From: David Woolley (forums_at_david-woolley.me.uk)
Date: Tue Mar 04 2008 - 14:48:41 PST
Greg. wrote:
> If you are no-top-reply freak - don't look below the line!
Or re-arrange it into an order that makes sense.
> Missing attribution (Ed?) wrote:
>> At 08:35 AM 3/3/2008, Greger Gimseus wrote:
>>> Currently there are 3 probes around Mars,
>>>
>>> 1) Mars Odyssey, 2) Mars Reconnaissance Orbiter (MRO) 3) Europe's
>>> Mars Express
>>>
>>> What possabilities would there be to recieve a 5W L-band / lower S-band
Is this 5W feedpoint power or 5W EIRP?
>>> signal, using <1dB LNA what dish size and integration time would be
>>> required for this?
What level of confidence do you want that you have actually received the
signal, and not just a noise anomaly? How stable is your receiver? Are
you prepared to correct for second order Doppler effects?
>> http://groups.yahoo.com/group/amateur-DSN/
>>
>> Several members of this international group have been receiving
>> signals from the Mars orbiters on the nominal 8.415 GHz microwave band
>> I believe that stations using as small as a 2m dish have successfully
>> detected some of the orbiters. The receiver commonly is a LNA + mixer
>> fed by a brick LO and followed by a VHF or UHF SSB receiver. Weak
>> signal detection is done using soundcard programs such as Spectran.
> I asked as more people have receivers in the L/S bands but not X,
> of course there's the way to mix a signal - but I'm talking about direct
> signal reception.
About the only thing that receives directly at these frequencies are
radar speed guns. You will not get filters narrow enough to reject an
image only about 22kHZ away at these sorts of frequency, and I suspect
that the phasing method will be very difficult to balance.
Also, I think it is unlikely that you could put all the gain at one
frequency without the whole thing going unstable.
-- David Woolley Emails are not formal business letters, whatever businesses may want. RFC1855 says there should be an address here, but, in a world of spam, that is no longer good advice, as archive address hiding may not work.
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