Add streaming audio to OP25 RPi scanner

Thanks to Graham Norbury, here is how to set up a Raspberry Pi OP25 scanner to stream audio to an icecast or other streaming server. I have updated my plug-and-play op25-rpi.img image at to include this capability (look for the or later-dated file). 1. Copy the following into a new file /etc/asound.conf on the Raspberry Pi (you’ll need to do this as root): # output device pcm.loopout { type dmix ipc_key 328211 slave.pcm “hw:Loopback,0,0″ } # input device […]

Read More Here! 0 Dongle Measurements (Part 1 — background)

I’m using several USB “dongle” SDR sticks from These nifty $20 devices can receive from 100 kHz to above 1700 MHz. They have a low noise amplifier in the front end that is adjustable from 0 to about 50 dB gain. I wanted to determine the impact of the gain setting on receiver performance, and the results are below. First, some introduction. The dongles use an 8 bit analog-to-digital converter (“ADC”). The number of bits sets the dynamic range, […]

Read More Here! 1