RTL-SDR for VHF Air Band AM Receiver on GNU Radio – Telecommunications, Navigation & Electronics

Introduction

In a previous post I looked at a simple receiver for VHF Air Band AM (Ref.1). In this post I add several new features in order to select from a stored set of local frequencies and a choice between source blocks.

GNU Radio Schematic VHF Air Band AM Receiver

Fig.1 GNURC Schematic for VHF Air Band AM Receiver with Channel Selection

Fig.2 QT GUI Chooser for Frequency Selector

Fig.3 GNURC Display Showing Volume Control, Station Selector Buttons, LPF Spectrum, Input Spectrum

Figure 1 shows the GNURC schematic. I have two source blocks shown for the RTL-SDR. Depending on your antenna/location one block may give better performance than the other. In my situation, the Soapy block does not have a residual DC component on the channel frequency. This however does not degrade performance. I demonstrate this in the video. Figure 2 shows the QT GUI Chooser which allows you a choice during run time to change the center frequency variable fc. I have 5 selections for my two local airports and the International Emergency Frequency of 121.500MHz. Figure 3 shows the display at run time: Volume Control, Radio Buttons for frequency selection, LPF spectrum (48KHz bandwidth) and input spectrum (2.4MHz bandwidth).