Technical Manual
Table Of Contents
- 1. Introduction
- 2. Hardware
- 3. The A431 Radio Module
- 3.1. About the A431 Radio Module
- 3.2. Functional description
- 3.3. Manufacturing Issues
- 3.3.1. Marking and labeling issues
- 3.3.2. Alignment Range and Switching Range
- 3.3.3. Tuning Procedure
- 3.3.4. Setting Up the Default Parameters
- 3.3.5. Definitions
- 3.3.6. Test Equipment Settings
- 3.3.7. Trimming Elements
- 3.3.8. Adjusting the Receiver Front End
- 3.3.9. Adjusting the VCOs
- 3.3.10. Adjusting the Crystal Reference
- 3.3.11. Checking the Receiver Parameters
- 3.3.12. Checking the Transmitter Parameters
- 3.3.13. Data Transfer Check
- 3.4. PCB Parts Placement
- 3.6. Frequency Reference Specifications
- 3.7. A431 Module’s Photographs
- 4. Software
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The A431 Radio Module
If the adjustments do not achieve the appropriate curve, check the power supply,
the cable connections to/from the test equipment, etc. Verify also that all the pins of
the FL1 and FL2 filters are properly soldered.
Figure 21. Helical Filter + LNA’s selectivity diagram.
3.3.9. Adjusting the VCOs
1. Flip the switch on the Testing Fixture to the Power/Sens. position.
2. Verify that the DUT is in receive mode (enter the RX command at the terminal
program).
3. Adjust the L15 coil (see Figure 20) until the voltage shown on the digital
voltmeter is 900 mV, ±50 mV (see also the note below).
4. Switch the unit to transmit mode by entering TX at the terminal.
5. Adjust the L7 coil (see Figure 20) until the voltage shown on the voltmeter is
again 900 mV, ±50 mV.
6. Press the enter key at the terminal to switch the unit off.
Note: A calibration may be needed due to the internal resistance of the voltmeter
and the serial resistor mounted on the Testing Fixture. The calibration is per-
formed by measuring the VCO voltage directly on the TP2 and by comparing
the value with that measured through the Testing Fixture. The values given
above are the real ones, measured directly.
If the above limits cannot be obtained, or the readout is unstable, verify the follow-
ing:
• The programmed operating frequencies are indeed 430 (Band 1), 440
(Band 2), 450 (Band 3) and 460 MHz (Band 4). To check this, type the com-
mand FREQ at the terminal prompt; the device will answer by returning the
current frequency.
• The respective commands (RX and TX) were issued.