Workshop - Build a P25 Digital Scanner with a Raspberry Pi and Software Defined Radios

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Build a P25 Digital Scanner with a Raspberry Pi and Software Defined Radios

In this workshop you will create a police scanner using open source software and common off-the-shelf hardware. By the end of this workshop you will have your own scanner capable of receiving and decoding P25 digital signals, complete with a responsive web interface.

Please read and understand the following before registering for this workshop:


  • A willingness to learn
  • A very basic understanding of police scanners and P25 trunking
  • While not required, some experience with the linux operating system, or even the command line on Windows, will be helpful
  • Please have all of the required equipment on-hand, or at least ordered, prior to signing up for the workshop (see list below). If ordering equipment, be sure to account for possible shipping delays so that you have everything before the first day of class.

Required Equipment

A P25 digital scanner is somewhat complex, and in order to successfully build one certain equipment will be required. Some of it is expensive. Just remember that the end result will be a system that is in some ways more capable than off-the-shelf scanners, and at a fraction of the cost of a new P25 scanner.

This is a "Bring Your Own Equipment" workshop. Bloominglabs is not supplying equipment/materials/kits this time. You are responsible for your own equipment. Bloominglabs is supplying the instruction to assemble and configure your own equipment.

Note: we have an Amazon Smile Account For Bloominglabs. If you use that link to place an order on Amazon, we get a little cut. Thanks!

Raspberry Pi 4

  • 1 Raspberry Pi Model 4 (1 GB memory is fine; more won't help much). A Raspberry Pi Model 3B+ is the absolute minimum, but you will get better performance with a 4 and that's what we are recommending.
  • 1 Power supply for Raspberry Pi 4 (USB-C connector, or a microUSB connector if using a Pi 3B+). Needs to provide at least 2.5 A.
  • 1 microSD card. Must be 8 GB or greater capacity, and Class 10 or better. Please bring a USB adapter to connect the microSD card to a PC if you have one; we'll have a couple extras if you don't own one, so this is not 100% required.

RTL-SDRs with antenna(s)

  • 3 RTL-SDR dongles (with TCXOs). Can you make it work with just two? Probably, but you'll be missing some radio traffic. Don't skip the TCXO (Temperature Controlled Crystal Oscillator). Recommended models include:
    • v3
    • Nooelec NESDR Smart v4
  • 3 antennas for RTL-SDRs. Or 1 antenna and a splitter feeding each SDR. Note that you don't need a fancy antenna to receive the tower site from Bloominglabs. If your RTL-SDR came with an antenna, that should be sufficient to get started.
  • Any cabling needed for your antennas. Note: most RTL-SDRs use SMA antenna connectors.

Miscellaneous Equipment

  • 3 USB-A extension cables. We suggest these cables be short, as in about 6 inches long, to keep the cables manageable. Longer is okay though if that's what you have already. The RTL-SDR's won't all plug in to the Pi without some sort of extension cables, as the form factor is too large.
  • Headphones or earbuds for laptop (optional, but highly recommended)


You will need a laptop in order to configure the Pi. Bloominglabs will provide laptops for the workshop, or you may bring your own. If bringing your own, try to have the following:

  • An SSH client, such at Putty or openssh
  • WiFi
  • A free USB-A port (or a way to adapt to one from USB-C)

Monday & Tuesday, July 26-27th, 2021 -- 6:00 PM to 9:00 PM both days

  • Format: In-Person, at Bloominglabs, 1840 S. Walnut St, Bloomington, IN
  • Cost: $50 for non-members, or $25 for members [bring your own equipment]
  • Optional equipment check: Tuesday July 20 (stop by any time between 7:00 PM and 9:00 PM to make sure you have everything on the required equipment list)
  • Maximum Class Size: 6
  • Registration deadline: Saturday July 17, 2021 (or when all seats are filled)


Registration for this workshop is now open. Please have all of the required equipment on-hand, or at least ordered, prior to signing up for the workshop (see list above).

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