With all this talk of NO-84, and me finally having a semi-operational ground station - I went looking for DopplerPSK, but every link I found was broken. Where can I get this software?
--Roy K3RLD
I originally used the link on 2M0SQL's excellent how-to page:
https://www.2m0sql.com/2018/10/29/using-the-no-84-psat-psk-transponder/
... which is:
http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
If that link isn't available, you're welcome to the copy I downloaded which has just been put at:
https://www.qsl.net/k/k4kdr//downloads/DopplerPSK_0.2.zip
-Scott, K4KDR
==========================
On Wed, Jun 12, 2019 at 10:53 AM Roy Dean via AMSAT-BB [email protected] wrote:
With all this talk of NO-84, and me finally having a semi-operational ground station - I went looking for DopplerPSK, but every link I found was broken. Where can I get this software?
--Roy K3RLD
Thanks, Scott, indeed the main site links seem to work but I've added the zip on my server now and linked on the page at the bottom https://www.2m0sql.com/2018/10/29/using-the-no-84-psat-psk-transponder/
73,
Peter, 2M0SQL
On Wed, 12 Jun 2019 at 16:10, Scott via AMSAT-BB [email protected] wrote:
I originally used the link on 2M0SQL's excellent how-to page:
https://www.2m0sql.com/2018/10/29/using-the-no-84-psat-psk-transponder/
... which is:
http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
If that link isn't available, you're welcome to the copy I downloaded which has just been put at:
https://www.qsl.net/k/k4kdr//downloads/DopplerPSK_0.2.zip
-Scott, K4KDR
==========================
On Wed, Jun 12, 2019 at 10:53 AM Roy Dean via AMSAT-BB [email protected] wrote:
With all this talk of NO-84, and me finally having a semi-operational ground station - I went looking for DopplerPSK, but every link I found was broken. Where can I get this software?
--Roy K3RLD
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
I'm very curious about this, thanks for sharing the links. Looks like the program adjusts the PSK modulation within the pass band of the uplink, and at 10 meters, that would be relatively small. It makes sense, however would this work if SatPC32 manages the uplink ? Secondly, I came across this on the website: "DopplerPSK does not provide any PSK31 demodulation; you should use a separate program for that purpose. DopplerPSK does not provide any compensation for downlink Doppler (which you would need for fully linear transponders)." Question 2 - why not use something like HRD for everything (doppler, psk, rotator, logging, etc) ? (I believe I tried it sometime back by routing of the downlink audio back into HRD) 73! Umesh k6vug
On Wednesday, June 12, 2019, 8:10:11 AM PDT, Scott via AMSAT-BB [email protected] wrote:
I originally used the link on 2M0SQL's excellent how-to page:
https://www.2m0sql.com/2018/10/29/using-the-no-84-psat-psk-transponder/
... which is:
http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
If that link isn't available, you're welcome to the copy I downloaded which has just been put at:
https://www.qsl.net/k/k4kdr//downloads/DopplerPSK_0.2.zip
-Scott, K4KDR
==========================
On Wed, Jun 12, 2019 at 10:53 AM Roy Dean via AMSAT-BB [email protected] wrote:
With all this talk of NO-84, and me finally having a semi-operational ground station - I went looking for DopplerPSK, but every link I found was broken. Where can I get this software?
--Roy K3RLD
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
While it might certainly be possible to put together a solution that would compensate your uplink so that its corresponding downlink through the transponder holds stationary on a single spot on the downlink audio spectrum, there are two reasons (at least) that I can think of to not go to that trouble:
#1, the DopplerPSK app takes care of it perfectly already. The work has been done.
#2, if memory serves, some radios do not respond to CAT frequency adjustments when transmitting. In this mode, your uplink radio is transmitting non-stop for the entire ~10 minute pass. If you have a hardware/software setup that can only change RF frequency when in receive mode, that will never happen during an NO-84 pass.
Lastly, like much satellite work, the uplink and downlink are two completely separate discussions in this mode. While the 10m uplink works extremely well with the DopplerPSK software and the HF radio of your choice, receiving & demodulating the PSK31 downlink can be done by any antenna/FM radio(or SDR), and computer combination of your liking. Just as one example, my setup is:
TX: Windows PC > DopplerPSK > Signalink > FT-857d > MyAntennas EFHW-8010
RX: 70cm X-Quad > SDRPlay RSP1 > HDSDR on Windows PC (doppler track w/ Orbitron) > FLDigi
-Scott, K4KDR
==============================
On Wed, Jun 12, 2019 at 8:20 PM [email protected] [email protected] wrote:
I'm very curious about this, thanks for sharing the links.
Looks like the program adjusts the PSK modulation within the pass band of the uplink, and at 10 meters, that would be relatively small. It makes sense, however would this work if SatPC32 manages the uplink ?
Secondly, I came across this on the website:
"DopplerPSK does not provide any PSK31 demodulation; you should use a separate program for that purpose. DopplerPSK does not provide any compensation for downlink Doppler (which you would need for fully linear transponders)."
Question 2 - why not use something like HRD for everything (doppler, psk, rotator, logging, etc) ? (I believe I tried it sometime back by routing of the downlink audio back into HRD)
73! Umesh k6vug
On Wednesday, June 12, 2019, 8:10:11 AM PDT, Scott via AMSAT-BB < [email protected]> wrote:
I originally used the link on 2M0SQL's excellent how-to page:
https://www.2m0sql.com/2018/10/29/using-the-no-84-psat-psk-transponder/
... which is:
http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
If that link isn't available, you're welcome to the copy I downloaded which has just been put at:
https://www.qsl.net/k/k4kdr//downloads/DopplerPSK_0.2.zip
-Scott, K4KDR
==========================
On Wed, Jun 12, 2019 at 10:53 AM Roy Dean via AMSAT-BB <[email protected]
wrote:
With all this talk of NO-84, and me finally having a semi-operational ground station - I went looking for DopplerPSK, but every link I found
was
broken. Where can I get this software?
--Roy K3RLD
Scott, Roy, Umesh, et al; Part of the problem with PSK31 is that it required the adjustment for changes in Doppler shift to be to be phase-continuous. I think the Doppler rate (delta-Doppler shift) at even 10m is too fast for most radios--what you often get with CAT control, even if you can update while transmitting, is PSK31 that jumps more than 31Hz per update, and that totally destroys the phase continuity required to tell a '1' from '0'. This was the "fun" problem that spurred me to take a swing at it over a summer vacation. When DopplerPSK applies "anti-doppler" on the transmitted signal, it does so at the baseband audio level. This works fine for 3Khz passbands on a 10m uplink, but if you want to do it with SSB transponders and VHF and UHF you'll need an SDR where you aren't limited by an IF filter. The same algorithm in DopplerPSK could be used on a complex signal in the SDR architecture, and it could work equally on TX and RX in the processing chain. To the accuracy of the orbital elements everyone uses, if everyone corrects their uplink and downlink properly there is no perceived frequency drift by anyone using the satellite. Just what you need for a GHz-range LEO with a narrow-band transponder, eh? Since the downlink of NO-84 is FM there is no Doppler shift in the baseband audio of the downlink--you hear what the satellite hears. If we get a mode-K satellite it might be worthwhile to do a baseband demodulator in a soundcard since the total change in Doppler shift will be small enough to fit in a conventional HF radio's IF passband in both directions. If the antiquated hosting site doesn't come back I'll get off my duff and find a "proper" place for it. It's nice to see people playing around with it. (Thanks for bridging the gap in the meantime, Peter.) Andy K0SM/2
On Wednesday, June 12, 2019, 9:24:12 PM EDT, Scott via AMSAT-BB [email protected] wrote:
While it might certainly be possible to put together a solution that would compensate your uplink so that its corresponding downlink through the transponder holds stationary on a single spot on the downlink audio spectrum, there are two reasons (at least) that I can think of to not go to that trouble:
#1, the DopplerPSK app takes care of it perfectly already. The work has been done.
#2, if memory serves, some radios do not respond to CAT frequency adjustments when transmitting. In this mode, your uplink radio is transmitting non-stop for the entire ~10 minute pass. If you have a hardware/software setup that can only change RF frequency when in receive mode, that will never happen during an NO-84 pass.
Lastly, like much satellite work, the uplink and downlink are two completely separate discussions in this mode. While the 10m uplink works extremely well with the DopplerPSK software and the HF radio of your choice, receiving & demodulating the PSK31 downlink can be done by any antenna/FM radio(or SDR), and computer combination of your liking. Just as one example, my setup is:
TX: Windows PC > DopplerPSK > Signalink > FT-857d > MyAntennas EFHW-8010
RX: 70cm X-Quad > SDRPlay RSP1 > HDSDR on Windows PC (doppler track w/ Orbitron) > FLDigi
-Scott, K4KDR
==============================
On Wed, Jun 12, 2019 at 8:20 PM [email protected] [email protected] wrote:
I'm very curious about this, thanks for sharing the links.
Looks like the program adjusts the PSK modulation within the pass band of the uplink, and at 10 meters, that would be relatively small. It makes sense, however would this work if SatPC32 manages the uplink ?
Secondly, I came across this on the website:
"DopplerPSK does not provide any PSK31 demodulation; you should use a separate program for that purpose. DopplerPSK does not provide any compensation for downlink Doppler (which you would need for fully linear transponders)."
Question 2 - why not use something like HRD for everything (doppler, psk, rotator, logging, etc) ? (I believe I tried it sometime back by routing of the downlink audio back into HRD)
73! Umesh k6vug
On Wednesday, June 12, 2019, 8:10:11 AM PDT, Scott via AMSAT-BB < [email protected]> wrote:
I originally used the link on 2M0SQL's excellent how-to page:
https://www.2m0sql.com/2018/10/29/using-the-no-84-psat-psk-transponder/
... which is:
http://www.frontiernet.net/~aflowers/dopplerpsk/dopplerpsk.html
If that link isn't available, you're welcome to the copy I downloaded which has just been put at:
https://www.qsl.net/k/k4kdr//downloads/DopplerPSK_0.2.zip
-Scott, K4KDR
==========================
On Wed, Jun 12, 2019 at 10:53 AM Roy Dean via AMSAT-BB <[email protected]
wrote:
With all this talk of NO-84, and me finally having a semi-operational ground station - I went looking for DopplerPSK, but every link I found
was
broken. Where can I get this software?
--Roy K3RLD
_______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
On 6/12/19 19:58, aflowers--- via AMSAT-BB wrote:
The same algorithm in DopplerPSK could be used on a complex signal in the SDR architecture, and it could work equally on TX and RX in the processing chain. To the accuracy of the orbital elements everyone uses, if everyone corrects their uplink and downlink properly there is no perceived frequency drift by anyone using the satellite. Just what you need for a GHz-range LEO with a narrow-band transponder, eh?
That's exactly what I do in the SDR I've been working on. It uses a Funcube dongle and Raspberry Pi (or any general purpose Linux or OSX system) and applies an optional frequency rate to the digital local oscillator. The Funcube samples at 192 kHz, so you have a lot of room. Right now it can do a quadratic phase function, i.e., it can sweep at a constant rate in frequency, which is a constant acceleration with continuous phase and frequency. (I'll have to think about which order PLL this corresponds to.)
It would be easy to extend this to higher orders, but because you can update everything very rapidly (it's all in software) I've seen no real need to do so.
Originally the SDR read the velocity data from a pipe, but more recently I've changed over IP multicasting for everything. A completely separate program, which can be on a different computer, multicasts the tracking data to the LAN and the SDRs (there can be more than one) pick it up and make the frequency computations based on the current frequency.
It all works very well. I tested it on one of the older Japanese cubesats that transmits a CW beacon on 70 cm. At first I thought I had a bug in my program because the CW shifted every time it started. Then I realized it was just a soft power system in an old satellite; the beacon remained rock steady in a 200 Hz CW filter from horizon to horizon. Naturally this requires accurate elements and clock time. It was a little weird hearing miscellaneous spurs sweep through the passband as the signal stayed in the middle.
All said, PSK31 still isn't the best choice for a LEO satellite with a lot of Doppler...
Phil
Hello Phil,
Nice application for SDR !
You can also use for check these satellites that emit continuous carrier.
http://amsat.org.ar/pass?satx=lo-19,co-55
73, lu7abf, Pedro
On 6/19/19, Phil Karn via AMSAT-BB [email protected] wrote:
On 6/12/19 19:58, aflowers--- via AMSAT-BB wrote:
The same algorithm in DopplerPSK could be used on a complex signal in the SDR architecture, and it could work equally on TX and RX in the processing chain. To the accuracy of the orbital elements everyone uses, if everyone corrects their uplink and downlink properly there is no perceived frequency drift by anyone using the satellite. Just what you need for a GHz-range LEO with a narrow-band transponder, eh?
That's exactly what I do in the SDR I've been working on. It uses a Funcube dongle and Raspberry Pi (or any general purpose Linux or OSX system) and applies an optional frequency rate to the digital local oscillator. The Funcube samples at 192 kHz, so you have a lot of room. Right now it can do a quadratic phase function, i.e., it can sweep at a constant rate in frequency, which is a constant acceleration with continuous phase and frequency. (I'll have to think about which order PLL this corresponds to.)
It would be easy to extend this to higher orders, but because you can update everything very rapidly (it's all in software) I've seen no real need to do so.
Originally the SDR read the velocity data from a pipe, but more recently I've changed over IP multicasting for everything. A completely separate program, which can be on a different computer, multicasts the tracking data to the LAN and the SDRs (there can be more than one) pick it up and make the frequency computations based on the current frequency.
It all works very well. I tested it on one of the older Japanese cubesats that transmits a CW beacon on 70 cm. At first I thought I had a bug in my program because the CW shifted every time it started. Then I realized it was just a soft power system in an old satellite; the beacon remained rock steady in a 200 Hz CW filter from horizon to horizon. Naturally this requires accurate elements and clock time. It was a little weird hearing miscellaneous spurs sweep through the passband as the signal stayed in the middle.
All said, PSK31 still isn't the best choice for a LEO satellite with a lot of Doppler...
Phil
Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb
On 6/19/19 13:55, Pedro Converso wrote:
Hello Phil,
Nice application for SDR !
You can also use for check these satellites that emit continuous carrier.
http://amsat.org.ar/pass?satx=lo-19,co-55
73, lu7abf, Pedro
Seemed like a natural to me, since radios never tune cleanly.
The question about the satellites is how stable those carriers really are. Doing this right requires a 2-way coherent Doppler transponder on the spacecraft. We really should fly one.
Phil
participants (7)
-
aflowers＠frontiernet.net -
k6vug＠sbcglobal.net -
Pedro Converso -
Peter Goodhall (2M0SQL) -
Phil Karn -
Roy Dean -
Scott