Regarding Observation 7320286 …
I’m interested in the received power as a function of time for this object. Looking at waterfall plots for SOLRAD-7B from lots of stations, when it is detected well, the power seems to be modulated in time/elevation. The power seems to be modulated slowly at low elevation and much faster at high elevations. Is that conclusion correct and, if so, why is this the case?
For example this obs 7337280.
How do you mean exactly ?
Isolating features in the transmission to get rid of the effect on the receiving station, amplitude is very hard. Even frequency can be tricky due to the requirement of good TLE and synchronized clock, the slight bend in the middle can be seen in obs where the clock is off for example.
I’m looking at the received power in the waterfall plots (the pixel values). The power seems to go to zero in a regular fashion as a function of time (and elevation). At the start and end of the pass (at low elevation), the power seems to go to zero slowly (large gaps in time between zeros). At higher elevations, the modulation seems to speed up (short gaps between zeros), with maximum rate of modulation at maximum elevation (middle of the pass). Are you saying that this is due to the receive station, not the transmitter? If so, why is this a feature of the receive station?
I’m still not sure what you mean with the zeroes and maximum rate of modulation.
Power is amplitude, and will be depending on the antenna type, location and obstacles. Take for example a turnstile, it has lower gain towards the horizon compared to straight up, this will result in stronger signal when at zenith.
Are you talking about demodulating the signal in any way or just looking at the waterfall ?
You can take a image of the waterfall and draw on it to describe what your thoughts are on this.
I have annotated an image, but can’t upload it. “Sorry, new users can not upload attachments”, apparently. Useful.
Hi! To find out what I can do, say @discobot display help.
Try again and let me know if uploading still isn’t available for you.
Trying the upload again. Seems to work. If that was due to you @fredy , thanks.
SOLRAD-7B-variable-modulation.pdf (343.2 KB)