User's Manual

TB8100 Calibration Kit User’s Manual Calibrating the TCXO 25
Setup for
Unbalanced Line
In
To calibrate the unbalanced input and output lines
1. Ensure you are already connected to the reciter.
2. Select the Reciter Calibration tab, and double-click Unbalanced Line
Calibration. The Unbalanced Line Calibration Wizard appears.
3. Attach an AC millivoltmeter to the unbalanced line output, and then click
Next.
4. Adjust the slider in the dialog box until the audio level on the millivoltmeter
reads 1 V
PP (0.354 VRMS) to calibrate the unbalanced line output, and then
click Next.
Note: Click Coarse to roughly adjust the audio level, and once you
get within range, click Fine for more precise control over the
settings. To move up or down 10 mV
PP, click either side of the
slider bar.
The unbalanced output is now calibrated.
5. Connect the unbalanced output to the unbalanced input, and then click
Finish.
The unbalanced input is now calibrated.
When you have finished calibrating the unbalanced lines, the icon on the
Reciter Calibration tab indicates that this task is complete.
Calibrating the TCXO
The TCXO (temperature compensated crystal oscillator) provides a reference
frequency from which all other RF frequencies are derived.
You will need to calibrate the TCXO if you suspect that the reciter (specifically,
the transmitter and receiver) is off-frequency. (Off-frequency is defined as being
outside the range of -1 to +1 ppm.) This may occur for a variety of reasons.
Over time the reciter frequency will become less accurate, so it is a good idea
to calibrate the TCXO every few years. Exactly how often you do this will
depend on the harshness of the conditions in which the base station is operating.
Ideally, you should calibrate the TCXO at a room temperature of 25 ± 5
degrees Celsius. Complete the calibration as quickly as possible since extended
transmission times increase temperature, which makes the calibration less
accurate.
1
3
5
6
4
2
1 Reciter 3 CTU 5 Unbalanced line input
2 25-way cable 4 System interface port 6 Unbalanced line output