[amsat-bb] Re: Satellite's

[Thomas Doyle]

There is no problem receiving the linear sats with the Dongles. The
dongle offers a big advantage in that you can see the whole 'band' at
once and spot people very quickly. SSB and CW reception is great. The
doppler correction with SDR-Radio works as well as the gold standard
SatPC32.

The extIO stuff for the cheap dongles are still in the early stages
and very geeky but they do for the most part work. The FCD is a much
more mature product so I have been working with that and waiting for
the other dongles to catch up.

Problems with integrating with transmitter control remains. SDR-Radio
links with external radios but I have been unable to figure out how to
offset the transmit frequency. I am currently working with HDSDR and
controlling it with and none other than SatPC32. HDSDR appears to be a
bit more flexible interms of connections with other gear. Omni-Rig
support is built into HDSDR and works great but has the same
limitations as SDR-Radio external radio control.

The other problem which is not as difficult is the front end overload
problem with the dongle. The sensitivity of the dongle is excellent
but the front end selectivity is almost non-existent. Filtering is
necessary and even with a 70 cm tuned cavity I am still having desense
that makes hearing the downlink difficult.

I am close to a SatPC32 <-> dongle system but there is probably
someone with a much better 'simple' or even a 'very simple' solution.
I would be very interested in hearing from anyone who has actually
achieved fully synchronized doppler corrected transmit control with a
dongle for the receiver. A reply offline would be best to prevent
flames.

As Steve Jobs liked to say "Just one more thing". The new AMSAT store
looks great. Take a look if you have not seen it. Thanks to those who
built it and thanks to Martha for keeping things going while it was
down.

73 W9KE tom...

On Wed, Aug 29, 2012 at 5:28 AM, Trevor . <m5aka at yahoo.co.uk> wrote:
> --- On Wed, 29/8/12, Kevin Deane <summit496 at live.com> wrote:
>> I am dying to work AO-7 for sure and VO-52, FO-29 but gave
>> up trying to do so without the right equipment.
>
> Yes full duplex is a must for working linear sats. If you already have an FT-857 you've already got the "hard part", generating SSB on 70 cm, sorted. All you need is a separate receiver.
>
> A $20 RTL2832-E4000 TV Dongle would appear the cheapest way of achieving that, see http://www.youtube.com/watch?v=kTh4DAmMzrM
>
> I've never used that dongle myself but it may well provide sufficient performance to receive a 2m satellite downlink. Has anyone used one to receive amateur linear sats ?
>
> 73 Trevor M5AKA
>
>
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-- 

Sent from my computer.

tom ...