D-Star protocol is 4.8kb/sec for voice 1.2 kb for FEC and 1.2kb for data. It is GMSK data, transmit rate is 3.6KHz max transmission rate, (7.2kb NRZ), deviation is 1.8 KHz for a modulation index of 0.5. BW per Carlson's rule is 7.2 KHz A vocoder module provides for the voice compression. The Data side is used for Call Sign, Name, City/ State, Brag Tape, GPS position, and Texting all done with voice simultaneously. D-Star is not very successful in mobile operation. I have had lots of conversations go R2D2 from a truck or car passing me. From a fixed position range is surprisingly good. When used on a Satellite this narrow mode I suspect is very sensitive to Doppler as well as multipath. Circular antennas on both ends will solve multipath, but Doppler shift must be dealt with. Art, KC6UQH
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Nathaniel S. Parsons Sent: Saturday, April 10, 2010 10:02 PM To: Tom Azlin N4ZPT Cc: AMSAT-BB Subject: [amsat-bb] Re: BeeSat at 4800 GMSK Ah, thanks for clarifying. Unfortunately, if I understand you correctly, we would have to talk to our satellite via digital voice, or at 128kbps, which would be great if we could! -Nate On Sat, Apr 10, 2010 at 10:15 PM, Tom Azlin N4ZPT <[email protected]> wrote: > Well, make that the digital voice part of the protocol. The high speed > digital data part is up to 128kbps which was not what I was thinking of. > > 73, tom n4zpt > > Tom Azlin N4ZPT wrote: > >> Hi Nate, >> >> the D-STAR protocol is only GMSK at 4800 bps and they selected a >> time-bandwidth product of 0.5. 4,800 bps or 4k8 is perhaps not talked about >> as that IS the standard for D-STAR. So the software there might be >> adaptable. that is the reason I thought to suggest it. >> >> Good luck and 73, Tom n4zpt >> >> >> >> Nathaniel S. Parsons wrote: >> >>> Hi Tom, >>> >>> My mind had indeed played a trick on me, and I remembered MFSK as MSK. >>> >>> As far as the DStar group goes, I don't see any mention of 4800 bps or >>> 4k8 >>> kbps on the public page, so if it's not the group's focus, I don't want >>> to >>> have to rely on that solution. >>> >>> Thanks, >>> -Nate KC2SVI >>> >> _______________________________________________ >> >> Sent via [email protected]. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >> >> _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb __________ Information from ESET NOD32 Antivirus, version of virus signature database 5016 (20100410) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 5016 (20100410) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 5016 (20100410) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
