[RTTY] rtty

[Jay]

At 05:26 PM 10/3/2008 -0700, Kok Chen wrote:
>When conditions are good, with PSK31 you need only about 0 dB SNR over  
>a 3 kc bandwidth to get moderately good print. 
>
>RTTY needs about 6 dB (4x) more power to achieve the same result as  
>PSK31 when conditions are good.
>
>However, as conditions deteriorate (multipath, flutter), PSK31 will no  
>longer get through even if you can hear him loudly through an SSB  
>filter (like my experience with PY0FT).  That is what I meant by not  
>doing any good by raising power when there is multipath and flutter.

Its the usage of 3 or 2.4 Khz SSB filters that cause nearly 100% of the
problems between RTTY operations and PSK31 operations.  Since PSK31 only
requires a very narrow bandwidth as does RTTY then it makes PSK31 ops angry
when the RTTY operator (contesting and using 250 Hz fitlers doesn't hear
nor is within say 500 Hz of the PSK31 Operator that all of hate and
disconent messages get sent and answered.  You find the exact same problem
with RTTY operators who use filters of 500 hz to 1.5 Khz or even 2.4 Khz
SSB filters.  They claim that station XX is QRMing them when they aren't
even being heard by station YY who is running narrower filters.  Which is
why I have long recommended 250 Hz fitlers for RTTY contesting.  True
tuning is a bit more work, but QRM is vastly reduced.

What SNR is needed with PSK31 using 250 Hz filters?   

Jay