Comtech EF Data SFC4200 - Manual (Page 20)

Operation SFC4200/SFC1275G Synthesized Frequency Downconverter
3-4 TM054 - Rev. 4.0
0 dB Attenuation)
LO 2.0 GHz @ +13 dB
3.2 AS/3048 M&C Controller Assembly
The Controller PWB Assembly is the controller, which monitors the Operator Front Panel, and
Remote Input used to control the frequency, gain and provide the fault detection functions of the
converter. The AS/3048 hardware features an Intel 80C32 microprocessor (Refer to Figure 5-2).
Peripherals on the controller include the following:
12 Bit Digital to Analog Converter (DAC)
8 Channel/8 Bit Analog to Digital Converter (A/D)
RS-485 UART
RS-232, -422, -485 UART
LCD Port
8 Bit Addressable Synthesizer Bus
5 Bit Addressable Converter Bus
Static Memory
Nonvolatile Memory
Serial Nonvolatile Memory
Read-Only Memory (ROM)
The 12 Bit DAC provides the precise current to the PIN Diode Attenuators in the converter. The
value of attenuation is determined through look-up of calibration data stored in non-volatile
memory. 000 to FFF written to the DAC provides an output voltage of 0.3 V – 8.50 V
respectively.
The 8-channel A/D Converter allows the AS/3048 to monitor various voltages within the
converter. The input to the A/D is 0 to 5 VDC. Voltages monitored by the A/D include the
square-law voltages from the IF and Fault of the synthesizer which allows the controller to
calculate signal strengths.
The Equipment RS-485 UART is independent from the Operator UART. Dual UARTS allow
equipment to be tied together as a system while giving the operator a single remote point of
contact. The operator serial interface is configurable via jumpers found on the AS/3048. Refer
to Figure 5-3 for the location of the jumpers.
The various memories found in the AS/3048 provide for program storage and calibration value
storage. In the event that the operator is requested to perform a software revision, replacement
of the PROM (U11) will be required. This operation should be performed with the power off and
in a static-free environment.
3.3 Synthesizer Modules
The Synthesizer module used in SFC Downconverters are stand-alone modules that provide the
synthesized local oscillator and the fixed IF local oscillator for the first and second mixers in the
converter.