Motorola Gtx2000 Lcs2000 68p02945c70 O Manual

7-6 Theory of Operation
Synthesizer Detailed
Functional DescriptionThe complete synthesizer subsystem consists of a reference oscillator (U5700), a
Fractional-N Synthesizer IC (U5702), two on-board voltage controlled oscillators,
a buffer stage (U5701), and two line-up ampliÞers (Q5707, Q5705).
Reference oscillator U5700 contains a temperature compensated crystal with an
oscillation frequency of 16.8 MHz. The output of the oscillator (pin 10 of U5700)
is then applied to pin 14 (XTAL1) of U5702 via C5733...

Theory of Operation 7-7 The serial interface (SPI_DATA) is connected to the microprocessor via the data
line (pin 5 of U5702), clock line (pin 6 of U5702), and chip enable line (pin 5 of
U5702). Proper enabling of these lines should allow the microprocessor to load
the synthesizer IC.
The output of the VCO is fed into the buffer input port (pin 1) of U5701. The
output of the buffer, pin 5 of U5701, is applied to the input of the feedback
ampliÞer (Q5703) through an attenuator network (R5735, R5733,...

7-8 Theory of Operation
Controller Detailed
Functional Description
GeneralThe radio controller consists of four main subsections:
¥Digital Control
¥Audio Processing
¥Power Control
¥Voltage Regulation
The digital section consists of a microprocessor, memory ICs, glue logic circuitry,
signal MUX ICs, On/Off circuit, and general purpose Input/Output circuitry.
The controller is based on the Motorola 68HC11K1 microprocessor (U0101), 8-
Kbyte SRAM (U0103), 128 Kbyte-OTP memory (U0102), and 4 Kbyte EEPROM...

Theory of Operation 7-9 Diode D5601 located on the PA section acts as protection against transients and
wrong polarity of the supply voltage.
Electronic On/OffThe radio has circuitry which allows radio software and/or external triggers to turn
the radio on or off without direct user action.
Some examples of where this is useful are: 1) automatic turn on when emergency
switch is engaged; 2) automatic turn on when ignition is sensed and off when
ignition is off.
Q0611 is used to provide SW B+ to the...

7-10 Theory of OperationWhen the IGNITION input goes above 6 V, Q0450, Q0612 and Q0611 turn on,
supplying SW B+ to the radio and enabling U0601 and U0631 to supply the
regulated voltage (+5 V and 9.3 V) to all the circuitry. ThemP starts to run the
software, reads the line EMER IGN SENSE, determines from the level
(Emergency has a different level) that the IGNITION input is active and sets the
B+ CONTROL (via the ASFIC-GCB2) to high and latches SW B+ to on.
While the IGNITION line drops below 6 V, Q0450...

Theory of Operation 7-11 SPI BUS is also used for the control head. U0106 buffers the SPI TRANSMIT
DATA and CLK lines to the control head. U0106 serves also to switch off the CLK
signal for the LCD display while it is not selected via LCD CE signal.
When themP needs to program any of these ICs, it drops down the chip select line
of the speciÞc IC to a logic 0 and then sends the proper data and clock signals. The
data sent to the various ICs are different. For example the ASFIC receives 21 bytes
(168...

7-12 Theory of OperationOn the K1mP the lines XIRQ (U0101-30), MODA LIR (U0101-77), MODB
VSTPY (U0101-76) and RESET (U0101-75) should be logic high during all
normal K1mP operation. Whenever a data or an address line becomes unloaded or
shorted to an adjacent line, a common symptom is that short negative pulses occur
on the RESET line, with a period of 20 msec. When two lines are short-circuited,
mid logic level (around 2.5 V) may be observed, while these lines are opposite
driven by two different ICs....

Theory of Operation 7-13 access signals (SI, SO and SCK) are generated by the K1mP and chip select (CS)
is generated by address decoder U0105.
Additional EEPROM is contained in the K1mP (U0101). This EEPROM is used
to store radio tuning and alignment data. Like the external EEPROM this memory
can be programmed multiple times and will retain the data when power is removed
from the radio.
Note:The external EEPROM plus the 640 bytes of internal EEP-
ROM in the 68HC11K1 comprise the complete codeplug.
Static...

7-14 Theory of Operation
Controller Audio &
Signaling Circuits
General
Audio Signalling Filter IC
(ASFIC)The ASFIC (U0201) used in the controller has four functions;
¥RX/TX audio shaping, i.e. Þltering, ampliÞcation, attenuation
¥RX/TX signalling, PL/DPL/HST/MDC/MPT
¥Squelch detection
¥Microprocessor clock signal generation (see Microprocessor Clock
Synthesizer Description Block).
The ASFIC is programmable through the SPI BUS (U0201-E3/F1/F2), normally
receiving 21 bytes. This programming sets up various...

Theory of Operation 7-15 Figure 7-3 Transmit Audio Paths
Filter capacitor C0210 provides low-pass Þltering to eliminate frequency
components above 3 kHz, and C0211 serves as a DC blocking capacitor. The
audio signal at U0201-B8 should be approximately 80mV for 3kHz of deviation
with 25 kHz channel spacing.
The FLAT TX AUDIO signal from accessory connector J0400-5 is buffered by
op-amp U0202-1 and fed to the ASFIC U0201-D7 through C0205.
External Mic PathThe external microphone signal enters the radio on...