Apreto Networks PacketMAX 5000, Installation And Operaion Manual

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PacketMax 5000 Installation and Operation Manual, 10007678 Rev J
Chapter 4. Installing the Base Station ODU Radio and Antenna
The IF cable between the BS and BSR carries a multiplexed signal along with the DC
voltage.
They are identified below and the user should pay particular attention to the
choice of IF cable, in field deployments as the cable loss is a function of length, fre-
quency and quality.
Following are the various signals the IF cable carries between BS and BSR.
DC voltage.
20 MHz reference signal.
70 MHz IF signal (bi-directional).
Telemetry link (260 and 420 MHz) for communication between BS-BSR and
BSR-BS (bi-directional).
When choosing IF cable of any given length and quality, the user should look at the
maximum allowable loss of the cable that is recommended below for reliable opera-
tion of the system. The below table allows sufficient margin for surge protectors and
connectors.
Table 4-1 is based on a nominal Base Station Radio operating voltage of
52 Volts DC and 75% duty cycle.
Apart from the above recommended cable loss characteristics, the RF shielding capa-
bility of the cable should be least 90 dB or better. As a last note, choice of quality
connectors and cables with good weatherability and outdoor rated is highly recom-
mended for reliable performance of the system.
Typical cable lengths for LMR Cables from Times Microwave, Inc
Following are the assumptions in coming up with the prescribed lengths.
Two surge protectors are used each with ~ 0.1 dB loss at 70 MHz.
Connectors on either end have a loss of ~ 0.1 dB each.
PM 3000 BS outputs a nominal voltages of 52V at the IF port.
Table 4-1 Maximum Allowable Cable Loss for IF Cable
Parameter Value
DC Resistance inner +Outer conductor. Maximum of 22 ohms
Loss at 20 MHz Maximum of 20 dB
Loss at 70 MHz Maximum of 9 dB
Loss at 260 MHz Maximum of 20 dB
Loss at 420 MHz Maximum of 20 dB
Cable Return Loss from 20 – 500 MHz 20 dB Typ
Table 4-2 LMR Cable Types and Maximum Lengths
Cable Type Max Length with surge protectors for
PM BSR
LMR-200-75 100 meters