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Re: WiSP, AO10 & FM sats



In a message dated 9/28/00 3:24:16 AM Eastern Daylight Time, 
mhart@terrigal.net.au writes:

>  Do any satellite tracking software tell you
>  the doppler shift on both the uplink and downlink freqs.

Hi Michael,

The only one I know of that does this is NOVA for DOS. In it's settings, you 
can specify that one of it's doppler readouts be the uplink doppler. There 
probably are others.

>  I have put "nominal" freqs into the satellites I am interested in for WiSP
>  under the Setup|Satellite Setup option.
>  There is a "Doplr" space in the main window and a "Doppler" space in the
>  Graphics tracking window [after I finally got the program to actually work]
>  but there in no numbers there.  How do I get the program to fill in these
>  numbers?

Bring up Tracking | Graphic Track
Select Tracking | Select Sateliite (select sat you want to set)
Select Tracking | Edit Keplerian Elements
Near the bottom enter a "Beacon Frequency"

>  OK.  Item #2.  AO10.  I think I heard AO10's beacon yesterday but haven't
>  heard it before or since. It would be helpful if someone were able to
>  give a reasonably detailed description of what AO10's beacon is currently
>  meant to sound like, how far off 810 I should stop searching for it and
>  generally its current status.

AO-10's Beacon is an unmodulated carrier. In USB, you'll hear a tone. Tuning 
range is ~ +/- 3.5 KHz.

>  FM sats.  I seem to be able to get into these for about one over again -
> particularly when they are going down the eastern coast of australia.  I
> have some mountains to the north and west (and a little further away to the
> south also) which limit my view until they come up to about 25 to 30 degrees
> on the 70cm downlink.  I belive WiSP has facilities for taking into account
> surrounding high objects.

Yes, Radio Horizon.

> I am not sure if my antenna has "holes" in its pattern.  I am
>  using a 5/8 ground plane tuned for 70cm for both the downlink (70cm) and
>  uplink (2m) - I expect there will be a hole when the sat is directly
>  overhead but otherwise these antennas don't have too much gain.

Yes, these antennas will be a huge compromise. 5/8 wave is designed to focus 
most of its energy at the horizon.

>  One of my biggest problems is trying to sort out real (wanted) signals from
>  the muck.  I seem to get some "birdies" as I have said before.  I also get
>  some intermodulation when I transmit.  This has thrown me a number of 
times.

Physical separation of your tranmit and receive antennas can help. Depending 
on where the birdies are being generated (computer in the shack??), moving 
the receive antenna further away may help. For instance, my 10M turnstile for 
the RS birds is located about 75' away from the shack (fed by hardline) to 
eliminate some computer generated birdies.

>  I though I was getting a real return from UO14 for over 30 minutes ;).

Max pass is always less than 20 minutes.....

>  Then
>  I turned the 70cm preamp off and it went away.  I find that with the 70cm
>  preamp on I get a lot of blanking on the receiver when I tune the
>  transmitter across the 2m band.  In some cases it blanks it out completely
>  with a huge signal strength and at other times I also get packet data in
>  with the distortion (but only when I am transmitting a carrier - I don't
>  have any packet gear).

Again, antenna separation can help. If this isn't possible, bandpass 
filtering on receive is needed (before the preamp!). My preamps have this 
built in. Also, cutting transmit power can help with intermod.

>  Today I thought I hear a carrier from my transmitter on the AO10 downlink.
>  I was xmitting on 435.125 and rcving on 145.900.  I heard the signal only
>  when transmitting and it would change freq as I adjusted the VFO.  OK 0-
>  well then I adjusted my output power from 100w down to <1W and turned the
>  antenna side on to the satellite (90 degrees away from it).  When I keyed 
up
>  the transmitter again it was still there :(((  Must be another intermod for
>  my radio.

It will be extremely difficult to work AO-10 with 5/8 wave antennas. (Not 
impossible, but very tough for even a seasoned veteran.) You really need some 
type of beam.

If you are going to attempt to find yourself on AO-10 can I make a 
suggestion??? _Please_ don't do it around 145.900. This is the center of 
transponder activity. It is possible you'll be interfering with others. Move 
up to 145.915 or higher....... The same is true for other SSB birds as 
well....... Also when trying to find yourself, adjust your downlink, not your 
uplink to find yourself. That way you won't be sweeping all over the 
transponder.

General rules for any satellite work.......
FM === Can you hear the downlink reliably??? If not, don't transmit!
SSB === Can you hear the beacon? If not, don't even try to transmit unless 
you can hear other conversations in the transponder passband. (some beacons 
are funky at times).

If you hear the beacon, note it's relative level. (S3, S5 etc) and when you 
transmit, limit your uplink power so that your return signal is never higher 
than the beacon.

Hope this helps.

73,
Mike, N1JEZ
AMSAT #29649
Local Area Coordinator
"A closed mouth gathers no feet."
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