[amsat-bb] WSJT-X FT8 QSO confirmed between W2JAZ and W5RKN on FO-29

David Swanson dave at druidnetworks.com
Tue Oct 17 18:53:43 UTC 2017

I appreciate the apology Ron. I'll consider this event water under the


-Dave, KG5CCI

On Tue, Oct 17, 2017 at 12:28 PM, Ronald G. Parsons <w5rkn at 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

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