[amsat-bb] EVA monitoring, has anyone been sucesful.

MM ka1rrw at yahoo.com
Thu Jun 14 10:05:15 PDT 2007

Monitoring the Space Suit EVA’s

Has anyone had much luck in detecting the weak signals
from the Space Suit transmitters during an EVA?

For the purpose of this article I will not mention the
exact frequency, I assume you will be able to easily
find them on the web.  Ill just use generic terms UHF
(200-299mc) for the American space suits and VHF
(100-199mc) to reefer to the Russian suits.

The Americans typically seem to use UHF frequencies
for the space suit communications.  The format seems
to be an AM mode (please feel free to correct me if I
am wrong).
NASA has a few pairs of split frequencies and simplex
frequencies that the crews can switch between during
an EVA.
The Russians use VHF frequencies.  I am not sure if
its AM or FM for EVA.

I am going to assume the power out put of these
transmitters is very low.  Does anyone have any
specific ERP values of the orbit and Suit voice
transmitters?  I would like to try to estimate the
amount of antenna gain that is needed to hear these
weak signals.

I have been trying to monitor this weeks space walks
without any success.  My station for monitoring the
200-mc portion of UHF is very limited.  The only radio
I have that can listen to AM and FM in that part of
the band is a Kenwood D700.  

I have noticed a lot of 4th harmonic interference from
the TV stations in Boston (channels 2 and 4).  The 4th
Harmonics from Ch 2 audio is heard clearly on 239mc
and Channel 4’s harmonic is on 287mc. There is also a
lot of video buzz and and related noice from these TV
stations in the 230 – 290 part of the band.

Any input would be welcome.

Thanks, Miles

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