provide for connection of as many as [255] [_____] control units.
When operating without line repeaters or other signal regenerating
or amplifying devices, communication system shall maintain
specified performance over a link length of 2287 meters 7500 feet.
When operating with signal-regenerating line repeaters,
communications system shall maintain specified performance over a
link length of 22 865 meters 75,000 feet. Control unit to central
alarm reporting and display processor communications link shall
also be capable of operating over a maximum of [two] [four]
[_____] standard voice grade telephone leased or proprietary
lines. Link shall be capable of operating half duplex over a Type
3002 data transmission pair and be capable of modular expansion.
Telephone lines shall be provided by the Government. Coordinate
and check out system operation. General characteristics and
telephone line service shall be as follows:
(1)
Connections:
Two- or four-wire
(2)
Impedance at 1000 Hz:
600 ohms
(3)
Transmitting level:
0 to 12 dBm
(4)
Transmitting level adjustment:
3 dB increments
(5)
Type:
Data
(6)
Direction:
Two-way alternate (half duplex)
(7)
Maximum speed:
[1.2] [5.12] [10.24] [_____] kilobaud
(8)
Maximum loss at 1000 Hz:
33 dB.
c.
Video hardwire links shall be as specified in paragraph entitled
"Video Transmission."
2.4.16.3
Radio Frequency Link
**************************************************************************
NOTE: Radio frequency links may not be allowed on
some Government facilities. Recommended usage for
RF links is as backup to hardwire links or to a
remote location lacking telephone lines. OPNAV
Instruction 2400.20E requires that funds shall not
be obligated for procurement of radio equipment
until frequency allocation authority has been
obtained. As soon as possible, but no later than
schematic design, the designer shall contact the
area radio frequency coordinator (usually the base
radio officer) to determine the availability of
radio frequencies and to ensure that the using
activity submits a DD Form 1494, "Application for
Frequency Allocation," for a Stage 1 ("Conceptual
Development") allocation (see DD Form 1494
Preparation Guide). Stage 1 allocation authority
(i.e., approval) must be obtained prior to
advertisement of the contract.
The 138 to 150.8 MHz band is the preferred range
since specific frequencies in this range are
SECTION 13703N
Page 44
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