Using a Raspberry PI for SDR Over TCP/IP

Assuming you are on ethernet (or fast Wifi N), audio quality should be great. There will a slight delay in changing to frequencies, and a large (2 to 5 second) delay in changing the monitored frequency window. These delays are reduced upon reducing the sample (step 4).

Confirm Installation

To confirm a proper setup and device stability etc, run the following code over SSH:

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rtl_test -t

Resulting in an output similar to:

Output of RTL_Test 
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Found 1 device(s):
      0:  ezcap USB 2.0 DVB-T/DAB/FM dongle
    Using device 0: ezcap USB 2.0 DVB-T/DAB/FM dongle
    Found Elonics E4000 tuner
    Supported gain values (18): -1.0 1.5 4.0 6.5 9.0 11.5 14.0 16.5 19.0 21.5 24.0 29.0 34.0 42.0 43.0 45.0 47.0 49.0
    Benchmarking E4000 PLL...
    [E4K] PLL not locked for 51000000 Hz!
    [E4K] PLL not locked for 2227000000 Hz!
    [E4K] PLL not locked for 1114000000 Hz!
    [E4K] PLL not locked for 1241000000 Hz!
    E4K range: 52 to 2226 MHz
    E4K L-band gap: 1114 to 1241 MHz

Server IP

Obtain devices IP address, either thru;

Obtain IP address of RPI 
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ipconfig # for wired lan
iwconfig # for wireless lan

Start RTL_TCP

Now over ssh put the device into listening mode, you can tell the program to only accept connections from a specific ip, or any.

RTL_TCP - Open to all clients
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rtl_tcp -a 0.0.0.0
RTL_TCP - Open to specific clients
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rtl_tcp -a 192.168.X.X

Configure Gqrx

Open Gqrx, goto the Configure I/O Devices prompt.

Gqrx - Configure I/O Devices 
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Device: RTL-SDR Spectrum Server
Device String: tcp=192.168.1.X:1234  # IP of RPI
Sample Rate: 1,500,000hz # Default
                         # Ideal is between 375,000 to 500,000

Results

Hit the power button, enjoy:

Notes:

  1. SDR instability, is likely due to plugging directly into the raspberry pi. Instead use a POWERED usb hub.