Re: [amsat-bb] WSJT-X FT8 QSO confirmed between W2JAZ and W5RKN on FO-29
Dave,
I some sense you are right, but this is a weak signal mode usable only when the satellite is far away so the Doppler shift change each second is very small. It isn’t the power being transmitted, but the power received at the satellite that matters, and it was being used only when the satellite was near maximum range. There were other signals on the transponder, both SSB and CW, that were so strong they were causing both amplitude changes and “FMing” of my downlink signal. During preliminary testing with the satellite near, I observed no noticeable changes to other signals in the passband when my signal was strong. Strong CW and SSB signals from others, due to their amplitude changes did produce noticeable changes to my downlink. This could be why we were not successful on AO-7, but were successful on our first try on FO-29, which is more tolerant of other strong signals on the passband.
Ron W5RKN
On Oct 14 14:34:56 UTC 2017, "Dave Webb KB1PVH" <kb1pvh at gmail.com> wrote:
Ron,
I feel your email is a little like "Do as I say, not as I do". Aren't you posting repeatedly asking people to use low power on AO-7, and here you are attempting a full duty cycle mode on AO-7.
Dave-KB1PVH
Sent from my Galaxy S7
On Oct 13, 2017 11:18 PM, "Ronald G. Parsons" <w5rkn at w5rkn.com> wrote:
A few days ago, Rick, W2JAZ, asked me if the new, short, weak signal protocol, FT8, could be used on satellites. I posited it might work near AOS or LOS where the Doppler corrections are small. FT8 is operationally similar to the older protocols but four times faster (15-second T/R sequences) and less sensitive by a few dB.
So we set out to configure our satellite stations to use WSJT-X with FT8. With some configuration advice from W0DHB, we each got our systems configured. Mine (W5RKN) is a Flex-6500 with two DEMI transverters running SmartSDR, SatPC32, FlexSATPC, and WSJT-X. Rick’s (W2JAZ) is a Flex-5000 with U/V module, running PowerSDR, SatPC32, FlexSATPC, and WSJT-X.
After a couple runs on AO-7 without success, we tried again tonight on the 0220Z (14 Oct) pass of FO-29. I started out at my AOS calling CQ W5RKN EM10. After several transmissions without success, the reply W5RKN W2JAZ FN29 popped up on the screen. Then followed the usual signal report, RRR and 73 transmissions.
As soon as I can figure out the appropriate fields for LoTW, we’ll log the QSO there.
I am not aware of other WSJT-X QSOs on the satellites, so I’d be interested in other’s experiences,
Ron and Rick
On the FO29 pass at 0155z this evening, I noticed a very hard time getting into the transponder. The pass was nearly overhead, and the 3w-4w that is normally sufficient was barely cutting it. I also noticed it was 'up and down' alot, whereas some moments it was easy to get in, then it would be nearly impossible. There were also pockets of 'noise' all over the transponder, that sounded somewhat digital, but I just couldn't place them. I found W5PFG in the passband (who was portable in a rare grid in western Texas) and he commented on the difficulty of working an otherwise easier bird tonight as well. I checked the screen, and no other birds were obviously in range, so I started scanning around the passband to see what I could hear. Up around 435.870 I found (or rather heard) what I was looking for. I fired up my recorder and captured this:
https://drive.google.com/open?id=0B8W_KstbAsD_VF9NbGR3ZXlicUE
For those not familiar, that is the telltale sound of MSK144. I work a fair amount of Meteor Scatter in addition to operating satellites, and the noise is unmistakable. Since my shack PC has wsjt-x installed, I quickly fired it up and went to the msk144 mode and after some quick tweaking started decoding the signal. This is a screenshot of what I saw:
http://druidnetworks.com/w5rkn-msk144-fo29.jpg
This signal continued for at least 8 minutes (that I recorded) in a 5 second T/R cycle while FO29 was passing high over North America. Every 5 second the digital signal would get transmitted, and all other SSB qsos would start to fail. You might call this an experiment, but I call it intentional QRM.
*For the record* You are not the first person to play with wsjt-x modes on the linear satellites. Some months ago during the late night hours on the XW's and FO29 when the footprint was primarily over the desert southwest and south pacific, I to "experimented" with FT8 and MSK144. I purposely ran my transmitted signal thru over 100ft of low grade coax to attenuate my uplink to ~1.5w ERP. I made sure the entire transponder was empty before starting, announcing myself, then started the transmission. I decoded myself successfully, said "Well that was dumb" and never did it again. I purposely didn't announce what I had done to the world because I knew someone would think they were being cool too, and would fire up a 2700hz wide 50% duty cycle mode on a high US pass and QRM people trying to make QSOs out of existence, because said individual would lack even basic situational awareness and courtesy to others. What is extra hilarious about the fact that it is you being the responsible party for destroying a pass, is your constant whining to this mailing list about people using too much power on AO-7, when you're one of the worst offenders. On July 16th this summer, I was roving in EM35 and you called me on the 2155z pass of AO7, and you got the first 3 letters of your callsign out before you killed the bird. I know it was you, because I had already made 3 QSOs right at my AOS with other stations using a reasonable amount of power, and as soon as you key'd up the whole bird started FMing and croaked before you even finished your call. You didn't get that grid that day, and after the stunt you pulled this evening - you won't be getting any grids from me in the future either.
-Dave, KG5CCI
On Sat, Oct 14, 2017 at 2:24 PM, Ronald G. Parsons w5rkn@w5rkn.com wrote:
Dave,
I some sense you are right, but this is a weak signal mode usable only when the satellite is far away so the Doppler shift change each second is very small. It isn’t the power being transmitted, but the power received at the satellite that matters, and it was being used only when the satellite was near maximum range. There were other signals on the transponder, both SSB and CW, that were so strong they were causing both amplitude changes and “FMing” of my downlink signal. During preliminary testing with the satellite near, I observed no noticeable changes to other signals in the passband when my signal was strong. Strong CW and SSB signals from others, due to their amplitude changes did produce noticeable changes to my downlink. This could be why we were not successful on AO-7, but were successful on our first try on FO-29, which is more tolerant of other strong signals on the passband.
Ron W5RKN
On Oct 14 14:34:56 UTC 2017, "Dave Webb KB1PVH" <kb1pvh at gmail.com> wrote:
Ron,
I feel your email is a little like "Do as I say, not as I do". Aren't you posting repeatedly asking people to use low power on AO-7, and here you
are
attempting a full duty cycle mode on AO-7.
Dave-KB1PVH
Sent from my Galaxy S7
On Oct 13, 2017 11:18 PM, "Ronald G. Parsons" <w5rkn at w5rkn.com> wrote:
A few days ago, Rick, W2JAZ, asked me if the new, short, weak signal protocol, FT8, could be used on satellites. I posited it might work near AOS or LOS where the Doppler corrections are small. FT8 is operationally similar to the older protocols but four times faster (15-second T/R sequences) and less sensitive by a few dB.
So we set out to configure our satellite stations to use WSJT-X with FT8. With some configuration advice from W0DHB, we each got our systems configured. Mine (W5RKN) is a Flex-6500 with two DEMI transverters
running
SmartSDR, SatPC32, FlexSATPC, and WSJT-X. Rick’s (W2JAZ) is a Flex-5000 with U/V module, running PowerSDR, SatPC32, FlexSATPC, and WSJT-X.
After a couple runs on AO-7 without success, we tried again tonight on
the
0220Z (14 Oct) pass of FO-29. I started out at my AOS calling CQ W5RKN EM10. After several transmissions without success, the reply W5RKN W2JAZ FN29 popped up on the screen. Then followed the usual signal report, RRR and 73 transmissions.
As soon as I can figure out the appropriate fields for LoTW, we’ll log
the
QSO there.
I am not aware of other WSJT-X QSOs on the satellites, so I’d be interested in other’s experiences,
Ron and Rick
Sent via AMSAT-BB@amsat.org. 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: http://www.amsat.org/mailman/listinfo/amsat-bb
First of all, let me apologize for any disruption I may have caused by my tests (experiment, interference, ...).
Last evening around 0120Z I was indeed transmitting MSK144 on a downlink frequency of 435.878 (at the satellite) on a pass of FO-29 with a 4 degree max elevation at my location with the satellite over the Atlantic. The pass was monitored by a station in Virginia as a test of using MSK144 at low angles. I deliberately transmitted near the upper end of the passband. I continuously monitored the passband on my panadapter and there were quite a few QSOs on that pass, all well below my frequency.
I also did a test around 0300Z as shown in your link (http://druidnetworks.com/w5rkn-msk144-fo29.jpg)
If I interfered with any of those QSOs, I am sorry. The test confirmed that MSK144 could be decoded at weak signal levels even in the face of Doppler shift.
As far as the AO-7 incident you mention below, I did on a couple occasions inadvertently cause a mode switch. I was certainly not the only station to cause this action. Because I knew how that action could accidently be caused, I did make a couple posts to AMSAT-BB to help others avoid this mistake.
Again, I am sorry for any problems this may have caused.
Ron W5RKN
From: David Swanson Sent: Monday, October 16, 2017 11:03 PM To: Ronald G. Parsons Cc: AMSAT-BB Subject: Re: [amsat-bb] WSJT-X FT8 QSO confirmed between W2JAZ and W5RKN on FO-29
On the FO29 pass at 0155z this evening, I noticed a very hard time getting into the transponder. The pass was nearly overhead, and the 3w-4w that is normally sufficient was barely cutting it. I also noticed it was 'up and down' alot, whereas some moments it was easy to get in, then it would be nearly impossible. There were also pockets of 'noise' all over the transponder, that sounded somewhat digital, but I just couldn't place them. I found W5PFG in the passband (who was portable in a rare grid in western Texas) and he commented on the difficulty of working an otherwise easier bird tonight as well. I checked the screen, and no other birds were obviously in range, so I started scanning around the passband to see what I could hear. Up around 435.870 I found (or rather heard) what I was looking for. I fired up my recorder and captured this:
https://drive.google.com/open?id=0B8W_KstbAsD_VF9NbGR3ZXlicUE
For those not familiar, that is the telltale sound of MSK144. I work a fair amount of Meteor Scatter in addition to operating satellites, and the noise is unmistakable. Since my shack PC has wsjt-x installed, I quickly fired it up and went to the msk144 mode and after some quick tweaking started decoding the signal. This is a screenshot of what I saw:
http://druidnetworks.com/w5rkn-msk144-fo29.jpg
This signal continued for at least 8 minutes (that I recorded) in a 5 second T/R cycle while FO29 was passing high over North America. Every 5 second the digital signal would get transmitted, and all other SSB qsos would start to fail. You might call this an experiment, but I call it intentional QRM.
*For the record* You are not the first person to play with wsjt-x modes on the linear satellites. Some months ago during the late night hours on the XW's and FO29 when the footprint was primarily over the desert southwest and south pacific, I to "experimented" with FT8 and MSK144. I purposely ran my transmitted signal thru over 100ft of low grade coax to attenuate my uplink to ~1.5w ERP. I made sure the entire transponder was empty before starting, announcing myself, then started the transmission. I decoded myself successfully, said "Well that was dumb" and never did it again. I purposely didn't announce what I had done to the world because I knew someone would think they were being cool too, and would fire up a 2700hz wide 50% duty cycle mode on a high US pass and QRM people trying to make QSOs out of existence, because said individual would lack even basic situational awareness and courtesy to others. What is extra hilarious about the fact that it is you being the responsible party for destroying a pass, is your constant whining to this mailing list about people using too much power on AO-7, when you're one of the worst offenders. On July 16th this summer, I was roving in EM35 and you called me on the 2155z pass of AO7, and you got the first 3 letters of your callsign out before you killed the bird. I know it was you, because I had already made 3 QSOs right at my AOS with other stations using a reasonable amount of power, and as soon as you key'd up the whole bird started FMing and croaked before you even finished your call. You didn't get that grid that day, and after the stunt you pulled this evening - you won't be getting any grids from me in the future either.
-Dave, KG5CCI
I appreciate the apology Ron. I'll consider this event water under the bridge.
Thanks.
-Dave, KG5CCI
On Tue, Oct 17, 2017 at 12:28 PM, Ronald G. Parsons w5rkn@w5rkn.com wrote:
First of all, let me apologize for any disruption I may have caused by my tests (experiment, interference, ...).
Last evening around 0120Z I was indeed transmitting MSK144 on a downlink frequency of 435.878 (at the satellite) on a pass of FO-29 with a 4 degree max elevation at my location with the satellite over the Atlantic. The pass was monitored by a station in Virginia as a test of using MSK144 at low angles. I deliberately transmitted near the upper end of the passband. I continuously monitored the passband on my panadapter and there were quite a few QSOs on that pass, all well below my frequency.
I also did a test around 0300Z as shown in your link ( http://druidnetworks.com/w5rkn-msk144-fo29.jpg)
If I interfered with any of those QSOs, I am sorry. The test confirmed that MSK144 could be decoded at weak signal levels even in the face of Doppler shift.
As far as the AO-7 incident you mention below, I did on a couple occasions inadvertently cause a mode switch. I was certainly not the only station to cause this action. Because I knew how that action could accidently be caused, I did make a couple posts to AMSAT-BB to help others avoid this mistake.
Again, I am sorry for any problems this may have caused.
Ron W5RKN
*From:* David Swanson *Sent:* Monday, October 16, 2017 11:03 PM *To:* Ronald G. Parsons *Cc:* AMSAT-BB *Subject:* Re: [amsat-bb] WSJT-X FT8 QSO confirmed between W2JAZ and W5RKN on FO-29
On the FO29 pass at 0155z this evening, I noticed a very hard time getting into the transponder. The pass was nearly overhead, and the 3w-4w that is normally sufficient was barely cutting it. I also noticed it was 'up and down' alot, whereas some moments it was easy to get in, then it would be nearly impossible. There were also pockets of 'noise' all over the transponder, that sounded somewhat digital, but I just couldn't place them. I found W5PFG in the passband (who was portable in a rare grid in western Texas) and he commented on the difficulty of working an otherwise easier bird tonight as well. I checked the screen, and no other birds were obviously in range, so I started scanning around the passband to see what I could hear. Up around 435.870 I found (or rather heard) what I was looking for. I fired up my recorder and captured this:
https://drive.google.com/open?id=0B8W_KstbAsD_VF9NbGR3ZXlicUE
For those not familiar, that is the telltale sound of MSK144. I work a fair amount of Meteor Scatter in addition to operating satellites, and the noise is unmistakable. Since my shack PC has wsjt-x installed, I quickly fired it up and went to the msk144 mode and after some quick tweaking started decoding the signal. This is a screenshot of what I saw:
http://druidnetworks.com/w5rkn-msk144-fo29.jpg
This signal continued for at least 8 minutes (that I recorded) in a 5 second T/R cycle while FO29 was passing high over North America. Every 5 second the digital signal would get transmitted, and all other SSB qsos would start to fail. You might call this an experiment, but I call it intentional QRM.
*For the record* You are not the first person to play with wsjt-x modes on the linear satellites. Some months ago during the late night hours on the XW's and FO29 when the footprint was primarily over the desert southwest and south pacific, I to "experimented" with FT8 and MSK144. I purposely ran my transmitted signal thru over 100ft of low grade coax to attenuate my uplink to ~1.5w ERP. I made sure the entire transponder was empty before starting, announcing myself, then started the transmission. I decoded myself successfully, said "Well that was dumb" and never did it again. I purposely didn't announce what I had done to the world because I knew someone would think they were being cool too, and would fire up a 2700hz wide 50% duty cycle mode on a high US pass and QRM people trying to make QSOs out of existence, because said individual would lack even basic situational awareness and courtesy to others. What is extra hilarious about the fact that it is you being the responsible party for destroying a pass, is your constant whining to this mailing list about people using too much power on AO-7, when you're one of the worst offenders. On July 16th this summer, I was roving in EM35 and you called me on the 2155z pass of AO7, and you got the first 3 letters of your callsign out before you killed the bird. I know it was you, because I had already made 3 QSOs right at my AOS with other stations using a reasonable amount of power, and as soon as you key'd up the whole bird started FMing and croaked before you even finished your call. You didn't get that grid that day, and after the stunt you pulled this evening - you won't be getting any grids from me in the future either.
-Dave, KG5CCI
On 10/17/17 12:28, Ronald G. Parsons wrote:
First of all, let me apologize for any disruption I may have caused by my tests (experiment, interference, ...).
To all,
Isn't our mission one of experimentation? What, exactly, is wrong with utilizing, with the proper power and bandwidth limitations, part of a transponder passband for non-SSB/CW modulation?
Yes, there are considerations regarding AO-7, but that is a problem we face using any mode on that satellite. CW signals routinely modulate the SSB voice signals, unless operators take care to restrict uplink ERP to the minimum necessary for a QSO.
Modes like Olivia, which has FEC and can track frequency changes (Doppler or otherwise), should be easily workable over satellite, and may not need to be much above the noise floor.
Ron may have been running a bit too much uplink ERP, but I don't think he needs to be beaten over the head for doing what Amateur Radio is all about: experimentation.
--- Zach N0ZGO
Experimentation isn’t the problem, too much power is. It’s bad enough on SSB, worse with CW, and killer on constant duty cycle modes like FT8.
I’m one of the few newer sat guys I think that actually likes CW on sats....BUT, I know that more than a couple watts of CW into my Arrow can kill the transponder for everyone else. With digi, the effect is far worse.
It’s already bad enough when I can tell that certain SSB stations have come on somewhere else in the passband, because my signal, which moments before was very loud using 500mW of uplink power, completely disappears even though I bump up the power to 5 or 10w.
I personally don’t see the point of a mode like MSK144 on sats, which is designed for extremely weak signal contacts like meteor scatter. But, if somebody wants to experiment that’s cool. Just keep the power down - WAY down, and I don’t think anyone would say a word about it. But no matter the mode, If one station is shutting out all others in the passband, well, you’re probably going to see some ranting lol.
73,
- Matthew nj4y
Sent from my iPhone
On Oct 17, 2017, at 15:17, Zach Metzinger zmetzing@pobox.com wrote:
On 10/17/17 12:28, Ronald G. Parsons wrote: First of all, let me apologize for any disruption I may have caused by my tests (experiment, interference, ...).
To all,
Isn't our mission one of experimentation? What, exactly, is wrong with utilizing, with the proper power and bandwidth limitations, part of a transponder passband for non-SSB/CW modulation?
Yes, there are considerations regarding AO-7, but that is a problem we face using any mode on that satellite. CW signals routinely modulate the SSB voice signals, unless operators take care to restrict uplink ERP to the minimum necessary for a QSO.
Modes like Olivia, which has FEC and can track frequency changes (Doppler or otherwise), should be easily workable over satellite, and may not need to be much above the noise floor.
Ron may have been running a bit too much uplink ERP, but I don't think he needs to be beaten over the head for doing what Amateur Radio is all about: experimentation.
--- Zach N0ZGO _______________________________________________ Sent via AMSAT-BB@amsat.org. 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: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (4)
-
David Swanson -
Matthew Stevens -
Ronald G. Parsons -
Zach Metzinger