Conventional two-way radio is quickly disappearing. It is being pushed aside by trunked radio, which offers a much better spectrum utilization. Trunked radio relies on computer-allocated radio frequency channels, and is therefore eminently suitable for reception by computer-based receivers such as the WiNRADiO range.

 The WiNRADiO Trunking Option is fully integrated with WiNRADiO receiver software, and is suited for monitoring of Motorola SmartNet® and MPT1327 trunking networks, the two most commonly used trunking systems world-wide.

 The WiNRADiO Trunking Option makes it possible to follow conversations on the trunked networks, relying on the control channel data transmitted by the base station, provide information about systems characteristics, log traffic activity, and automatically build up databases of trunking networks.

 The WiNRADiO Trunking Option is designed to work with all versions of WiNRADiO receivers. The software takes advantage of the ubiquitous and economical PC sound card to implement the latest digital signal processing algorithms for data decoding and analysis.

 The WiNRADiO Trunking Option is low-cost, and is intended mainly to satisfy the needs of a serious radio monitoring enthusiast as well as for budget-conscious professional surveillance applications.

The components of the WiNRADiO Trunked Option are provided in the form of XRS plug-ins, selectable by clicking on an item in a menu. The SmartNet and MPT1327 modules are similar in appearance and functionality. The XRS plug-ins ensure upward compatibility with all future versions of XRS-capable receivers. (For more information about the XRS technology refer to the XRS Web site.)

Would you like a little trunking theory? If yes, click here.

Both SmartNet and MPT1327 decoders have separate, very similar, virtual control panels. Each panel diaplays a group of system characteristics extracted from the control channel signalling. This information makes it possible to observe the received system status at a glance and to finely tune the receiver for maximum performance.

Here is a brief description of the individual fields (there is a much more detailed explanation in the Trunking Option User's Manual and the on-line help):

 System ID is the value that the mobile stations are looking for in order to avoid interfering with other similar networks.

 System type shows the version of protocol used on the current control channel.

 System time has a value only if the trunking network is broadcasting time and date frames. This information is sent by the base station.

 System Site No. is important only when the system has several base stations. In such case every base station has a site number allocated.

 Control channel index is a number sent by the base station and used by the mobile stations to determine the base allocation frequency and jump to the appropriate channel when necessary.

 Control channel frequency is the frequency corresponding to the control channel index. This value is useful when the decoder is working in 'Single Receiver Mode'.

 Accepted frames indicates the percentage of correctly received frames. When the receiver is properly tuned to the data channel and the volume is also properly set, this value is close to 100%. A normal value is between 95% and 100%, but the decoder still works well with values as low as 60%. To improve this figure, finely tune the receiver frequency until the number of accepted frames reaches the maximum value and only then adjust the receiver or sound card volume for maximum performance.

 Channel step initially used by the SmartNet protocol was 12.5kHz below 300MHz and 25kHz above. Nowadays, the system administrator decides the channel spacing, depending on the type of the mobile stations used by the system. As the software cannot detect automatically which channel spacing is used, this value needs to be set manually.

Brief explanation of the panel controls:

 Signal input

Depending on the type of signals available at the WiNRADiO receiver output, you may select one of the two radio buttons labeled 'Audio' and 'Discrim'. If the only output available is the speaker output, the 'Audio' button is the only choice. If the receiver has a frequency discriminator output (a 'Data' output on the WiNRADiO external receiver range) using this, and checking the 'Discrim' button, will improve decoding.

 On air

This table contains the list of currently used traffic channels. You can select one of the available traffic channels by simply double-clicking the desired channel.

 Automatically tune to traffic channel

If you click on 'Automatically tune to traffic channel', the receiver will tune to the first traffic channel decoded from the control channel data. Otherwise the receiver can be immediately tuned to any of the traffic channels displayed in the 'On air' table if you double-click on the desired channel.

 Return to control channel

If you click on 'Return to control channel', this will force the receiver to move from a voice channel back to the control channel.

 Secondary receiver

The Trunking Option can use two WiNRADiO receivers if available. You can activate the 'Secondary receiver' from here.

 Log file

All trunking activity can be recorded in a log file. The log file can be generated in two different common formats: comma separated (CSV) and plain text (TXT). The CSV format is useful for spreadsheets and database applications.

 Database browse, System information edit

If you click on 'Database browse' or 'System information edit', this invokes the respective Trunking Option functions, further described below.

The WiNRADiO Trunking Option automatically maintains a dedicated database, separately for SmartNet and MPT1327 networks. As this database contains a significant amount of important information, a special browsing facility is included. The database browser allows the user to inspect trunking system information recorded in the database file of all the systems that were received in the past, even if only for several seconds.

Here is a brief explanation of the various fields of the browser window:

 System ID makes it possible to select one of the systems that were monitored at least for a few seconds since the first running of the decoder.

 Description contains an optional general description of the currently selected system. It can be changed using the 'System Information Editor' window.

 Base frequency of the currently selected system. In most cases it is only a theoretical figure from which all other channel frequencies are computed.

 Channel size is the size of a channel in the currently selected system. Its value is required for correct tuning to the traffic channels, and can be changed using the main control panel of the decoder.

 Last control channel index is the index of the channel on which the control data signal of the current system was received last time.

 Frequency is the frequency on which the control signal of the current system was received last time.

 Received Station IDs is the list of all station IDs encountered during monitoring the current system. If, for any of them, there is a comment ('alpha-tag') defined through the System Information Editor, it will be displayed after the station ID.

 Control channels is the list of control channels encountered while monitoring the current system. Generally, each control channel corresponds to a site with a complete base station. In large installations there might be two or more sites of the same system, every one with its control channels. The list of control channels may have some common values. This depends on the channel allocation strategy adopted by the system administrator. All this information is useful when the system is surveyed for correct usage of the allocated frequencies.

 Traffic channels is the list of traffic channels used by the current system. Any channel on which there was at least one conversation will appear in this list.

 Refresh info button, when clicked, stores the latest information on the currently monitored system in the database file.

 Tune to button, when clicked, automatically tunes the main receiver to the last frequency on which the control channel of the current system was found.

The MPT1327 Database Browser is very similar. It contains some additional information which is characteristic of the MPT1237 system.

The WiNRADiO Trunking Option also includes a System Information Editor. This is used for editing of the currently monitored trunked system information. The information includes general system description, and radio units and group comments. This is where you can assign aliases (often called 'alpha-tags') to the station IDs for easy identification of on-air stations.

Note the edit box for the user-defined system description; a list containing all the radio and group IDs that were received during the previously monitoring activity, and another edit box for the user-defined radio alias or group description.

 IBM PC compatible (100 MHz Pentium or higher)
 Windows XP
 8 MB of RAM, 3 MB of free disk space
 SoundBlaster compatible 16-bit sound card
 WiNRADiO 1000/1500/3000 or G305 receiver