Digital Modes

  1. 1. Weak Signal Propagation Reporter (WSPR)
  2. 2. NBEMS - Narrow Band Emergency Messaging Software
  3. Digital Voice
  4. 10.0 Digital Voice Codecs
  5. Hotspots - standalone digital radio IP gateways
    1. DV Dongle
    2. DV4Mini
    3. DVMega Rpi Shield
    4. OpenSPOT by SharkRF
    5. Nano Spot by Micro-Node International
    6. MMDVM - Multi Mode Digital Voice Modem
    7. MMDVM_HS_Hat for the Raspberry Pi Zero
    8. MMDVM Hotspot Duplex - Repeater Board
    9. ZUMSpot Libre Kits
    10. JumboSpot - a Chinese copy of the Zumspot
    11. Pi-Star - A web Based Digital Voice Dashboard and Configuration Tool
  6. Digital SSTV Encoders/Decoder
  7. 15.0 DIY Transceivers
  8. Yaesu System Fusion
  9. Building a MMDVM Repeater
  10. Digital Hardware
  11. Codeplugs
  12. Reflectors
  13. ALE - Automatic Link Establishment


1. Weak Signal Propagation Reporter (WSPR)

VK4PK Whispering Pi
KB9AMG's WSPR Grids by km/Watt
Joe Taylor K1JT - WSPR Application Instructions
VHF and Over WSPR overview
The Raspberry Pi as a Stratum-1 NTP Server
Maidenhead to log/lat grid squared
QRP-Labs Ultimate3S QRSS/WSPR Transmitter Kit
Chirp Reception and Interpretation
The MAR-6+ Monolithic Amplifier

WSPR Frequencies: UV5R-PTT-pinout.jpg
Band Dial freq (MHz) Tx freq (MHz)
160m 1.836600 1.838000 - 1.838200
80m 3.592600 3.594000 - 3.594200
60m 5.287200 5.288600 - 5.288800
40m 7.038600 7.040000 - 7.040200
30m 10.138700 10.140100 - 10.140300
20m 14.095600 14.097000 - 14.097200
17m 18.104600 18.106000 - 18.106200
15m 21.094600 21.096000 - 21.096200
12m 24.924600 24.926000 - 24.926200
10m 28.124600 28.126000 - 28.126200
6m 50.293000 50.294400 - 50.294600
2m 144.488500 144.489900 - 144.490100



2. NBEMS - Narrow Band Emergency Messaging Software

Narrow Band Emergency Messaging Software (NBEMS) is an Open Source software suite that allows amateur radio operators to reliably send and receive data using nearly any computer (Windows, Mac, and Linux) and any analog radio without requiring a dedicated digital infrastructure or specialized modem hardware.

NBEMS uses the FLDIGI suite of software routines that emulate the hardware modem, compute the error correction and format many standard message forms (to include ICS forms). FLDIGI emulates many modems for different applications; we use the MT-63-2KL for UHF/VHF messaging. NBEMS works with Windows, Linux and Mac computers and can be used on HF too. There is even an Android app.

ARRL - Narrow Band Emergency Messaging Software (NBEMS)
Narrow Band Emergency Messaging System


3. Digital Voice

10.0 Digital Voice Codecs

AMBE codec etc., as you might expect, has been tried up by the big boys, but it seems there are some attempts at amateur decoding.
KB9MWR Blogspot - 2010 article "An AMBE open source compatible codec?"
Radio Reference - Digital Speech Decoder (software package)


For Digital Voice (DV), there are four applications that have been used for transmitting digital voice on the amateur bands

  1. WinDRM,
  2. DRMDV,
  3. FDMDV (AMBE Vocoder based), and
  4. FreeDV (Codec2 Vocoder based).
WinDRM and DRMDV are based on the DRM (Digital Radio Mondiale) system adapted for amateur use by Cesco HB9TLK. FDMDV and FreeDV (Frequency Division Multiplexed Digital Voice) is a system devised by Peter Martinez G3PLX of PSK31 fame. DRM and DRMDV signals are wider than FDMDV/FreeDV which is only 1.1kHz, but they do incorporate a level of FEC (Forward Error Correction) whereas at the moment FDMDV/FreeDV does not. Therefore, DRM and DRMDV require a more powerful computer than FDMDV and FreeDV.

Wikipedia - Digital mobile radio
Wikipedia - Time-division multiple access

Jared Szechy - Digital Speech Decoder

Jared Szechy's DSD package is able to decode several digital voice formats from a discriminator tap audio and synthesize the decoded speech. Speech synthesis (encoding) requires mbelib, which is a separate package.

DSD github download of dsd-1.7.0-dev
DSD Build Instructions
DSD Supported Formats


Hotspots - standalone digital radio IP gateways

A very good discusion on hotspots by Toshen, KEØFHS can be found here:
Hanging out with hotspots The Personal Access Point

DV Dongle

The DV Dongle connects to your PC or Apple Mac via a USB port and provides
encoding and decoding of compressed audio using the DVSI AMBE2000 full
duplex vocoder DSP chip. - The DV Dongle


DV4mini Internet Gateway

DV4mini just acts as an Internet gateway (hotspot). The Internet networks that it can access are various, and depend on the system used (eg C4FM Fusion), but it can't directly go onto Yaesu's Wires-X network as their gateways (hotspots) are their own boxes that have to be individually subscribed to them.

The DV4mini can bridge networks, so for example I've had my DV4 mini on the FSC0001 network and talking to our 70cm repeater on the Wires-x network (as I'm near enough to the repeater). Some others have permanently bridged networks using a similar technique.

There is also a version of the DV4mini with the AMBE chip piggybacked so you can use it with a microphone / speakers directly. There are also lots of other products doing similar things - like openspot I think.

Helitron DV4mini USB stick installation and setup

DVMega - RPi Shield

DVMega's RPi Shield

SharkRF's OpenSPOT

SharkRF's OpenSPOT

Supports DMR (Brandmeister, DMRplus), D-Star (DCS, REF/DPlus, XRF/DExtra, XLX),
System Fusion (FCS, YSF Reflector) networks. SharkRF's OpenSPOT

Nano Spot by Micro-Node International

SharkRF's OpenSPOT


NANO-SPOT is a completely self-contained digital hotspot supporting DMR, Dstar, P25 and System Fusion communications. Fully assembled and tested in a ruggedized extruded aluminum enclosure. All that's required for operation is a power source and a WiFi based internet connection. Pi-Star Digital Voice Software pre-loaded and easily upgraded via software.

Micro Node International web site:

MMDVM_HS_Hat for the Raspberry Pi Zero

MMDVM_HS_Hat for the Raspberry Pi Zero
mmdvm_hs-hat .png

This is the source code of ZUMspot/MMDVM_HS, personal hotspot (ADF7021 version of the MMDVM firmware), based on Jonathan G4KLX's MMDVM software. This firmware supports D-Star, DMR, System Fusion, P25 and NXDN digital modes.

This software is intended to be run on STM32F103 microcontroller. Also, Arduino with 3.3 V I/O (Arduino Due and Zero) and Teensy (3.1, 3.2, 3.5 or 3.6) are supported. You can build this code using Arduino IDE with Roger Clark's STM32duino package, or using command line tools with ARM GCC tools. The preferred method under Windows is using STM32duino, and under Linux or macOS (command line) is using STM32F10X_Lib.

juribeparada/MMDVM_HS - Firmware for ZUMspot / MMDVM_HS (D-Star, DMR, YSF, P25 and NXDN)
This project provides a Raspberry Pi Hat for the MMDVM_HS Hotspot. It was designed for the Raspberry Pi Zero, but should work on any other Pi with the Hat interface.
mathisschmieder/MMDVM_HS_Hat - MMDVM_HS Hat for the Raspberry Pi (Zero)"

ZUMSpot Libre Kits - No Longer Available

ZUMSpot Libre Kit

MMDVM May 8, 2017 · Ready to Ship the ZUMSpot Libre Kits by Bruce Given. Has the ST Link and the Blue pills all programmed with Boot loaders and MMDVM code so all you have to do is solder it together and plug it into a MMDVMhost... Send a email and we will get them out the door this week.

The source code is available for download at
A Video about the construction of the MMDVM Zumspot Libre Kit which is based upon
the "Blue Pill" STM32 controller and all assembled upon an adapter board.

MMDVM Hotspot Duplex - Repeater Board

This is the MMDVM hotspot duplex version.
MMDVM Hotspot - The Duplex Version
Also more current details are available on bi7jta's Blog:

Pi-Star - A web Based Digital Voice Dashboard and Configuration Tool

Pi-Star is a web based digital voice dashboard and configuration tool written by Andrew Taylor MW0MWZ, and in the format of a custom, pre-configured SD Card image for the Raspbperry Pi and other ARM based single board computers.
Andy's web site is
Pi-Star can be downloaded here:


Digital SSTV Encoders/Decoder

KG-STV is a new, completely different digital SSTV system solely for transmitting and receiving pictures similar to analogue SSTV.

John Wells M5AML- Digital SSTV

The seven digit Call Connection Service


DIY Transceivers
Theory of Single tone detection with the Goertzel algorithm


Yaesu System Fusion

C4FM-FUsion is a system developed by YAESU. It is based like DMR on 4FSK, and also transmits 4 frequencies with a total data rate of 9600 bits/s. It uses the same AMBE+ Codec as DMR, but needs only 3600 bits/s. The extra bits are used in C4FM-Fusion in a different ways. They can be used for data transfer (e.g. GPS) but also for additional error correction to make the speech more stable during interference. There is also a mode for high speech quality which uses all bits for speech only.

gr-ysf is a collection of GNU Radio Modules to decode Yaesu System Fusion (YSF) C4FM packets.


Building a MMDVM Repeater manufacture a MMDVM shield for the RPi. Their site is: - Repeater Builder

The latest firmware for the Repeater Builder can be found here:


Digital Hardware

Baofeng DM-R5 Handheld Radio

Baofeng DM-R5 Manual Download
Baofeng DM-R5 Software Download
Radioddity Baofeng RD-5R DMR
Radioddity-GD-77-Dual-Band-Dual-Time-Slot-V-UHF-DMR-1024CH- DMR Radio
Rocky Mountain Radio - Baofeng-DM-R5-test-results
Baofeng DM-5R Buyer Beware

Radioddity GD77

Radioddity GD77 - Radioditty Download page

AnytoneAT-D868UV Dual Band DMR Radio = Wouxun.US Download page

  • Pi-Star Digital Voice Software Pi-Star Digital Voice Software

    Motorola DR3000 Repeater

    The Motorola DR3000 is a $5,000 repeater. It has trunking capabilities. Motorola salesperson recommend looking at Hytera or even better a Vertex EVX-R70 at about $3000. Apparently they are hard find them since Motorola has dominated the market.

    Tytera TYT MD-8500

    GB3GR MD-8500 DMR Repeater"

    Internally the system appears to have been made from two 70cm stock TYT Mobile radio units TH-9000D modified to become one RX and one TX. There is a custom built control mechanism which utilizes an ARM processor with two audio/digital processing chips. There is at present no way to change the firmware that controls the repeater. The Tytera TYT MD-8500 UHF 400-470MHz DMR Digital & Analog repeater is available from Aliexpress.
    Tytera TYT MD-8500 UHF 400-470MHz DMR Digital and Analog Repeater
    The suppliers is TYT:

    Front View and internal views of the MD-8500 DMR Repeater consists of HR-9000D Radios and a Logic control box.

    DMR Repeater Under side view shows duplexer and control logic box
    Overview of Adaptive TDMA


    Building a Amateur radio DMR contacts list




    Australian DMR Reflectors - VKDMR

    Dashboard Reflector - Repeaters

    Dashboard Reflector - Hotspots

    D-Star Reflectors

    Reflector -

    To list the latest list of activity for Queensland"

    A reflector can be considered to be similar to a repeater, but with no RF capabilities. Reflectors are Internet connected servers, generally in datacentres, which receive a transmission from a connected gateway (via the Internet) and send it out to all other connected gateways for retransmission, via RF in the case of a repeater. The term gateway is used in the broader sense, which includes devices such as dongles and DVAPs (See Diagram below).


    An example of an Australian XLX reflector is the "DCS014 (XLX014) Multiprotocol Reflector and Gateway".
    It can be found here: - The Australian Reflector

    "XLX AMBE Reflector"

    The XLX AMBE is a server running on debian linux. It runs as a daemon service.
    The software is available from github and operates on several network.
    The XLX Multiprotocol Gateway Reflector Server
    It requires apach2 web server, php, and g++.
    The software looks pretty simple to install. The hardware hookup may be another matter.
    Also would chew the bandwidth if it became a popular reflector.
    The ports it uses tells a lot about it. Hopefully, it support transcoding between all protocols, though I seriously doubt it …
    XLX Server requires the following ports to be open and forwarded properly for in- and outgoing network traffic:

    TCP port 80    (http) optional TCP port 443 (https)
    TCP port 8080  (RepNet) optional
    UDP port 10001 (json interface XLX Core)
    UDP port 10002 (XLX interlink)
    TCP port 22    (ssh) optional TCP port 10022
    UDP port 30001 (DExtra protocol)
    UPD port 20001 (DPlus protocol)
    UDP port 30051 (DCS protocol)
    UDP port 8880  (DMR+ DMO mode)
    UDP port 62030 (MMDVM protocol)
    UDP port 10100 (AMBE controller port)
    UDP port 10101 - 10199 (AMBE transcoding port)

    The Brandmeister Reflector Network

    BrandMaster/BrandMeister is an operating software for Master servers participating in a worldwide infrastructure network of amateur radio digital voice systems. BrandMeister allows you to connect to MOTOROLA DMR-MARC and Hytera DMRplus networks this means you operate on both infrastructures the same time. - What is BrandMeister

    The UK Reflector - CQ-UK

    The CQ-UK group provide links to FM, C4FM, DMR and D-STAR to allows all modes to be able communicate with the other in one place regardless of Repeater access or equipment owned. Thanks to the hard work of MI5DAW Rickie, GM7KBK Ernie DMR C4FM and D-star can now communicate together thru the CQ-UK room.

    CQ UK's C4FM Fusion reflector is named CQ-UK and has a dtmf node id of (27793)

    Rickie MI5DAW hosts an XLX925 reflector with extensive digitallinking from his home here in Belfast and maintains a web site He has two modules going A and B and further plans to create more Modules and linking. At the moment the xlx925 runs A module and xlx922/xlx925 run B module.

    D-Star ircddb


    ALE - Automatic Link Establishment

    Automatic Link Establishment, commonly known as ALE, is the worldwide de facto standard for digitally initiating and sustaining HF radio communications.[1] ALE is a feature in an HF communications radio transceiver system that enables the radio station to make contact, or initiate a circuit, between itself and another HF radio station or network of stations. The purpose is to provide a reliable rapid method of calling and connecting during constantly changing HF ionospheric propagation, reception interference, and shared spectrum use of busy or congested HF channels.

    A standalone ALE radio combines an HF SSB radio transceiver with an internal microprocessor and MFSK modem.

    Automatic Link Establishment
    HFLINK - Home of Automatic Link Establishment

    Glenn Lyons VK4PK
    Ver:gnl20180510 - pre published v1.0