the SID MID If no conflict data is detected by the STB the installation process for the selected HED is completed and the couple STB HED is identified Another HED can be installed starting from point 1 ETSI 34 ETSI TR 102 252 V1 1 1 2003 10 N Mount TDTs N Power on the head end Configuration of TDT Set the output RF channel frequency used one of the unassigned channels must be chosen Set the SID MID etcof the TDT Configuration of STB Select the manual option by OSD Select the TDT to be install Set the input frequency Other TDT to be install Installation completed Figure A 2 A 2 4 Operation During normal operation the STB will use the tuning command to control the HED In order to avoid any potential confusion with multiple masters accessing the Control Channel bus and to avoid any contention schemes other than a random back off the command and reply if required will use the address and pin_code to fully identify the slave and master However it is probably better NOT to request a reply to minimize bus activity and let the STB monitor the lock of its own tuner if there is no change within a given time out it can repeat the tuning request automatically until the tuner detects a change ETSI 35 ETSI TR 102 252 V1 1 1 2003 10 Annex B DiSE
56. twork components user taps etc With reference to figure 2 the SMATV MATYV distribution systems currently adopt two technological solutions a Use of passive components splitters user taps in the common parts of the network The user taps are connected between themselves with only one cable and can be implemented with resistive or inductive elements In some case the user tap is directly included in the user outlet through outlet In order to provide the viewers with the maximum number of attractive channels the large majority of SMATV installations using passive components are equipped with channel pre selection at the Head end b Use of multiswitch in the common parts of the network The multiswitches are connected between themselves with a certain number of cables five or nine in some cases One of these cables carries the terrestrial channels and the others connected to a four output LNB two LNBs in case of nine cables carry the satellite channels Each end user is connected to a multiswitch with only one cable In the following clauses the main technical characteristics of some SMATV MATYV installation are reported in terms of frequency response for the purpose of identifying the best implementation of the Control Channel system 5 3 1 SMATV MATV installations with resistive taps Installations which make use of resistive taps were used in the past and are still used in old installations Resistive taps have in general poor
57. y Rights IPRs essential or potentially essential to the present document may have been declared to ETSI The information pertaining to these essential IPRs if any is publicly available for ETSI members and non members and can be found in ETSI SR 000 314 Intellectual Property Rights IPRs Essential or potentially Essential IPRs notified to ETSI in respect of ETSI standards which is available from the ETSI Secretariat Latest updates are available on the ETSI Web server http webapp etsi org IPR home asp Pursuant to the ETSI IPR Policy no investigation including IPR searches has been carried out by ETSI No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 or the updates on the ETSI Web server which are or may be or may become essential to the present document Foreword This Technical Report TR has been produced by Joint Technical Committee JTC Broadcast of the European Broadcasting Union EBU Comit Europ en de Normalisation ELECtrotechnique CENELEC and the European Telecommunications Standards Institute ETSI NOTE The EBU ETSI JTC Broadcast was established in 1990 to co ordinate the drafting of standards in the specific field of broadcasting and related fields Since 1995 the JTC Broadcast became a tripartite body by including in the Memorandum of Understanding also CENELEC which is responsible for the standardization of radio and television receivers The EBU is a profe
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