Icom FR6000 Series, Руководство по продажам, Страница: 8 / 62

2-3 6.25 kHz FDMA Technology
Other methods were also considered, including ACSB
and the proposed APCO Project 25 Phase II CQPSK.
However, both required a more expensive linear
amplifier in the transmitter and neither is compatible
with existing analog FM hardware.
Instead, 4LFSK modulation was selected using FDMA
for transmission. This method has a number of
advantages:
•
better communication range
•
simpler design
•
easy to maintain and service
•
lower cost for business and industry customers
•
compatible with existing FM radio hardware
Icom’s first radio with this technology is the
Background Background Background Background
As existing spectrum becomes increasingly scarce, the
demand for more options grows. The FCC essentially
created additional spectrum by adding hundreds of new
licenses with 6.25 kHz bandwidth. To take advantage of
this opportunity, Icom and Kenwood entered into a joint
agreement to develop 6.25 kHz technology. This
technology is a new digital communications protocol that
provides quality voice and data, and is designed as a
non-proprietary protocol. It accomplishes this by using
4LFSK (4-Level Frequency Shift Keying) and FDMA
(Frequency Division Multiple Access).
History History History History
This technology was developed in response to an FCC
revision of the rules concerning transmitters in the
6.25kHz Digital mode ready* 6.25kHz Digital mode ready* 6.25kHz Digital mode ready* 6.25kHz Digital mode ready*
The IC-FR5000/FR6000 series are 6.25kHz digital mode ready*, the IC-FR5000/FR6000 series
provides 6.25kHz digital narrow mode communication, and increases efficiency of channel
allocation and use of spectrum.
*For the USA version digital mode is turned ON, for the EXP version it is turned OFF when shipped from the
factory. Please ask your dealer for details.
8
Icom’s first radio with this technology is the
F3061/F4061. To enable backwards compatibility, the
radio is both analog and digital and also works in 25 kHz
and 12.5 kHz channel bandwidths (conventional and
LTR™ trunked operation in analog mode).
This new digital protocol, NXDN™ (Next Generation
Digital Narrowband) has been registered as a trademark
by Icom Inc. and Kenwood Corporation. IDAS (Icom
Digital Advanced System) is the system based on this
NXDN™ technology.
The product range is steadily expanding , from handheld
transceivers to mobile transceivers to repeaters. All
products are/will be available for VHF and UHF bands.
revision of the rules concerning transmitters in the
150MHz to 174MHz and 421MHz to 512MHz range. To
receive FCC certification after January 1
st 2005,
transmitters must have proved compliant as a multi-
mode device. This requirement could be achieved by
using 6.25 kHz channel bandwidth. In addition to the
FCC requirement, Europe and Japan are also moving
toward 6.25 kHz technologies. Because some in the
industry believed that this requirement could not be met
by 2005, the FCC suspended this requirement. (A new
deadline of January 1
st 2011 has been set.)
Icom, however, went ahead to meet this requirement. It
was impossible to do using analog technology, so it
became necessary to develop a new digital protocol.