[amsat-bb] ARISS Packet

Alan wa4sca at gmail.com
Tue Feb 28 23:22:44 UTC 2017


In your original post, you said " I have no decoding packets whatsoever either 
from ARISS or terrestrial on 144.390."  Since RX is in fact working, the most 
likely transmission problem with the Flex is that compared with traditional 
rigs, there is considerable latency, or delay, between the audio input and 
transmission.  The result is that the transmitter cuts off before the full 
packet is sent.  Fortunately there is a parameter, TXtail, which will keep the 
transmitter keyed for a period after the audio is sent.  Somewhere in 
Soundmodem, probably the Modem tab, IIRC.  Try setting it for 500 ms or so, 
and see if that helps.  It solved my problem.  After you get it working, you 
can cut that back a bit, if desired.  How much is a complicated function of 
sampling rates, buffer sizes, etc.

Another issue is deviation.  Too much is much worse than too little.  I find 
that setting VAC at -14 gives me 3 KHz deviation.



<-----Original Message-----
<From: Richard Lawn [mailto:rjlawn at gmail.com]
<Sent: Tuesday, February 28, 2017 17:01 PM
<To: Alan Biddle <wa4sca at gmail.com>
<Subject: RE:ARISS Packet
<Decoding for me either at ARISS downlink freq or 144.390 isn't the problem. I
<seem to have no luck getting any confirmation packets back at 144.390 and I
<should think using WIDE I should at least see my own packets echoed back.
<Rick, W2JAZ

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