Technical Manual

16
Wireless Sensor Interface A720 (addIT™)
The settings for the transmitter section check (TX-TEST):
• COUNT: (should show the transmitter carrier frequency);
• POWER: (should show the transmitter carrier power).
Note: If using the Testing Fixture, a calibration should be performed to check the losses in the an-
tenna switch, cables, etc. Depending on these losses (which at 450 MHz can amount up to 6
dB), it may be needed to adjust the RF LEV value accordingly (up to 10 µV). Similarly, the
measured output power must be correspondingly downgraded (see also “Checking the Trans-
mitter Parameters” on page 18).
3.3.3. Adjusting the Receiver Front End
• Mount the DUT on the testing fixture and connect it to the PC via the serial
cable;
• Select the appropriate instrument profile depending on the device’s band
(High or Low);
• Turn on the receive subsystem of the DUT by entering the
RX
command at the
terminal;
• Check that the switch on the Testing Fixture is in the
Wobble
position;
• Adjust the filter FL3 until you obtain a curve similar with one of those shown
in Figure 4. (depending on the band); this is done by successively adjusting the
two trimming screws located on the filter.
If this is not possible, check the power supply, the cable connections to/from the test
equipment, etc. In addition, verify if you have approx. 1.1 volts on the test point TP4.
Finally, check if all 8 pins of the filter FL3 are properly soldered.
Figure 4.
Helical filter’s diagrams for Low Band and High Band devices.
Low Band High Band