Harris M7300 Installation And Product Safety Manual page 18

MM-014763-001, Rev. E
The radio and control head exceed tough environmental specifications included within military standard
MIL-STD-810F, the radio industry standard TIA/EIA-603, and the radio standard established by the U.S.
Forest Service.
An M7300 radio operating on an OpenSky radio network uses Time-Division Multiple-Access (TDMA)
digital modulation technology on the radio frequency link. TDMA allows multiple radio users to share a
single RF channel. In addition, a single RF channel can support simultaneous digital voice and data
communications.
OpenSky employs Advanced Multi-Band Excitation (AMBE
developed by Digital Voice Systems, Inc. When operating on an OpenSky radio network, AMBE gives
an M7300 the ability to provide exceptional voice quality via the limited bandwidth of the radio
frequency path, even when the received RF signal is weak (i.e., even in "fringe" areas). AMBE is
performed by a Digital Signal Processor (DSP) integrated circuit within the radio programmed to perform
an AMBE compression algorithm during mobile transmissions, and an AMBE expansion algorithm
during mobile reception.
Speech compression electronic circuitry—be it AMBE or another type such as IMBE
referred to as "vocoding" circuitry for voice coding, or simply a "vocoder" circuit.
The M7300 mobile radio supports operation on APCO Project 25 phase I compliant Common Air
Interface (P25 CAI) trunked radio networks, and operation in a talk-around mode in accordance with the
APCO Project 25 phase I standard. P25 radio systems utilize Improved Multi-Band Excitation (IMBE)
speech and data compression technology, also developed by Digital Voice Systems, Inc.
Like AMBE technology, IMBE technology allows the M7300 to deliver exceptional voice quality, even
in areas where the received RF signal strength is weak. IMBE replicates human speech better than other
voice compression technologies, resulting in better voice quality and better speaker recognition. The
Telecommunications Industry Association (TIA) funded an independent study to evaluate compression
technologies. The findings showed that when compared with other industry-recognized compression
technologies, IMBE provided the highest voice quality. In the study, radio users were asked to listen to
coded speech produced by four different compression technologies (i.e., vocoder circuits) operating under
a variety of conditions. The users rated the speech on a scale of one to five, with five being the best
quality. Under each operating conditions, IMBE was rated the best.
The M7300 mobile radio can also operate using Harris' digital voice technology called ProVoice. Like
P25 radio systems, ProVoice also employs IMBE technology.
EDACS and ProVoice trunked radio networks employ analog FM and 2-level Gaussian Frequency-Shift
Keying (GFSK) modulation techniques on the RF channels. Data is transmitted on an RF channel at a
9600 bits-per-second rate.
For over-the-air secure radio communications, the M7300 mobile radio may be equipped for 64-bit DES
(Data Encryption Standard) encryption or 128/256-bit AES (Advanced Encryption Standard) encryption.
With encryption, voice and/or user data signals transmitted and received by the radio on an RF channel
are digitally encrypted ("scrambled") to virtually eliminate unauthorized monitoring via the RF channel.
CAUTION
18
Harris recommends the buyer use only an authorized representative to install and
service this product. The warranties provided to the buyer under the terms of sale shall
be null and void if this product is installed or serviced improperly, and Harris shall have
no further obligation to the buyer for any damage caused to the product or to any person
or personal property.
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) speech and data compression technology
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