Blogs

What is MAP27?

MAP27 is defined as Mobile Access Protocol for MPT1327 communications equipment.

In brief, it permits data exchange between MPT radio trunking equipment and external equipment such as a data terminal, which may be a laptop computer. The external equipment is able to command the radio to set up calls.

What is Lone Worker?

Lone Worker is a safety system incorporated in many types of on-site portable radio systems.  

The radio will sense whether a user has made a transmission within a preset period. If there has been no radio activity within this period, the handset will provide an audible alert.

What are the benefits of a Trunked Radio System?

There are many benefits in having a trunked radio system, some of which are listed below: 

• Extremely Flexible
  Trunked radio combines many of the functions of a mobile telephone with the best of conventional PMR. Calls are made on a one to one or one to group basis with user friendly confidence tones to inform the user of the progress of the call. If the called unit is not in range, the caller is informed. Once the call is connected, only those parties involved in the call will hear the conversation. 
   
  Trunked radio equipment exploits the power of the Trunked principle to serve the requirements of the mobile user. When calls are received while the user is not present, the details of the callers will be stored so that the call can be returned at a convenient time. Facilities to pass messages to the displays of other radios are included, reducing the need for routine voice communications.
   
  Connect to a Telephone Network (when supported by the trunked network operator) Trunked radios are often equipped to make and receive calls between the Trunked radio network and private or public telephone networks (where supported by the Trunked network operator). The required
  number may be dialled on the keypad, or recalled from a pre-programmed list of approved numbers.  

• Spectrum Efficient
  In a Trunked radio system, all radio users share all channels. In a Trunked system, no channel stays unused when a need for communication exists. The automated Trunking controller immediately allocates a free channel when requested.   

• Private 
  Users only hear the conversation intended for them because they have exclusive use of the channel. At all other times, their radio will be silent. Since communication in a Trunked radio communication system happens on an arbitrary channel selected by the system, it becomes difficult for unauthorised users to monitor the voice communication of a particular group of users. The degree of privacy can be even further enhanced on a Trunked system by adding voice encryption, if supported by the system architecture.  

• System Reliability 
  A fault on a conventional system can take out all of the users on that channel and they are prevented from communicating unless they all know in advance what channel to switch to if another is available. This situation never occurs in a Trunked radio system. If a repeater station falls out, the Trunking controller registers the fallout and does not assign the repeater as a voice channel, until it has been repaired or the disturbance has disappeared.  

• Cost Effective
  It is possible to buy airtime on existing systems - no need to own your own site or system. Most Trunked network operator's charge a fixed monthly rate based on the area of service provided. A fleet manager will be able to budget exactly for the cost of his communications - no nasty surprises when the airtime bill arrives!   

• Wide Area Coverage
  There are national or regional systems which users are able to buy space on - so gain wide radio coverage without the expense of hardware or licensing.

What is Radio Trunking?

Radio trunking is a method employed on medium to large business radio systems to make the best use of the scarce radio channels that are available in New Zealand today.

On a conventional medium to large radio system, businesses will normally use several channels. This usually means that communication within each user group on the system is often on the same channel. The restricting of access to a particular channel for a user group means that communication between groups can be difficult or impossible. 
 
The pressure on radio channels is such that channels are often reused and it may be necessary to share with other user groups, possibly from an unrelated organisation. In this situation, when a shared channel is in use by a particular user group other users must wait until the conversation is finished. At the same time, some channels might be free but the user cannot make use of them. 
 
A Trunked radio system makes use of several radio channels centrally managed by a Trunked Controller to provide communication between radio users. When a user makes a call, the Trunked Controller automatically allocate a free channel and sends a message to the radio units involved in the call instructing them to change to the free channel. This means that a conversation can be made if ANY CHANNEL is available, unlike a conventional system where the user must wait for a particular channel to be available. This process is entirely automatic and transparent to the user. Call set up is very fast, very similar to cellphone operation.

What safety features are available on VHF and UHF mobile radios?

The radio can transmit an emergency ID message, showing the unit number, and may repeat that emergency status message until cancelled.

This is essential for public safety and plant security , as well as in any hazardous high risk area.

Tait have intrinsically safe versions available for use in explosive environments.

Man down alarm automatically transmits an emergency call if the radio is horizontal for a pre-programmed period of time. This is ideal where people work alone in hazardous conditions and may not be able to call for help if incapacitated.

Operating frequency range explained

VHF and UHF offer different propagation advantages

The operational band width of the radio is measure in MHz. VHF covers NZ frequency range 136-174 and UHF covers 400-470 MHz. 

Radio Channels (spectrum efficiency)

25kHz channel spacing is the traditional technology many radios still rely on

12.5 kHz channel spacing allows double the number of users within the same amount of spectrum, and is how many radios now operate. Tait radios offer 25 or 12.5 kHz operation, all within the same radio. 6.25 kHz is the future of channel spacing, allowing four times as many users. This involves digital technology, which allows crisp, clear data and voice signals.

Mil-spec explained

Mil-spec (MIL-STD) ratings are the test standards set by the U.S Military

Mil-spec radios have a rugged design to provide reliable performance, even in the most demanding environments. Many Icom PMR radios have passed these demanding MIL-STD tests, better known as 810 C/D/E & F.

The Li-ion Battery

Tait, Motorola, Uniden, Icom etc offers Lithium Ion (Lion) batteries for their handheld radios

Li-ion offers a number of key advantages over other, older battery types. Ounce per ounce, Li-ion batteries offer more capacity than their older counterparts. This allows battery packs to be smaller and lighter, without sacrificing operating time. The memory charging issues that can plague Ni-Cd batteries and even some Nickel Metal Hydride (Ni-MH) batteries are virtually non-existent with Li-ion. In fact, you can charge a Li-ion battery while it’s on a radio. Leave the radio turned on while charging and monitor while you charge – you can’t do that with Ni-Cd. (Just don’t transmit while charging!) Additionally, Li-ion handles hot weather better than Ni-Cd's, and has average cold weather performance.

Repeater applications explained!

In its own right a repeater can be a useful tool to increase the operating range of your VHF or UHF radio system

With its relatively high transmitting power & external antenna, a well-sited repeater will provide an excellent platform to boost signals beyond the range of non-repeater networks. Whether it is sited at the centre of your operating network or at a location prone to weak coverage, the repeater will instantaneously re-transmit received audio without any noticeable delay. This high power re-transmission improves your operating range as the original signal effectively gets a piggy back ride.
 
In addition to the basic advantages associated with a repeater, you can further enhance your radio network by personalising repeater operation to suit your requirements:

• Multi-User Groups/Community Base Station (CBS)
  If you operate a large number of radios on your network, you may want to improve the efficiency of the system by splitting these radios into user groups i.e. managers, maintenance, catering, deliveries etc. Radios on the network can be programmed to communicate only within their own group or with certain other groups. Other groups will not hear communications not intended for them and thus can continue work without unnecessary distraction or delay.
   
  Even if you do not operate a large system, why not share your repeater with other users in your area - delivery companies, taxi firms, security guards etc. could all benefit from such a system. You could sell radios to these users and quickly recoup your initial outlay or hire radios to have a regular monthly income. Clever management of the user groups would allow a higher volume of operators to be spread over a whole 24hr day without saturating the radio channel i.e. security guards at night, delivery firms early in the morning etc. Remember that as network owner/manager you still have complete control over the system and can add/remove clients or adjust operation to suit your changing requirements. 

• Telephone Interconnect
  By adding a telephone interconnect or telephone patch (telepatch) to your repeater system you can allow authorised users to place and receive telephone calls to the PSTN or PABX - whichever is connected to the repeater. When not in telepatch mode the system acts as a conventional repeater, providing improved operating range for your radio users. To access telepatch mode, an authorised user will transmit an access code to the repeater, a valid code will trigger the repeater to transmit a dial tone over the radio channel. The user can then dial into the telephone system using the repeater as an interface. Upon connection of a successful call, the radio user assumes full control of the conversation - this is because the radio can only talk or listen, not both together (semi-duplex). To end a call, the radio can transmit the access code or wait for the system to time-out and return to repeater mode. If the repeater is called over the PSTN or PABX, it will transmit a ringing tone over the radio channel to indicate to the radio users that a telephone call is present. To answer the call, an authorised user simply needs to transmit the access code to be connected to the telephone caller.
   
  Multi-User Groups or Community Base Station (CBS) with Telephone Interconnect Combine the advantages of a repeater with multi-user group system and telephone access - the best of both systems. 

Trunking System

A Trunking system is a more advanced radio network

Typically for much larger or high-usage operators and basically comprises of a number of repeaters interfaced together at a single site, although multiple sites are also possible. Trunking systems are inherently more expensive but they do offer far more flexibility over a conventional repeater system. The limitations of a conventional repeater system are that they use a single radio channel which when busy can not be used by other radios, who subsequently have to wait for the channel to become free. It is therefore essential that such systems maintain a strict operating procedure to ensure conversations are kept as short as possible to free up the radio channel for other users. A trunked radio system overcomes this problem by having multiple channels available for use simultaneously - if a channel is busy the system will switch to another. While there are many trunking networks available, a widely used common system is offered under the MPT 1327 protocol - this is an operating procedure that allows any MPT 1327 equipment to integrate together regardless of the manufacturer.
 
Individual calls (group calls are also possible) made on a trunking system are fully private i.e. only the caller & callee will hear the conversation. This is also true for trunking networks which have a telephone interface fitted - a popular option, sometimes even standard equipment. Trunking sites can also be linked together to allow inter-site or roaming communications - typically these links are either via conventional telephone line or microwave link.