[600MRG] WSQ - A Weak Signal QSO mode for LF/MF [-25dB snr]

[Brian Pease]

I have done some bench testing of a WSQ2 link with real atmospheric 
noise bursts.  The mode really works down to its -25dB limit.  The best 
thing about it seems to be its ability to sync & re-sync quickly after a 
drop out.  Remarkable performance considering that it is not time-synced 
and has no forward error correction or fancy coding and does not require 
precise tuning or post processing. Being a 1 tone at a time FM mode, it 
is bothered by continuous tones within its receive bandwidth.  I 
recommend the "enhanced" version of WSQ2 by DL4YHF at qsl.net/dl4yhf/wsq 
which has a squelch setting, adjustable audio tones, a spectrum line 
during receive, AGC on/off, etc.
On 2/11/2015 6:48 AM, Ralph Wallio, W0RPK wrote:
> http://www.qsl.net/zl1bpu/SOFT/WSQ.htm
>
> Amateur Radio enthusiasts who are interested in the LF and MF bands 
> will be familiar with WSPR. Used as a propagation probe or beacon, 
> WSPR allows very weak signals to be detected, frequently as weak as 
> -27dB SNR or lower. However, once you have established that a signal 
> path exists, how then do you hold a QSO?
>
> But what QSO mode matches WSPR for sensitivity?
>
> WSPR is not a QSO mode, and is very slow, so you cast around for 
> something else - to find that no 'chat' modes offer performance 
> anywhere near the -27dB sensitivity of WSPR. Not Morse, PSK31 or even 
> CMSK will reach this sensitivity. Even DominoEX4 will only manage 
> about -18dB SNR. The best offering is JASON, with a sensitivity of 
> about -25dB, but it is
>
> V... E... R... Y...     S... L... O... W...
>
> How frustrating!
>
> So, Con ZL2AFP and Murray ZL1BPU decided to do something about this 
> problem - to take on the challenge to design a QSO mode capable of 
> sensitivity performance near that of WSPR, and much faster than JASON: 
> fast enough to allow real QSOs. To do this required a completely new 
> approach. Using a new IFK design with more tones, plus text 
> compression techniques, we have achieved not quite a comfortable 
> 'chat' speed, but at least enough typing speed to allow contact and to 
> exchange information within a few minutes. Novice CW operators have 
> been doing much the same for decades (although not at -25dB SNR!).
>
>
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