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Could IDAS™ MultiTrunk™ be Your Next LMR Solution?

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Icom's IDAS and MultiTrunkEven after years of successful deployments, IDAS MultiTrunk remains a mystery for much of the LMR community. This lack of exposure is unfortunate because a properly deployed NXDN Type-D system is a reliable, cost effective, and bandwidth efficient straightforward solution. While P25 has all the hype these days, its implementation is cost prohibitive for many smaller public safety or commercial agencies. These entities typically require modest coverage area, yet more talk paths than a conventional system can offer, and the level of reliability that public safety demands. This mid-level solution is where MultiTrunk really shines. Read More...

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How Can I Get Radio Coverage in “Dead” Spots?

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A two-way radio system using a repeater may have great coverage except in areas, such as parking garages and basements of buildings, whose environmental factors create stubborn “dead” spots. In these locations, the repeater signal reaches the radio, but the handheld cannot reach back to the repeater. The traditional solution to this problem is to add Bi-Directional Amplifier and Distributed Antenna System within the building. Although this is a proven approach to get signals into problem areas, it can be complicated and costly. The complication comes from ensuring the signal is not overlapping the original in a manner that interferes with itself.  The costliness is due to the need of running antenna coaxial cable from the amplifiers to the trouble zone, which may require many feet of cable and possible drilling through walls. Read More...

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How to Extend Radio Range Without Adding a Repeater?

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When there’s a need to extend the coverage of handheld two-way radios, the first option is usually a repeater. However, a repeater isn’t the full answer. A repeater will typically put out much more power and have a better antenna system than the portable radios with which it is communicating. This presents an unbalanced system where the transmit power of the repeater reaches much further than the transmit power of the handhelds.

IDAS LINQVOTE Diagram

Couldn’t this be resolved by turning the power of the repeater down to match the handheld? The reality is that often times mobile radios installed in vehicles and handheld radios are in use on the system. Mobile radios typically have greater transmit power than handhelds. Reducing the repeater power output to match the lowest powered device – the handheld – significantly constrains the system coverage, making the usable radius of the system much less than what it could be. Read More...

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Key Differences between FDMA vs. TDMA Technology

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FDMA (Frequency Division Multiple Access) and TDMA (Time Division Multiple Access) technologies are used in P25 and in business and industrial digital radios (P25 Phase I & NXDN™ for FDMA; P25 Phase II & DMR for TDMA).

The basic difference between FDMA and TDMA is the definition of a channel and how it is used.

In FDMA, a particular bandwidth (e.g. 6.25 kHz) at a particular frequency (e.g. 150.000 MHz) is used to define a channel. This is the way channels have been allocated in analog land mobile radios (LMR) for decades. All information is contained in the channel – compressed to the smallest frequency footprint. Analog radio bandwidth has recently shrunk from 25 kHz to 12.5 kHz, which is about the limit for analog technology without seriously degrading radio voice quality. With digital technology, channel bandwidth can be compressed to a spectrum-efficient 6.25 kHz by using vocoders and error correction. Read More...