System Fusion by YaesuRoger Reini, KD8CSE

Overview Digital communications in amateur radio and the case for C4FM

Yaesu’s implementation of C4FM: System Fusion

History of Digital Modes in Land Mobile 1980’s: first digital LMR radios appear, using GMSK (GFSK) technique

Now, GMSK is out of favor, and C4FM (4-level Frequency Shift Keying) is dominant

2003: first GMSK transceiver released for amateur radio market

2004: Icom’s D-STAR released; it also uses GMSK

2011: Motorola LMR’s Digital Mobile Radio released, using C4FM; DMR-MARC demonstrated it for Amateur Radio at Dayton

Types of Digital Communication Systems Modulation: GMSK, π/4 DPQSK, C4DM (4-level FSK)

Communication type: FDMA (Frequency Domain Multiple Access), TDMA (Time Domain Multiple Access)

Protocol

GMSK Simple, used in earlier cell phone

systems

Performance exceeded by other systems

D-STAR uses GMSK

π/4 DPQSK (4-minute pi DPQSK) High-grade modulation method,

produces low distortion

Requires linearity (like SSB transceivers) and complicated circuitry to implement

Not commonly used in LMR

C4FM Modulation At same bandwidth, C4FM circuit

can be simplified and the Bit Error Rate approved

Main modulation method in LMR these days

Yaesu using this as the basis for SystemFusion in the amateur market

FDMA vs TDMA FDMA circuitry is simpler than TDMA

TDMA reduces transmission time by one-half or more, reducing power consumption

Is C4FM compatible with D-STAR? No, it’s not; different modulation techniques (GMSK vs C4FM)

Is this a problem in the amateur radio world?

Not really; an example of the experimentation that amateur radio is known for

Is C4FM Digital always the superior mode? No, it isn’t; there will be instances when analog is superior

We amateurs know that different modes have different advantages and that some are preferred in certain circumstances

C4FM is another mode available to amateurs, increasing our capabilities; it’s another tool in our toolbox

Yaesu’s implementation: System Fusion Three C4FM modes, using 12.5 kHz bandwidth:

V/D Mode – Voice/Data simultaneous communication, half for voice, half for data and error correction

Voice FR (full rate) Mode – all bandwidth used for voice, top audio quality

Data FR Mode – all bandwidth used for data

Analog FM – 25 kHz; used when signals too weak for digital

AMS (Automatic Mode Select) Transceiver recognizes the incoming mode (C4FM digital or analog FM) and

switches over to match that mode

No need to remember to manually switch the mode on the transceiver

Enables mixed-mode communication on compatible repeaters

If a SystemFusion repeater is installed, you’re not locked out if you don’t have a SystemFusion transceiver

New Functions Gained with C4FM Digital GM (Group Monitor) Function – see where group members are

located

Snapshot Function – transmit images taken with camera microphone

Smart Navigation Functions Simultaneous Voice and Data transmissions allows APRS-type position data to be

sent while transmitting Backtrack navigation – allows one to return to a preset point (useful for hiking)

Equipment that is C4FM capable Repeater DR-1 144/430 dual band C4FM/FM repeater

HT FT1DR 144/430 dual band C4FM/FM 5W transceiver

Mobile FTM-400DR 144/430 dual band C4FM/FM 50W transceiver

For More Information Yaesu – www.yaesu.com; link to System Fusion page

FT1DR 2m/70cm HT

FTM-400DR 2m/70cm mobile

DR-1X digital 2m/70cm repeater