Tagged: dsd

Pocket 25: An Android P25 Phase 1 Digital Voice Radio Decoder

Thank you to reader "EN53" for submitting news about a newly released open source Android app called Pocket 25. Pocket 25 is an Android-based APCO Project 25 (P25) phase 1 digital voice decoder based on the DSD-Neo decoder engine. It was developed by Sarah Rose (aka SignalsEverywhere), whose other software we have posted about in the past.

APCO P25 phase 1 trunked digital voice systems are commonly used in the United States, Canada, Australia, and other countries by emergency services. As long as the P25 network is unencrypted, it is commonly decoded to audio with an RTL-SDR and decoding software such as DSDPlus or SDRTrunk.

Pocket 25 allows users to now decode P25 signals on portable Android devices. An RTL-SDR can be connected to an Android device via a USB-OTG cable, or a remote networked RTL-SDR can be used via an rtl_tcp connection. The app also supports RadioReference accounts, automatic GPS site hopping, smart filtering, and logging.

In the readme, Sarah also notes that, because Pocket 25 is based on the DSD-Neo engine, it supports additional digital voice protocols, including DMR, NXDN, and others. However, the interface is designed around P25, so non-P25 systems may show incorrect metadata.

The software is open source and code can be found on the GitHub. There is also an active discussion about the app on RadioReference.

Pocket25 | Running DSD-Neo on Android!

Scanner School Podcast + Webinar: This is Why You Need an SDR

Scanner School is an online site providing tutorials, podcasts and reviews all about the radio scanning hobby. They are currently planning a Webinar for February 23, 2021 titled "Why Every Scanner User Needs an SDR: The #1 Underrated Tool that should be in your setup". You can sign up to the webinar here. In addition to the upcoming webinar they have also already released episode 165 of their podcast titled "This is Why You Need an SDR". The topics covered in the podcast are listed below.

  • An SDR means that anything normally handled by the hardware of the radio is now handled by the computer, and the physical hardware serves as an interface.
  • The only limitation on the SDR hardware you buy is the frequency range and the amount of RF it can digest.
  • SDR receivers have come a long way since they were first hacked into existence.
  • SDRs used to be difficult to set up, but that’s no longer true.
  • You don’t need advanced computer skills to run SDR software.
  • SDR software can run on PC, Linux, Mac, Raspberry PI, and even Android.
  • An SDR is more flexible and less expensive than a traditional radio.
  • You can turn a $30 USB stick into something as powerful as an SDS200 in an afternoon.
  • All you need to get started is an SDR USB stick, a computer, and the free starter software SDR Sharp.
  • Once you get set up with FM broadcast stations, aviation, and other analog systems, Phil’s SDR course will go into how to set up digital reception.
  • If you download DSD+ Fast Lane or Unitrunker you can monitor trunking systems.

Frugal Radio: SDR Guide Ep 9 – P25 LSM Trunking with one RTL-SDR V3 and DSDPlus

In his latest episode of his SDR Guide series Rob from Frugal Radio provides a walkthrough on using DSDPlus Fastlane to decode trunked P25 with just one RTL-SDR V3 dongle. In the video he explains each of the various DSDPlus windows, and demonstrates decoding of a Simulcast system in his area.

DSDPlus is a program capable of decoding various digital audio protocols such as DMR and P25. The "Fastlane" version is a $25 paid upgrade which allows you to download the latest version that contains more features.

2021 SDR Guide Episode 9 : $25 DSDPlus P25 LSM trunking walkthrough using 1 x $25 RTL-SDRv3

DSDPlusUI Now Available as a Plugin for SDR#

At the beginning of 2020 Annunaki (@StupotSinders) released his third party user interface for DSDPlus. DSDPlus is a digital speech decoder capable of decoding protocols such as P25 P1, DMR, NXDN and more with an SDR such as the RTL-SDR. As it is a command line tool, it can be a little daunting for some users, which is where the GUI comes in handy.

Recently Annunaki has released an SDR# plugin version of DSDPlusUI. This makes it so you can visualize the digital voice signals at the same time as controlling and decoding with DSDPlus. The plugin is available on the DSDPlusUI website at dsdplusui.com. To use it you will need to be using SDR# 1777 or later.

DSDPlusUI as a plugin for SDR#

Simple dPMR Decoder Plugin for SDR# Released

Over on rtl-sdr.ru programmer Vasili has released his latest SDR# plugin which is a dPMR decoder (note that this site is in Russian). dPMR is short for "Digital Private Mobile Radio" and is an open non-proprietary digital voice protocol. Vasili writes:

Simple dPMR decoder. No external dependencies, no settings, uses SDR # audio path. Designed for listening to unencrypted dPMR channels.

To install the plugin simply copy the dll's from the zip file into the SDR# folder, then copy the line from the magline.txt text file into the plugins.xml file which can be opened with any text editor.

We note that there is also an open source version of DSD which includes a dPMR decoder which we posted about here.

Simple dPMR Decoder Plugin for SDR#

DSD (Open Source) with dPMR Decoding and Windows Binaries Released

Digital Speech Decoder (DSD) is an open source program for decoding signals containing digital speech, such as DMR and P25. The open source version has been mostly surpassed in use over the last few years by the closed source DSD+ version. However, work is still ongoing on the open source version, and a recent fork by Louis-Erig HERVE @LouisErigHerve has added support for Digital Private Mobile Radio (dPMR) decoding.

dPMR is an open, non-proprietary trunked radio standard that supports both data and digital voice transmission. A licence free variation for short range communications called dPMR466 uses the 446.1–446.2 MHz band. Other modes allow for efficient peer to peer to peer operation (mode 1), operation with a base station repeater (mode 2), or with a trunking signal (mode 3).  All dPMR signals operate in FDMA mode with an efficient bandwidth of only 6.25 kHz. dPMR is also known as Icom IDAS and Kenwood NEXEDGE.

Code for Louis-Erig's DSD fork can be found on his GitHub, and he has also released binaries for Windows on his website. Over on his Twitter he has also been mentioning that he has been able to get around the basic privacy modes on DMR.

dPMR radios, data stations and repeater hardware.
dPMR radios, data stations and repeater hardware.

DSDPlusUI: A Graphical User Interface for DSD+

Over on Twitter Annunaki (@StupotSinders) has been teasing some screenshots of a GUI for DSD+ that he's been developing over the past few weeks. And now he has released the software which is called "DSDPlusUI". DSD+ is mostly command line based, so a GUI could be useful for newbies. The software can be downloaded from the DSDPlusUI groups.io page.

DSD+ (aka Digital Speech Decoder) is a free closed source program that is compatible with RTL-SDR and various other SDRs which is used to decoder digital speech protocols such as P25 P1, DMR, NXDN and more. DSD+ Fastlane is a paid upgrade which allows subscribers to receive the latest updates to the software early. 

DSD+ GUI by Annunaki
DSD+ GUI by Annunaki

SignalsEverywhere: P25 Trunking with Just One RTL-SDR and DSDPlus Fastlane

Over on YouTube Corrosive from the SignalsEverywhere channel has uploaded a new video showing us how to set up P25 trunking and decoding with DSDPlus Fastlane and only a single RTL-SDR.

Normally two dongles are required to follow a P25 trunking system. One dongle continuously receives the trunking channel, and a second tunes to the voice channel chosen by the trunking channel. However, the latest DSDPlus Fastlane has a feature that allows one only dongle to be used. It works by tuning back and forth between the control and voice channel. The disadvantage is that trunking information could be missed while tuned to a voice channel, so some calls could be missed.

RTL SDR Setup P25 Trunking With 1 SDR and DSDPlus FastLane