Digital Modes

    Table of Contents

  1. WSPR - Weak Signal Propagation Reporter (wsjt-x)
  2. NBEMS
  3. Digital Voice
  4. D-STAR
  5. DMR
  6. DMR Repeaters Frequencies
  7. Yaseu System Fusion
  8. Hotspots
  9. Building a MMDVM Digital Repeater
  10. Digital Hardware
  11. Reflectors
  12. Digital SSTV Encoders/Decoder
  13. Echolink
  14. ALE - Automatic Link Establishment

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

source:source: [Top][Home]

8.0 nbems

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



Digital Voice

For Digital Voice (DV), there are four pieces of software that have been used for transmitting digital voice on the amateur bands - WinDRM, DRMDV, FDMDV (AMBE Vocoder based), and 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

FreeDV (codec2 based vocoder) on the Raspberry Pi

FreeDV software can be used with the RPi to add a small, low-power, free software digital voice (DV) modem to an HF radio.

Matt Roberts - Published: 2018-03-12 Updated: 2018-03-28
Matt Roberts KK5JY - Building and Running FreeDV on Raspberry Pi

FreeDV QSO Finder
Here are some videos about the SM1000 FreeDV Adpapter:
Youtube - David Rowe VK5DGR presents on codec2 and SM1000
HRN 193: Digital Voice is Exploding (maybe) on HamRadioNow - David Rowe VK5DGR
David VK5DGR spoke at AREG on the 15th of May 2015 about his FreeFV project to get
digital voice working on HF and his latest device, the Sm1000 embedded modem that
allows FreeDV to be adapted onto almost any radio."> Vimeo - IntrodJumbospot.htmlucing FreeDV Digital Voice on HF and the SM1000 Embedded Modem
David Rowe VK5DGR - Home Page


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)


AMBE - Advanced Multiband Excitation

AMBE - Advanced Multiband Excitation

David Rowe's Codec2

Codec2 is an open source alternative which uses half of the bandwidth of AMBE to encode speech of similar quality, created by David Rowe and lobbied by Bruce Perens. Codec2 still continues to evolve, with additional "modes" being developed, refined and made available on a continuous basis. This has resulted in an open source codec that has progressively increased its robustness and performance – when subjected to some of the most challenging RF and acoustic environments.

FDMDV - Frequency Division Multiplex Digital Voice (AMBE Vocoder based)

FDMDV - Frequency Division Multiplex Digital Voice

FDMDV (Frequency Division Multiplex Digital Voice) is based on 15 carriers using the 1400 LPC CODEC. High power in each carrier combined with a narrow 1.125 KHz bandwidth provide good robustness with fast sync for a near SSB experience. FDMDV is new and not derived from DRM technology.

FDMDV - Digital Audio over HF SSB


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

Wireless Holdings DV4mini

DVMega - RPi Shield

DVMega's RPi Shield

DV Mega on Rpi -

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


15.0 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

Digital Handheld Radios

Baofeng DM-R5 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

    Reflector -
    Reflector -
    Reflector -">Reflector -
    To list the latest list of activity for Queensland"

    To list the latest list of activity for Queensland"

    D-Star Reflectors

    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)

    The home of CQ-UK is

    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
    Youtube - Quick-Start Guide to Automatic Link Establishment

    Echolink requires 5200/tcp, 5198/udp, and 5199/udp ports to be open.
    The application test shows that they fail but this appears to be a false report
    as the application works well despite the reported errors. This maybe a result of
    running the application ion wine emulation on Ubuntu Linux.


    Uncomplicated Firewall (ufw) - A good tutorial on UFW

    The terms to describe a ports state are confusing. Here is a summary of their meanings:

    The "netstat -atnp" command does not show 5200, 5298, 5199 ports as open.

    The nmap command shows the ports as closed.

    The command "nc -l port-no" will run a "service" on the port and as there is now a
    service "listening" on the port an nmap scan should show the port as open.

    Opening the ports required for Echolink to operate is one issue, but a far bigger issue appears
    to be obtaining a reliabale proxy server.

    Echolink worked fine this morning, 9th April 2018, on both the Laptop and the Android phone.
    Now, four hours later neither will connect! Still using the Optus Hauwei E5186s-61a wireless modem.
    The log on the Laptop shows "2018-04-09 12:51:23 ConnectAttemptFailed VK4RBS-R Timed out."

    This is setup image from Laptop.

    I suspect the proxy servers are failing intermittently, so I changed the setting
    on the laptop to this and it all works again. (Selected the proxy at random form the list.)


    A browser search of reveals the following:

    Address type	IPv4   
    ASN	47610 - RWTH-AS
    ISP	Achses
    Organization	RWTH Aachen University

    Maybe this proxy server was not responding.

    Qtel- a native Linux Echolink Application

    Qtel, the Qt EchoLink client, is a graphical application used to access the EchoLink network.
    and is available from
    It can be install with the linuc "apt" utility by typing the following command at the terminal.

    At this point I can run Qtel but cannot get a connection.


    Advanced repeater controller and EchoLink software for Linux including a GUI, Qtel - The Qt EchoLink client">


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