Frequently Asked Questions

Q. What is SmarTrunk II?

The SamrTrunk II Digital Trunking System is a reasonably priced, wireless communications system which supports group dispatch, individual selective calling and telephone interconnect applications. It is widely used for applications below 800 MHz, with over 6,000 systems and 500,000 subscribers in over 98 countries worldwide. By relying on low cost, conventional radio equipment and add-on logic boards, SmarTrunk II is able to offer many advanced features typically found in much higher cost systems.

Q. How does SmarTrunk II differ from other trunking formats?

The most recent FCC interpretation of "trunking" found in the Part 88 rules uses the word "centralized" to described a trunking system which utilizes a dedicated control channel to provide mobile control. Since the SmarTrunk system does not utilize a dedicated control channel, we have chosen to call SmarTrunk II a "decentralized" or "Scan-Based" system.

Because there is no central controller required, SmarTrunk II is generally much less expensive and easier to license than centralized trunking systems.

Q. What is a "Scan Based" system?

Unlike centralized systems, scan based systems do not require exclusive RF channels. The channel selection intelligence is located in the mobiles. When a subscriber initiates a call, the mobile unit searches for a clear channel based on the absence of either system CTCSS tone or carrier. When a clear channel is located, the mobile unit places a request for service. After validating the subscriber's ID, the channel controller completes the connection and provides a talk path for the duration of the call.

Q. How are incoming calls processed?

When the mobile unit is an idle condition, the receive audio and the PTT functions are disabled. During this time the mobile is scanning for a system "call collect" tone. When the call collect tone is detected, the mobiles stops scanning and listen for  it's correct digital data pack. When the correct data pack is detected, the receive audio and the PTT function is enabled and normal radio operation begins. All unaddressed radio's resume scanning. At the end of the call the repeater disconnects and the mobiles that were communicating resume scanning.

Q. What type of signalling format does the SmarTrunk system use?

SmarTrunk II is a proprietary BPSK digital signalling format which is not compatible with any other trunking or signalling protocols. Over the air ID's are encrypted to discourage privacy. As such, it is highly immune to "hackers" and unauthorised system users.

Although proprietary, SmarTrunk II available for a wide range of radio models from ten different radio manufacturers. Therefore, unlike some other trunking formats, you are not "locked in" to a single source for radio infrastructure or subscriber equipment.

Q. What is the average connect time for SmarTrunk calls?

The initial connect time is typically one to two seconds, depending on the type of call requested, the number of channels in the system, and the channel availability at the tine of request. Once a channel is acquired, it is held for the duration of the conversation; therefore, subsequent PTT's are instantaneous.

Q. What base station equipment is required for a SmarTrunk system?

A typical SmarTrunk channel would consist of the following items:

  • One SmarTrunk Model ST-853 Station Controller per repeater.
  • Any VHF of UHF radio repeater per channel-Alinco, Icon, Kenwood, Kyodo, Motorola, Standard, Tait, Yaesu/Vertex or other suitable station repeater.
  • Antenna system - duplexer or combiner depending on the number of SmarTrunk channels. Coaxial cable and connectors as required.
  • A power supply for the radio repeaters and the SmarTrunk controllers.

Each controller in the SmarTrunk system is capable of providing all system services up to a maximum of 16 channels per system.

Q. What modem do you recommend I use for my SmarTrunk system?

An external model is required to remotely program the ST-853 controllers via a phone line. We recommend either our ST-913 External Modem (which is a complete kit of all items required). SmarTrunk does not support all makes and models of modems. Please call the SmarTrunk factory if you have any questions.

Q. What mobile and portable radios are available for SmarTrunk operation?

SmarTrunk supports over 50 makes models of portable and mobile radios from ten different manufacturers. See Appendix A for a complete listing of radios supported by SmarTrunk II.

Q. What equipment is required to program the SmarTrunk II controllers and logic boards?

The ST-853 SmarTrunk II controller is programmed with a PC compatible computer, using a DOS program available from SmarTrunk. (Mobile radio logic boards are programmed from the keypad or, in some cases, from a PC in conjunction with the radio programming software).

Q. Is any additional equipment required to support telephone interconnect?

No. All ST-853 controllers come fully equipped with telephone interconnect capability. Each controller has two standard RJ-11 telephone jacks which accept normal two wire, loop start lines from a PBX or the PSTN.

Q. Do all SmarTrunk II subscriber radios require a DTMF keypad?

No. Group dispatch calls are placed simply by pressing PTT (Push To Talk). Subscribers who place or receive only group dispatch calls do not need a keypad. Only those users placing telephone calls or private calls to other users require a radio equipped with keypad.

Q. Is it possible to connect a mobile radio to a standard telephone instrument or a fax machine?

Yes. A subscriber radio may be connected to a fax machine, a standard telephone instrument and even a computer modem if it is equipped with the ST-869 Radio/Telephone Interface Module. The ST-869 includes both the SmarTrunk II logic board and telephone interface circuitry providing talk battery, ring voltage and an RJ-11 phone jack. (A full-duplex subscriber radio is required when supporting modem applications.)

Q. Can the SmarTrunk system operate in a co-channel environment?

Yes. In fact, this is one of the key advantages of the SmarTrunk II protocol. Due to the de-centralized system control concept, the system utilizes a distributed control method which is available on any channel in the system. This eliminates the need for a dedicated control channel to manage the system. The mobile radios perform automatically by the SmarTrunk logic boards. The SmarTrunk channel monitor function may be programmed in the radio to detect either Carrier or CTCSS Tone as the channel busy status.

Q. How many users per channel can the SmarTrunk system accommodate?

There are many factors which determine the practical number of users per channel in any trunking system, including: 1)The type of operation on the system, i.e., dispatch, mobile to mobile, mobile telephone; 2) The level of service desired; and 3) The number of channels in the system. For example, based on our Traffic Analysis Study and input from our system operators, the following loading figures may apply for a typical five channel system:

Q. Who provides product warranty for SmarTrunk equipment?

SmarTrunk products are warranted by SmarTrunk Systems, Inc., against defects in materials and workmanship for a period of two years from the date of shipment. This warranty policy is honoured by the SmarTrunk factory. Radios and other system equipment are warranted by the respective manufactures.


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