Automatic Vehicle Monitoring (AVM)

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Automatic Tram Location System (AVM)
Mpt1327 clone.png
Frequencies 517.875 MHz,507.225 MHz
Frequency Range 507.225 MHz - 517.875 MHz
Mode NFM
Modulation FFSK
ACF
Emission Designator
Bandwidth 7.5 kHz
Location Australia
Short Description Proprietary FFSK data network used for public transport telemetry. It is primarily used to track and control vehicles, and facilitates PTT-ID for communication with tram drivers.
I/Q Raw Recording Download file
Audio Sample

The Automatic Vehicle Monitoring (AVM) system was implemented on Melbourne's public Bus and Tram network in the 1980s. It is primarily used to track and control vehicles, and facilitates PTTPush To TalkPress to TransmitMinistries of Postal, Telephone, and Telegraph Service (Soviet Agency)-ID for communication with tram drivers.

There are five fleet controllers (see frequencies) which send a poll to each vehicle every 10 seconds, and the tram will transmit its current location, route, distance, speed, door status, alarms along with some other data, including odometer information on the uplink frequency.

Since 2009 the AVM data feeds the PIDs at tram stops and stations, as well as the TramTracker app for mobile devices.

Frequencies[edit]

Voice Channels
Channel Frequency (MHzMegaHertz (MHz) 10^6 Hz) Usage
9 507.200 Fleet Ops
14 507.250 Unknown
10 507.275 Unknown
13 507.300 Fleet Ops
16 507.600 Fleet Ops
8 507.700 Fleet Ops
15 507.850 PA Announcements
11 508.450 Events
12 509.375 Unknown
Data Channels
ID Frequency (MHzMegaHertz (MHz) 10^6 Hz) Location
507.225 Melbourne Central Tower
507.500 Melbourne Central Tower
507.550 Eureka Tower
507.575 101 Collins Street
507.875 Rialto Towers

Samples[edit]

Uplink

This sample below is the uplink channel. Note the rapid FFSKFast Frequency-Shift Keying data bursts from multiple mobile units:
AVM uplink.png


Voice Transmissions

Data is also transmitted at the end of each mobile voice transmission:
Tram driver communication:

Short conversation between driver and dispatch:


Additional Links[edit]