User's Manual

545C Operations Manual

02/10/2012 Prerelease DCN 00001789-A

An internal lithium ion battery is used to maintain the internal real time

clock and battery backed RAM. This battery operates the clock in a

power down state for a period of approximately 6 months. This battery

should be removed if the unit is stored for extended periods of time.

In -03 or later versions of the units, the lithium ion battery has been

replaced with a rechargeable nickel metal hydride battery. This battery

is located at the rear of the unit with Velcro. (You have to open the

rear lid to get access to it.) A short jumper is used to connect the

battery to the processor board. This jumper should be removed if the

unit is stored for long periods of time (longer than 2 months). The

battery must be connected before the unit will start operating.

3.4 Transceiver

The transceiver assembly contains a receiver, transmit and receive

frequency synthesizers, and a modulator. The MCC-545C receiver and

modulator support 9.6 kbps Gaussian Minimum Shift Keying (GMSK).

GMSK Receiver

• Input bandpass filter (37-50 MHz )

• RF amplifier (17 dB)

• Low pass image filter (Fc=50 MHz)

• Mixer

• IF amplifiers and filters (10.7 MHz)

• Noise blanker

• Mixer, 2nd IF filter and amplifier (100 kHz), and RSSI circuit

• Phase lock loop frequency discriminator

• GMSK bit detector and clock generator

Synthesizer (1st and 2nd local oscillator and transmit oscillator)

• Reference Oscillator (12.8 MHz +/- 2.5 PPM)

• Tx phase lock loop (74-100 MHz output, 20 kHz steps)

(86-92 MHz, 20 kHz steps in FCC ID: BIB54505003-01)

• A divide by 2 circuit (37-50 MHz output, 10 kHz steps)

(43-46 MHz, 10 kHz steps in FCC ID: BIB54505003-01)