Absolutely!

The recommendation at the time of launch was to limit power output to no more than 100W ERP (which is about 25 watts to a small antenna like an Elk or an Arrow). This is even more critical now since the solar panels are almost certainly not supplying enough power to drive the transmitter to it's full power output. At certain times of the year, there are poor solar angles on the panels too, which reduces power availability. Remember too that AO-7 will enter a period where it eclipses on every orbit over the south pole within the next week or so. That period will last for about 9 weeks. It should be in Mode B every day as a result, but from what I've read about past eclipse cycles, it can act a bit odd during that time.

On too many passes, I hear distorted audio and reflections throughout the transponder from it being hit too hard with SSB and especially CW. CW, being full power at key down, unlike SSB, is even harder on a linear transponder.

If everyone would just have the courtesy to keep their uplink power to a reasonable level, AO-7 can be a very enjoyable satellite with a large footprint providing the best DX opportunities currently available. Unfortunately, this problem is not new as a glance at the AMSAT Newsletters from 1974-1981 shows.

I recommend the following reading: The Editorial + Letter from W4NUL/5 in the March 1976 AMSAT Newsletter, the AMSAT-OSCAR-7 QRP Test Telemetry Report in the November 1976 AMSAT Newsletter, and the June 1976 QRP Test Results from the December 1976 AMSAT Newsletter. All available here: http://www.ka9q.net/AMSAT-Newsletter-1976.pdf

Please calculate your ERP ( http://www.csgnetwork.com/antennaecalc.html ) and keep it to no more than 100W.

73,

Paul Stoetzer, N8HM Washington, DC

On Fri, Apr 25, 2014 at 11:12 AM, Dave Webb KB1PVH [email protected] wrote:

Only when people are running too much power. It's called FM'ing.

Dave-KB1PVH

Sent from my Verizon Wireless Droid RAZR On Apr 25, 2014 11:10 AM, "Peter Wilson" [email protected] wrote:

...

Just worked IK8YSS on AO-07.

Haven't worked this satellite for a while and whilst I know the bird is very old, the audio on this pass was very distorted.

Is this common?

Peter

G8KEK

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program!

...

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Paul,

Thank you for such a detailed response, for a newbie like me (only 63 years old) this is all very interesting - and logical.

As you quite rightly say, this satellite should be treasured due to its footprint………..

Thanks again

Peter

G8KEK

From: [email protected] [mailto:[email protected]] On Behalf Of Paul Stoetzer Sent: 25 April 2014 19:23 To: Dave Webb KB1PVH Cc: Peter Wilson; AMSAT -BB Subject: Re: [amsat-bb] Re: AO-07 Distorted audio

Absolutely!

The recommendation at the time of launch was to limit power output to no more than 100W ERP (which is about 25 watts to a small antenna like an Elk or an Arrow). This is even more critical now since the solar panels are almost certainly not supplying enough power to drive the transmitter to it's full power output. At certain times of the year, there are poor solar angles on the panels too, which reduces power availability. Remember too that AO-7 will enter a period where it eclipses on every orbit over the south pole within the next week or so. That period will last for about 9 weeks. It should be in Mode B every day as a result, but from what I've read about past eclipse cycles, it can act a bit odd during that time.

On too many passes, I hear distorted audio and reflections throughout the transponder from it being hit too hard with SSB and especially CW. CW, being full power at key down, unlike SSB, is even harder on a linear transponder.

If everyone would just have the courtesy to keep their uplink power to a reasonable level, AO-7 can be a very enjoyable satellite with a large footprint providing the best DX opportunities currently available. Unfortunately, this problem is not new as a glance at the AMSAT Newsletters from 1974-1981 shows.

I recommend the following reading: The Editorial + Letter from W4NUL/5 in the March 1976 AMSAT Newsletter, the AMSAT-OSCAR-7 QRP Test Telemetry Report in the November 1976 AMSAT Newsletter, and the June 1976 QRP Test Results from the December 1976 AMSAT Newsletter. All available here: http://www.ka9q.net/AMSAT-Newsletter-1976.pdf

Please calculate your ERP ( http://www.csgnetwork.com/antennaecalc.html ) and keep it to no more than 100W.

73,

Paul Stoetzer, N8HM

Washington, DC

On Fri, Apr 25, 2014 at 11:12 AM, Dave Webb KB1PVH <[email protected] mailto:[email protected] > wrote:

Only when people are running too much power. It's called FM'ing.

Dave-KB1PVH

Sent from my Verizon Wireless Droid RAZR On Apr 25, 2014 11:10 AM, "Peter Wilson" <[email protected] mailto:[email protected] > wrote:

Just worked IK8YSS on AO-07.

Haven't worked this satellite for a while and whilst I know the bird is very old, the audio on this pass was very distorted.

Is this common?

Peter

G8KEK

---

Sent via [email protected] mailto:[email protected] . 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 [email protected] mailto:[email protected] . 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

What about this cause?

Space Weather News for April 25, 2014 http://spaceweather.com

X-FLARE: On April 25th, an active region near the sun's western limb erupted, producing an impulsive X-class solar flare. A pulse of extreme UV radiation from the flare ionized Earth's upper atmosphere and caused a shortwave radio blackout on the dayside of Earth. However, a CME hurled into space by the explosion will miss our planet. Check http://spaceweather.com for updates.

Rick - WB3CSY

On Fri, Apr 25, 2014 at 12:32 PM, Alan [email protected] wrote:

Peter,

That can happen when the illumination is poor, but also if there is someone using too much power. They can bounce the entire transponder, resulting in very choppy, distorted audio.

73s,

Alan WA4SCA

<-----Original Message----- <From: [email protected] <[mailto:[email protected]] On Behalf Of Peter Wilson <Sent: Friday, April 25, 2014 10:04 AM <To: [email protected] <Subject: [amsat-bb] AO-07 Distorted audio < <Just worked IK8YSS on AO-07. < < < <Haven't worked this satellite for a while and whilst I know <the bird is very <old, the audio on this pass was very distorted. < < < <Is this common? < < < <Peter < <G8KEK < <_______________________________________________ <Sent via [email protected]. 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 <

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Hi Bryce,

Just to remember for the history:

AO40 uses LEILA wich continuously scanned the Mode-S passband and superimposed an intermitted sound like a horn over those uplink signal wich peaks where more than 10 dB belove the beacon level.

In addition LEILA suppressed several dB and distorted those uplink signals that do not reduced immediately their EIRP

73" de

i8CVS Domenico

----- Original Message ----- From: "Bryce Salmi" [email protected] To: [email protected] Cc: "Peter Wilson" [email protected]; [email protected] Sent: Friday, April 25, 2014 10:37 PM Subject: [amsat-bb] Re: AO-07 Distorted audio

I wonder if it would be possible to build a system that used rssi to limit each signal and act accordingly. I think ao40 had something similar.

A digit sat could be sent the tx power and use that in combination with rssi to adjust itself too. Just some quick thoughts

Bryce