[RTTY] re VE3NEA rtty-modems tests - is MMTTY obsolete?

[David Hachadorian]

----- Original Message ----- 
From: <f6irf at free.fr>
To: <rtty at contesting.com>
Sent: Friday, April 15, 2005 7:18 AM
Subject: [RTTY] re VE3NEA rtty-modems tests - is MMTTY obsolete?


> >Alex's plots show that TrueTTY is 3 dB more sensitive than MMTTY 
> >when
>>presented with an RTTY signal in the simple white noise case.  But
>>both demodulators require *much* more SNR when faced with the real
>>world conditions, i.e., "Fig 17."  It is probably because of this
>>variability why most people don't notice that MMTTY is poorer than
>>TrueTTY, even though TrueTTY beats MMTTY by an even bigger margin 
>>for
>>the selective fade case.

--------------------------

After I saw those plots, I tried TrueTTY, but the manual squelch was a 
show-stopper for me in real-world usage. If you set the squelch too 
high, it won't decode weak signals. If you set it too low, there is a 
continuous stream of garbage characters. If you try to set it right on 
the hairy edge, changing band conditions and QRM will almost 
immediately require a different setting. Perhaps TrueTTY performs well 
in the laboratory, but it didn't work for me on the air.

Dave Hachadorian, K6LL
Yuma, AZ