[Lowfer] New CMSK Program ... WE2XGR/2 in CMSK mode

[w1tag at charter.net]

Bill,

I agree with that assessment. This particular implementation of MSK was designed for QSO's and text transmission in a low BW and with the ability to use a non-linear PA (and still be friendly to those around you). It's no competitor to WOLF, for example, and would not be a good choice for the conditions you describe. As there are now people running hundreds of watts in Amateur and Experimental work at 500 and 137 kHz, the bandwidth and PA issues are pretty significant. 

John, W1TAG

---- Bill de Carle <ve2iq at magma.ca> wrote: 
> At 07:53 AM 8/5/2010, Jay, W1VD wrote:
> >John W1TAG and I have been testing a 'pre beta' version of CMSK - 
> >a  program developed jointly by
> >ZL2AFP and ZL1BPU/ZL1EE. The beta version has now been released and 
> >a description and download is
> >available at:
> >
> >http://www.qsl.net/z/zl1bpu/CMSK/cmsk.htm
> >
> >This program was developed specifically for use at LF and MF, runs 
> >MSK using a varicode (very
> >similar to that used by PSK31), and  uses Forward Error Correction 
> >(FEC). Initial tests have shown
> >it to be very robust in the presence of static and fading. It's well 
> >known that frequency shift
> >keying work best in the presence of static - amplitude modes, like 
> >PSK, do not compare favorably.
> >Apparently the military realized this years ago as virtually all of 
> >their VLF, LF and MF
> >transmissions are frequency shift keying. John and I have confirmed 
> >this with our tests on LF and
> >MF.
> 
> There is more to the story and one shouldn't assume MSK is the 
> ultimately superior mode in every case.
> While the bit-error rates of PSK and MSK are comparable when signals 
> are relatively strong, in low static
> winter conditions when we are trying to copy extremely weak lowfer 
> signals in a more white-noise-like
> environment, PSK will increasingly out-perform MSK as the SNR 
> decreases.  I would think at VLF the much
> smaller bandwidth of MSK for a given message rate would be the 
> overriding consideration.
> 
> Bill VE2IQ
> 
> ______________________________________________________________
> Lowfer mailing list
> Home: http://mailman.qth.net/mailman/listinfo/lowfer
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Lowfer at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html