Hello Wes, I saw the test file. It is nice except the long suite of figures, which could be a cause of possible systematic failure (with many errors following a first error) . Better would be to keep only the call signs which include figures and letters and produce a good diversity (and so a more precise statistic result).
Also it would be perhaps interesting to transmit the RTTY characters through 2 different programs because a program could produce a not exactly nominal RTTY transmission and its decoding could match this transmission (for example, the stop must be 1.5 bits but can vary in fact). If, with two different transmissions, the results are the same, they can be considered as reliable. 73 Patrick ----- Original Message ----- From: Wes Cosand To: digitalradio@yahoogroups.com Sent: Saturday, January 23, 2010 12:42 AM Subject: Re: [digitalradio] Comparison of RTTY software sensitivity - New tests Patrick, thank you for your kind note. I discovered, as you have known for a long time, that testing RTTY is not easy because of random figures/letters shifts. As you said, a single inappropriate shift can mess up a lot of characters! That makes the statistics difficult. My test text file is at http://mysite.verizon.net/wz7i/Text%20file%20for%20testing%20communications%20software.html I used call signs and about 30% five number groups to try to deal with this issue. I tested with UOS off because of the number groups. It may be that I should have used a shorter file and then tested it with different audio files a number of times to get reasonable statistics but that seemed too much work... chuckle... The error bars on the graph might have been significant. Instead I tried to run a long enough text file to average out all the random shifts. It probably wasn't long enough to try to analyze the data too closely. I, too, tested with AFC off. I used the audio frequencies used for FSK so that is a difference. Our audio levels were about the same -- 40% sounds about right. As I said earlier, it is possible that I have incorporated some error in my methods. It is possible that I am "straining at gnats and swallowing camels" :-) Thank you for your patience with me. 73 de Wes, WZ7I
