Listening to Digital Voice communications

I recently have had several inquiries from folks interested in listening to digital voice modes. So this week I came across this interesting article that does a pretty good job of answering some of those questions. The article explains the equipment required to continue listening to many digital Amateur and public service radio transmissions. It covers most of the digital voice modes and the basic functionality of each mode. Though written from the perspective of a Canadian Ham/SWL, it is very applicable to what is happening around the world.

from Scanner Digest #72 (Summer 2015)
CANADA Report - John Leonardelli - VE3IPS

ve3ips@gmail.com

Buzz Buzz Bzzzzrrrp - The Short Guide to Digital Radio

The world of scanning is changing as we move from an

analog world to a digital one. Each digital mode has

different characteristics in how the analog voice is

converted to and decoded from digital. Linking methods

vary across each mode and inter-operability is lacking

between them. Many local amateur radio club nets that

offered interesting listening are now moving to the digital

modes. However, many ARES/RACES groups continue to

offer analog and digital mode nets to test out the

communication readiness.

Every scanner hobbyist needs

to be prepared to listen in on all modes.

Many of these modes require appropriate radios to

monitor them with some SDR methods as well. Please

note that appropriate radio licenses are required to

transmit legally on amateur radio, business and public

band frequencies. In many cases, users will disable

transmit allowing the commercial radio to be used

primarily as a receiver. Many scanner listeners are also

ham radio operators so experimenting in a new digital

mode can be an interesting experience. I am not going to

go into any technical details as those can be easily

gathered on a web search. Let’s explore how a savvy

radio listener can hear these new digital modes and better

understand them.

D-Star

JARL developed the protocol back in 2004 and has a well established

global amateur radio repeater network already

in place.

D-Star allows 2 linking methods. The Call Sign routing

allows you to communicate with another ham user where

you connect to the local repeater and through an internet

gateway connect with a defined ham user by their call

sign.

The other method is via linking into “reflectors” where

users can meet and communicate among each other.

Examples of popular reflectors are the REF001C Mega

repeater, REF005A for the United Kingdom and Listen to

HamNation on Wednesdays nights on REF014C.

Icom is the only manufacture of this equipment. They offer

5 handhelds and mobiles to choose from. The ICR-2500

Scanning receiver does offer an optional Digital Voice

card for reception of this mode. The other method is to

purchase an Icom radio with D-Star for reception. There

are also many boards like the DVDongle that can receive

signals on your computer. You do need to be licensed

amateur radio operator in order to transmit.

APCO P25

Project 25 has been THE North American standard for

LMR Public safety agencies for years. It is part of a

trunked radio system and has two modes of operation.

Phase 1 uses a FDMA standard and the newer Phase 2

offers a 2 slot TDMA standard. This is where a lot of

change has occurred as the older systems have migrated

to Phase 2. Because of this standard change, older

scanners are not equipped to receive the new system due

to the modulation method. The newer scanners such as

the, Uniden BCD436HP, BCD536HP, HomePatrol2, BCD325

P2, BCD996P2 and Whistler WS1080, WS1095 and

PSR-800 (GRE Brand) have the codecs that decode the

proper signals. Along with the migration to Phase 2 many public service

agencies have moved to encryption making reception

impossible. There is some amateur radio activity so check the ARRL

Repeater on-line app for what’s available in your

community. The Toronto GTA has access to a couple of

Ham Radio VHF and UHF P25 repeaters.

The Toronto Public Safety service and York Region has

moved to the new Phased 2 system with encryption.

DMR

Digital Mobile Radio is the fastest growing segment of the

digital mode hobby. It is based on Motorola MOTOTRBO

technology. It also offers the largest selection of radios to

choose from. Linking is done via talk groups and they are

managed at the local repeater level. The protocol allows 2

time slots to be available in a single channel. The talk

group concept is an interesting one as you program your

local DMR repeater as a Zone then add your 16 talk

groups. A popular talk group is called North America (Talk

Group 3). There are also various technical nets where a

lot of information is shared and can make for some

interesting listening.

Popular radios are the Motorola 6550 and 7550, Yaesu

Vertex EVX-539, Hytera PD-782 and various new Chinese

entrants. The most popular is the SC700/750 from

Connect Systems.

Toronto has the VA3XPR repeater that is also linked to

the VE3OBI, VE3XPR, and the VE3UHM repeater

provided extended geographical coverage for the golden

horseshoe in the local talk group. This mode has become

the fastest growing digital segment in LMR and Ham

radio.

Check listing for LMR service providers using this mode

for their regional networking services.

dPMR

This is a popular digital mobile radio technology in Europe

with many dPMR446 users on the license free radio band.

This is very popular in the UK. Several Chinese

manufacturers and Motorola make radios. Analogue

PMR446 covers band 446.0–446.1 MHz and digital

dPMR/DMR cover 446.1–446.2 MHz which is in the North

American ham band plan. These radios are illegal for

North American use. However, do not be surprised to find

activity here as many may have purchased these radios

overseas on cruise ships.

Yaesu Fusion

This is also known as C4FM and is another relatively new

digital mode from a Japanese manufacturer. It’s gaining a

lot of popularity as repeater clubs migrate their older

equipment to the newest for a promotional cost of $500.

You do need to be a licensed ham radio operator as your

call sign needs to be entered into the radio. It also

supports the ability to send data and Yaesu has added

microphones with a built in camera allowing photographs

to be sent across the network. What’s interesting about

this mode is that it also supports analog FM transmissions

and like DStar supports GPS functionality. Yaesu now

offers 2 handhelds and 2 mobiles to choose from. Yaesu

using their WIRES modems to allow connectivity between

repeaters. It has not had a lot of success in North America

but that may soon change. Currently, the Fusion mode is

for local communications. It is understood that Yaesu is

looking to increase the level of connected repeaters in the

coming years.

Toronto currently has two repeaters using Fusion and its

VE3TWR and VE3SKY. There should be 8 more club

repeaters coming on-line this summer. Watch activity

increase thereafter.

Kenwood NXDN

This is another variation of a commercial digital mode

called NEXEDGE. The activity is sparse as there are few

amateur radio repeaters but it is growing in the larger

cities. The equipment is purchased through a local

Kenwood LMR dealer. Icom also supports this standard

with their iDAS brand. There are two repeaters in Canada

VE7NYE and VE3SKV. Check Radio Reference for NXDN

networks with LMR users on it.

TETRA

Terrestrial Trunked Radio is a European trunked radio

standard that has been the backbone of European Public

Safety. It uses a 4 slot TDMA method as its protocol. It is

starting to make headway into North America. The

Toronto Transit Commission has chosen TETRA

technology for its analog system replacement that will be

implemented over the next few years and it’s the system

that will be used by the Toronto PanGames 2015.

It offers a great talk around method, better spectrum

management and improved operations with a direct mode

operation (DMO). DMO allows communications without

repeaters and you can also use a Trunked Mode

Operation (TMO) for use of TETRA repeaters to

communicate. This is done seamlessly.

There is discussion among amateur radio users about

using TETRA for another digital mode to use as

equipment becomes more available.This mode was very

popular in use for the Toronto Panam 2015 Games.

Alinco Digital

Not to be left out, Alinco does offer a digital board for

selected transceivers but its review has not been

favourable and its use has not been widespread. If anyone

has any experience please email e and I can include

some information in the next column.

It does have its own proprietary standards and info is hard

to come by.

How to Receive these Digital Modes?

There are several ways to receive these modes:

1) Amateur radio transceivers. The Icom D-Star,

DMR, and Yaesu Fusion are the easiest methods

2) Commercial radio transceivers. Motorola, Tait,

Sepura, Kenwood, Vertex and Hytera come

quickly to mind as these are typically purchased

from ham friendly land mobile radio dealers. You

do need to buy programming software and for

Motorola it can be $300 for a 3 year term.

3) European FRS radios for dPMR

4) Icom 2500 D-Star and P25 capable receiver

5) Uniden/Bearcat and Whistler/GRE new P25

Phase II scanners

6) AOR Scanners with the add-on ARD300 $900

7) AOR Stand-alone DV1 scanning receiver $1500

8) DSD+ Decoding software running on a PC

connected to a discriminator tap on a scanner or

SDR Dongle

9) Web based receivers that are streaming local

digital audio

The reviews for the new AOR boxes are showing some

great promise to make listening to digital communications

with a simple to use stand-alone receiver as we get

through the initial adoption process and it will get better

and at a lower cost if the SDR receiver manufactures build

their version of a stand-alone receiver.

The challenge that I have with DSD+ is its lack of

portability as many have installed the software on a

netbook and use an older scanner that had the

discriminator tap mod completed. It does not fit easily on

your belt or as an easy mobile in your car but it is doable.

The other challenge with DSD+ is that it can decode all

DMR communications on a repeater across its 2 time slots

but cannot differentiate among different talk groups. This

can make a jumble of conversations confusing when both

time slots on the repeater happen. A scanner listener only

could have a DMR radio programmed with transmit

disabled for the ham radio portion so they can scan and

listen to specific talk groups just like a regular SmartNet

talk group would work.

There is a lot of activity going on right now with digital

modes and the best way to enjoy it is to jump in and start

using the new technologies available to us.

Thanks to John;VE3IPS, for giving us permission to share his article.

...and be sure to check out Scanner Digest at: http://www.scannerdigest.com/