User's 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
- 3.6. Frequency Reference Specifications
- 3.7. A431 Module’s Photographs
- 4. Software
37
Adjusting the Crystal Reference
• No parts are missing, or have the incorrect value, or are badly soldered (check
the parts around U2 and U10).
3.3.10. Adjusting the Crystal Reference
1. Switch the unit to transmit mode by entering TX at the terminal.
2. Observe the indication shown by the Service Monitor: adjust R75 (see
Figure 17) until the carrier frequency indicates 435000000 (Band 1), 445000000
(Band 2), 455000000 (Band 3), or 465000000 MHz (Band 4) ± 200 Hz,
respectively.
3.3.11. Checking the Receiver Parameters
1. Switch the DUT to receive mode by entering RX at the terminal.
2. Switch the Service Monitor to RX TEST mode, on the appropriate frequency
(435 / 445 / 455 or 465 MHz respectively); the level should be -118dBm (see
also “Test Equipment Settings” on page 34).
3. Verify that the S/N ratio is at least 12 dB; in addition, if a scope is also
connected, a clear 1 kHz sine wave should be visible, with a relatively low
amount of noise superimposed.
4. Switch the DUT to pulsed mode by pressing the Enter key. After several
seconds, you will see the image on the scope pulsing at about one-second
intervals.
5. Switch the RF generator output off.
6. Verify that the RSSI threshold is correct by typing the command RSSI; the actual
value must be lower than the threshold set. If this is not the case, repeat the
RSSI command several times—perhaps the frequency is in use (a radio receiver
set on the operating frequency would help detect foreign transmissions). If the
threshold difference is marginal, it must be increased by using the RSSI
<value> command (it must be 20 to 30% higher than the actual value).
If any of the above targets are not reachable, visually verify first that the U8 chip is
correctly soldered and that there are no shorts between its pins (most problems usu-
ally appear around this chip).
3.3.12. Checking the Transmitter Parameters
1. Switch the DUT to transmit mode by typing the command TX 0 at the terminal.
2. Switch the Service Monitor to TX TEST mode, on the appropriate frequency
(435 / 445 / 455 or 465 MHz respectively). You should see the following
parameters on the Service Monitor readout:
a. Carrier: 435000000 ± 200 Hz (or 445000000 / 455000000 / 465000000
respectively)
b. Output Power: 26.5 dBm (+ 0.5 dBm / - 1 dBm)