U.S. Coast Guard Research and Development Center
Contents
1. Access Threshold 100 00 Planes B C D E Configuration 2 5 Created 10 05 1333 Figure 30 Post equatorial plane maximum gaps in access to Curacao GES in minutes 24 Availability Availability is the amount of time on any given day that the system 15 available for use This parameter should not be confused with coverage System availability could be affected when e traffic exceeds the capacity of the system e asatellite or GES fails e asatellite is removed from service for testing Although a mobile user may have coverage the system cannot be used if either the satellite or GES providing that coverage is unavailable Unlike a GEO system where each satellite covers a third of the globe LEO satellites continuously move with respect to the Earth s surface In the case of a GEO satellite failure an enormous amount of users would completely lose service whereas a LEO satellite failure would result in a temporary loss of service for a small number of users According to STK simulations the average Orbcomm satellite pass 1s about 14 minutes The average gap between satellite passes is about two minutes These numbers were corroborated by actual system testing Therefore if an Orbcomm satellite fails a user will experience a maximum gap of 18 minutes before the next healthy satellite in the plane passes overhead as shown below in figure 31 Failed Satellite satellite Footprint 2 min gap between satellite passes2. 0 03 30 0 03 00 0 02 30 0 02 00 0 01 30 0 01 00 0 00 30 0 00 00 1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 Sample Latency Average Figure 32 229 Byte message latency Figure 32 shows the latencies of the 229 byte test messages sent from the CGC TYBEE over a 24 hour period Messages were sent every ten minutes so a total of 144 messages were evaluated The solid line represents the individual latencies while the dotted line is a cumulative average The minimum latency recorded during this period was 36 seconds while the maximum was 14 minutes and 38 seconds The average latency for this period was 2 minutes and 18 seconds 28 Time hh mm ss Latency of Monitoring MSGs sent from Tybee SC once every 60 minutes 0 33 00 0 32 00 0 31 00 0 30 00 0 29 00 0 28 00 0 27 00 0 26 00 0 25 00 0 24 00 0 23 00 0 22 00 0 21 00 0 20 00 0 19 00 0 18 00 0 17 00 0 16 00 0 15 00 0 14 00 0 13 00 0 12 00 0 11 00 0 10 00 0 09 00 0 08 00 0 07 00 0 06 00 0 05 00 0 04 00 0 03 00 0 02 00 0 01 00 0 00 00 1 2 3 4 5 6 7 8 9 40 41 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Sample Latency Average Figure 33 1405 byte message latencies Figure 33 shows th
3. 18 min Figure 31 Consequences of Satellite Failure Since the same failed satellite will pass over a stationary user several times in a 24 hour period the total amount of lost satellite usage will accumulate to approximately 1 hours per day if the satellite 1s not restored In actuality satellites in other planes would be providing simultaneous coverage for the majority of this time so the user most likely would not even notice the outage Although latency would probably increase slightly the message would still go out with the next pass by a healthy satellite 25 If a GES fails the consequences would be much more drastic than a single satellite failure Coverage would be severely limited in the vicinity of the failed GES Users would have to rely on other GES sites which could be several hundred miles away For this reason each Orbcomm GES site has two fully independent antenna systems with associated RF and control equipment for complete functional redundancy Orbcomm posts status reports on its websites indicating when system components are not available On a typical day during our testing at least one or two satellites were unavailable causing a minor decrease in coverage For the most part Orbcomm maintains a current library of the status reports so interested users can have an accurate representation of the health of the constellation Reliability Reliability is a measure of a system s dependability Since Orbcomm is a relati
4. 5 FAE STELLARE 5 icu E M D AB 11 PATROL TIONS 11 HC ALSO INSTALLATIONS de ded 13 HH 60 INSTALLATIONS isi arda pe ___ ene 16 SYSTEM PERFORMANCE odes eva 20 COVERAOGPBN ANA CY I CA LM MALE 20 ZU ATDABIBEDY 2 51 2er _6_ _ ________ ___ 25 a 26 PANG GAM REPETI PER Nee TK Se EUREN ERES RE 26 ee E ne ben i ae NE M M e IA SUE 27 IN VV TN nk sa ___ _____ a adah 27 Gi LL ELM UI MEM A 2 Oe A ge ag aaa ve ELM LM te aa E a a KN 30 COST re tere uM pu MM MM E DM LLL M ME E LM ELT RU 30 SECUPDDY niece itum a a A daa MIO EL LH d DAI ID Ot ULM d LL a a LE 31 CONCLUSIONS RR 32 RECOMMENDATIONS 33 REFERENCES a E a a Ia AS a UN BK aa ePi se o a Dd 34 APPENDIX ORBCOM GROUND EARTH STATION GES LOCATIONS A 1 APPENDIX B AVIATION ANTENNA COMPARISONS MAXRAD 1 APPENDIX COVERAGE DURATION AND REVISIT TIME GRAPHS C 1 APPENDIX D PATROL BOAT ORBCOMM US
5. V HEP ANTENNA 14 HC 150 VHF ANTENN A aaa a ANG E ED 14 130 ORBCOMM TRANCEIVER MOUNTED BELOW RADIO TABLE 15 HC 130 LAPTOP COMPUTER ON RADIO TABLE eee 15 HC 130 GPS SPLITTER MOUNTED BELOW RADIO 16 HH 60 ORBCOMM TRANSCEIVER MOUNTED ON EXTENDEDUOAVIONICS RACOR s eee HIEL 00 VHFANTENN A crara Rede E bein eren 18 60 ORBCOMM GPS ANTENNA ccc cece cence ec 18 HH 60 KNEEBOARD WITH MOUNTED LAPTOP COMPUTER 19 HH 60 BREAKOUT BOX MOUNTED PORT SIDE OF AIRCRAFT 19 LENGTH OF SATELLITE PASS DEPENDS UPON DISTANCE FROM CENTER OB FOOTPRINT cioe sehen ces bao cta i atibus aae dee 20 LENGTH OF USER SATELLITE GATEWAY CHAIN 21 POST D PLANE ACCESS TO CURACAO ccc ccc cece cee eens een 23 POST D PLANE MAXIMUM GAPS IN ACCESS TO CURACAO GES 23 POST EQUATORIAL PLANE ACCESS TO CURACAO 5 24 POST EQUATORIAL PLANE MAXIMUM GAPS IN ACCESS equ OU GA E RI MEAM DEDI CONSEQUENCES OF SATBELLIDIBEJPFPAILURE isees zsssutexewetenvsesesves 25 2 2958 VE MESSAGE LATENCY xO his Nia eei 28 1405 BYTE MESSAGE LATENCY ccccc ccc RI RR RH ehh eee 29 130 618 SYSTEM ANTENNA VS MAXRAD rere 1 HC 130 ELT ANTENN
6. allowed us to send PGP encrypted messages via Orbcomm with no cutting and pasting involved The version of SatEx we were using was a demo version however so the process was not perfect For example when working with SatEx Outlook you cannot see whether or not a satellite or gateway is in view It 15 therefore difficult to determine whether or not a message can be sent or not StelComm and SatEx use the same Communications port and cannot run simultaneously 3 In order to send a PGP encrypted message to someone you must know his or her public key PGP comes with key distribution software which is used to manage all the users public keys This software is installed on a server which 15 a virtual key ring where copies of all users public keys are kept Users can access the key ring in order to find their desired recipient s public key Public keys must be protected from tampering to be sure that a public key really belongs to the person to whom it appears to belong This is accomplished through a combination of digital certificates and trusted user authentication methods to ensure that no keys are compromised The PGP software was installed on a Standard Workstation III SWI terminal at the R amp D Center and aboard the three patrol boats The key server with the public key ring was managed from the Advanced Comms Lab Since the patrol boats were mainly underway they did not have a method to dial in to the key server Instead four sets
7. current constellation The A plane is shown in blue the B plane is orange the C plane is green plane 15 magenta and plane 15 red PA m Ir malem LA e ah Figure 1 Orbcomm Satellite Constellation as of October 1999 ax 115 150 1655 Figure 2 Orbcomm Satellite Constellation as of October 1999 Ground Segment The ground segment consists of Gateway Earth Stations GESs Gateway Control Centers GCCs and the Network Control Center NCC Gateway Earth Station The function of the GES 15 to link the ground segment with the space segment They are located all over the world including four in the United States Arizona Washington Georgia and New York A complete listing of all locations can be found in Appendix A The GES receives orbital information from the GCC and tracks satellites as they cross the sky using a steerable high gain VHF antenna There is a backup antenna at every GES for redundancy User data are passed between the GES and the satellites at 56 7 kbps Gateway Control Center The is the interface between Orbcomm and standard terrestrial based networks Orbcomm can support a wide range of communication protocols including X 400 X 25 leased line dial up modem public or private data networks and e mail networks In general any standard e mail address jane doe generic isp net is all that is needed to communicate with Orbcomm devic
8. define the behavior of each of the available stimulations for Deliberate lagging and Triggered logging Triggered logging is the action of preparing lag record in message as a result of an event that was triggered by one of the stimulations v Figure 9 StelComm Application window Monitoring The Position Report feature 1s used to send six byte position reports at regular intervals This application runs only when a satellite 15 in view new position report will not be queued until the previous Position Report is transmitted The position will be derived from the GPS input if available Otherwise the unit will use a Doppler calculation to estimate position The unit can also be programmed to transmit a fixed position if the SC 15 not mobile The position report interval 1n seconds 15 entered by the user as shown in figure 10 a Ah Possis dose Merang Postion repart Figure 10 StelComm Application window Position Report 10 Sat Ex Although StelComm was our primary messaging application we also successfully used Microsoft Outlook as an e mail client We tested the beta version of a software connector called Sat Ex which allows the user of any Windows 95 or Windows 98 PC to send and receive messages over the ORBCOMM system Outlook was used as the e mail application but StelComm was still required for viewing status setting parameters and configuring applications on the EL 2000G Ou
9. effective for automatic position reporting and short messaging however current pricing schemes render the system cost prohibitive for longer messages These pricing schemes are charging 0 01 per character over and above the monthly access fee and flat message rate It is important to keep in mind that although Orbcomm is touted as a global system a mobile user needs both a satellite and an earth station to send and receive data in normal operation Since there are no Orbcomm earth stations near Hawaii Alaska Guam etc the system will not work in these areas Orbcomm SATCOM Data Communications Automated Distribution limited to U S Coast Guard only Other requests Position Reporting shall be referred to the U S Coast Guard Research and 17 Key Words 18 Distribution Statement Development Center Groton CT 06340 6096 19 Security Class This Report 20 Security Class This Page 21 No of Pages 22 Price UNCLASSIFIED UNCLASSIFIED 111 EXECUTIVE SUMMARY The Coast Guard s mobile communications requirements are increasing at such a rate that they will exceed capabilities currently provided by High Frequency HF Department of Defense DOD military satellite MILSATCOM and Inmarsat systems Furthermore existing systems are outdated and expensive to maintain Commercial mobile satellite communications SATCOM systems are a logical choice to meet the Coast Guard s expanding communications requirements while reducing
10. from mobile units It 1s inexpensive and simple enough to be used in conjunction with or as a backup to another SATCOM system which could be used for sending longer messages and or providing voice capability Orbcomm is the only system of its kind available commercially today Most of the other commercial SATCOM systems on the market are designed for voice and are therefore more complex and expensive Although some of these systems will offer data as well a dial up connection billed by the minute is usually required making short messages impractical For these reasons Orbcomm should be considered as a significant element of the Coast Guard s future communications architecture vi TABLE OF CONTENTS EXECUTIVE SUMMAR Y V e 1 ORBCOMM SYSTE M tee aos Up OE Ea 1 EN m d DM 2 GROUND SECMEN gts 3 GATEWAY EARTH STATION cccccccsssscccessccccessececcesscccsesecccsestccececseseseesaceesetsesesecsasececssssescaassesetauseestsseesctaseeeesaueeens 3 GATEWAY CONTROI CBEN TER iuste de aceite Sead se 3 NETWORK CONTROL ENT ER 3 U EROE MEN aaa a aia aa a LM md ia a a aaa 4 SENDING MESSAGE cccscoccscescsceccecsccscsccscscscsceseececeecscescecestecesescscescscscscesescesescecescscesescesescecesees 4 SYSTEM IESFANDEVALUAZLTIGON
11. investment in infrastructure There are many different commercial SATCOM companies entering the market Not all of these companies will succeed The R amp D Center s Advanced Communications Technology team is investigating and evaluating these systems as part of its Mobile Communications Infrastructure project The objective of the project is to identify the systems that will most effectively meet the Coast Guard s communications requirements at the lowest cost The R amp D Center produced the report entitled Technology Assessment of Mobile Satellite System Alternatives Johnson et al 1998 This report provided an overview of all potential new and emerging commercial SATCOM systems In May 1998 the Mobile Communications Requirements report was delivered detailing the specific functional requirements for communications systems aboard various Coast Guard platforms As individual systems are tested and evaluated the results are documented in a test and evaluation report Such reports have been published for the American Mobile Satellite System AMSC BOATRACS and Inmarsat Mini M systems This report describes the Orbcomm system evaluation Currently Mobile Communications Cost Benefit Analysis Mobile Communications Security Analysis and Comparison of Mobile Satellite System Alternatives to Coast Guard Communications Requirements reports are being written Future systems to be evaluated include Iridium Globalstar a
12. it would be very unlikely to receive a garbled message If proper acknowledgement is not received for each packet sent Orbcomm will simply re send the information Results of one year of field testing verified that there were no reported instances of changed or unreadable messages The system can be considered highly accurate 26 Interoperability This is a measure of how well the system interfaces or integrates with existing systems Orbcomm is able to interface seamlessly with the PSTN in order to send information to or from any standard Internet address Anyone with the capability to send e mail can send a message to someone with an Orbcomm SC Orbcomm addresses are of the same format as other Internet addresses e g RDC1 Orbcomm net The Orbcomm system was also successfully integrated with the First Coast Guard District s Operational Web Link OWL 2 0 program OWL 2 0 is a law enforcement application used by HU 25 Falcon fixed wing aircraft in the First District which allows the aircrewman to query an extensive database of commercial vessels and automatically compose and send sighting reports to a predefined set of users This was tested in the Advanced Comms Lab but not in the field If desired the Coast Guard could run a dedicated line from Orbcomm s NCC directly to the Coast Guard e mail gateway in order to keep official traffic off the Internet This would increase the security of our information and prevent delays and bottl
13. that is much more secure than the standard 56 bit DES algorithm In March 1997 the Deputy Director of the NSA William Crowell stated If all the personal computers in the world 260 million were put to work on a single PGP encrypted message it would still take an estimated 12 million times the age of the universe on average to break a single message The sender first composes a message in plain text PGP compresses the message and then creates a unique session key which is a random number generated from random movements of the user s mouse and random keystrokes he or she 1s prompted to type in The session key uses a conventional encryption technique to encrypt the plain text The session key itself is then encrypted to the recipient s public key and is sent to the recipient along with the message The recipient s copy of PGP will use his or her own private key to recover the unique session key which is in turn used to decrypt the conventionally encrypted plain text message StelComm does not support PGP however there is a cumbersome way to make it work The message body can be cut and pasted into NotePad or any other text editor where PGP 1s supported The text 15 encrypted and then copied back into the StelComm message body block The recipient of the message must follow this process in reverse in order to read the original message Since PGP is designed to be plugged in to Microsoft Outlook the SatEx software patch
14. 20050006 Revision B Dulles VA Orbcomm Global L P 1998 Orbcomm Serial Interface Specification E80050015 Revision C Dulles VA Orbcom Global L P http www orbcomm com Stellar April 1998 EL 2000 EL 2000G Data Communicator Users Guide 34
15. A MAXRAD 1 HH 60 ELT ANTENNA VS memi B72 ALLEN 574 ANTENNA VS MAXRAD ccm eeu Dod viii FIGURE 1 FIGURE C 2 FIGURE 3 FIGURE 4 FIGURE C 5 FIGURE C 6 FIGURE D 1 FIGURE D 2 FIGURE D 3 TABLE 1 TABLE 2 TABLE 1 LIST OF ILLUSTRATIONS CONT D COVERAGE DURATION SAN 1 REVISIT TIME SAN DIEGO COVERAGE DURATION SAN eene nenne C 2 REVISIT TIME CABO SAN LUCAS Ga BA 2 COVERAGE DURATION GUATEMALA ecce ee C 3 REVISIT TIME TEM AIA cite siesta C 3 CGC LONG ISLAND COST SUMMARY D CGC EDISTO ORBCOMM COST SUMMARY D 2 ORBCOMM COST SUMMARY D 3 LIST OF TABLES COVERAGE DURATION FOR TYBEE STK SIMULATION 12OCT 99 22 REVISIT TIME FOR CGC TY BEE STK SIMULATION 12OCT 99 22 ORBCOMM GROUND EARTH STATION GES LOCATIONS 1 1X INTRODUCTION The objective of the R amp D Center s Mobile Communications Infrastructure Project is to investigate and evaluate commercial satellite solutions that may meet the Coast Guard s current and future communicati
16. AGE COSTS ee ee eee eee neun D 1 Vil FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 FIGURE 11 FIGURE 12 FIGURE 13 FIGURE 14 FIGURE 15 FIGURE 16 FIGURE 17 FIGURE 18 FIGURE 19 FIGURE 20 FIGURE 21 FIGURE 22 FIGURE 23 FIGURE 24 FIGURE 25 FIGURE 26 FIGURE 27 FIGURE 28 FIGURE 29 FIGURE 30 FIGURE 31 FIGURE 32 FIGURE 33 FIGURE 1 FIGURE B 2 FIGURE B 3 FIGURE B 4 LIST OF ILLUSTRATIONS ORBCOMM SATELLITE CONSTELLATION AS OF OCTOBER 1999 2 ORBCOMM SATELLITE CONSTELLATION AS OF OCTOBER 1999 3 ORBCOMM MESSAGE PROCESS FLOW ccc cece sees I e hene 4 ORBCOMM TEST BED SYSTEM ARCHITECTURE eR RI 5 COMPONENTS OF STELLAR EL2000G eterne ten 6 STEECONMM STATUS WINDOW idt Umen eren uiid aed lola 7 STELCOMM PARAMETERS WINDOW eH RI e e eere 8 TELCOMM MESSAGES WINDOW hehe renes 9 TELCOMM APPLICATION WINDOW MONITORING RR 10 STELCOMM APPLICATION WINDOW POSITION 10 PATROL BOAT ORBCOMM TRANCEIVER MOUNTED ABOVE CHART TABLE 12 PATROL BOAT LAPTOP COMPUTER LOCATED ON BRIDGE 12 PATROL BOAT VHF MAXRAD ANTENNA cece eee eaaa eea aee 12 PATROL BOAT GPS ANTENNA MOUNTED ON 13 HC 150
17. C TYBEE STK Simulation 120CT 99 Revisit Times hh mm ss Minimum Maximum Average Total San Diego 0 00 20 0 13 35 0 03 39 3 54 25 Cabo SanLucas 0 00 22 01946 0 06 35 9 27 00 Guatemala 0 00 27 2 09 00 0 13 00 14 12 00 The results show that coverage was adequate near San Diego The longest measured gap in coverage was 13 minutes This is acceptable for non urgent Coast Guard tracking and messaging As the cutter moved south in the scenario though coverage declined drastically Near Guatemala the longest gap in coverage was over two hours Gaps such as this are unacceptable for most Coast Guard applications Orbcomm is aware of this deficiency and 15 taking steps to improve coverage in the lower latitudes In November 1999 Orbcomm plans to launch seven more satellites which will constitute the D plane This plane will be inclined 45 degrees at an altitude of 775 km Figure 27 shows coverage contours near Central America and the northern tip of South America Orbcomm has a GES in Curacao which is represented by the small blue square in the figure The contour lines around it represent coverage as a percentage of a 24 hour period In this graphic only access to the Curacao GES is considered even though access to other GESs may have been possible Coverage is best close to the GES because there is an increased likelihood of having both a satellite and GES Coverage deteriorates as a direct function o
18. Fin Cade Originated g siz 65536 Gun Search mad a Terminated msg save time 85400 Shutdown If Battery voltage is unde Second Serial None Debug C Dual Mode 1 Dual Made 2 Mag requeue optio Do not nstalled C n a C 5 502020 C 5 502022 C 5 502024 C Requeue Figure 7 StelComm Parameters window The Messages window shown in figure 8 allows the user to compose send and receive messages reports and Globalgrams Sending and receiving messages using StelComm is very straightforward The subject line message priority acknowledgement level message body type and recipient address are entered in the Message Details screen Although there is no address book capability there 1s an option to pre program up to nine speed dial e mail addresses which can be quickly selected from the ndicator pull down box The user must hit the Add button after each address 1n order to send the message to multiple recipients There is a seven recipient maximum per message The text of the message is typed in the Message Body screen The system does not currently support the sending of message attachments At the bottom of the Message Body screen the user must hit the Send button when the message is complete Messages will be listed on the appropriate nbox and Outbox screens until they are either deleted or sent EM Messages MEH Message De
19. PC system or the Environmental Response On Scene Command and Control OSC2 system Orbcomm equipment and service is economical for automatic position reporting and short messaging It 15 not the best solution for sending lengthy messages Installation 1s simple and the same hardware can be used on both aircraft and boats There is no other system available today that can provide the same features at such a low price Orbcomm should be strongly considered as a potential component of the Coast Guard s future communications architecture 33 REFERENCES Anteon 1998 Coast Guard s Mobile Communications Requirements Johnson Gregory W Turban Jon and Erickson Robert April 1998 Technology Assessment of Mobile Satellite System Alternatives Unpublished report U S Coast Guard R amp D Center Groton CT ADDITIONAL REFERENCES OF INTEREST Note Although the following references have not been specifically referred to in this report they are of direct interest to this project Marshall Sheila R and Patrick Ralph C 1997 STK User s Manual Version 4 0 for Windows 95 NT Maryland Analytical Graphics Inc Network Associates Inc 1998 An Introduction to Cryptography PGP Version 6 0 USA Network Associates Inc http www nai com Orbcomm Global L P 1997 Orbcomm System Overview A80TDO008 Revision B Dulles VA Orbcomm Global L P 1998 Orbcomm Gateway Customer Access Interface Specification D
20. TH HF RADIOS FAILED ORBCOMM WAS OUR ONLY CONTINUOUS TWO WAY CONNECTION WITH THE OUTSIDE WORLD FROM PASSING POSIT RPTS TO TYBEE AND DII TO FINALIZING LOGISTICS WITH OUR SHIP S AGENT IN MEXICO TO MAKING ME AWARE OF AND KEEPING US OUT OF THE PROJECTED TRACK OF TROPICAL STORM MADELINE I AM THANKFUL THAT WE HAD THE ORBCOMM SYSTEM ONBOARD EXAMPLE USCG R D CENTER CAUGHT ONE OF MY E MAILS THAT I SENT TO CGC TYBEE ASKING IF HE KNEW OF ANY SIGNIFICANT WX SYSTEMS BESIDES T S KAY WHICH WAS WEAKENING R D CENTER SENT ME A WX RPT DESCRIBING 3 TROPICAL STORMS IN THE AREA TWO OF THESE STORMS LESTER AND MADELINE WERE SUPRISES WE NEVER RCVD ANY MSG TRAFFIC ON THEM THEREFORE DID NOT KNOW THEY EXISTED The aircraft users on the other hand typically only flew for a few short hours so they did not need to rely on the messaging aspect of the system as heavily Both the patrol boat and aircraft users found the automatic position reporting feature extremely valuable RECOMMENDATIONS No one system 15 going to be able to meet all of the Coast Guard s communications requirement at a reasonable cost The ideal architecture will most likely be a combination of systems offering unique capabilities Orbcomm could play an important role in that architecture With little additional effort the position reports could be fed into a real time display of operational assets at a command center such as the Search and Rescue Command and Control Personal Computer C2
21. U S Coast Guard Research and Development Center 1082 Shennecossett Road Groton CT 06340 6096 Report No ORBCOMM TEST amp EVALUATION FINAL REPORT NOVEMBER 1999 Distribution limited to U S Coast Guard only Other requests shall be referred to the U S Coast Guard Research and Development Center Groton CT 06340 6096 Prepared for U S Dept of Transportation United States Coast Guard Office of Communications Systems G SCT Washington DC 20593 0001 NOTICE This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange The United States Government assumes no liability for its contents or use thereof United States Government does not endorse products or manufacturers Trade or manufacturers names appear herein solely because they are considered essential to the object of this report This report does not constitute a standard specification regulation Marc B Mandler Ph D Technical Director United States Coast Guard Research amp Development Center 1082 Shennecossett Road Groton CT 06340 6096 Technical Report Documentation Page 1 Report No 2 Government Accession Number 3 Recipient s Catalog No Orbcomm Test and Evaluation November 1999 6 Performing Organization Code Project No 9250 7 8 Performing Organization Report No RDC 271 99 T Author s Amy B Grable 4 Title and Subtitle 5 Re
22. a sent to an SC can be initiated from any computer using common e mail systems such as Microsoft Outlook Eudora or cc Mail The NCC or GCC transmits the information in the reverse direction to terminate at the SC ORBCOMM ORBCOMM Satellite Satellite Uplinks GCC located at VHF 148to150MHz Network Control center 137 to 138 MHz 4800 9600 bps 25 and 50 KHz UHF 400 MHz E d 7 zi E 4 Ma Business Communications Customer Personal Communications Location Figure 3 Orbcomm message process flow SYSTEM TEST AND EVALUATION The system was initially tested in the Advanced Communications Laboratory at the R amp D Center Field testing was conducted by installing the system aboard three 110 ft Island Class patrol boats two HH 60 Jayhawk helicopters and one HC 130 Hercules fixed wing airplane Figure 4 depicts the test bed system architecture Network Control Center PSTN RDC Lab Figure 4 Orbcomm test bed system architecture The Stellar EL2000G At the time of initial testing there were very few subscriber communicators available on the market The Stellar EL2000G data communicator was chosen because it was the furthest along in development and production This unit is simply an intelligent wireless modem designed for the Orbcomm system Features include continuous remote operation data logging messaging tracking sensor monitoring position reporting and power managem
23. ated messages in the unit s memory queue LED indicator showing whether or not a satellite is in view ID number of the satellite in view and GPS Position Stellar Communicator Manager 1 36 unit version is 4 32 6031 1 02 ee me SANUS p AD UTC Time and Dat Packet errore Connected bw Tim m msg Sat in 17 04 29 Wednesday 03 03 99 0 1 0 0 24 apeh Latitud Longitud Gps 41 31626 7206469 Delete message Figure 6 StelComm Status window The Parameters window shown in figure 7 enables the user to configure settings and access debug data From here the user can import parameters from a file update software or firmware set a password or PIN code set preferred gateway for searching and sending messages set buffer sizes display the unit s serial number set minimum battery voltage level allowed before shutdown determine message queuing operation enable or disable GPS set interval between sequential GPS measurements set parameters specific to a position report view and store to a file real time details of unit operation set speed dial numbers for default reports and messages define priority used to send default messages specify which features can be modified remotely and change default units for date temperature distance etc Unit Parameters Parameters Update software Password Queue Siz Desired Terminated siz 65536
24. be used to create simulations or scenarios involving objects such as satellites earth stations targets and more Element sets containing a satellite s actual orbital data can be downloaded from AGI s web site STK plugs these data files into high precision propagation algorithms to constantly update the satellite s predicted location thereby animating the scenario The element sets are updated weekly at AGI s web site If no actual orbital data is available satellites can be created and added to a scenario using STK s Orbit Wizard This was very important during early stages of testing before Orbcomm had launched all of its satellites Because of the incomplete satellite constellation there were only a few hours of the day during which testing could be conducted We were able to take advantage of the limited coverage time by scheduling our testing according to predicted availability The accuracy of the STK simulation was verified by comparing the predicted coverage by a particular satellite to the actual coverage of that satellite as indicated by the StelComm status window STK consists of a basic software version and various add on modules The Chains module was used to group all of the Orbcomm satellites into a constellation The known gateway locations were also entered into the scenario and grouped into a constellation Targets were entered into the scenario to represent the R amp D Center and all of the field test bed units A
25. chain is completed when a target and gateway are both in the footprint of the same satellite A completed chain represents coverage for that particular target Initial testing indicated that quality of coverage seemed to be consistent regardless of longitude however it was affected significantly with changes in latitude A scenario was generated to demonstrate the difference in coverage at three different geographic locations CGC TYBEE was used as a target in the scenario The three locations were 21 e Homeport San Diego 32 68 N 117 23 W e Cabo San Lucas Mexico 22 24N 109 23 W e Guatemala 13 92N 90 78 W The scenario was run over a 24 hour period for all three locations The coverage duration and revisit times were measured Coverage duration 15 the amount of time the TYBEE had access to a complete chain while revisit time is the length of time TYBEE had to wait between coverage intervals The minimum maximum average and total coverage duration and revisit times were measured The results are shown below in tables 1 and 2 Graphical results can be found in Appendix C Table 1 Coverage Duration Measurements for CGC TYBEE STK Simulation 120CT 99 Coverage Duration hh mm ss Minimum Maximum Average Total San Diego 0 00 48 0 13 35 0 11 06 20 05 35 Cabo San Lucas 0 00 30 01322 0 07 54 14 33 00 Guatemala 0 00 16 0 10 58 0 07 05 9 48 00 Table 2 Revisit Time Measurements for CG
26. e The conversion from standard Simple Mail Transfer Protocol SMTP to Orbcomm s proprietary messaging language 15 transparent to the end user Network Control Center The NCC is located in Dulles VA and serves as the GCC for the United States Its main function is to manage the Orbcomm network elements and the Unites States gateways through telemetry monitoring system commanding and mission system analysis Orbcomm certified controllers are on duty at the NCC 24 hours a day and seven days a week to ensure satellites are functioning properly User Segment The user segment is made up of various types of subscriber communicators SCs including hand held devices for personal messaging fixed units for remote monitoring and mobile units for tracking applications Manufacturers include Magellan Panasonic Stellar and Scientific Atlanta The terminals offer a wide range of capabilities and cost anywhere from 500 2000 operate in the VHF frequency band transmitting at 2400 bps and receiving at 4800 bps Sending a Message Figure 3 shows how a message is sent using Orbcomm message sent from an SC is received at the satellite and relayed down to one of the GESs that connects the Orbcomm ground system with the satellites The GES then relays the message via satellite link or dedicated terrestrial line to the NCC The NCC routes the message to the final destination via e mail dedicated telephone line or facsimile Messages and dat
27. e criteria defined in the Coast Guard s Mobile Communications Requirements report The purpose of this evaluation was to determine whether a satellite data communications system like Orbcomm could benefit Coast Guard communications by improving performance meeting requirements not currently being met and or reducing cost Specific system evaluation parameters included coverage availability reliability accuracy interoperability bandwidth latency ease of use and cost Some testing was conducted in the Advanced Communications Laboratory at the R amp D Center and some was conducted aboard Coast Guard boats and aircraft ORBCOMM SYSTEM ORBCOMM is a low earth orbit LEO data only satellite communications system owned by a partnership of Orbital Sciences Corporation and Teleglobe Inc of Canada The FCC granted the company a commercial license in October of 1994 Their system is capable of sending and receiving short text messages monitoring remote equipment and tracking mobile units Automatic position reporting is accomplished using embedded GPS or an inherent Doppler position calculation The user terminal or subscriber communicator SC transmits in the 148 150 MHz frequency range at 2400 bps and receives in the 137 138 MHz frequency range at 4800 bps Like any SATCOM system ORBCOMM is made up of three segments space ground and user Space Segment The space segment is the constellation of satellites ORBCOMM is current
28. e latencies of the 1405 byte test messages sent from the CGC TYBEE over a 31 hour period The test messages were sent every hour for a total of 31 messages The minimum latency measured during this period was 2 minutes and 11 seconds while the maximum was 31 minutes and 18 seconds The average latency for this period was 9 minutes and 38 seconds Note Although the above results are specific to CGC TYBEE they are representative of the results obtained at the other five units During early latency testing we noticed that some of the test messages were lost completely Lost messages were detected by examining the queue times in the spreadsheet If the interval was greater than ten minutes for 229 byte test messages or one hour for 1405 byte test messages we knew that a message had been lost After extensive troubleshooting we were able to solve the problem by manually adjusting the frequency offset potentiometer inside the Stellar EL2000G The manufacturer has since created a software patch so that manual intervention 15 no longer necessary After upgrading our software we did not lose any more test messages 20 Another problem we experienced during testing was duplicate messages If an SC does not receive final acknowledgement from the gateway that its message has been received it will re send it Duplication results when the entire message has been sent but the SC does not receive final acknowledgement so it sends the message again This see
29. e of three candidate aviation antennas The two systems were monitored to determine how often they had access to a satellite Two of the three candidate antennas are already used on the HC 130 for other VHF applications These were the 618 System Antenna and the Emergency Locator Transmitter antenna they were borrowed from AR amp SC for testing purposes One other antenna which was recommended at the 1998 Orbcomm Users Conference was bought commercially It is a blade antenna manufactured by Antenna Specialists Division of Allen Telecom Inc Model ASP 574ORB The 618 System antenna proved to have the best performance Graphical results of the antenna comparisons can be found in Appendix B The VHF antenna was mounted on top of the aircraft toward the front figures 15 and 16 The SC was mounted below the radioman s table in the cockpit figure 17 The laptop computer running StelComm was operated from the radioman s table figure 18 The GPS interface was split from the aircraft s existing GPS system figure 19 13 Figure 15 HC 130 VHF Antenna Figure 16 HC 130 VHF Antenna 14 LI d E Figure 18 HC 130 Laptop computer on radio table 15 Figure 19 HC 130 GPS splitter mounted below radio table HH 60 Installations The Orbcomm system was installed on two HH 60 Jayhawk helicopters at U S Coast Guard Air Station San Diego The installations were conducted with the support of the Office of Aeronautical E
30. enecks often associated with the Internet Bandwidth Bandwidth is the width of a communications channel Essentially it is a measure of how much information can be transferred by the channel The Orbcomm system 15 capable of sending data at 2400 bps and receiving data at 4800 bps In a packet switched system like Orbcomm however the bandwidth 15 not as much of a concern as it would be in a circuit switched system where a dial up connection 15 established Users are billed by the size of the message not the amount of time it takes to transmit As long as the transmission time is not unreasonable Orbcomm users need not be concerned with the bandwidth Latency Latency is the end to end delay of information sent over the system The time it takes to physically transmit a message over the satellite channel is negligible compared to other delays For example the message will sit in a queue at the GES if SC terminated or at the SC if SC originated until the SC has both a satellite and a gateway to link to Additional delays may be caused by earth station switching network congestion or system failures For the purposes of this study these intermediate delays were not measured individually Latency was calculated simply by subtracting the time the originator hit the send key from the time the message arrived in the recipient s inbox For consistency only messages originated at the SC were considered Several thousand SC originated me
31. ent The EL 2000G is compact and lightweight but extremely rugged The box consists of a case battery charger RS 232 port analog and digital I O and embedded GPS The EL2000 is the same piece of equipment without the GPS The 12 volt DC 0 8 amp hour rechargeable lead acid battery will power the unit for up to six hours in standby operation and up to three weeks in sleep mode Uninterrupted operation is provided by the built in battery charger which will accept anywhere from 9 to 36 volts DC EL 2000G Block Diagram VHF Antenna 9 36 VDC SIGNAL Serial Interface PROCESSING BOARD Discrete I O ORE BOARD EL 2000G Figure 5 Components of Stellar EL2000G The EL 2000G is designed to interface with personal computers sensors alarms and other equipment via the standard I O cable We used Pentium laptop computers running Microsoft s Windows 95 operating system and StelComm software to control the unit StelComm is available free of charge at the manufacturer s web site and is used to view status set parameters send and receive messages and configure applications The Status window shown in figure 6 shows the current state of communications between the EL 2000G and the Orbcomm system Details include UTC time and date as reported by GPS number of downlink packet errors total number of gateways connected to the satellite in view number of terminated messages in the unit s memory queue number of origin
32. f an increase in distance from the GES The contour lines in figure 28 represent the maximum gap length in minutes for the same geographic location and time period 22 Real Time Scenario zauthcem arb Gap Threshold 0 0 minutes Planes B F G D Configuration 1 11 Created 10 05 1999 Figure 27 Post D plane access to Curacao GES 198 0 174 8 d N15 1 7 198 B ex Real Time Availability Scenario southcom arb Access Threshold 100 004 Planes B F G D Configuration 1 11 Created 10 05 1999 Figure 28 Post D plane maximum gaps in access to Curacao GES in minutes 23 Orbcomm also plans to launch eight more satellites into an equatorial plane sometime 1n late 2000 This plane will be inclined zero degrees at an altitude of 800km Figures 29 and 30 show percent access to the Curacao GES and gaps in access to the Curacao GES respectively These graphics show that coverage will greatly improve in the lower latitudes when the Orbcomm satellite constellation 15 complete Therefore it 15 probable that Orbcomm will provide an acceptable level of service in most areas the Coast Guard operates Real Time Scenario LIS Curacao orb Threshold 0 0 minutes Planes B C D E Configuration 2 5 Created 10 05 1999 Figure 29 Post equatorial plane access to Curacao GES 5 0 Real Time Avalabilit M Scenario USA GES
33. ich is a multi word password If a user were to forget his or her passphrase a new key pair would have to be generated and validated by a trusted user All user profiles would have to be managed from a central location where users could dial in to obtain other user s public keys Although PGP could work with a system like Orbcomm implementation would be time consuming complicated and training intensive Cost This parameter includes both fixed prices for equipment and recurring fees for usage The price of the Stellar EL2000G is approximately 750 with embedded GPS VHF antennas were less than 200 each Like most systems the major cost driver for Orbcomm is service Orbcomm service is provided through Value Added Resellers VARs Similar to cellular telephone service providers Orbcomm VARs offer different pricing plans The average cost for service 15 about 15 20 month plus 0 01 byte of data Fixed length reports such as position reports cost approximately 0 20 each with no additional cost per character Using this cost structure a typical 3000 Kb message would cost 30 00 to send For this reason many of the VARs are offering a promotional pricing plan until a more reasonable pricing scheme can be negotiated with Orbcomm One such plan being offered on GSA schedule costs a flat rate of 27 month per SC for unlimited service This plan is only being offered for 18 months beginning FY99Q4 and may or may not be available in the fut
34. laptop computer running StelComm was located on the chart table when in use figure 12 A MAXRAD MFB VHF Series omni directional fiberglass antenna was mounted on the mast ladder for the RF interface figure 13 The magnetic GPS antenna was mounted on the ship s speaker figure 14 DC power was provided from the boat s internal power supply 11 Figure 13 Patrol boat VHF MAXRAD antenna 12 Figure 14 Patrol Boat GPS antenna mounted on speaker HC 130 Installations The Orbcomm system was installed on one HC 130 Hercules class aircraft at U S Coast Guard Air Station Sacramento The installation was coordinated with the support of the Office of Aeronautical Engineering G SEA and the U S Coast Guard Aircraft Repair and Supply Center AR amp SC The Electromagnetic Compatibility EMC Safety of Flight Testing SOFT was conducted by NAVAIRWARCEN Patuxent River MD Unlike other SATCOM systems there is not a transceiver specifically manufactured for the aviation community Therefore we were able to use the Stellar EL2000G SC for the aircraft testing as well as the shipboard testing Several tests were conducted in the Advanced Comms Lab to find a VHF antenna comparable to the MAXRAD antenna and suitable for aviation In order to determine the best candidate two separate systems were set up in the lab The systems were identical with the exception of the RF interface one of the systems used the MAXRAD antenna while the other used on
35. ly made up of 28 Microstar satellites with a launch of seven more expected in early November and another eight in late 2000 The main function of these satellites 1s to complete the link between a mobile user and an earth station or gateway ORBCOMM 15 a bent pipe system so both the user and a gateway must be within the footprint of the same satellite in order to communicate in real time There is no inter satellite communication however if no gateway is available a satellite can store data in its memory until it passes over a gateway A message sent using this store and forward process is called a Globalgram Globalgrams must be pre designated by the user are limited to 128 characters and cost more than standard messages The current constellation of satellites consists of five separate orbital planes A B C F and G The A B and C planes each contain eight satellites and are inclined 45 degrees at an altitude of 775 km The D plane which is scheduled for launch in early November will consist of seven satellites and will also be inclined 45 degrees at an altitude of 775 km The F and G planes each consist of two satellites in a near polar orbit at an altitude of 825 km These two planes are inclined 70 degrees and 108 degrees respectively The planned launch in 2000 will put eight more satellites in an equatorial orbit zero degrees at an altitude of 800 km b bringing the total constellation to 43 Figures 1 and 2 below depict the
36. med to occur only when the message was split between two different satellite passes Duplicate messages were identified by setting a flag in the spreadsheet to alert us when two or more messages had the same queue time This problem has not been resolved by Orbcomm yet It is more of an annoyance than a major problem since no information 15 lost however the user will be billed for two messages instead of one Ease of Use At the end of the testing period users were interviewed to determine how they felt about the system In general the users found the system very easy to use StelComm can be learned by most users in about an hour of training Since most users are already familiar with Microsoft Outlook from using SWIII little or no training was necessary to use SatEx with Outlook The automatic position reporting feature was extremely easy to use Once the unit is configured to send position reports at a designated time interval the user does not have to intervene The laptop computer could be turned off or detached and the SC would still continue to send position reports until it either lost power or was manually reconfigured The PGP encryption module described later in this section was very difficult to manage and use Unlike current secure systems like the Coast Guard s High Frequency Data Link Orbcomm users are responsible for encrypting and decrypting each message Each individual user 15 assigned a key pair and a passphrase wh
37. nd ICO Additionally an updated version of the Technology Assessment of Mobile Satellite System Alternatives report will be produced in order to keep up with the dynamic mobile SATCOM marketplace Orbcomm is a low cost data only SATCOM system designed for monitoring remote equipment tracking mobile assets and sending and receiving short messages The transceivers are relatively small inexpensive and low power The same transceiver can be used across all platforms as long as an appropriate VHF antenna is provided Service can be purchased through any number of Value Added Resellers VARs There is a small charge for monthly service similar to what you would pay for cellular service Position reports can be sent automatically to a predetermined e mail account at a cost of approximately 0 25 each Messages cost about 0 35 each plus an additional 0 01 per character The penny per character pricing scheme is cost prohibitive for long messages but reasonable for short messages The system is not intended for sending attachments In summary Orbcomm has the potential to meet some but not all of the Coast Guard s communications requirements The feature with the most value to the Coast Guard is probably the automatic position reporting The position report interval can be set up ahead of time so that no user interface 15 required to track mobile units engaged in Coast Guard operations The system 1s also 1deal for sending short messages to and
38. ngineering G SEA and the U S Coast Guard Aircraft Repair and Supply Center AR amp SC The Electromagnetic Compatibility EMC Safety of Flight Testing SOFT was conducted by NAVAIRWARCEN Patuxent River MD The Stellar EL2000G was mounted in the extended avionics rack figure 20 The HH 60 Emergency Locator Transmitter ELT antenna was tested in the Advanced Comms Lab for use as the RF interface but performed poorly Results of this test can be found 1n Appendix B The DMC 63 3 A VHF FM antenna was recommended by AR amp SC and resulted in satisfactory performance lab testing results are not available The antenna was mounted on the auxiliary door on top of the aircraft figure 21 so that the door could be swapped out for an unaltered one at the end of the testing period The GPS interface was provided by a small patch antenna which was mounted on a bracket in the cockpit over the co pilot s head figure 22 16 The R amp D Center affixed a small laptop computer to a kneeboard figure 23 in order to make it easy for an aircrewman to operate StelComm breakout box figure 24 was fabricated to provide a power interface data interface and control mechanism for the SC and the laptop computer The power interface consisted of a single 5 Amp circuit breaker in the avionics rack The aircraft s 28Vdc power was distributed to the EL2000G and to the breakout box At the breakout box the power was fused to protect the aircraft from a failure
39. of key pairs one for each patrol boat and one for the R amp D Center were created by the R amp D Center for testing purposes The key pairs were loaded onto three PGP equipped laptop computers and the SWIII at the R amp D Center The laptops were then shipped to the boats where users could send and receive PGP encrypted messages to the other three recipients Since the key pairs were created at the R amp D Center and not by each individual user the system was no longer secure and was not used to send sensitive information PGP pass phrases were given out over the telephone and all personnel on the boat used the same pass phrase The users were kept busy with day to day Coast Guard operations and considered the additional steps necessary to encrypt and decrypt messages a burden Enough messages were sent however to determine that the system will support PGP On average message size increased by 33 percent after encryption This increase in message size did not have a significant effect on latency but would be a cost issue if we were paying a penny per character CONCLUSIONS The Orbcomm system is a low cost commercial SATCOM alternative that has potential to improve communications in the Coast Guard It 1s ideally suited for automatic position reporting and short messaging It is not cost effective or practical to use the system for sending lengthy messages The system cannot accommodate file attachments or graphics The same hardware with the e
40. of the Orbcomm system From the breakout box the power was distributed to the aircrewman s kneeboard Internal to the kneeboard the power was converted to 15Vdc and supplied to the laptop computer The data interface was established between the EL2000G s serial port and the laptop computer s serial port via the breakout box A control mechanism was established between the breakout box and the EL2000G in order to turn the unit on or off gt 1 gt Y m i Figure 20 HH 60 Orbcomm transceiver mounted on extended avionics rack 17 z LE 1 F 1 Figure 21 60 VHF antenna We Figure 22 HH 60 Orbcomm GPS antenna 18 Figure 23 HH 60 Kneeboard with mounted laptop computer Figure 24 HH 60 Breakout box mounted port side of aircraft 19 SYSTEM PERFORMANCE Coverage Coverage is the geographic area in which a mobile user has access to the satellite system Although the 28 Orbcomm satellites currently in orbit provide global coverage they do not provide simultaneous global coverage In other words not every inch of the Earth s surface 15 in the footprint of a satellite at all times It takes approximately 1 5 hours for each satellite to orbit the Earth Since the Earth is also rotating at a slower rate each time the satellite orbits it s path will shift with respect to the Earth s surface So a user in a given location will be covered by several different possibly overlap
41. ons requirements The solution will not likely be a single system but rather a combination of satellite HF and VHF systems It must be accurate robust interoperable secure and timely Although MILSATCOM will continue to be a DOD requirement Coast Guard communications can be preempted by higher priority DOD requirements Commercial SATCOM bridges the gap between MILSATCOM and complete loss of satellite communication service and may provide substantial cost savings At least 40 different commercial SATCOM companies will be offering service in the next five years These systems will differ in both physical attributes and functional capabilities The goal is to identify the systems that will most effectively meet the specific operational requirements of the Coast Guard at the lowest cost The first step taken by the R amp D Center as part of the Mobile Communications Infrastructure Project was to identify all existing and emerging SATCOM systems in the Technology Assessment of Mobile Satellite System Alternatives report Next the Coast Guard s Mobile Communications Requirements report Anteon 1998 was written to collect and document specific operational requirements of different missions and platforms within the organization The R amp D Center is in the process of testing and evaluating several of the candidate systems documented in the Technology Assessment of Mobile Satellite System Alternatives report to determine if they meet th
42. ping satellite footprints during the course of a day Coverage depends on many factors For example if a satellite passes directly overhead a user will experience the full diameter of the satellite s footprint On the other hand if the satellite does not pass directly overhead the user will benefit for a shorter time span Figure 25 illustrates this point Satellite footprint Figure 25 Length of satellite pass depends upon distance from center of footprint It 15 important to remember however that a user needs a gateway as well as a satellite to send messages in the real time mode For the purposes of this study coverage will be defined as the amount of time the user has both a satellite and a gateway in view In figure 26 the shaded eray area depicts actual coverage duration The circles represent the footprint of a satellite as 1t moves from left to right In step 1 the gateway 15 just coming into the satellite footprint In step 2 the user 15 just coming into the satellite footprint Step 3 shows the gateway leaving the satellite s footprint and step 4 shows the user leaving it The only time the user is able to send a message in real time 1s during the intersection of steps 2 and 3 20 GATEWAY USER Ng gt gt 4 Figure 26 Length of user satellite gateway chain duration A software package called Satellite ToolKit STK manufactured by Analytical Graphics Inc AGI was used to predict coverage STK can
43. port Date U S Coast Guard Research and Development Center 1082 Shennecossett Road Groton CT 06340 6096 11 Contract or Grant No 9 Performing Organization Name and Address 10 Work Unit No TRAIS 12 Sponsoring Organization Name and Address 13 Type of Report amp Period Covered Final Report U S Department of Transportation 14 Sponsoring Agency Code United States Coast Guard Commandant G SCT Office of Communications Systems U S Coast Guard Headquarters Washington DC 20593 0001 Washington DC 20593 0001 15 Supplementary Notes The R amp D Center s technical point of contact is LTJG Amy B Grable 860 441 2671 email agrable rdc uscg mil 16 Abstract MAXIMUM 200 WORDS The Orbcomm Low Earth Orbit LEO satellite communications SATCOM system was tested and evaluated at the U S Coast Guard R amp D Center as part of the ongoing Mobile Communications Infrastructure project The objective of the project is to investigate new and emerging SATCOM systems that may satisfy the Coast Guard s rapidly increasing communications requirements Orbcomm is a low cost data only system used for monitoring remote equipment tracking mobile assets and sending receiving short messages After initial testing in the R amp D Center s Advanced Communications Laboratory the system was installed aboard three 110 foot coastal patrol boats two HH 60 Jayhawk helicopters and one HC 130 Hercules fixed wing aircraft The system is very cost
44. ssages were collected over a twelve month period for this analysis Since the uplink from the SC to the satellite 2400 bps is slower than the downlink from the satellite to the SC 4800 bps we were measuring a worst case latency situation In order to remove the end user from the process the Monitoring function of StelComm was used to automatically generate test messages Readings for date time latitude longitude altitude speed and heading were taken every two minutes compiled into the body of a message 27 Time hh mm ss and sent to a predefined e mail address at the R amp D Center every ten minutes or every hour We had the test bed units vary between sending the small and large messages in order to test the latency of different size messages over the system The messages sent every ten minutes were 229 bytes while the messages sent every hour were 1405 bytes A spreadsheet was set up to keep track of these test message latencies The queue time was extracted from the sent time stamp on the message itself while the received time was obtained from the R amp D Center s server mail log These times were subtracted to determine the end to end latency Latency of Monitoring MSGs sent from Tybee SC once every 10 minutes 0 15 00 0 14 30 0 14 00 0 13 30 0 13 00 0 12 30 0 12 00 0 11 30 0 11 00 0 10 30 0 10 00 0 09 30 0 09 00 0 08 30 0 08 00 0 07 30 0 07 00 0 06 30 0 06 00 0 05 30 0 05 00 0 04 30 0 04 00
45. tails Message Default Message Message subjec way Message priori Non urgent Ack leve Aux Message body Acknowledgement Expected TEXT Heceipient address and indicator Heceipient addres Indicato None Message address and indicators lis Address Indentit Primary Blind Copied Figure 8 StelComm Messages window The Application window allows the user to program the SC parameters for several built in autonomous applications The SC can be programmed to monitor digital and analog inputs determine the unit position time date power save logic external power indication and more After the SC is programmed it will operate automatically performing the preprogrammed functions The Monitoring feature shown in figure 9 was used to automatically generate and collect data for our system evaluation This feature allows the user to configure an application for monitoring internal system parameters as well as external sensors and alarms The standard I O cable will accept up to six digital inputs and up to three analog inputs X Application Application Set up Power down Monitoring Position repart Step 3 step 3 In this step the number of lag records in a message is defined message will be transmitted when the number of log records reaches this number Log records in 4 messag 4 In the following steps you will
46. tlook offers many features not available in StelComm such as spell checking folder support auto archiving multiple user profiles and address book Furthermore users required minimal training since most had used Outlook on the Coast Guard s Standard Workstation The beta version of Sat Ex v 1 0 050 2 we tested had some obvious inadequacies It does not support Rich Text Format RTF which is what most e mail clients use If an RTF message is received by a unit running Microsoft Outlook via Sat Ex the message body will be unreadable The message would have to be read using StelComm which has the capability of converting RTF messages to plain text Another disadvantage 15 that Sat Ex and StelComm both utilize the same communications port on the laptop to interface with the transceiver so both applications cannot be running at the same time Therefore the user cannot use StelComm to monitor the system status or set parameters while running Sat Ex The manufacturer of Sat Ex claims that future versions will support RTF as well as data compression and encryption Patrol Boat Installations The Orbcomm system was installed on CGC TYBEE CGC EDISTO and CGC LONG ISLAND all homeported in San Diego CA The installation was coordinated with support from the 11 Coast Guard District Patrol Boat manager and the Electronics Systems Support Detachment San Diego The Stellar EL2000G was mounted above the chart table on the bridge figure 11 A
47. ure 30 Appendix D contains actual cost data for CGC LONG ISLAND CGC TYBEE and CGC EDISTO from July 1998 through June 1999 Although we were not charged character usage fee during the beta test period the graphs show how much we would have spent under one of the VAR pricing plans Actual message traffic was collected during the testing period and separated into three categories 1 general 2 CG business and 3 position reports Only the CG business related messages and the position reports were considered relevant to this study It is clear from the graphs that costs for sending position reports are insignificant compared to the cost for sending messages Security This metric is a measure of how well the system will protect the privacy and integrity of user data Orbcomm and its VARs do not offer any type of encryption however commercial off the shelf COTS encryption packages may be used in conjunction with Orbcomm We tested a software package called Pretty Good Privacy PGP which may be used to send Sensitive But Unclassified SBU message traffic Only hardware solutions are authorized by the National Security Agency for transmitting classified information PGP is listed on the National Institute of Standards and Technology website as conforming to the Federal Information Processing Standard Publication 46 2 Data Encryption Standard DES The current version of PGP uses a 168 bit triple DES algorithm
48. vely new system there were several bugs Most of the problems we encountered with the system were resolved by working together with Orbcomm and Stellar technical support personnel More of these bugs will be worked out as time goes on As explained in the previous section failure of an Orbcomm satellite user will result in decreased coverage If the satellite cannot be restored right away the other satellites in its plane can be controlled to spread out in order to cover the gap If this were to occur the gaps between satellite footprints would increase from two minutes to about four minutes Since Orbcomm satellites are much less complex than traditional communications satellites they are relatively inexpensive to replace The satellites have a lifetime of approximately five years at which time they must be replaced anyway Each GES site 1s equipped with two fully independent antenna systems with associated RF and control equipment Each antenna has its own separate communications link this helps ensure complete functional redundancy Although the Stellar EL2000G units are extremely rugged we did have one failure during testing The unit was replaced by the company at no charge Accuracy Accuracy is a measure of the absence of error In the case of a data system such as Orbcomm this simply means that the information is unchanged when transmitted from sender to receiver Since Orbcomm employs error checking and error correcting algorithms
49. xception of the VHF antenna can be used across all platforms Orbcomm service costs the same no matter where you are geographically Orbcomm does not provide continuous global coverage however gaps in coverage in areas where the Coast Guard operates most frequently are small enough that delays are not unreasonable Currently areas closer to the equator are poorly served Coverage begins to deteriorate significantly south of 22 degrees north latitude This deficiency will be resolved when Orbcomm completes its satellite constellation late next year Construction of new ground earth stations will also increase the amount of time a user has access to the system In general the patrol boat users found the messaging feature to be more valuable than their aircraft counterparts did This 15 probably because the patrol boats were usually underway for weeks at a time sometimes without any means of reliable communications The Commanding 32 Officer of the CGC LONG ISLAND made the following comments in relation to Orbcomm in a patrol summary 11 COS COMMENTS A PATROLLING ALONG AT THE S END OF THE BAJA PENINSULA DURING HURRICANE SEASON INVOLVES SOME RISK FOR USCG UNITS DOING SO WITHOUT ANY LONG RANGE COMMUNICATIONS INCREASES THE RISK FACTOR EXPONENTIALLY TWO PIECES OF NON STANDARD GEAR HELPED KEEP ORIG OUT OF TROUBLE ORBCOMM AND INMARSAT MINI M THE GEAR PROVED IT S IMPORTANCE PRIOR TO OUR HF FAILURE AS DETAILED IN EXAMPLE BELOW AFTER BO
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