That's pretty interesting that you feel we need 1 Watt or so for 9600 baud downlink, Mark. I'm not sure if anyone thought about that. We have also been talking about multiple speed uplinks. I.e. one receiver at 1200, 1 at 9600, or whatever. Personally I want a 1200 baud uplink for my *&)E^T# IC9700, which is otherwise a great radio :-)
73,
Burns Fisher, WB1FJ *AMSAT(R) Engineering -- Flight Software*
On Tue, Oct 25, 2022 at 12:04 PM Jonathan Brandenburg via pacsat < pacsat@amsat.org> wrote:
---------- Forwarded message ---------- From: Jonathan Brandenburg jbrandenburg@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question On 10/25/2022 10:45 AM, Mark L. Hammond wrote:
My question--is there one day each week where you'd like me to turn ON Falconsat-3 for about 24 hours of operations?
Thank you for the offer, Mark!
This might be the kick in the pants I need to finally assemble my satellite packet station. I'll get to work on that right away. In the meantime, I hope others on this list are more prepared than I am.
Jonathan
-- Jonathan, KF5IDY
---------- Forwarded message ---------- From: Jonathan Brandenburg via pacsat pacsat@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question
pacsat mailing list -- pacsat@amsat.org View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat@amsat.org To unsubscribe send an email to pacsat-leave@amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
I think I said 500mW to 1W. :-). We know from AO-51 that 1/2 watt is ok. More is better :)
Mark N8MH
On Tue, Oct 25, 2022 at 12:21 PM Burns Fisher (AMSAT) wb1fj@fisher.cc wrote:
That's pretty interesting that you feel we need 1 Watt or so for 9600 baud downlink, Mark. I'm not sure if anyone thought about that. We have also been talking about multiple speed uplinks. I.e. one receiver at 1200, 1 at 9600, or whatever. Personally I want a 1200 baud uplink for my *&)E^T# IC9700, which is otherwise a great radio :-)
73,
Burns Fisher, WB1FJ *AMSAT(R) Engineering -- Flight Software*
On Tue, Oct 25, 2022 at 12:04 PM Jonathan Brandenburg via pacsat < pacsat@amsat.org> wrote:
---------- Forwarded message ---------- From: Jonathan Brandenburg jbrandenburg@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question On 10/25/2022 10:45 AM, Mark L. Hammond wrote:
My question--is there one day each week where you'd like me to turn ON Falconsat-3 for about 24 hours of operations?
Thank you for the offer, Mark!
This might be the kick in the pants I need to finally assemble my satellite packet station. I'll get to work on that right away. In the meantime, I hope others on this list are more prepared than I am.
Jonathan
-- Jonathan, KF5IDY
---------- Forwarded message ---------- From: Jonathan Brandenburg via pacsat pacsat@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question
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And to be fair that is G3RUH/GMSK with no FEC. I’m sure there are more efficient options these days?
73, Drew KO4MA
Sent from my iPhone
On Oct 25, 2022, at 12:46 PM, Mark L. Hammond marklhammond@gmail.com wrote:
I think I said 500mW to 1W. :-). We know from AO-51 that 1/2 watt is ok. More is better :)
Mark N8MH
On Tue, Oct 25, 2022 at 12:21 PM Burns Fisher (AMSAT) wb1fj@fisher.cc wrote: That's pretty interesting that you feel we need 1 Watt or so for 9600 baud downlink, Mark. I'm not sure if anyone thought about that. We have also been talking about multiple speed uplinks. I.e. one receiver at 1200, 1 at 9600, or whatever. Personally I want a 1200 baud uplink for my *&)E^T# IC9700, which is otherwise a great radio :-)
73,
Burns Fisher, WB1FJ AMSAT(R) Engineering -- Flight Software
On Tue, Oct 25, 2022 at 12:04 PM Jonathan Brandenburg via pacsat pacsat@amsat.org wrote:
---------- Forwarded message ---------- From: Jonathan Brandenburg jbrandenburg@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question On 10/25/2022 10:45 AM, Mark L. Hammond wrote:
My question--is there one day each week where you'd like me to turn ON Falconsat-3 for about 24 hours of operations?
Thank you for the offer, Mark!
This might be the kick in the pants I need to finally assemble my satellite packet station. I'll get to work on that right away. In the meantime, I hope others on this list are more prepared than I am.
Jonathan
-- Jonathan, KF5IDY
---------- Forwarded message ---------- From: Jonathan Brandenburg via pacsat pacsat@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question
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--
Mark L. Hammond [N8MH]
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On 10/25/2022 11:48 AM, Andrew Glasbrenner wrote:
And to be fair that is G3RUH/GMSK with no FEC. I’m sure there are more efficient options these days?
Answering a bit for Bill as I know he's not online a lot right now (and he can correct me if I get it wrong)
I agree there are more efficient options. I think the initial plan is supporting the basic protocols to support the vast majority of stations that are already assembled. This is with an eye toward implementing additional options on the uplink(s), potentially while in orbit. For example FX.25 would be a very nice early addition.
Jonathan
On Tue, Oct 25, 2022 at 12:48:41PM -0400, Andrew Glasbrenner wrote:
And to be fair that is G3RUH/GMSK with no FEC. I’m sure there are more efficient options these days?
It depends on what you mean by "efficient". You won't find anything at those speeds that is more computationally efficient. Especially since that modulation is done by hardware in what we are working on.
It's difficult for me to believe that 9600 baud would work on a satellite without FEC. But, maybe so.
Anyway, anything with better performance (against noise, multipath, fading, etc.) is going to take more CPU time. With the hardware we are using, it's probably not feasible to run anything else. You would need either a faster CPU, or more likely due to power concerns, a CPU with a DSP built in, like the AM571x Sitara series from TI.
-corey
73, Drew KO4MA
Sent from my iPhone
On Oct 25, 2022, at 12:46 PM, Mark L. Hammond marklhammond@gmail.com wrote:
I think I said 500mW to 1W. :-). We know from AO-51 that 1/2 watt is ok. More is better :)
Mark N8MH
On Tue, Oct 25, 2022 at 12:21 PM Burns Fisher (AMSAT) wb1fj@fisher.cc wrote: That's pretty interesting that you feel we need 1 Watt or so for 9600 baud downlink, Mark. I'm not sure if anyone thought about that. We have also been talking about multiple speed uplinks. I.e. one receiver at 1200, 1 at 9600, or whatever. Personally I want a 1200 baud uplink for my *&)E^T# IC9700, which is otherwise a great radio :-)
73,
Burns Fisher, WB1FJ AMSAT(R) Engineering -- Flight Software
On Tue, Oct 25, 2022 at 12:04 PM Jonathan Brandenburg via pacsat pacsat@amsat.org wrote:
---------- Forwarded message ---------- From: Jonathan Brandenburg jbrandenburg@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question On 10/25/2022 10:45 AM, Mark L. Hammond wrote:
My question--is there one day each week where you'd like me to turn ON Falconsat-3 for about 24 hours of operations?
Thank you for the offer, Mark!
This might be the kick in the pants I need to finally assemble my satellite packet station. I'll get to work on that right away. In the meantime, I hope others on this list are more prepared than I am.
Jonathan
-- Jonathan, KF5IDY
---------- Forwarded message ---------- From: Jonathan Brandenburg via pacsat pacsat@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question
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--
Mark L. Hammond [N8MH]
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It's difficult for me to believe that 9600 baud would work on a satellite without FEC. But, maybe so.
UO-22, KO-23, KO-25, TO-31, AO-51, GO-32, MO-36, Falconsat-3, and literally dozens of cubesats have and do utilize 9k6 without FEC.
73, Drew KO4MA
On Sat, Oct 29, 2022 at 07:09:05PM -0400, Andrew Glasbrenner wrote:
It's difficult for me to believe that 9600 baud would work on a satellite without FEC. But, maybe so.
UO-22, KO-23, KO-25, TO-31, AO-51, GO-32, MO-36, Falconsat-3, and literally dozens of cubesats have and do utilize 9k6 without FEC.
What kind of ground station is required? Do you need circular polarized antennas, antennas with serious gain, tracking? Or can this be done with more normal equipment, like a 3-element yagi like you can use for FM voice on a satellite?
I assume the satellites are stabilized somehow? Fading will kill 9600 baud.
I ask because I don't have any direct experience with this sort of stuff. Maybe I should try to work Falconsat-3, just for experience. Or if someone in the Dallas area plans a contact I can tag along.
-corey
73, Drew KO4MA
pacsat mailing list -- pacsat@amsat.org View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat@amsat.org To unsubscribe send an email to pacsat-leave@amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
Hi Cory, a few responses below.
On Sat, Oct 29, 2022 at 8:51 PM Corey Minyard minyard@acm.org wrote:
On Sat, Oct 29, 2022 at 07:09:05PM -0400, Andrew Glasbrenner wrote:
It's difficult for me to believe that 9600 baud would work on a
satellite without FEC. But, maybe so.
UO-22, KO-23, KO-25, TO-31, AO-51, GO-32, MO-36, Falconsat-3, and
literally dozens of cubesats have and do utilize 9k6 without FEC.
What kind of ground station is required?
As much as you can afford ;). You can copy a bit of data using a ground plane, but not a good solution for actually using digital birds.
Do you need circular polarized antennas, antennas with serious gain
Gain yes, circular helps but isn’t essential
, tracking?
tracking generally, yes, because of gain
Or can this be done
with more normal equipment, like a 3-element yagi like you can use for
FM voice on a satellite?
FS-3 has a 70cm downlink, so lots of gain is still pretty short. It’ll take several elements. Probably a low noise preamp, too.
I assume the satellites are stabilized somehow?
Yes, often using just a bar magnet in the bird.
Fading will kill 9600 baud.
Many of us have been doing it via satellites for 30 years, so it works ;-)
I ask because I don't have any direct experience with this sort of stuff. Maybe I should try to work Falconsat-3, just for experience. Or if someone in the Dallas area plans a contact I can tag along.
You might consider getting AMSAT’s Getting Started guide. It has lots of good stuff in it.
-corey
73, Mark N8MH
--
Mark L. Hammond [N8MH]
I worked FalconSat-3 reliably for many years using an "arrow" antenna. It was the 4 element "alaskan arrow" and I did mount it on an AZ-EL rotator on the roof, but it worked fine. I had a homebrew masthead preamp with the Down East Microwave (DEMI) board but that was mainly because the FT-736R is deaf on 70cm. The antennae were linearly polarized and it worked pretty well. I did get some slight increase when I later upgraded CP antennas using the LEO pack, but it was workable without. We should remember though that FalconSat-3 is pretty large with 1.25 watts of power, but it only has the same sort of 1/4 wave whip antennae that a cube sat would have.
I was using an old 9600 baud TNC from the 1990s. We should note that software TNCs like Direwolf are considerably better at decoding noisy frames. See WB2OSZs test results: https://github.com/wb2osz/direwolf. We can also get another coding gain by using FEC, see https://github.com/wb2osz/direwolf/blob/master/doc/AX25_plus_FEC_equals_FX25.... I saw a comment early that FEC is compute intensive, but we ran RS(255/223) on all the FOX cubesats. It did not cope with FEC on receive (unless it is used in the software commands?) but it did perform DSP filtering for the DUV signal. So we can likely make that work.
With that said, 9600 baud packet is only going to be about twice as fast as 1200 baud unless we make some changes to the protocols. There is simply too much overhead in each packet and the packets are too short to get the advantage of the additional bit rate. I intend to do some actual measurements and calculations for this, but the Direwolf author has yet another paper on this here: https://github.com/wb2osz/direwolf/blob/master/doc/Why-is-9600-only-twice-as.... Some of that is not true for our link because we are full duplex, but most of it is true. The combinations of very short frames, 20 bytes of overhead per frame and TX delays mean that the actual data transmitted does not scale as you would expect.
73 Chris
On Sat, Oct 29, 2022 at 9:18 PM Mark L. Hammond marklhammond@gmail.com wrote:
Hi Cory, a few responses below.
On Sat, Oct 29, 2022 at 8:51 PM Corey Minyard minyard@acm.org wrote:
On Sat, Oct 29, 2022 at 07:09:05PM -0400, Andrew Glasbrenner wrote:
It's difficult for me to believe that 9600 baud would work on a
satellite without FEC. But, maybe so.
UO-22, KO-23, KO-25, TO-31, AO-51, GO-32, MO-36, Falconsat-3, and
literally dozens of cubesats have and do utilize 9k6 without FEC.
What kind of ground station is required?
As much as you can afford ;). You can copy a bit of data using a ground plane, but not a good solution for actually using digital birds.
Do you need circular polarized antennas, antennas with serious gain
Gain yes, circular helps but isn’t essential
, tracking?
tracking generally, yes, because of gain
Or can this be done
with more normal equipment, like a 3-element yagi like you can use for
FM voice on a satellite?
FS-3 has a 70cm downlink, so lots of gain is still pretty short. It’ll take several elements. Probably a low noise preamp, too.
I assume the satellites are stabilized somehow?
Yes, often using just a bar magnet in the bird.
Fading will kill 9600 baud.
Many of us have been doing it via satellites for 30 years, so it works ;-)
I ask because I don't have any direct experience with this sort of stuff. Maybe I should try to work Falconsat-3, just for experience. Or if someone in the Dallas area plans a contact I can tag along.
You might consider getting AMSAT’s Getting Started guide. It has lots of good stuff in it.
-corey
73, Mark N8MH
--
Mark L. Hammond [N8MH]
pacsat mailing list -- pacsat@amsat.org View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat@amsat.org To unsubscribe send an email to pacsat-leave@amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
Removing individuals since you are all on pacsat.
Excellent points, Chris. To be more specific about your FEC statement: The slow old STM32L, as you say, does do digital signal processing--it filters the audio signal to leave a gap below 300Hz for data, it uses the Goertzel algorithm (essentially three buckets of an FFT), and it filters the DUV data square waves to keep them under 300Hz. The uplink on 1E does have FEC, but not the same one.
It is shocking how much processing can be done on the STM32L, and the TMS570 is faster.
73,
Burns Fisher, WB1FJ *AMSAT(R) Engineering -- Flight Software*
On Sun, Oct 30, 2022 at 10:27 AM Chris Thompson chrisethompson@gmail.com wrote:
I worked FalconSat-3 reliably for many years using an "arrow" antenna. It was the 4 element "alaskan arrow" and I did mount it on an AZ-EL rotator on the roof, but it worked fine. I had a homebrew masthead preamp with the Down East Microwave (DEMI) board but that was mainly because the FT-736R is deaf on 70cm. The antennae were linearly polarized and it worked pretty well. I did get some slight increase when I later upgraded CP antennas using the LEO pack, but it was workable without. We should remember though that FalconSat-3 is pretty large with 1.25 watts of power, but it only has the same sort of 1/4 wave whip antennae that a cube sat would have.
I was using an old 9600 baud TNC from the 1990s. We should note that software TNCs like Direwolf are considerably better at decoding noisy frames. See WB2OSZs test results: https://github.com/wb2osz/direwolf. We can also get another coding gain by using FEC, see https://github.com/wb2osz/direwolf/blob/master/doc/AX25_plus_FEC_equals_FX25.... I saw a comment early that FEC is compute intensive, but we ran RS(255/223) on all the FOX cubesats. It did not cope with FEC on receive (unless it is used in the software commands?) but it did perform DSP filtering for the DUV signal. So we can likely make that work.
With that said, 9600 baud packet is only going to be about twice as fast as 1200 baud unless we make some changes to the protocols. There is simply too much overhead in each packet and the packets are too short to get the advantage of the additional bit rate. I intend to do some actual measurements and calculations for this, but the Direwolf author has yet another paper on this here: https://github.com/wb2osz/direwolf/blob/master/doc/Why-is-9600-only-twice-as.... Some of that is not true for our link because we are full duplex, but most of it is true. The combinations of very short frames, 20 bytes of overhead per frame and TX delays mean that the actual data transmitted does not scale as you would expect.
73 Chris
On Sat, Oct 29, 2022 at 9:18 PM Mark L. Hammond marklhammond@gmail.com wrote:
Hi Cory, a few responses below.
On Sat, Oct 29, 2022 at 8:51 PM Corey Minyard minyard@acm.org wrote:
On Sat, Oct 29, 2022 at 07:09:05PM -0400, Andrew Glasbrenner wrote:
It's difficult for me to believe that 9600 baud would work on a
satellite without FEC. But, maybe so.
UO-22, KO-23, KO-25, TO-31, AO-51, GO-32, MO-36, Falconsat-3, and
literally dozens of cubesats have and do utilize 9k6 without FEC.
What kind of ground station is required?
As much as you can afford ;). You can copy a bit of data using a ground plane, but not a good solution for actually using digital birds.
Do you need circular polarized antennas, antennas with serious gain
Gain yes, circular helps but isn’t essential
, tracking?
tracking generally, yes, because of gain
Or can this be done
with more normal equipment, like a 3-element yagi like you can use for
FM voice on a satellite?
FS-3 has a 70cm downlink, so lots of gain is still pretty short. It’ll take several elements. Probably a low noise preamp, too.
I assume the satellites are stabilized somehow?
Yes, often using just a bar magnet in the bird.
Fading will kill 9600 baud.
Many of us have been doing it via satellites for 30 years, so it works ;-)
I ask because I don't have any direct experience with this sort of stuff. Maybe I should try to work Falconsat-3, just for experience. Or if someone in the Dallas area plans a contact I can tag along.
You might consider getting AMSAT’s Getting Started guide. It has lots of good stuff in it.
-corey
73, Mark N8MH
--
Mark L. Hammond [N8MH]
pacsat mailing list -- pacsat@amsat.org View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/pacsat@amsat.org To unsubscribe send an email to pacsat-leave@amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
-- Chris E. Thompson chrisethompson@gmail.com g0kla@arrl.net
Right. Sorry. I guess I was thinking "a lot more" compared to our 100mW at 1200 bps. 73,
Burns Fisher, WB1FJ *AMSAT(R) Engineering -- Flight Software*
On Tue, Oct 25, 2022 at 12:46 PM Mark L. Hammond marklhammond@gmail.com wrote:
I think I said 500mW to 1W. :-). We know from AO-51 that 1/2 watt is ok. More is better :)
Mark N8MH
On Tue, Oct 25, 2022 at 12:21 PM Burns Fisher (AMSAT) wb1fj@fisher.cc wrote:
That's pretty interesting that you feel we need 1 Watt or so for 9600 baud downlink, Mark. I'm not sure if anyone thought about that. We have also been talking about multiple speed uplinks. I.e. one receiver at 1200, 1 at 9600, or whatever. Personally I want a 1200 baud uplink for my *&)E^T# IC9700, which is otherwise a great radio :-)
73,
Burns Fisher, WB1FJ *AMSAT(R) Engineering -- Flight Software*
On Tue, Oct 25, 2022 at 12:04 PM Jonathan Brandenburg via pacsat < pacsat@amsat.org> wrote:
---------- Forwarded message ---------- From: Jonathan Brandenburg jbrandenburg@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question On 10/25/2022 10:45 AM, Mark L. Hammond wrote:
My question--is there one day each week where you'd like me to turn ON Falconsat-3 for about 24 hours of operations?
Thank you for the offer, Mark!
This might be the kick in the pants I need to finally assemble my satellite packet station. I'll get to work on that right away. In the meantime, I hope others on this list are more prepared than I am.
Jonathan
-- Jonathan, KF5IDY
---------- Forwarded message ---------- From: Jonathan Brandenburg via pacsat pacsat@amsat.org To: pacsat@amsat.org Cc: Bcc: Date: Tue, 25 Oct 2022 11:04:28 -0500 Subject: [pacsat] Re: Introduction and Falconsat-3 question
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--
Mark L. Hammond [N8MH]
participants (6)
-
Andrew Glasbrenner -
Burns Fisher (AMSAT) -
Chris Thompson -
Corey Minyard -
Jonathan Brandenburg -
Mark L. Hammond