Icom FR6000 Series, Руководство по продажам, Страница: 9 / 62

6.25 kHz FDMA Technology
Icom’s has implemented this technology in the
FR5000/6000 series. Backwards compatibility to
analog only radios enables a planned migration path to
“digital” with existing radios operating analog only and
new radios operating analog and digital.
General specifications: General specifications: General specifications: General specifications:
Access Method : FDMA
Transmission Rate : 4800 bps
Modulation
: 4-level FSK
S SS Spectrum Co pectrum Co pectrum Co pectrum Considerations (VHF & UHF)* nsiderations (VHF & UHF)* nsiderations (VHF & UHF)* nsiderations (VHF & UHF)*
While most users are operating on 25 kHz channels,
they will have to migrate to 12.5 kHz bandwidth by
2013. Narrowband migration has not succeeded until
now, because of any incentive to do so.
9
Modulation : 4-level FSK
Vocoder : AMBE+2™
Codec Rate : 3600 (Voice 2,450 + Error
Correction 1,150 bps)
Modulation with 4LFSK uses a symbol mapping scheme.
When the radio receives a binary number, that number
is mapped to a symbol, which is interpreted as a
1050Hz frequency deviation.
The deviation is detected, filtered and “unmapped” as a
binary signal for transmission.
Range Range Range Range
Audio quality over distance is also greatly improved with
Icom’s 6.25 kHz technology. Instead of the early
degradation of audio that you see in an analog signal,
the 6.25 kHz digital audio quality remains higher over a
comparable distance.
A channel is defined by the deviation either side of the
center line frequency. Migrating from a 25 kHz channel
to a 12.5 kHz channel on the same centerline frequency
is a 1-for-1 move. There is no increase in the capacity to
load radio users.
There are 500 new 6.25 kHz frequencies (VHF and UHF)
available now. Most are unused because no 6.25 kHz
radios were available. With Icom’s FDMA technology,
frequency coordinators have total flexibility to either
assign a 6.25 kHz channel within an existing 25 kHz or
12.5 kHz channel or as a stand-alone frequency some
where else on the band. A frequency coordinator will
coordinate channels for minimum adjacent channel
interference.
Most users on 25 kHz
Must move to 12.5
kHz by 2013
500 unused 6.25 kHz
channels, no radios
* Some of the content above applies to the U.S.A. only.