On 3/18/2017 2:42 PM, Mike Waters wrote:
I was wondering about just how narrow we can go on JT9, JT65, or WSPR.
Below is some information on the bandwidth required for JT-65. This was
copied from one of the JT-65 websites.
JT65A operators use USB VFO FREQUENCY for spots.
JT65A signal is about 1.3+kHz higher than the VFO frequency
The JT65A Passband is about 355Hz. Bandwidth is about 200Hz.
JT65A may be used in the 500Hz bandwidth segments of bandplans.
Normal operation of JT65A is a sync audio frequency of 1270.5Hz.
Sync tone is the reference mouse-click frequency for JT65.
JT65A signal bandwidth extends about 200Hz above 1270.5Hz sync.
The lowest tone of the JT65 signal is normally 1270Hz.
The system allows approximately +/-600Hz auto-tuning on receive.
WSPR requires that an SSB filter be used and the radio has to be set to
the specified frequency for that mode. You can change the bandwidth to
anything your radio will give you but you can't change the dial
frequency. That will change the frequency of the tones and cause the
decoding to stop.
PSK31 works OK down to 50 Hz bandwidth on my radio. Although I would
not recommend tuning around with that bandwidth. Radio dial frequency
can be anything that gets the signal in the bandwidth.
Jerry, K4SAV
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