FreeDV Quick Start Guide
Contents
1. still does not control PTT try DTR or combination of both Call Sign VKSDSG David r Test Frames Ir Enable Tools Options 6 Under Tools go to Options Enter your call sign and any optional information name location etc This will be sent to the receiving station along with the voice To test the flatness of the TX radio s filters checking Test Frames sends data to the receiving station for evaluation using the Test Frame Error window Do not check this for normal DV contacts Microsoft Sound Mapper Input 44100 Realtek HD Audio Input 44100 Virtual Cable 1 44100 Virtual Cable 2 F ro m pala Virtual Cable 3 T Saio Virtual Cable 4 XCV r S sano Virtual Cable 5 ue Virtual Audio Streaming S p e a ke E SASSO USB Audio none All devices must be set to same rate Device Virtual cable 26 SampleRate 48000 v Rec2s To Speaker Headphones use Sound Mapper Output Realtek HD Audio output Virtual Cable 1 Virtual Cable 2 TO Virtual Cable 3 Virtual Cable 4 Virtual Cable 5 Headset Virtual Audio Streaming UE nda Speaker none Device Microsoft Sound Mapper Output 9 Sample Rate 48000 Play 2s Tools Audio Configuration Receive Device efit Sample Rate Microsoft Sound Mapper Input 44100 Realtek HD Audio Input 44100 Virtual Cable 1 44100 Virtual Cable 2 F ro m 44100 Virtual Cable 3 44100 Virtual Cable 4 Headset Virtual Cable 5 Virtual Audio2. Streaming M IC 44100 44100 USB Audio none 44100 44100 On Ow La IN ee All devices must be set to same rate Device uss Audio Sample Rate 48000 Rec2s To Radio Device lodan Default Sample Rate Microsoft Sound Mapper Output Realtek HD Audio output I Cable Virtual Cable 2 To XCVR Virtual Cable 3 va Cable 4 M He Virtual Cable 5 Virtual Audio Streaming USB Audio none Set all to 48000 sample rate Device vrtualcable1 1 SCS S CS S ape Rate 3800 gt Receive Transmit AP Tools Audio Configuration Transmit 7 7 Go to the Tools pull down menu and select Audio Config Sound cards USB adapters VAC and or USB headsets installed on the PC will be listed Select the PC s internal sound card USB interface for the From To Radio receive and transmit data Select the USB headset for the To Speaker Headphones From Microphone voice out and input To test the selection click on the Rec 2s tab look for a 2 second deflection in the scope from the radio s speaker output audio or from speaking into the mic Next click on the corresponding output device and listen for an 800Hz tone followed by a deflection in the scope If audio levels have not been previously set for use with another digital mode like PSK31 then they will need adjusting to avoid over or under driving your MIC input of your radio or overdriving the input of the sound card MIC or LI
3. Dependent on your receiving location s noise floor expect good decoding at S4 5 To judge the quality of the data signal being received expect SNR of gt 15dB while receiving an S9 signal again depends on your noise floor Multi path distortion QRM and fading obviously have an adverse effect on the SNR Providing a SNR Report is a good way to report the received signal level Higher the better 9 11 Syne The radio button appears when the received signal is in sync with the transmitter Sync is derived from the BPSK binary phase shift keying Pilot Tone signal in the center of the FDM carriers The small Red Marker at the bottom of the display defaults at 1500 Hz should be centered in between the BPSK signal tracks It can be within 200Hz and still provide sync 12 BER Bit Error Rate is an end to end performance assessment of the transmitter receiver and the propagation between BER is the percentage of errors defined by the formula Number of errors Total number of bits sent 13 Squelch Checked box activates squelch with a default of 1 5dB Experience has found decoding of low SNR signals is possible in multipath fades and QRM by taking advantage of the fast recovery sync of FreeDV Experiment with the squelch level in different signal and noise conditions This setting correlates with the received signal SNR Bit Error Rate BER Spectrum Occupancy by Mode 14 Mode 1400 V0 91 was the initial mode
4. Doc Release 0 2 1 Sept 13 FreeDV g FreeDV Quick Start Guide Here is a one page doc that should get you started on HF DV For detailed instructions see the detailed document 1 Hardware For TX and RX two sound devices are required One internal sound card a USB sound interface or a transceiver with a built in sound device will be used for the data The second device may be Gamer or equivalent USB headset for the voice I O Any modern PC with USB ports and a sound card will work If you just want to listen to digital voice then only one soundcard device is needed 2 Install FreeDV with the Windows installer Select the two sound devices and test them with Audio Config tools Next select a conventional com port for PTT or a serial device using USB with Hamlib In Tools gt Options add your call sign name location Keep this text entry as short as possible 3 Radio DSP Turn off TX and RX DSP processing Think flat BP filters no speech compression Turn off the radio s TX monitor 3 Tuning Set the radio dial on frequency try 14 236 then click on Start FreeDV needs about 3dB SNR to decode without voice dropouts The small Red Marker at bottom of the Waterfall must be on the BPSK Pilot tone carrier normally at 1500Hz to obtain sync Use the mouse to move the Red Marker Do not retune once sync has been established For more frequencies visit http gso k7ve org QSO Finder 4 Power Run only 20 of the ra
5. NE IN See Receiving Digital Voice and Transmitting Digital Voice topics for these adjustments API tab shows Port Audio info Note If you have a 9600 input and output on your radio usually on a round DIN ACC connector this is the best connection for every digital mode Your radio usually in a menu should be configured for 9600 or no pre emphasis de emphasis if it has this available If the radio s configuration menu has a 1200 9600 setting leave it permanently on 9600 If not available FreeDV will still work fine with Mic speaker connections FreeDV must be stopped to change Audio and PTT configurations F T DE i LPC Post Filter Enable Beta 0 20 W 0 1 kHz3dB Boost Gamma 0 50 Bass Treble Freq m 8 0 Freq ll 1911 Gain I 14 0 Pel Enable req do Gan j 98 o H 35 Default Default Speaker Out Equaliser Treble Freq m 66 Gain __ _ 6 4 Freq 1833 Gain U 8 8 Mid WM Enable Freg P__ 1650 Gain _ _ E 7 Default 20dB 15dB 1006 db db 5dB 10d8 15dB S00Hz 1000Hz 1500Hz 2000Hz Microphone In Equaliser Speaker Out Equaliser Tools Filter and Equalizers 8 8 Under Tools go to Filter Adjustment of the Equalizer will depend upon the mic your voice characteristics Testing has found voice quality may be improved with most mics by raising the mid range frequency and Gain Similar changes for the Speaker equalization may show impr
6. developed and is retained for compatibility It is also the narrowest mode 1125Hz with 14 carriers but has no FEC within the CODEC2 so it is not as robust Normally on HF 1400 should only be used for compatibility with early beta releases 1600 mode is the default and has 300 bits of FEC in CODEC2 allowing up to a 10 BER before falling apart Experience has shown that 95 of the QSOs are using this mode because of its robustness and narrow BW compared with Wide 1600 Wide 2125Hz which has 2x 150Hz carrier spacing helps combat the effects of Doppler on long paths with severe deep multipath It has been found effective for DX contacts requiring multiple hops On a busy band 1600 Wide will be more susceptible to adjacent channel QRM 15 Control Start Stop FreeDV must be in Start mode to begin receiving With no FreeDV signal present the waterfall will display band noise indicating audio is being routed to FreeDV s input If no noise is observed slowly raise the audio level using Windows sound mixer Recording MIC or LINE IN until the level is blue in color A signal will have more amplitude and depending upon its strength the carriers will change color and become lighter blue to red Strong interference SSB and strong noise QRN will be red in color PTT may be activated with either the mouse or toggling the PC spacebar 00Hz 1000Hz 1500Hz 2000Hz 2500Hz i Waterfall Scatter Frm Radio Frm Hic To Spkr Hdphns p Default 1600 Mod
7. dio s rated output Peak power is much higher Avoid ALC action 5 Mode Start with the default 1600 It is more robust than 1400 for HF and only 150Hz wider 6 Equalizer Bring up the mid range treble gain and lower the bass for the mic and speaker 7 Voice decoding begins immediately after the received signal is tuned in in sync Expect sync around 2dB SNR and good voice decoding around 4dB SNR The higher the better 8 Squelch Start with the default of 1 5 dB 9 Split operation allows changing the receive frequency without affecting the transmit frequency 10 Analog mode bypasses DV and routes audio for SSB and analog frequency monitoring 11 Videos Microsoft Windows Users Quick Start and Video Guide for Microsoft Windows Users are available at FreeDV org Please take a few minutes and watch these instructional videos FreeDV g FreeDV Digital Voice for HF Detailed Document MS FreeDV 0 96 5 Beta 13 7 W Slow Sync fa Bit Error Rate Reset Bits 120382 flo Errs 368 Sto BER 0 003 Level Split Analog 500Hz 1000Hz i1500Hz 2000HzZ 2500Hz 4 Waterfall Scatter Frm Radio Frm Mic To Spkr hdphns b Clear WASNUT Rick in CO v 0 96 5 Beta FreeDV Graphic User Interface FreeDV is a HF Digital Voice program for Windows Linux and Apple utilizing an FDM modem and the open source low bit rate CODEC2 Compatible with SSB radios FreeDV provides communications voice audio occupying le
8. e Waterfall 16 carrier FDM signal with 75Hz carrier spacing Red marker showing sync on DQPSK Pilot tone Spectrum 1600 Spectrum 16 carrier FDM signal with 75Hz carrier spacing with sync on center of Pilot tone at 1500Hz 00Hz 1000Hz Frm Radio 1500Hz 2000Hz 2500Hz 4 Waterfall Scatter Frm Mic To Spkr Hdphns p 1600 Wide Mode Waterfall 16 carrier FDM signal with 150Hz carrier spacing Change in color amplitude indicates fading Ode 5d 10d6 20d6 220d 20d 49d 40d SOOHz 1000Hz 1500Hz 2000Hz 2500Hz Spectrum 1600 Wide Spectrum 16 carrier FDM signal with 150Hz carrier spacing to minimize adverse Doppler effect on DX paths Frm Radio Frm Mic Scatter Plot H V points of the 4 QPSK phases with a tight cluster good signal while fading X shape Scatter i Waterfall To Spkr Hdphns b 0 08 1 08 2 08 3 08 40s 5 05 q Frm Radio Frm Mic To Spkr Hdphns Timing amp Frequeni From Radio Carrier audio level received at the input of the soundcard 11 1 0 0 6 0 6 0 4 0 2 0 0 0 2 0 4 0 6 0 8 1 0 oa e li ate Dea Dee 0 08 108 2 08 3 08 4 08 5 08 4 To Spkr Hdphns Timing Frequency A Test Frame Errors p 4 Scatter FrmRadio FrmMic To Spkr Hdphns Timing A p Audio to Speaker Headphones Timing Delta Level of audio feeding the USB headset or a Plot showing estimate of the best sampling time speaker Adjust for max peaks lt 1 Changes indicate difference
9. experienced a few ferrites on the interface cables and at the mic input may help remove this annoyance for the listener Voice quality is dependent on the type of microphone but low cost PC electret mics can provide good voice audio Logitech and Altec Lansing HS are known to work fine The FreeDV equalizer can improve the audio quality Minimize ambient noise pick up by lowering the mic level as low as possible while speaking in a normal level close to the mic element Loud fans or other non voice audio in the background may be picked up and transmitted as noise Mics in PC cameras are generally not recommended To check for noise pickup watch the center green base line on the Tx display when not speaking into the mic It should not show any deflection 26 More information Want more information on FreeDV Check freedv org often and the links including David Rowe s posts at http www rowetel com blog page 1d 452 Like FreeDV Please consider a donation at freedv org for the developers Acknowledgements Thanks to David Rowe VKSDSG for his technical support Bruce Perens K6BP for his inspiration and Rick Peterson WA6NUT for his comments and review of the document Corrections questions additions comments may be directed to mel melwhitten com Mel Whitten KOPFX 02 Sep 13 Rev 0 2
10. g the sound devices identify and locate their associated Windows Mixers and slider controls Adjust these to mid range as a starting point Keep them handy so they will be easily accessible throughout the installation The mic Record mixer adjusts the audio level from the receiver and the Playback mixer adjusts the audio fo the transmitter If currently using a digital mode such as PSK31 the transmitter and receiver levels should be relatively close Equally important is the mixer slider controls for the USB headset since the mic and headphones will require adjustment 2 FreeDV for Windows will execute and run on about any home or laptop PC with a dual core or higher Intel AMD CPU Virtual Audio Cables VAC commonly used with SDR radios is compatible Dependent upon your hardware interface and radio PTT rig control may be configured for VOX Hamlib or a serial port Flex HPSDR and other SDRs may use a virtual com port pair Software Name Date modified Type SIZE di bin 8 26 2013 11 58 AM File folder Uninstall exe 8 26 2013 11 58 AM Application 121 KB Window files for FreeDV 3 Go to FreeDV org then under Download click on Windows binary files and execute the program This will install for Windows XP 7 and 8 software including an uninstall file The bin folder will 4 contain dll s freedv exe and the PTT Hamlib dll s for CAT control No other files will be created after configured No additional software needed After installati
11. h a right click inside the display window Dark areas sometimes called notches indicate presence of multipath fading Under these conditions which are very common on HF the spectrum display will show the individual carriers 14 or 16 constantly changing in amplitude 17 To obtain sync with the transmitted signal precise lt 200Hz tuning is required but easily accomplished using the mouse for click tuning while observing the Waterfall or Spectrum displays First tune the receiver dial to the operating frequency try 14 236 USB If a signal is present with an SNR of at least 2 3dB decoding should start when the Red Marker at the bottom of the display is within the BPSK tracks same waterfall appearance as PSK31 sync signal If the Red Marker is not centered then move the mouse cursor to the center and left click Instantly the signal should sync and voice will be decoded and sent to the headset or speakers Once in sync the radio s frequency dial should not be moved FreeDV s AFC will track small drifts of the signal Normally the sync should be centered in the display at 1500 Hz to ensure the FDM signal for all modes is within the Tx Rx band pass of the transceiver 18 The input level from the radio to FreeDV should be adjusted using the Mixer so the waterfall FDM carriers are mostly blue to green in color If too high the Level bubble will flash a warning A slightly higher level may be needed for the Spectrum disp
12. in TX RX clock FEEELSi 15 J4 E EF EEE 4 14S E EEE 1344 GEE EE ERE 1343 13 2 EEPEL S13 14 5 EE EE EEE 13 13 goGk SRR SSS Sea eh EEE EEEE EEE EEEE EEEE EEE SSE ane SES 0 08 1 08 2 08 4 08 4 08 5 08 Z 3 2 e z B A A a q Frm Mic To Spkr Hdphns Timing amp Frequency A Testf p 4 Timing A Frequency A Test Frame Errors b Frequency Delta Test Frame Errors Frequency difference between receiving station Display of a test frame received Straight lines and transmitting station frequency are carriers with no errors No signal on right f Headset Earphone Propertie Headset Earphone f 65 CHI Balance Headset Microphone 7 Typical Win7 USB Headset Mixer adjustments for Voice Input and Output 2 sound device inci Level Too High Specirum Scatter i Waterfall Firm Radio Frm Mie To Spkrl Multiple Signal Displays Audio Level Indicator 16 Multiple Signal Displays Various displays are available to view the received signal The default display is the waterfall Click on the tabs below for more On transmit the Frm Mic scope is used for showing input audio from the Mic To add a display left click on the display tab and drag it vertically to the top Next release the left click button when a light blue background is showing Displays can be arranged in various horizontal and vertical positions The waterfall color may be changed to monochrome or all blue hues wit
13. ion With no voice input the thin center baseline on the display should not show any deflection If it does this indicates unwanted noise is being picked up 1 e loud fans within the ham shack or from RF interference Note The DV signal has a rather high peak to average power PAPR ratio meaning the RF amplifier needs additional head room for the multi carrier s higher peak power Otherwise these peaks will be distorted and cause errors in the data sent to the CODEC2 The peaks are quite fast and a conventional peak reading wattmeter will not accurately read them The average power output should not exceed 20 25 of your SSB transmitter Tip Call sign name text data is being sent repeated continuously during transmit at a low bit rate 25bit sec When initializing a contact transmit for 10 15 seconds minimum to ensure the receiving station receives your call and location in the text box Analog SSB 20 Clicking on this button bypasses DV and routes mic and speaker audio for SSB It may also be used to quickly monitor the frequency for analog transmissions Other Features 21 Split allows independent tuning of the RX frequency without affecting the transmitter s frequency This is useful in three ways and nets to avoid changing the transmit frequency for stations entering the QSO not on the established frequency Clear N4DV Gerry in Lecanto FL Text Box for Call ID QTH info 22 The call sign name
14. lay Stronger signals in the waterfall will display the carriers in different shades of blue green and red Multipath selective fading results in a various darker patterns displayed in the waterfall as the amplitude of the carriers are being reduced 13 Note Window s mixer sliders are used for all level adjustments For SDR radios with Virtual Audio Cables such as PowerSDR use the application s software adjustments VAC Rx Tx Gain 4 Power Setting RX1 Meter TX Meter RAI Meter TX Meter Keep ALC lt 0 For typical 100w radio run lt 25w average power 1 0 0 8 0 6 0 4 02 0 0 02 0 4 0 6 DE 1 0 0 0s 1 08 2 08 3 08 4 08 Waterfall Specirum Scatter Frm Radio Frm Mic To SpkrHdphns Transmit Display Microphone input level Transmitting Digital Voice 19 First verify the radio is operating full output on SSB The final output drive will be set using the sound device selected in Tools gt Auto Config gt Transmit gt To radio If not started click on Start and then PTT Quickly adjust the RF output level and then watch the Frm Mic display while speaking in a normal voice Adjust for 75 maximum deflection Any voice input too high will cause clipping Adjust RF power for approximately 25w average with a 100w transceiver This is an important setting to avoid distortion and lowering SNR at the receiving station If necessary reduce the drive level for no 14 ALC act
15. location text is sent in a continuous loop and displayed in the text box Use Tools gt Options to enter your info for transmitting The Clear button may be used to clear the box Operating Tips Where to Begin 23 Start by looking for activity on 20m 14 236 USB FreeDV s FDM carriers make a distinctive noise but are half the width of SSB Avoid confusing the digital EasyPal picture transfer OFDM signals on 14 233 with DV FreeDV QSO Finder http gso k7ve org written by John K7VE 1s available on line for the DV community Current stations on the air frequencies in use and a chat line are available Just log on with your call sign and enter a frequency The list of suggested frequencies 1s at the bottom of the page If you do not see them some browsers may require you to pull the window down to display the entire page A call sign look up is available for stations logged in Just click on their call sign Thank you John 15 Calling CQ 24 Call sign name text data is being sent repeated continuously at a low bit rate 25bit sec during transmit When calling CQ or initializing a contact calling a station transmit for 10 15 seconds minimum to ensure the receiving station receives your call and location in the text box Be sure to check the FreeDV QSO Finder at http gso k7ve org RFI and ambient shack noise and RFI 25 RFI can cause noise and annoying sounds to be transmitted and decoded along with the voice If
16. on execute FreeDV from the start menu For other operating systems see the listing under Download Use Hamlib PTT OR Rig PC S C amp Use Serial Blaster Com Port port PIT FreeDV VOICE PC to Radio Interface Connections 4 For conventional SSB radios connect the cables via RIGblaster instructions or equivalent interface to the PC and Radio input outputs The radio s or SignaLink USB port with Hamlib PTT control may be used Connect a USB headset to the PC for the voice I O If a separate sound card or USB sound device is preferred over the headset then install it with a mic and amplified speakers Audio Contig PTT Config Options Filter Start Stop Play File Mic In Start Stop Record File From Radio Start Stop Play File From Radio Restore defaults Tools Pull down Menu PTT Config VOX PTT Settings Half Duplex Hamlib Settings I Use Hamlib PTT Rig Model sile zie Serial Device Serial Port Settings PTT Port If Use Serial Port PTT I DTR V Use RTS If RTS V PTT Configuration 5 Under Tools go to PTT Config and select the Com Port for the radio s PTT control recommended over use of VOX control Either Hamlib PTT or conventional Serial Port Settings may be used Select the Serial Device or COM port for PTT DV RTS V is normally used for rig control If the radio is keyed into transmit after clicking Apply change the polarity Then click OK If
17. ovements also Adjustment of the LPC Post Filter may be adjusted to improve the subjective speech quality On the air reports and experimentation will be needed to make final adjustments Playing File k3dec to Mic Input Recording File N4DV From Radio Playing File wa6nut into From Radio Tools Recording Features 9 Under Tools options for Recording and Playback are available Currently the record playback files Mic in must be sampled at 8 kHz using 16 bit samples Off the air DV may be recorded and played back through the PC speakers Currently recordings may not be played back into the radio mic input These dialog boxes will appear in the lower left hand corner below the options call sign name text box while running The recordings are 30 seconds in length which is the same time as a DV signal requires to move from the bottom to the top of the waterfall display SNR Squelch gt Control Sync _ g Start Bit Error Rate Reset Mode Bits 0 T 1400 VO 91 0 0 Errs 0 15 f 1600 Slow BER 0 0 ad 1600 Wide SNR BER Receive Squelch Mode Control Receiving Digital Voice 10 SNR Signal to Noise Ratio is shown both in a visual indicator and numerically Since SNR estimation will continually fluctuate sometimes rapidly over an HF channel it can be averaged using the Slow option SNR of approximately 3dB is required to begin decoding voice This is a rather low level noisy signal so some dropouts can be expected
18. ss than half the bandwidth of conventional SSB Some Technical Specs 1125Hz BW 50 baud 14 QPSK Quadrature Phase Shift Keying voice data Narrow Mode 1275Hz BW 50 baud 16 QPSK voice data Default Mode 2125Hz BW 50 baud 16 QPSK voice data DX Robust Mode with 2x carrier spacing 150Hz 1 Center BPSK Binary Phase Shift Keying carrier with 2x power Pilot tone sync tuning 25bit s text rate for call ID Name Location expanded G3PLX Varicode FreeDV Specification at freedv org for additional description 3 Tip Microsoft Windows Users Quick Start and Video Guide for Microsoft Windows Users videos are available for FreeDV This is an excellent source of help for installing and operating FreeDV and may be found at freedv org Take a few minutes to view these before starting the setup SignaLink usB ees Hamlib oe PTT gt MI A T he A 0 O integrated GSE Sound Card Serial Port PTT PC USB Headset Radio to PC Interface Hardware 1 Sound card and PTT control setup is the same as other digital modes such as PSK31 except DV requires a Gamer or equivalent USB headset for voice input and output As an alternative to the headset a second sound card with its mic speaker may be used Like other digital modes a Radio to PC interface either homemade or purchased 1s necessary to provide isolation and relay control for PTT To listen only just one sound card is needed After connecting installin
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