DRAFT D
TNM-M-E-0001 Page 20
3.3.6 Reference Oscillator
TCXO U700 determines the overall frequency stability and frequency setting of the radio. The
frequency setting is achieved by adjusting its ADJ voltage with the Alignment Tool. In addition,
the ADJ input is used in a frequency control loop with the receiver I and Q signals to provide
receiver AFC. U700 operates at 14.4MHz and is specified at ±2.5ppm frequency stability over
the temperature range -25° to +75°C.
3.4 Control
Refer Figure 3-4
3.4.1 DSP and FPGA
The SRM9000 transceiver operates under the control of a DSP (U102) and FPGA (U106)
combination which together with a number of other dedicated devices perform all the operational
and processing functions required by the radio. The FPGA is configured by the DSP under
software control to provide the following functions:
• Channel set-up of all operating frequencies
• Modulation processing and filtering
• De-modulation processing and filtering
• TX power output reference
• Receiver front end tuning
• Serial communications with alignment tool, microphone and control head
• Modem functionality for data modulation
• All signalling / CTCSS generation and decoding
• CO control
• Receiver muting control
• TX / RX switching
• PLL detect
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