Etrunk 3.7 Documentation


Some time ago there appeared on USENET a program and its source code that provided the rudimentary ability to decode Motorola Type I, II, and IIi trunking radio system data. That program was nurtured and refined by a number of contributors. Then, a rudimentary program for decoding Ericsson EDACS data channels was posted to USENET. That rudimentary program was used to investigate further the parts of the data stream necessary to adapt Trunker to EDACS systems. This document represents the results of merging those two efforts. 80% of the code and features is shared by both Trunker and Etrunk.

Current Feature Status

This software provides a rudimentary implementation of Trunker for EDACS. It differs from the Motorola Trunker in the following ways:

Even with this reduced feature set, a user of ETRUNK should be able to monitor a EDACS system, collect information about talkgroups and radio IDs, and track both individual and group calls.

Please Start by Reading the Motorola (Trunker) Documentation

Etrunk is so much like Trunker, please start by reading the Trunker document, then see subsequent sections about how ETRUNK may be different...

ETRUNK and Commercial Trunking Radios

Since there is currently no (inexpensive) EDACS trunk-tracking scanner on the market, ETRUNK (and its predecessor, EDACS.EXE) are the only way to track conversations on EDACS systems. The GE/Wiz scanner attachment does not track actual conversations, only allows the scanner to detect the end of the conversation on the current frequency. The next one it detects may not have the same call on it.

Use of System ID (SysId) as Primary Index

Like its partner, Trunker, ETRUNK uses a system identifier to associate data files with trunked systems. Since these identifiers may not be unique within a geographical area, it may be necessary to keep a working directory for each unique EDACS system you monitor, and it will probably not be practical to jump from one system to the next without stopping Etrunk.

Networked Radio Systems

Larger EDACS systems share group and radio IDs. Support for networked systems is not presently available. Each repeater in the system is treated as a separate system.Until ETRUNK can distinguish between repeaters, it will be necessary to switch the proper xxxxSYS into the directory with the common group and radio data files.

Handling Bandplans for Each EDACS System

No standard bandplan is available to map LCNs to frequencies. A manual approach is required to determine the frequencies and update the ETRUNK data file.

  1. With no xxxxSYS.TXT file in the current directory, start ETRUNK.
  2. Once all of the LCNs associated with the system appear on screen, exit ETRUNK with the 'Q' command.
  3. Edit the xxxxSYS.TXT file. Change all of the hex frequencies (e.g. 0x001...0x007) with the corresponding frequency in a F8.4 format (e.g. 855.0200).
  4. Save the file.
  5. Run ETRUNK again and monitor or track the system as desired.

Here is a sample xxxxSYS.TXT file for an EDACS system:

Clinton County,Ohio EDACS System

Meanings and Possible Values of Key Fields, where different from Trunker

Field Name Values Meaning
Flavor EDACS System System has either a single repeater or multiple repeaters all simultaneously broadcasting on the same frequencies.
Networked This networkable site has broadcast information about its peers so is believed to be part of a networked system.
SCAT Single Channel EDACS A special type of system for outlying areas that uses a single radio frequency for both the control stream and the audio signals.
Type 00000000 ETRUNK forces a bank map of all zeros. Type-1 or Type-2 maps do not apply to EDACS systems.
0 All EDACS systems must be manually frequency-mapped.


Quality of Signal

If you cannot achieve sufficiently good reception to reach 90% accuracy on the data channel, you will be losing information and may have difficulty receiving the audio as well. The EDACS version of Trunker provides a spinner in addition to the blinking '@' sign; both show up when you turn on the 'F'rameIndicator command. If things are working well the spinner should reach a vertical position every second. Slower progress means quality is degraded, perhaps by trying to run ETRUNK under Windows, or because of poor radio reception. Under degraded conditions, ETRUNK will lose some calls and may not show calling radio IDs.

Copyright © 1997 & 1998 Neal R. Fildes, All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, electrical, chemical, optical, mechanical, photocopying, recording or otherwise without the prior written permission of the copyright owner.
All Trademarks referenced are the property of the respective companies, reference made only for clairifaction of products. This page is NOT affliated with Motorola in any way. Motorola, SmartNet, SmartZone, Privacy Plus, Type I, Type II, Type IIi, ASTRO, MTS2000, and MTX2000, STX-200, MTX-200 are registered trademarks of Motorola, Inc.
Ericsson, AEGIS, and EDACS are registered trademark of Ericsson, Inc.
GE is a registered trademark of General Electric Corporation
Multi-Net, EF Johnson, and LTR are registered trademarks of EF Johnson, Inc.
Trunktracker, BC235xlt, BC295xlt, Bearcat, and Uniden are registered trademarks of Uniden Corporation