Any idea what this is?
Seems to be stopping and starting a regular intervals. Audio attached.
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Comments
Hi, image and audio file do not match...
If it is really 6765 USB, it's most likely Bangkok meteo FAX.
If it is 7150 LSB it's most likely one of the many, and increasingly difficult to identify, Amateur data modes.
Regards,
Martin
Hi Martin, I read somewhere that some people are trying LoRa like modulations in the HF bands. Same chirp principle here, but no data seen. Or is it a submillisecond propagation time measurement ?
T
Ah sorry - I must have uploaded the wrong audio file. Standby
I am only familiar with LoRa data in a horizontal line, not diagonally.
I once had a LoRa/LoRaWAN access point running for a while.
Regards, Steffen
Hi, @jimjackii : "I am only familiar with LoRa data in a horizontal line, not diagonally."
What ! ? 😉
(image credit )
The appearance on a waterfall depends on the sweep rate (in frequency) and the bandwidth of the pulses, and of course the frequency and the time resolution of the waterfall display.
If you use a high frequency resolution, the sampled signal (to be fourier transformed) last one or more symbols and then you see a ~ brickwall spectrum, that you mention as horizontal lines.
But the fundamental of the coding lies in the linearly frequency modulated pulses, and the phase of the "saw tooth" code the data.
Cheers, Terry
Upload of the correct audio
Also - LoRa in HF bands?
Hi all, thanks for the audio file. We can hear and see that it is not a real linear frequency sweep, but a "staircase" function with ~ 2.5 sec Pulse Repetition Frequency.
(audio freq in Hz vs time)
May be someone wobulating the passband of his transmitter, simply ?
Cheers, T
I seem to vaguely remember that VARA HF modem has a test / setup mode that generates sweeps.
However, I can't find an example, so I may be wrong.
Regards,
Martin
Seems quite different.