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Re: Minor issue with packet uplink on 145.990



On 27 May 2001, at 11:54, Bob Bruninga wrote:

> But the degree to which the 146.010 theory is correct, tells users that
> their best chances to avoid that are to work for success early in the pass by
> transmitting  5 KHz low during approach.

And Alan Leech wrote:

> I reckon that the explanation regarding a short TXDelay
> on ISS, may be the answer. Many of us dont hear, or see, our own frames
> digi'd, but others do.

For what its worth: I don't do any doppler correction... and have good 
results, especially at the beginning of the pass. I do fair at the end of the 
passes.  Because I can't elevate the antennas, the higher the ISS is, the 
harder to get in... but sometimes still have some success. I attribute the 
horizontal beam being better for at least some small reason due to the 
driven element "aiming up" (ignoring all the parasitic elements) better than 
my ground plane (or what the radiation of a vertical driven element would be).

Maybe I'm crazy, but I've felt this way since I first started having success in 
1993.  I used to have the 10 vertical elements on my beam too (they got 
destroyed last year... a long story).  I used to feed the vertical beam, the 
horizontal beam, and the ground plane all into a coax switch... and I would 
switch between them to see what gave me the best receive signal... then 
would use that for transmit. I *ALWAYS* felt the horizontal beam was best 
for the old SAREX missions.  But I was not as convinced with the Mir.

The 01/61 repeater pair is the "main repeater" in the county where I now live.

I also wonder about TNC parameters, both onboard ISS and also what is 
being using by earth stations.  I am not that well versed in their exact 
details, but I offer the following that I use here (and I usually see my own 
digi's repeated).
DWAIT 0
AXHANG 300 ms
AXDELAY 300 ms
TXDELAY 300ms

I think my PERSIST and SLOTTIME are at the Kantronics default... but will 
check if there is more interest in these values.  Are there some other 
settings that might help or hurt our chances?  Well, checked anyway... 
PERSIST is 63 (25%) and SLOTTIME is 100 ms.

Stan/W4SV

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