Dear experts, I tried to receive SSTV signals using RTL-SDR and a specific antenna kit during the ISS transit at midnight.（145.8M）It failed; there was no signal fluctuation at all on the waterfall chart.
Let me introduce my plan:
RTL-SDR Blog Version 4
The antenna kit includes a pair of longer antennas, with one half extended approximately halfway. The kit also includes extension cables for connecting the antennas. Using a nanoVNA, I tested the standing wave ratio at 145.8 MHz and found it to be around 1.1.
The antenna is mounted outside a window on the sixth floor, and the ISS's transit phase as it ascends has minimal obstruction. The antenna's axis is parallel to the ground and perpendicular to the ISS's orbital direction.
SDR # + Latest RTL-SDR driver
This is the software configuration:
Previous tests:
Receives local FM broadcasts, with a maximum SNR of +50 dB, and approximately 30 dB in the aviation segment, allowing for clear audio.
Use a handheld device before crossing the border.（UV-5RH）When transmitting at 145.8 MHz, the waterfall plot shows a signal with a peak SNR of +60 dB.
Problem symptoms:
There were no signal fluctuations observed on any of the SDR waterfall plots for the entire path segment.
Within the largest 30-second time window where the angle of elevation is closest to its maximum, the handheld radio can receive relatively clear SSTV signals.
I also tested the downlink signal from the FM forwarder during our transit through the ISS two days ago, but there was no response.
Could you please help me diagnose this? I'm new to this and have no experience, so thank you in advance for your assistance!
闽ICP备2021006864号-7
闽公网安备35020602002794号