[GreenKeys] RTTY receiver noise immunity?

[Jim Walls]

On 04/20/2021 08:36, Nick England wrote:
> I’ve been in a discussion with the USS Iowa guys about what to expect 
> when there’s no RTTY signal just receiver noise. They are concerned 
> because they get a bunch of garble when there’s no signal and the AGC 
> turns up the gain.
>
> Note. This discussion is not about noisy RTTY signals but responding 
> to noise when there is NO RTTY signal.

My recollection from decades ago, was that on HF (no squelch), if there 
was no signal, I would print continuous garbage.  I think that was using 
an ST-6 for a TU.  However most of my HF RTTY was with a HAL 2100 (if I 
remember that device model), and it did not matter since it was on a 
screen.  The mechanical equipment was primarily used on VHF where there 
is squelch, so I could leave one of the model 28 machines on Autostart 
without wasting paper or having thousands of characters print on the 
last position of the line until it happened to decode a CR.  I also 
built a Sel-Cal and WRU unit that I used as well on VHF.

-- 
73
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Jim Walls - K6CCC
jim at k6ccc.org
Ofc:  818-548-4804
http://members.dslextreme.com/users/k6ccc/
AMSAT Member 32537 - WSWSS Member 395