TB8100 base station Calibration Kit User’s Manual MBA-00011-05 March 2005
Contents Preface ..............................................................................................................iii Enquiries and Comments ..................................................................iii Updates of Manual and Equipment ...................................................iii Copyright .........................................................................................iii Disclaimer .......................................................................................
Calibrating the PA Bias ........................................................................ 24 Calibrating the Forward and Reverse Detector Bias Voltages ............... 25 Calibrating the PA Power .................................................................... 25 Troubleshooting Tips ..................................................................... 26 Calibrating the Supply Voltage ............................................................. 27 Calibrating the Power Management Unit ........
Preface Welcome to the TB8100 Calibration Kit User’s Manual. This manual provides you with information about the Tait TB8100 Calibration Kit in PDF format. You can view it online or print it if you want a paper copy. It describes how to use Version 02.05 of the Calibration Kit. Enquiries and Comments Any enquiries regarding this manual as well as any comments, suggestions and notifications of errors should be sent to support@taitworld.
Publication Record iv Preface Version Date Description 1.0 June 2003 First release of the manual for Version 1.0.0 of the Tait TB8100 Calibration Kit software. 02.00 March 2004 Minor quality issues resolved and software changes documented for Version 02.00. 02.01 (MBA-00011-03) September 2004 Carrier Frequency Offset Adjustment procedure for reciter version 00.03+ added. PA store supply voltage and PMU output voltage calibration added. 02.
Basic Tasks The TB8100 Calibration Kit is a Windows-based software program that allows you to adjust the switching ranges of Tait TB8100 base stations (both receiver and transmitter), and to flatten the receiver response across that switching range. The TB8100 Calibration Kit is also used to calibrate the reciter, the PA, and the PMU after servicing. Using the TB8100 Calibration Kit When you start the TB8100 Calibration Kit, the main program window appears.
About the Toolbar The toolbar gives you quick access to commonly used menu commands. For example, instead of selecting Base Station > Calibrate, you can click the Calibrate icon on the toolbar. Connect Connects the TB8100 Calibration Kit to the base station and opens the communication channels. Switch Base Station Lets you select another base station to calibrate if there are multiple base stations in the rack (not currently supported).
Equipment Required You need the following equipment for field calibration: ■ Calibration and test unit (CTU) (order code TBA0ST1) which comes with the cables you will need for connection to the reciter/PA and the PC. For more information about the CTU, please refer to TN-778 The TB8100 Calibration and Test Unit.
Field Calibration The following procedures can be carried out in the field.
Power Amplifier Procedure Connection Equipment Required Calibrating the PA bias Inside subrack None required Calibrating the forward & reverse detector bias voltages Inside subrack None required Calibrating the PA power Inside subrack None required Storing supply voltages Inside subrack Variable voltage external power supply Procedure Connection Equipment Required Output voltage calibration Inside subrack Digital multimeter Power Management Unit Selecting the Communications Port Before
Setup 5 4 6 8 2 1 7 3 1 PC 5 16-way cable 2 RS-232 cable 6 Reciter 3 CTU 7 Power cable 4 Programming port 8 10-30 V DC power supply To connect to the reciter 1. Remove the reciter from the subrack (for instructions, see the Installation and Operation Manual). 2. Set up the equipment as follows. ■ Connect the reciter to the calibration and test unit (CTU) using the 16way cable. ■ Connect your computer to the CTU by plugging the RS-232 cable into the programming port.
Connecting to a Reciter via the Control Panel For calibration procedures that do not require access to tuning holes, you can leave the reciter in the subrack and connect your PC to the control panel as follows. Equipment ■ An IBM compatible PC ■ RS-232 cable Setup 1 3 4 2 1 Base station 3 RS-232 cable 2 Serial port 4 PC To connect to a reciter in the subrack 1. Connect your computer to the base station by plugging the RS-232 cable into the serial port of the base station’s control panel.
Troubleshooting Application Errors All application errors are recorded in a log file called “CalError.log”. The data, time, location, and any other useful information is stored in this file, which may be helpful when troubleshooting. The file is saved in the Logfiles subfolder of the application folder and stores up to 1000 of the most recent logged items. Verifying the Software Version If you need to verify the version of the TB8100 Calibration Kit, select Help > About.
Adjusting the Frequency Setup Before the TB8100 base station is installed, connected, and configured, you must prepare it for operation by adjusting the switching range of the reciter, and flattening the receiver response across the base station’s switching range. Note: If the required switching range for the base station has already been defined, you don’t need to perform these procedures. To prepare the base station for operation 1. Adjust the receiver lock band 2. Tune the receiver front end 3.
6. Adjust the receiver VCO trimmer until the actual band matches the desired band. The bands turn green. Click Finish. This stores the lock band in the on the Frequency Setup tab indicates that this task is reciter. The icon complete. Proceed to tune the front end. Tuning the Receiver Front End The second step in tuning the reciter frequency is to tune the receiver front end. Tuning aims to maximise the receiver’s sensitivity and to flatten its response across the lock band (switching range).
Tuning a K-Band, H-Band, or L-Band Receiver Front End To tune the receiver front end, follow these steps. 1. Ensure you are already connected to the reciter (see “Connecting to a Reciter Outside the Subrack” on page 5). 2. Select the Frequency Setup tab, and double-click Tune Receiver Front End. The Tune Receiver Front End Wizard appears. 3. Connect the CTU’s noise source to the receiver input, turn the noise source on, and then click Next. 4.
6. Click Finish. The icon task is complete. on the Frequency Setup tab indicates that this Tuning a VHF Receiver Front End To tune the receiver front end, follow these steps. 1. Ensure you are already connected to the reciter (see “Connecting to a Reciter Outside the Subrack” on page 5). 2. Select the Frequency Setup tab, and double-click Tune Receiver Front End. The Tune Receiver Front End Wizard appears. 3.
Adjusting the Exciter Lock Band If you are preparing the base station for operation, adjusting the exciter lock band is the third step in tuning the reciter. Alternatively, this procedure can be performed independently of the other two calibration wizards on the Frequency Setup tab. Adjusting the exciter lock band defines the range of frequencies that the base station is able to transmit on.
Calibrating the Reciter The reciter is fully calibrated in the factory, but if the reciter is serviced you may need to perform the following procedures: ■ Calibrating the Exciter ■ Calibrating the RSSI ■ Audio Calibration To compensate for frequency drift, you may need to perform the following: ■ Carrier Frequency Offset Adjustment (Older Reciters) or ■ Carrier Frequency Offset Adjustment (Newer Reciters) All these procedures can be done independently of each other, although it is recommended that
Setup 3 2 1 4 1 Reciter 3 RF attenuator (only required if using a PA) 2 PA (optional) 4 Modulation meter To calibrate the FCL 1. Ensure that the Calibration Kit PC is connected to the reciter. 2. Select the Reciter Calibration tab, and double-click FCL Calibration. The FCL Calibration Wizard appears. 3. Attach an appropriate Load and Modulation meter to the PA or exciter output, set the meter to measure the RMS deviation, and then click Next. (If you are using a PA, it will now transmit.) 4.
Calibrating the VCO This is step three of calibrating the exciter. Once you have tuned and calibrated the FCL, you calibrate the VCO at frequencies across the whole lock band. This involves selecting a sub-band, adjusting the lock band trimmer, and then moving on-screen sliders to adjust the deviation to 3 kHz for each of a set of frequencies.
You should now adjust the exciter lock band because it was re-tuned several times during this procedure. This means that the exciter is no longer on the required frequency. Calibrating the RSSI Calibrating the RSSI (received signal strength indicator) ensures that the reciter's internal RSSI values accurately reflect the actual received signal strength. Changing the receiver's lock band can alter the calibration accuracy by about 1 dB.
Audio Calibration You should calibrate the audio outputs/inputs if the system interface has been replaced or changed at all. Note: The balanced and unbalanced lines can be calibrated independently of each other. Calibrating the Balanced Lines Calibrating the balanced lines adjusts their gain, so that when you set line levels using the TB8100 Service Kit software, the actual line level correctly reflects the Service Kit settings. (Refer to the TB8100 Service Kit User’s Manual for further information.
To calibrate the balanced input and output lines 1. Ensure that the Calibration Kit PC is connected to the reciter. 2. Select the Reciter Calibration tab, and double-click Balanced Line Calibration. The Balanced Line Calibration Wizard appears. 3. Attach an AC millivoltmeter and terminate the balanced output in 600 ohms (either using the load on the CTU or looping the balanced output to the balanced input), and then click Next. 4.
Setup for Unbalanced Line In 5 6 1 3 4 2 1 Reciter 3 CTU 5 Unbalanced line input 2 25-way cable 4 System interface port 6 Unbalanced line output To calibrate the unbalanced input and output lines 1. Ensure that the Calibration Kit PC is 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.
Carrier Frequency Offset Adjustment (Older Reciters) The carrier frequency is derived from a reference frequency generated by the reciter’s TCXO (temperature compensated crystal oscillator). The reference frequency can drift over time, causing an offset to the carrier frequency. When you connect to a reciter with hardware version 00.02 or earlier, the Calibration Kit provides the following procedure that enables you to adjust the carrier frequency and remove the offset.
Carrier Frequency Offset Adjustment (Newer Reciters) The TCXO (temperature compensated crystal oscillator) provides a reference frequency from which all other RF frequencies are derived. Reciters with hardware version 00.03 and above have a voltage-controlled TCXO, with a pot for adjusting the reference frequency to remove any carrier frequency offset. The Carrier Freq Offset Adjustment wizard provides assistance with this procedure.
5. Attach an appropriate load and frequency counter (or a test set) to the exciter or PA output, and then click Next. The exciter now begins transmitting on the center frequency of its lock band. The Wizard displays a message similar to the following: “Adjust RV1400 to set frequency within 0.1ppm or 48Hz of 485 MHz” 6. Use the tuning tool to adjust the TCXO tuning control (RV1400) so that the reciter is transmitting exactly on frequency. 7. Click Finish.
Calibrating the Power Amplifier The PA is fully calibrated in the factory, but if the PA is serviced you may need to perform the following procedures: ■ Calibrating the PA Bias ■ Calibrating the Forward and Reverse Detector Bias Voltages ■ Calibrating the PA Power ■ Calibrating the Supply Voltage Perform the procedures in the above order. Important: It is recommended that only accredited service centers and Tait engineers perform these procedures.
Calibrating the Forward and Reverse Detector Bias Voltages The RF detectors, used for measuring the forward and reverse power, operate with a small bias current. The resulting bias voltage from each detector (with no RF present) is read and stored inside the PA. These voltages are used when calculating the Antenna VSWR (Voltage Standing Wave Ratio).
Setup for Inline Power Meter 2 5 1 3 4 1 Reciter 3 PA 5 Load 2 16-way cable 4 RF Power Meter Note: Cables and connectors can easily cause a power loss of several watts if either too long or poorly terminated. Always use the shortest possible leads (or connectors instead of leads) between the PA and power meter set-up. To calibrate the PA transmit power 1. Ensure that the Calibration Kit PC is connected to the base station. 2. Select the PA Calibration tab, and select Calibrate PA Power. 3.
VSWR The VSWR (Voltage Standing Wave Ratio) is monitored at the RF output of the PA during calibration. The software will not allow calibration into a load VSWR > 1.3:1. If a calibration step cannot be stored, check that the load VSWR is <1.3:1. It is recommended that the load should have an input VSWR <1.2:1. Calibrating the Supply Voltage The Calibrate Supply Voltage procedure stores DAC values for a set of different PA supply voltages.
Calibrating the Power Management Unit There is only one calibration procedure for the PMU: calibrating its output voltage. Calibrating the PMU Output Voltage Calibrating the PMU output voltage adjusts the voltage to be 28.00 V. This procedure is only carried out when a replacement control card or microprocessor is fitted to the PMU. Normally, the output voltage will be accurate without calibration.
Index A AC millivoltmeter see equipment Antenna VSWR (Voltage Standing Wave Ratio) 25 audio level calibrating 19, 20 B balanced input calibrating 19 balanced output calibrating 19 band 1 entering 4 base station connecting to 7 disconnecting from 7 bias current required for each power level 24 RF detectors 25 C calibration test kit see equipment calibration test unit (CTU) connecting to computer 6 connecting to reciter 6 see also equipment calibration wizards Balanced Line Calibration Wizard 19 Calibrate F
H hardware version 1 entering 4 L lock band definition 9 see exciter see receiver log files application errors 8 commands received and sent 8 Low Pass Filter (LPF) 25, 25 M modulation meter see equipment module number 1 O operating range see switching range P PA calibrating bias current 24 calibrating RF detector bias voltages 25 calibrating the supply voltage 27 calibrating transmit power 25 connecting to 7 details 1 faulty gain stage 26 low RF input power 26 PCB module 25, 25 peak deviation measuring
