Docker RTL MUS Server

Purpose

This Docker container will create a RTL Multi-User Service allowing you to use your RTL dongle(s) with more than one application at a time.

To do this, we wrap rtl_tcp and rtl_mus in a lightweight Alpine Linux docker container and expose the service on the default rtl_tcp port 1234.

You then simply connect to this where you would connect to any other RTL_TCP service. It can be run multiple times for more than one RTL dongle too.

This container should work on most Linux operating systems including Raspberry Pi's.

Warnings

Disable Kernel modules

To use this script you must have blacklisted the RTL Kernel modules on the Docker host.

To do this, run the following:

sudo tee -a "blacklist rtl8xxxu
blacklist dvb_usb_rtl28xxu
blacklist rtl2832
blacklist rtl2830" > /etc/modprobe.d/blacklist-rtl.conf

After doing the above, you must reboot your Docker host for these to take effect.

Using multiple applications at once

When using multiple applications at once, changing the receiver frequency will not inform the other applications.

They will get the new IQ data for the new frequency but they will still display the old frequency.

Example:

• Application A connects and tunes the receiver to 100 MHz
• Application B connects and tunes the receiver to 200 MHz
• Application A still displays 100 MHz but is receiving IQ data for 200 MHz

This is a limitation of RTL_TCP - Keep this in mind when using this container. It's not my fault.

Building the container image

This guide expects that you...

• Have basic Docker and Linux knowledge
• Have Docker running (you get no errors when you run sudo docker ps -a)
• You know the device indexes of your RTL dongle(s) if using more than one

To build the Docker container, run the following command:

sudo docker build --label rtl_mus -t "jasongaunt/rtl_mus:1.0" .

This won't take long and will then provide you with a local Docker image you can run.

Running the container(s)

One dongle with default configuration

If you only have one RTL dongle and want to get this running immediately, run the following command:

sudo docker run -d --name rtl_mus_device_0 --restart=always --device /dev/bus/usb -p 1234:7373 jasongaunt/rtl_mus:1.0

That will create a basic RTL MUS server with the following defaults...

• Device Index: 0
• Sample Rate: 2400000 (2.4 MS/s)
• Device Gain: 0 (0 = Automatic Gain)
• Device PPM: 0
• Device Bias Tee: Off
• Device buffers: 15
• Device linked list buffers: 500

You should be able to connect straight away on port 1234.

More than one dongle and / or advanced configuration

If you need to tweak the RTL settings, or run this service multiple times, a more advanced command is required:

sudo docker run -d \
  --name rtl_mus_device_0 \
  --restart=always \
  --device /dev/bus/usb \
  -p NEWPORT:7373\
  -e 'DEVICE_INDEX=DEVICE_ID' \
  -e 'DEVICE_SAMPLE_RATE=2400000' \
  -e 'DEVICE_PPM=0' \
  -e 'DEVICE_GAIN=0' \
  -e 'DEVICE_BIAS_TEE_ENABLE=0' \
  -e 'DEVICE_BUFFERS=15' \
  -e 'DEVICE_LINKED_LIST_BUFFERS=500' \
  jasongaunt/rtl_mus:1.0

You will need to run this for every device and CHANGE THE FOLLOWING:

• Change rtl_mus_device_0 to suit the device name
• Change NEWPORT for every device, for example:
  • 1234:7373 for device 0
  • 1235:7373 for device 1
• Change DEVICE_INDEX=DEVICE_ID for every device, for example:
  • DEVICE_INDEX=0 for device 0
  • DEVICE_INDEX=1 for device 1

You do not need to specify every -e option, they will inherit the defaults in the previous section.

If however you have more than one device, you MUST at least specify the -e 'DEVICE_INDEX=DEVICE_ID' \ for each device as described above.

Here is an example on how to run two dongles with their default configurations:

sudo docker run -d \
  --name rtl_mus_device_0 \
  --restart=always \
  --device /dev/bus/usb \
  -p 1234:7373 \
  -e 'DEVICE_INDEX=0' \
  jasongaunt/rtl_mus:1.0

sudo docker run -d \
  --name rtl_mus_device_1 \
  --restart=always \
  --device /dev/bus/usb \
  -p 1235:7373 \
  -e 'DEVICE_INDEX=1' \
  jasongaunt/rtl_mus:1.0

You can then connect to the first dongle on port 1234 and the second dongle on port 1235.

Authors

Jason Gaunt (this Docker wrapper repository) András Retzler [email protected] (RTL MUS service)