On Thu, Oct 22, 2009 at 12:23 AM, Rein Couperus <rein at couperus.com> wrote: >> I wonder how many people bother to think about why PSK250 is an >> especially bad protocol to use on HF and what might be a better >> choice? There are many hams who don't really understand or realize >> just how the ionosphere mangles the signal and which types of signals >> will perform better under different propagation conditions. Maybe >> after learning that the pskmail sysops will change their operating >> practices. > > This is agressive text, and it shows the author has no clue as to what we are > doing with pskmail...
You are perhaps right about my comments on the specifics of PSKmail but not about my comments on propagation in general. I have a great deal of clue about the effects of HF propagation on various modulation schemes. > We have 5 years experience with this, and we would not be using PSK250 if it > did not work... > When it works it is 4x faster than any other mode. And there is the operant phrase -- "when it works". Yes, PSK250 is going to work under some conditions, e.g. single-hop propagation near the MUF where multipath is nonexistent. Once you start to get multipath the doppler phase modulates the signal greatly increasing bit error rate. > In those cases where ?it does not work we are using THOR22 or MFSK32, > depending on band condx. That is very sensible because the modes based on MFSK, e.g. Thor, DominoEX, MFSK16/32, etc, are designed with long integration times. They are also noncoherent so phase modulation due to doppler is no factor. > Actually, we use PSK250, PSK125, THOR22, THOR11, THOR8, MFSK32, MFSK16. > We can switch modes during a session. By using RSID on the servers (using > fldigi-3.13) > the mode is no issue anymore.... Still PSK250 Is used 90% of the time... I understand. Thank you for clarifying. Next time I will do better homework first. I was not aware that pskmail was adaptive based on conditions. I must admit, I painted pskmail with a broad brush based on my general experience that hams will generally come up with a substandard way of doing things and then cling to that with a tenacity suggesting religion. -- 73 de Brian, WB6RQN/J79BPL
