[amsat-bb] Re: Still not getting into the ISS...

G0MRF@aol.com G0MRF at aol.com
Tue Jan 6 09:57:17 PST 2009

Hi Roger.
In the recent past the squelch appears to have been set fairly high. As  
witnessed by the repeated signals being essentially noise free.
It is now much easier to track the correct uplink on 2m as the doppler  shift 
is small compared to the 12.5kHz or so (a guess) bandwidth of the ISS  
receivers IF filter.
Unfortunately, I believe the D800 is unable to operate with the squelch  open 
due to overheating problems. Not that anyone is complaining, this ARISS  
operation is great!
But the D800 is not a purpose built satellite repeater. Given a choice, a  
SO50 type approach would give easier access for operators while saving power /  
heating and RF pollution. A CTCSS detector that initiated a timer, or perhaps 
a  system that simply allowed the repeater to stay open for 10 or 15 seconds 
after  loss of the tone  would allow people to 'net' onto the correct uplink  
frequency, or hear when their signal had a fade or collision with another  
I suppose the ARISS equipment will be upgraded at some point in the future  
and maybe some dedicated hardware with simple to operate controls for the crew  
(and remote commanding from the ground) will overcome these minor  problems 
with an otherwise very successful system.
Still, 5 Watts downlink is quite amazing and unlike any conventional  
satellite we have. Where's my 2m amp......
David  G0MRF
In a message dated 06/01/2009 10:07:23 GMT Standard Time, rogerkola at aol.com  

An  interesting thought...could they have the squelch engaged while  also
requiring tone? I personally haven't been able to get in on 80 degree  passes
over New England with 25 watts and an omni at 5:30 AM local  time.

Reception is just fine, but there are a lot of "empty" spaces in  between
contacts that could be collisions I  guess...


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