Digital Mobile Radio Solutions [PDF]

Zitiervorschau

S OLUTIONS DIGITAL MOBILE RADIO

W hat is DMR Radio? Digital Mobile Radio (DMR) is an open digital mobile radio standard defined in the European Telecommunications Standards Institute (ETSI) Standard TS 102 361 parts 1–4 and used in commercial products around the world. DMR, along with P25 phase II and NXDN are the main competitor technologies in achieving 6.25 kHz equivalent bandwidth using the proprietary AMBE+2 vocoder. DMR and P25 II both use two-slot TDMA in a 12.5 kHz channel, while NXDN uses discrete 6.25 kHz channels using frequency division.

DMR was designed with three tiers. DMR tiers I and II (conventional) were first published in 2005, and DMR III (trunked) was published in 2012, with manufacturers producing products within a few years of each publication.

HQT has developed private network solutions with integrated hardware and software and provides product series covering DMR Tier-II series. HQT TI OMAP SERIES products are fully self-developed and high-end digital, which are completely compliant with ETSI TS 102 361 protocol. Besides, all HQT TI OMAP SERIES products can be upgraded to DMR Tier III without buying any new devices.

W hy Digital? DMR Tier II covers licensed conventional radio systems, mobiles and hand portables operating in PMR frequency bands from 66–960 MHz. The ETSI DMR Tier II standard is targeted at those users who need spectral efficiency, advanced voice features and integrated IP data services in licensed bands for high-power communications. ETSI DMR Tier II specifies two-slot TDMA in 12.5 kHz channels.

INCREASED CAPACITY WITHIN EXISTING 12.5kHz REPEATER CHANNELS

Today’s Analog 12.5kHz FDMA

Digital: 12.5kHz TDMA

SLOT 2

SLOT 2

SLOT 1

Regulatory Emissions Mask

SLOT 1

Transmitted Signal 1

SLOT 2 SLOT 1

SLOT 2 SLOT 1

SLOT 2

SLOT 2

SLOT 1

Transmitted Signal

Ti m

e

SLOT 1

Transmitted Signal 2

Frequency 12.5kHz Channel

• One voice call for each channel • One repeater for each channel

12.5kHz Channel

• Two time slots enable two voice calls(or data transmissions)for each channel • One repeater does the work of two • No licesing changes required

By comparison with FDMA in the figure above, TDMA offers a proven method for achieving 6.25 kHz equivalency in 12.5 kHz repeater channels — a major benefit for users of increasingly crowded licensed bands. Instead of dividing the channel into two smaller slices, TDMA uses the full channel width, dividing it into two alternating time slots. As a result, TDMA essentially doubles repeater capacity while preserving the well-known RF performance characteristics of the 12.5 kHz signal. From the perspective of RF physics — that is, actual transmitted power and radiated emissions — the 12.5 kHz signal of two-slot TDMA occupies the channel, propagates, and performs essentially the same as today's 12.5 kHz analog signals. With the added advantages of digital technology, TDMA-based radios can work within a single repeater channel to provide roughly twice the capacity of analog while offering RF performance equivalent to, or better than, today's analog radio.

Advantages of Two-slot TDMA for professional organizations are listed below: •

Increased Spectral Efficiency

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Advanced Features and Flexibility

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Lower Equipment Costs

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Longer Battery Life

For more information about the difference between FDMA and TDMA, please go to: http://www.hqtsolutions.com/news-information/tdma-how-it-works.html

The advantages of digital two-way systems include: •

More simultaneous talking paths are possible, and information such as unit ID, status buttons, and enhanced text messages can be embedded into a single digital radio channel.

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Bandwidth consumption is reduced.

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Digital signals can be handled by standardized antenna systems and existing infrastructure equipment.

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The digital conversion of a user's voice reduces external background noises. And the digital technology platform is ideal for reducing environmental noise levels during transmission, such as inside noisy manufacturing and processing plants or outside in windy conditions.

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A number of new software applications are available for use with the digital platform.

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The digital platform provides a migration path that allows for simultaneous use of digital and analog radios.

D igital DMR Two-way Radios Instead of Analog Improved Audio Clarity The DMR Digital technology provides improved noise reduction and protects voice quality over a longer distance than analog, especially noticeable towards the end of the transmission range, where analog radios will have a lot of static and background noise. The digital processing of the signal allows the receiving radio to screen out the background noise and reconstruct the signal even when it is very weak. This keeps the transmission clear and increases the effective range of the digital radios over analog radios where the signal clarity and strength drops off dramatically at the end of the coverage zone.

Better Battery Life and Power Usage Getting through a full 10-12 hour work shift on a single battery charge has always been a challenge for the analog handheld two-way radios. The DMR technology uses the transmitter of the radio only half of the time compared to a narrowband analog radio, which reduces the drain on the radio's battery almost by half. This increases the actual talk time of a single battery charge by up to 40 percent. Overall battery consumption per call is reduced, and longer usage time in the field will be noticed between recharges.

DMR digital radios double the capacity over existing analog equipment A regular analog two-way radio system uses an entire 12.5KHz narrowband channel to provide a single talk path for communication. However, the benefit of using a DMR digital radio system is that it supports two simultaneous and independent calls over the same narrowband 12.5kHz channel. This results in doubling the channel capacity of the radio system which allows businesses to split departments and users into different completely independent and private talk groups.

HQT DIGITAL TWO-WAY RADIOS HQT has been specializing in developing and providing DMR private network solutions including Emergency Dispatch System, Digital IP Multi-site Connect System, Real-time Positioning Solution and Commercial Recording Solution, and products such as DMR Tier-II & Tier-III digital portable radios, digital mobile radio, digital repeater and dispatch system for several years. Now we are devoting to develop and launch more solutions and products.

DH-9800

DH-8800

DM-9800

DR-9200

HQT DH-9800

HQT DM-9800

HQT DR-9200

• IP67 Standard;

• 256-bit Encryption;

• IP Multi-site Connect;

• Large-sized TFT Display;

• IP Data/Defined Data;

• Support Trunking Extensions;

• Multiple Reprogrammable Buttons;

• Rich Second-developments;

• Adopt TDMA Digital Technologies;

• Compliant with MIL-STD-810 C/D/E/F/G.

• Support Analog and Digital Modes.

• Support Both Analog and Digital Modes.

Shenzhen HQT Science & Technology Co., Ltd. Tel: (+86)-755-86028800 Fax: (+86)-755-86028872 Website: www.hqtsolutions.com Address: East of Building M-8, Central Zone, Hi-tech Industrial Park,Nanshan District, Shenzhen, P.R.C. 518057

Learn more about TDMA protocol and digital mobile radio standards at: www.dmrassociation.org