We have set up a new Ground Station and we are facing some challenges getting a clear signal, and we were hoping the community might give us some advice.
Our equipment, located at the roof of our building in Athens and set up in series in this order, is:
thank you @fredy ! The gain variable really improved the signal (NOAA19NOAA15). Unfortunately though the demodulated data is still noise. Is there something else that you can think of that we can tune? Thanks again for your help!
Allright. Are you running DC (bias) over the coax ? In that case we can probably rule out the cable as an issue. What’s supplying the DC/bias btw ?
The signal is still very weak for such a setup. Do you have the possibility to hook a VNA or some antenna analyzer up to the antenna ?
Also, you should probably change the antenna config for that station to 135-140MHz as the SAW filters the rest.
There is no DC bias over the coax. The LNA gets power from a external power source. Unfortunately since there is no DC bias over the cable, the preamplifier embedded in the antenna is off. We don’t have an antenna analyzer. We also just changed the antenna config as you suggested.
Err, is it a preamp with bypass relays ? A plain LNA will absolutely block most signal if not powered.
I’m looking at the specs now, why do you have a sawbird lna there at all ? using a pure SAW filter would make more sense. Having a 17dB gain LNA screaming in to a 41dB gain LNA at VHF seems waay overkill if not just making it into squarewave. Hook it up to a 100MHz+ oscilloscope and find out (:
Internal low-noise preamplifier with typ. 17 dB gain.
High selectivity due to high-Q-filter in the 137 MHz range.
41dB of RF gain at 137.5MHz
2.6MHz 3dB bandwidth
Other satellite signals within 136-138MHz