Nortel BTR 2400, Руководство по установке

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1-6 BTR 2400 Release 1.1
411-1333-200 Preliminary July 1998
BTR 2400 Component Descriptions
Diplexer / Power Supply
The diplexer separates the IF input signals and the DC power supply. The
isolation between the IF path and the power supply path is more than 45 dB.
There is also a transient voltage protector on the board to protect the
transceiver from possible lightning damage.
The 60 VAC/48 VDC power from the diplexer is first regulated to 15 VDC,
and then sent to all the modules.
Mixer
The BTR 2400 uses a third harmonic mixer. The mixer uses a 8.3 GHz local
oscillator (LO) signal to convert the IF input signals to the 24.25-25.45 GHz
microwave frequency band. The same LO is used to downconvert the
incoming microwave signals to the receive IF frequency band.
Dielectric Resonance Oscillator (DRO)
The Dielectric Resonance Oscillator is equipped with a TCXO reference
oscillator. When the DRO is phase-locked, it provides a 8.3 GHz microwave
frequency with the same frequency stability as the reference crystal.
When the DRO is phase-locked, the phase-locked voltage at the test port on
the DRO can vary from 3 VDC to 12 VDC depending on the chassis
temperature and the input reference frequency. The voltage at the alarm test
port is approximately 5 VDC.
When the DRO is unlocked, the phase-locked voltage becomes an oscillating
ramp wave. The voltage at the alarm test port goes down to 0 VDC.
Isolator
Four isolators provide adequate return loss in the BTR 2400. Each isolator’s
maximum forward insertion loss is 0.5 dB, and its return loss is greater than
20 dB.
Bandpass Filter
The bandpass filter removes the undesired sideband elements and LO
leakage, and passes the required sideband signals.