Nortel Networks BTRCTR2400-T Benutzerhandbuch

1-6   BTR 2400 Release 1.1

411-1333-200   Preliminary   July 1998

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. 

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.

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.

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.

The bandpass filter removes the undesired sideband elements and LO 
leakage, and passes the required sideband signals.