On Thu, Oct 20, 2011 at 4:20 PM, Ed Wilson <ed.wil...@ymail.com> wrote:
> Thanks for the info, Tim. > .... I do not want to put out some of the "garbage" that I sometimes > see.... ============ JT65 is not PSK,and differs from it in many ways. The program is extremely thoroughly documented and the info there is correct, and well worth the read. Here is a quote from the JT65 manual: "WSJT generates a single-frequency sine wave at any instant while transmitting. Except during station identification, there is no “key up” time; signal amplitude is constant, and one tone changes to the next one in a phase-continuous manner. As a result, WSJT does not require a high degree of linearity in your power amplifier. You can use a class C amplifier without generating unwanted sidebands or splatter." In other words, only one frequency is transmitted at a time; IM won't happen because there's nothing to intermodulate. There is no on-off shaping because the transmission is continuous. If you're hearing garbage it may be from one of the numerous other modes that appear on or near the JT65 calling frequencies. Moreover, a few minutes spent on JT65 will reveal that many stations send short comments instead of the canned responses, and many mention that they are running 50 or 100 watts. The incorrect idea that it is a 5W mode is possibly due to confusion with WSPR. A passband of 1000 hz will pass all the signals in a JT65 calling band. Flex radios are good at producing a tunable 1 Khz passband, but actually just about any radio with DSP will do the same. If there's an offending signal near the one you want, you can always crank the passband down tighter or notch it (autonotch won't work for this purpose, but manual will). 73, Tony KT0NY _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
