2

Let's imagine we're at ground station trying to receive UHF signal transmitted from moon at 433 / 2400 MHz. Our antenna with 25dB gain (circular polarization) points to the moon. Our LNA has 1dB NF.

What realistic spectral power density of noise we should expect in this situation?

I am interested in realistic estimation - not counting on just temperature of receiver/moon. We have cosmic radio background - solar, galactic, both directly and reflected... We have antenna's side-lobes picking signals from elsewhere... We have hot moon that is NOT covering whole main lobe of the antenna. There must be other tricks which affect the results which you are aware of and I am not.

SDsolar
  • 2,107
  • 1
  • 17
  • 36
BarsMonster - R2AYN
  • 406
  • 1
  • 3
  • 15

1 Answers1

2

It's very difficult to say. Factors like ambient man-made noise around you can vary by orders of magnitude based on your location. Likewise, your radio system's internal noise and ability to reject ambient noise can vary by orders of magnitude. The difference between a \$20 RTL-SDR dongle in an urban environment and a \$2,000,000,000 array of receivers operated by a national space agency is quite large.

Assuming you want to know this in relation to your previous question, the noise floor might be low enough that you can achieve near the theoretical maximum capacity, or you may not be able to communicate with your satellite at all. The environmental factors are just too variable to make a more precise prediction.

You can empirically determine the noise floor with a spectrum analyzer, and that's probably the simplest and most accurate way to answer your question.

Community
  • 1
Phil Frost - W8II
  • 52,635
  • 8
  • 91
  • 225