How to Identify Digital Phone How to Identify Digital Phone Modes on VHF/UHFModes on VHF/UHF

David Witkowski, W6DTWDavid Witkowski, W6DTW

Revision 1.2Revision 1.2

PurposePurpose Provide recorded audio of various digital Provide recorded audio of various digital

systems so that hams without digital gear systems so that hams without digital gear can identify (in some cases) modes they can identify (in some cases) modes they might hear on VHF/UHF bandsmight hear on VHF/UHF bands

Show spectra of various digital systemsShow spectra of various digital systems Covers:Covers:

D*StarD*Star APCO Project 25 Phase 1 (aka “P25”)APCO Project 25 Phase 1 (aka “P25”) NXDN™NXDN™ DMR Tier 2 (functionally akin to MotoTRBO™) – DMR Tier 2 (functionally akin to MotoTRBO™) –

uplink (mobile)uplink (mobile)

MethodologyMethodology Equipment:Equipment:

Anritsu S412E LMR Master™ for signal Anritsu S412E LMR Master™ for signal generation and spectrum analysisgeneration and spectrum analysis

Kenwood TS-2000 w/ Ham Radio Deluxe’s Kenwood TS-2000 w/ Ham Radio Deluxe’s “Audio Grabber” for audio recordings“Audio Grabber” for audio recordings FM Mode, 5 KHz deviationFM Mode, 5 KHz deviation D*Star was K6MDD (147.475, Mt. Diablo) recorded D*Star was K6MDD (147.475, Mt. Diablo) recorded

off the air from CM97off the air from CM97 P25, NXDN, and DMR were generated by the P25, NXDN, and DMR were generated by the

S412E, cabled to the TS-2000 through an S412E, cabled to the TS-2000 through an attenuatorattenuator

K6MDD D*StarK6MDD D*Star

““Digital Smart Digital Smart Technologies for Technologies for Amateur RadioAmateur Radio”” JARL, ICOMJARL, ICOM Modulation: GMSK Modulation: GMSK

impressed on FM impressed on FM modulatormodulator Ref: K6WX “FM Ref: K6WX “FM

Spacing Requirement Spacing Requirement for Amateur for Amateur Transceivers”Transceivers”

D*Star Sound Sample (Click to play)

K6MDD D*Star SpectrumK6MDD D*Star Spectrum

APCO Project 25 Phase 1APCO Project 25 Phase 1

Aka “P25” - Federal Aka “P25” - Federal standard for standard for encryption & encryption & interoperabilityinteroperability

Some amateur use in Some amateur use in SF Bay AreaSF Bay Area

Modulation: Modulation: Continuous 4-level Continuous 4-level FM, 9600 bps (4800 FM, 9600 bps (4800 baud, 2 bits/symbol), baud, 2 bits/symbol), 12.5 kHz channel12.5 kHz channel

P25 Sound Sample (Click to play)

APCO Project 25 P1 SpectrumAPCO Project 25 P1 Spectrum

NXDNNXDN

ICOM/Kenwood ICOM/Kenwood response to P25response to P25

Modulation: 4-level Modulation: 4-level FSK, 9600 bps, 12.5 FSK, 9600 bps, 12.5 kHz bandwidthkHz bandwidth

In audio, almost In audio, almost perfectly identical to perfectly identical to P25P25

NXDN Sound Sample (Click to play)

NXDN SpectrumNXDN Spectrum

ETSI DMR Tier 2 (Simplex)ETSI DMR Tier 2 (Simplex)

Uplink (HT to Base) Uplink (HT to Base) uses 2-slot TDMA in a uses 2-slot TDMA in a 12.5 kHz bandwidth12.5 kHz bandwidth

Downlink does not Downlink does not pulsepulse

Note how in simplex Note how in simplex the spectrogram the spectrogram appears to “pulse”, appears to “pulse”, audio has “machine-audio has “machine-gun” soundgun” sound

DMR Simplex Sound Sample (Click to play)

ETSI DMR Tier 2 Simplex ETSI DMR Tier 2 Simplex (Spectrogram)(Spectrogram)

ETSI DMR Tier 2 (Repeater)ETSI DMR Tier 2 (Repeater)

Differs from the Differs from the simplex signal, both simplex signal, both timeslots usedtimeslots used

Sound is a constant Sound is a constant “churning” versus the “churning” versus the “sputtering” in simplex“sputtering” in simplex

Note that bandwidth Note that bandwidth is still 12.5 kHzis still 12.5 kHz

DMR Repeater Sound Sample (Click to play)

ETSI DMR Tier 2 ETSI DMR Tier 2 (Repeater Spectrum)(Repeater Spectrum)

CommentsComments P25 and NXDN are almost impossible to P25 and NXDN are almost impossible to

distinguish with spectrum or audiodistinguish with spectrum or audio No known NXDN amateur systems – yetNo known NXDN amateur systems – yet

D*Star easy to identify – you can hear a brief D*Star easy to identify – you can hear a brief “beep” of 2400 Hz audio before data“beep” of 2400 Hz audio before data

MotoTRBO simplex easy to identify – has a MotoTRBO simplex easy to identify – has a pulsed sound (because it’s a TDMA mode) – pulsed sound (because it’s a TDMA mode) – sounds like a “machine gun” or “helicopter”sounds like a “machine gun” or “helicopter”

MotoTRBO Base/Repeater has a constant MotoTRBO Base/Repeater has a constant “grinding noise” more like P25 or NXDN“grinding noise” more like P25 or NXDN

OverviewOverview As of March 2011 several digital voice As of March 2011 several digital voice

mode repeaters have appeared on the SF mode repeaters have appeared on the SF Bay Area VHF/UHF bandsBay Area VHF/UHF bands D*StarD*Star P25P25 MotoTRBO (variant of ETSI DMR Tier 2)MotoTRBO (variant of ETSI DMR Tier 2)

There has been some confusion about There has been some confusion about this; people hearing digital audio on their this; people hearing digital audio on their analog FM rigs have erroneously blamed analog FM rigs have erroneously blamed “noisy” or “splattering” D*Star systems“noisy” or “splattering” D*Star systems

Change LogChange Log Version 1.0 (unmarked)Version 1.0 (unmarked)

Initial posting 27-March-2011Initial posting 27-March-2011 Contains P25 Phase 1, NXDN, D*Star Voice, and MotoTRBO MS Contains P25 Phase 1, NXDN, D*Star Voice, and MotoTRBO MS

(“Mobile Station”) on simplex(“Mobile Station”) on simplex

Version 1.1Version 1.1 Posted 28-March-2011Posted 28-March-2011

Adds MotoTRBO BS (“Base/Rptr Station”) using O.153 “PN9” and Adds MotoTRBO BS (“Base/Rptr Station”) using O.153 “PN9” and TSCC patternsTSCC patterns

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