[amsat-bb] Re: PSK v. APRS
It could but it would require a dedicated computer. Packet just works within the TNC or radio. On 06-Jun-11 20:07, Greg Dober wrote: > > > Could a system like the ISS be switched to a PSK31 or similar mode in the > future? ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
My pet hate is AX.25 1200bps FM which every satellite seems to use, it uses too much bandwidth, too much power and has no forward error correction. BPSK systems such as that to be used on ARISSat-1 can provide 1000 bps with error correction in less than 1/10th the bandwidth. But the reason AX.25 1200bps FM is still used for new satellites is because there's so much infrastructure, TNC's, PC software etc, already inplace, it's the easy option. Currently there is no single standard for sending data using BPSK not even the data rate is standardized. I believe the BPSK telemetry on FOX will use a different standard to ARISSat. FUNcube and UKube-1 will also use different versions running 1200bps and 9600bps respectively. Personally I think 9600bps BPSK will be the one to go for in the long term but none of these BPSK systems are flying yet. So until they are and are proven to work in space I think AX.25 1200 FM will continue to be used. Getting new equipment on the ISS has an incrediably long lead time and of course relies on someones goodwill to pay some $5,000 a kilo freight charges, so realistically I can't see any significant changes to the ISS equipment for sometime to come. 73 Trevor M5AKA --- On Mon, 6/6/11, Greg Dober wrote: > Bob, > > Guess the APRS dilemma was like splitting the atom. > The real use and the > unintended use. > > > Could a system like the ISS be switched to a PSK31 or > similar mode in the > future? How well would PSK work with Doppler > etc? I use it on HF, but was > wondering if FM and satellites could be feasible. I > believe this was > mentioned as possibly being part of Fox's system. > > 73 > Greg > N3MVF ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
Trevor et al, Thanks for your responses. Very enlightening. Greg N3MVF -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Trevor . Sent: Monday, June 06, 2011 5:39 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: PSK v. APRS My pet hate is AX.25 1200bps FM which every satellite seems to use, it uses too much bandwidth, too much power and has no forward error correction. BPSK systems such as that to be used on ARISSat-1 can provide 1000 bps with error correction in less than 1/10th the bandwidth. But the reason AX.25 1200bps FM is still used for new satellites is because there's so much infrastructure, TNC's, PC software etc, already inplace, it's the easy option. Currently there is no single standard for sending data using BPSK not even the data rate is standardized. I believe the BPSK telemetry on FOX will use a different standard to ARISSat. FUNcube and UKube-1 will also use different versions running 1200bps and 9600bps respectively. Personally I think 9600bps BPSK will be the one to go for in the long term but none of these BPSK systems are flying yet. So until they are and are proven to work in space I think AX.25 1200 FM will continue to be used. Getting new equipment on the ISS has an incrediably long lead time and of course relies on someones goodwill to pay some $5,000 a kilo freight charges, so realistically I can't see any significant changes to the ISS equipment for sometime to come. 73 Trevor M5AKA --- On Mon, 6/6/11, Greg Dober wrote: > Bob, > > Guess the APRS dilemma was like splitting the atom. > The real use and the > unintended use. > > > Could a system like the ISS be switched to a PSK31 or > similar mode in the > future? How well would PSK work with Doppler > etc? I use it on HF, but was > wondering if FM and satellites could be feasible. I > believe this was > mentioned as possibly being part of Fox's system. > > 73 > Greg > N3MVF ___ Sent via AMSAT-BB@amsat.org. 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 AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
Sounds just like yet another "anti wide" rant to me. John, W0JAB ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
Hi John, I'm not so sure it's an anti-wide rant. It is a discussion on a possible way to get more efficient use from the limited bandwidth and power on the bird. I love playing with RTTY on HF and packet on VHF, but when you head down to 14.070 and see all the stations on the sliver of band qso'ing, it seems appealing to use to eliminate overcrowding on a satellite. Greg N3MVF -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of John Becker Sent: Monday, June 06, 2011 7:23 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: PSK v. APRS Sounds just like yet another "anti wide" rant to me. John, W0JAB ___ Sent via AMSAT-BB@amsat.org. 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 AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
Greg, you're overlooking something - the time dimension. Yes, packet is a one-at-a-time affair, but those packets move quickly - 1200bps vs 31bps for PSK31. So, each station only has the bird tied up for a short period of time. You could think of it as a form of time division multiplexing. 73 de AJ4MJ On Mon, Jun 6, 2011 at 7:43 PM, Greg Dober wrote: > Hi John, > > I'm not so sure it's an anti-wide rant. It is a discussion on a possible > way to get more efficient use from the limited bandwidth and power on the > bird. I love playing with RTTY on HF and packet on VHF, but when you head > down to 14.070 and see all the stations on the sliver of band qso'ing, it > seems appealing to use to eliminate overcrowding on a satellite. > > Greg > N3MVF > > -Original Message- > From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On > Behalf Of John Becker > Sent: Monday, June 06, 2011 7:23 PM > To: amsat-bb@amsat.org > Subject: [amsat-bb] Re: PSK v. APRS > > Sounds just like yet another "anti wide" rant to me. > > John, W0JAB > > > > ___ > Sent via AMSAT-BB@amsat.org. 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 AMSAT-BB@amsat.org. 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 AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
At 11:42 AM 6/7/2011, Justin Pinnix wrote: >Greg, you're overlooking something - the time dimension. > >Yes, packet is a one-at-a-time affair, but those packets move quickly - >1200bps vs 31bps for PSK31. So, each station only has the bird tied up for >a short period of time. You could think of it as a form of time division >multiplexing. Of course, if everyone is using computer frequency control, then dozens, if not hundreds of simultaneous QSOs can take place. In other words, frequency division multiplexing. 73 de VK3JED / VK3IRL http://vkradio.com ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
> My pet hate is AX.25 1200bps FM [on] satellites... > ...But the reason AX.25 1200bps FM is still used > for new satellites is because there's so much > infrastructure, TNC's, PC software etc, already > inplace, it's the easy option. Actually, there is another very important reason. Link budget. With AX.25 one can have a 2W transmitter on a cubesat which has enough power to hit an HT on the ground with a whip antenna. The same cubesat running BPSK might be restricted to only 200mw. The difference is the Duty Cycle. The AX.25 packet only lasts 1 second say once every 10 seconds for an average power of 200mw. Which is the same power as the continuous power of the BPSK (200 mw) which is all there is available from the cubesat bus. But the advantage of the AX.25 BURST mode is 10 TIMEs the RF power to the user on the ground. For FM mobile-to-mobile satellite communications on OMNI antennas, that is why we use AX.25, to extend satellite links to mobiles. There are of course other issues and BPSK does have better performance for the SAME power, but as you say, there are not that many mobiles with SSB and all the hardware necessary to auto-tune the radio to track the Doppler. Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
Hi Bob, I accept what you are saying about burst mode but it's possible to develop a BPSK system that does burst mode too. A BPSK system with Forward Error Correction can offer a 16 dB advantage over AX.25 1200 FM. As you say there's loads of FM rigs out there so receiving AX.25 is simple and that's the reason everyone still uses it but for the future we should be looking to more efficient means of communication. 73 Trevor M5AKA --- On Tue, 7/6/11, Bob Bruninga wrote: > > My pet hate is AX.25 1200bps FM > [on] satellites... > > ...But the reason AX.25 1200bps FM is still used > > for new satellites is because there's so much > > infrastructure, TNC's, PC software etc, already > > inplace, it's the easy option. > > Actually, there is another very important reason. > Link budget. > > With AX.25 one can have a 2W transmitter on a cubesat which > has enough power > to hit an HT on the ground with a whip antenna. The > same cubesat running > BPSK might be restricted to only 200mw. > > The difference is the Duty Cycle. The AX.25 packet > only lasts 1 second say > once every 10 seconds for an average power of 200mw. > Which is the same > power as the continuous power of the BPSK (200 mw) which is > all there is > available from the cubesat bus. > > But the advantage of the AX.25 BURST mode is 10 TIMEs the > RF power to the > user on the ground. > > For FM mobile-to-mobile satellite communications on OMNI > antennas, that is > why we use AX.25, to extend satellite links to mobiles. > > There are of course other issues and BPSK does have better > performance for > the SAME power, but as you say, there are not that many > mobiles with SSB and > all the hardware necessary to auto-tune the radio to track > the Doppler. > > Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
A packet satellite can also be operated simplex (TX and RX on the same frequency). That means a single antenna and no diplexer for both the bird and ground station equipment. On Tue, Jun 7, 2011 at 10:16 AM, Trevor . wrote: > Hi Bob, > > I accept what you are saying about burst mode but it's possible to develop > a BPSK system that does burst mode too. > > A BPSK system with Forward Error Correction can offer a 16 dB advantage > over AX.25 1200 FM. > > As you say there's loads of FM rigs out there so receiving AX.25 is simple > and that's the reason everyone still uses it but for the future we should be > looking to more efficient means of communication. > > 73 Trevor M5AKA > > --- On Tue, 7/6/11, Bob Bruninga wrote: > > > My pet hate is AX.25 1200bps FM > > [on] satellites... > > > ...But the reason AX.25 1200bps FM is still used > > > for new satellites is because there's so much > > > infrastructure, TNC's, PC software etc, already > > > inplace, it's the easy option. > > > > Actually, there is another very important reason. > > Link budget. > > > > With AX.25 one can have a 2W transmitter on a cubesat which > > has enough power > > to hit an HT on the ground with a whip antenna. The > > same cubesat running > > BPSK might be restricted to only 200mw. > > > > The difference is the Duty Cycle. The AX.25 packet > > only lasts 1 second say > > once every 10 seconds for an average power of 200mw. > > Which is the same > > power as the continuous power of the BPSK (200 mw) which is > > all there is > > available from the cubesat bus. > > > > But the advantage of the AX.25 BURST mode is 10 TIMEs the > > RF power to the > > user on the ground. > > > > For FM mobile-to-mobile satellite communications on OMNI > > antennas, that is > > why we use AX.25, to extend satellite links to mobiles. > > > > There are of course other issues and BPSK does have better > > performance for > > the SAME power, but as you say, there are not that many > > mobiles with SSB and > > all the hardware necessary to auto-tune the radio to track > > the Doppler. > > > > Bob, Wb4APR > > > ___ > Sent via AMSAT-BB@amsat.org. 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 AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
That's half duplex, not simplex. On 07-Jun-11 14:55, Justin Pinnix wrote: > A packet satellite can also be operated simplex (TX and RX on the same > frequency). ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
Guess I learned the ITU version :-) http://en.wikipedia.org/wiki/Simplex_communication On Tuesday, June 7, 2011, Nigel Gunn G8IFF/W8IFF wrote: > That's half duplex, not simplex. > > On 07-Jun-11 14:55, Justin Pinnix wrote: > > A packet satellite can also be operated simplex (TX and RX on the same > frequency). > > ___ Sent via AMSAT-BB@amsat.org. 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
[amsat-bb] Re: PSK v. APRS
Yep. Traditionally, a simplex channel is one that can ONLY receive or transmit but not both, as in a telemetry beacon or a broadcast radio or TV station. Half-duplex refers to a channel where both reception and transmission can take place but only one at a time. Your operation of an FM repeater, for example, is half-duplex although the repeater is actually operating full-duplex on two frequencies. Full-duplex refers to a system that receives and transmits simultaneously. A wired telephone and cellphone come into this catagory as does nost peoples use of a lineat satellite transponder. On 08-Jun-11 03:33, Justin Pinnix wrote: > Guess I learned the ITU version :-) > > http://en.wikipedia.org/wiki/Simplex_communication > > On Tuesday, June 7, 2011, Nigel Gunn G8IFF/W8IFF wrote: >> That's half duplex, not simplex. >> >> On 07-Jun-11 14:55, Justin Pinnix wrote: >> >> A packet satellite can also be operated simplex (TX and RX on the same >> frequency). >> >> > -- Nigel A. Gunn, 1865 El Camino Drive, Xenia, OH 45385-1115, USA. tel +1 937 825 5032 Amateur Radio G8IFF W8IFF (was KC8NHF 9H3GN), e-mail ni...@ngunn.net www http://www.ngunn.net Member of ARRL, GQRP #11396, QRPARCI #11644, SOC #548, Flying Pigs QRP Club International #385, Dayton ARA #2128, AMSAT-NA LM-1691, AMSAT-UK 0182, MKARS, ALC, GCARES, XWARN, EAA382. ___ Sent via AMSAT-BB@amsat.org. 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
