Motorola APX 2000 - Keypad Operation

3-6 Basic Theory of Operation: Analog Mode of Operation
3.2.2 Transmitting
When the radio is transmitting, microphone audio is digitized and then processed by the DSP and
sent to the Trident IC (see Figure 3-7, Figure 3-8, Figure 3-9 and Figure 3-10) via the SSI interface.
The Trident IC processes the SSI data for application to the voltage controlled oscillator as a
modulation signal.
Figure 3-7. Transmitter (VHF) Block Diagram
Figure 3-8. Transmitter (UHF1/UHF2) Block Diagram
Trident IC
Synthesizer
Loop Filter
TX VCO
RX/TX
VCO
RF Switch Matrix
TX Buffer Amp
TX Driver Amplifier
Transmitter Final
FET VHF
Harmonic
LP Filter
Ref. Oscillator
Antenna Connecto
r
Directional
Coupler
Antenna
Switch
TO RX
GPS
Reverse Power
Detection
Log Amp Power Detector
Digital RF Attenuator
Trident IC
Synthesizer
Loop Filter
TX VCO
RX/TX
VCO
RF Switch Matrix
TX Buffer Amp
TX Driver Amplifier
Transmitter Final
FET UHF
Harmonic
LP Filter
Ref. Oscillator
Antenna Connecto
r
Directional
Coupler
Antenna
Switch
TO RX
GPS
Reverse Power
Detection
Log Amp Power Detector
Digital RF Attenuator