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Unitrunker Screenshot monitoring a Motorola system


UniTrunker supports control channel monitoring for the following trunking types:

UniTrunker also supports downloading system information from the Web Service.

UniTrunker does not currently support LTR Passport or MultiNet.

UniTrunker cannot monitor or decode conventional P25 data or audio. However, a program called kNACk is included with the Unitrunker distribution. kNACk can be used to capture NAC codes on a P25 conventional system.

What Can UniTrunker Display?

  • Basic system information - system type, system id, talkgroups, and radio ids.
  • Basic site information - site or cell number, and list of channels.
  • Site call activity - who's talking, on what channel, and to whom.
  • Neighboring Site information - list adjacent cell or sites with control channels.
  • User roaming - what radios are registed to a particular site.
  • User affiliation - what talkgroup a user has requested.
  • Patches - a dispatcher initiated action that joins two or more talkgroups together.



Public Alpha - released July 28, 2008 (Version

Previous Generation

Public Beta #18 - released February 27, 2008 (Version

Listen, Priority and Lockout Explained

Each time a call is announced over the control channel - the target of that call - which may be a group or radio id - is examined. There are three things the [L]isten logic considers to determine the next call for listening ...

1) target's listening rank or priority (a number),

2) target's Listen flag as Yes or No,

3) target's Lockout flag as Yes or No

The program does not currently consider the listen/lockout/priority of the source radio ID.

On the [L]isten panel, your options are ...

1) Listen as Yes or Ignore,

2) Priority Threshold as some number 1 to 99, or Ignore.

3) Lockout as No or Ignore.

To be clear we need to make a distinction between the target's Listen flag and the [L]isten option's Listen flag. Likewise for target's lockout and target's priority vs. Listen option's lockout and listen option's priority threshold settings.

A call is evaluated as a candidate (a "listen worthy" call) if the following is true:

The channel has a frequency associated with it (eg. not blank or zero).

... AND ... the target's Listen flag is set to true or the [L]isten option's Listen flag is set to [ignore]

... AND ... the target's Priority is less than or equal to the [L]isten option's Priority threshold OR the threshold is set to [ignore]

... AND ... the target's Lockout flag is set to false or the [L]isten option's Lockout flag is set to [ignore].

If a call passes this criteria ... there is one final consideration before the radio can be tuned to the call. Is the voice radio currently assigned to a call and, if so, is the priority of this new call numerically less than the currently monitored call?

If the voice radio is parked or the new call out-ranks the current call, the radio is tuned to the new call.

What are the Call Types available?

Colum "T" = "Type" which would be [G]roup or [I]individual (iCall)

Colum "CT" = "Call Type" - See below

For EDACS systems:

Fon - Telephone call

Tst - LCN tester

Dat - Data call

Ana - Analog Voice Call

Emg - Emergency Analog Voice Call

Dig - Digital (ProVoice or Aegis) Voice Call

EmD - Emergency Digital Voice Call

For Motorola:

(Note that these follow the TG+n values in order.)

(none) - Analog voice call

All - All talkgroup (analog)

Em - Emergency (analog)

XP - Crosspatch (analog)

EXP - Emergency Cross Patch (analog)

EMS - Emergency Multiselect (analog)

? - Reserved

MS - Multi Select (analog)

Dig - Digital voice call

DAT - Digital All Talkgroup

DEm - Digital Emergency

DXP - Digital Crosspatch

DEX - Digital Emergency Crosspatch

DEM - Digital Emergency Multiselect

? - Reserved

DMS - Digital Multi-select

For P25 systems:

P25 call type is the call's priority - a single digit from 1 to 7. "4" is the default normal priority.

Emergency calls prefix this digit with the letter "E".

Frequently Asked Questions

Q: Do I need a radio with discriminator tap?

A: The short answer - Yes. The long answer - You may be able to decode 3600 baud Motorola control channels with a 50-70% decode rate without a discriminator tap. This is totally dependent upon the scanner/receiver and sound card you are using. You will not be able to decode EDACS, or APCO Project 25 without a discriminator tap. MPT1327 is the exception. It generally decodes equally well with speaker audio or discriminator audio. With the GRE PSR-500 and PSR-600 you do not need a discriminator tap; the program reads through a USB cable attached to the radios' PC/IF port. UniTrunker has support for EDACS, Motorola and P25 systems with the PSR500/600.

Q: Do I need a slicer?

A: No.

Q: Do I need a computer that runs DOS?

A: No. This program does not run on DOS.

Q: Will this work on Windows? If so, what version?

A: Yes - Windows 95 (with IE4 or later), Windows 98, ME, 2K, and XP (all flavors).

Q: What types of trunked radio systems can I monitor?

A: Motorola, EDACS, APCO Project 25, and MPT1327.

Q: How can I use this to listen to calls on a trunked radio system?

A: Yes. You need a second radio that accepts computer control to tune to voice calls as they occur.

Q: Does the program permit downloading talkgroup information from the Web Service?

A: Yes - you can download Motorola and APCO P25 systems by trunking system ID. You can download EDACS by looking up the RR DB SID (that's the ID # assigned by the database to each trunked system). You must be a paid member with a valid user id for this feature.

Q: Can I import my trunker data files?

A: Yes - read the Hints section of the documentation that describes how to do this.

Q: How do I install this MSI file?

A: For Windows XP, double-click on the file. For earlier Windows, you may need to install something from Microsoft.

Q: How much does it cost?

A: Nothing. As long as you follow the license and copyright notice - the program is free. No registration either.

See also