[RTTY] RTTY Digest, Vol 131, Issue 14

[Villy Madsen]

On 2013-11-11 23:40, rtty-request at contesting.com wrote:
> G3KNU wrote:
>
>> >Hi just about every time  during an exchange in a  contest the prefix of
>> >my
>> >call sign is clipped or corrupted, but if my call ( I wish everyone would)
>> >is
I have noticed the same issue fairly frequently

There are a number of possible reasons, but I think that many people 
tend to forget that RTTY demodulators need to be able to sync up before 
they can start decoding the signal.  At a minimum a couple of spaces 
need to be sent to allow your demodulator to synchronize.  I usually use 
space enter, but even that might be too parsimonious - especially under 
poor signal conditions.

I can also see AGC being an issue - I almost always run with the AGC 
turned off.  If the signals are strong enough I turn on the AIP 
(Advanced intercept point - which really means on a TS850 that you are 
turning the preamp off).  If the signals are stronger, I click in some 
attenuation to bring them down to something reasonable.

I am also using an inrad roofing filter with additional bandwidth 
narrowing using the slope tuning on 2 inrad 2.1 khz filters.  I do have 
a 250 hz filter in there, but I find that it doesn't work as well as 
using the 2.1khz filters in tandem (and offset to give the desired 
bandwidth).

I do think that there are those who try and trim down their exchanges to 
an extreme.  It doesn't take many repeats during to make up for the 
extra time eaten up by an extra space or enter in each exchange.

Villy  ve6sq