Also, Gary, what frequency Tol setting do you have? I see Jim's freq reading is -77Hz, so if you have Tol set to 50Hz, for example, it'll miss Jim's signals. It defaults to 400Hz at startup, so
Andy www.g4jnt.com This email has been scanned for damaging side-effects by the health and safety police, is guaranteed to contain no substances hazardous to health, but may contribute to dissolvin
That sync figure not 'poor'. The mode will decode with values as low as 3 or 4. Just not as good as it could be in pure noise at that S/N. Pulse type QRM interferes with the decoding process mor
There is a way... If you can arrange an oscillator so that it can be pulled onto the four WSPR tone frequencies (separated by 1.46Hz ) by two logic lines. This could be as simple as two resistors, on
See annotations below Andy www.g4jnt.com 2010/1/22 Rik Strobbe <[email protected]> As said I haven't read any instructions / manual but maybe the figures WSJT7 spits out on the readable c
JT4 is based on the old 11025Hz sampling, which is badly supported by modern soundcards unlike WSPR which is based on 12kHz sampling. This has lead many an op to get poor decoding performance on ot
There is an absolute limit to signalling efficiency, determined by Shannon in 1948 of -1.64dB S/N (normalised bandwidth) WSPR/WSJT are within about 3 - 4dB of the limit, so we'll only ever get this
I noticed the current draw on my 500kHz beacon transmission had dropped this morning, so dragged a scope into the shed and looked at the relative phase of voltage and current to the antenna. The two
The type of ground locally probably enters into the propagation equation without influence on the ERP figure, and may be enhancing my signals a dB or so. For example, I am on quite good conductive
Yes, as Paul suggests, it does look as if AGC is the culprit. Narrowing the Rx bandwidth right down to 7Hz won't make any difference to decoding ability provided there is no AGC pumping from out of
I was looking at driving push-pull transmitters from fundamental drive signals quite recently. How about a frequency doubler? The output doesn't have to have 1:1 mark-space ratio as it only cl
Watch & check your sampling rate calibration. for this mode. Andy www.g4jnt.com This email has been scanned for damaging side-effects by the health and safety police, is guaranteed to contain no subs
For some of us, fun does not mean simple... It means using the latest techniques, learning as we go along and trying new ideas It would be nice if amateur radio could stay no more than a decade behin
After posting that, I realised the JT4 PIC/DDS beacon code is designed for 100% duty cycle operation, viz JT4, CW + carrier, which is a bit antisocial (certainly the wide bandwidth CW bit). And more
VERY TRUE.......... One solution for narrow band would them be to filter the output to remove the fundamental (and any other odd order) componets that cause the asymetry Andy www.g4jnt.com This ema
may be egg-sucking-lecture, but you have got JT4A set haven't you?. Not B...G. Andy www.g4jnt.com 2010/1/21 Gary - G4WGT <[email protected]> Andy, You wrote :- Watch & check your sampling rate cal
If you are able to derive the transverter LO from the transverter's master oscillator do so. That way errors will be cancelled out and any frequency drift will be now be in direct proportion to the
All the critical filtering is done in the software, and results in a 1.46Hz noise bandwidth - which is what the software measures and reports upon. Your observation that a narrower IF bandwidth is
AFAIK The is no 'simple guide' JT4x was never originally going to be one of Joe's supported modes, although after our extensive use on uWaves it certainly is now. JT65x was the more popular and d
