Author Topic: Reception problem nearby signals  (Read 561 times)

Offline kovac

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Reception problem nearby signals
« on: October 21, 2018, 02:10:37 AM »
First: I'm sorry for my English because it's not my native language.

Hello.

I made an air traffic control receiving station using an RTL2832u SDR; one 1/4 antenna; and SDR # v1.0.0.1.1666 for the purpose of making the signal available to the LIVEATC site. I live 6 miles from the airport and can receive PERFECTLY the Control Tower and aircraft flying at high levels up to 200 miles.

The problem begins when aircraft are flying low and close to my house, which is on the approach route to the airport. The SDR # shows the signal "exploding" in several waves and you do not hear anything at all from the aircraft, but I still hear the signal of the Control Tower perfectly.

The RF GAIN setting of the sdr # is -4dB. If I change the value from "RF GAIN" to + 17.9dB, I can hear the aircraft coming in at low altitude PERFECTLY, but now I do not hear the Control Tower and neither the aircraft flying high and very far.

I'm a beginner in these radio affairs. I wonder if there is a solution to this problem, as it is totally impractical to change the value of RF GAIN at all times.

Thank you.



Offline szpajder

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Re: Reception problem nearby signals
« Reply #1 on: November 13, 2018, 03:13:40 PM »
This is a common issue with RTL dongles. They have a low dynamic range, ie. they can't receive both weak and strong signals simultaneously, at the same gain level. You need an SDR with a higher dynamic range - Airspy HF+ is said to be much better on this matter, however I don't own one myself, so I haven't done a 1:1 comparison with RTL.

Another, cheaper option is to try a shorter (ie. worse) antenna - given that you're so close to the airport, even that small 10cm stick which often comes bundled with RTL dongles should do reasonably well.