TB8100 base station Calibration Kit User’s Manual MB8100-90-00-806 March 2004
Contents Preface ..............................................................................................................iii Enquiries and Comments ..................................................................iii Updates of Manual and Equipment ...................................................iii Copyright .........................................................................................iii Disclaimer .......................................................................................
Calibrating the Power Amplifier ................................................................... 27 Calibrating the PA Bias ........................................................................ 27 Calibrating the PA Power .................................................................... 28 Troubleshooting Tips ..................................................................... 29 Calibrating the Forward and Reverse Detector Bias Voltages ............... 29 Index .................................
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 02.00 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.
■ TB8100 Service Kit User’s Manual. The Service Kit is a Windows-based software program that makes it easy to monitor and configure a Tait TB8100 base station. You can also use it to carry out diagnostic tests on the base station and to update its firmware. The Service Kit also has online Help. Technical notes are published from time to time to describe applications for Tait products, to provide technical details not included in manuals, and to offer solutions for any problems that arise.
About TB8100 Calibration Kit The TB8100 Calibration Kit is a Windows-based software program that allows you to adjust the switching ranges of the receiver and transmitter, and flatten the receiver response across the switching range. Accredited Tait service centers can use the TB8100 Calibration Kit to calibrate the reciter and the PA after servicing. Tour of 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. Calibrate Runs the Calibration Wizard for the currently selected task.
Basic Tasks Before you start tuning and calibrating the base station, make sure that: 1. You have all the necessary equipment for the particular procedure(s) that you want to perform, and 2. Your PC is connected to the base station or reciter. If you want to define the switching range for a base station (if this has not already been done), start here: “Adjusting the Frequency Setup” on page 15.
Tuning Tool The recommended tuning tool (for adjusting the front-end helical filters and the VCOs in the reciter) is included in the calibration test kit (see Equipment Required). It can also be ordered separately (order code 937-00012-00). 20 mm Bit shape: Blade diameter: 2.2 mm Blade thickness: 0.4 mm Reciter Tuning Holes The following topics show the location of the holes for tuning the front-end helical filters, and the VCO (Voltage Controlled Oscillator) in the reciter.
2. Tune each of the resonators in the first set once to give the best response. 3. Insert the tuning tool into the first hole of the second set. You can start with the top hole and proceed down to the bottom hole, or vice versa (again, never start with the centre hole). 4. Tune each of the resonators in the second set once to give the best response. 5. Repeat this procedure as necessary to refine the response.
Connecting to the Base Station Depending on the procedure you are performing, you may need to remove the reciter from the subrack and connect to it via the calibration test unit (CTU). The following tables summarise, for each procedure, whether or not you need to remove a module from the subrack, and what equipment (in addition to a PC and the TB8100 Calibration Kit software) you will need.
Connecting to the Reciter Outside the Subrack For the reciter calibration procedures that require access to the tuning holes, you will need to remove the reciter from the subrack and connect to it as follows.
Connecting to the Reciter/PA in the Subrack For the PA calibration procedures and the reciter calibration procedures that do not require access to the tuning holes, you can leave the modules in the subrack and connect your PC to the base station 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 the base station 1.
Basic 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 folder (..\Program Files\Tait Programming Applications\TB8100 Service Kit\LogFiles), and stores up to 1000 of the most recent logged items.
14 Basic Troubleshooting MB8100-90-00-806 © TEL 2004
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 (optional) 2. Tune the receiver 3.
Tuning the Receiver The second step in tuning the reciter frequency is to tune the receiver front end. Tuning the receiver flattens the receiver’s response across its lock band (switching range). To help you do this, there is a graph of the RSSI readings in step two of the Tune Receiver Front End Wizard. A number of RSSI readings are measured across the 10 MHz band. These readings are then continually averaged to produce the graph.
5. Once you have roughly tuned the front-end helical filters, click Fine (slow). Continue to fine tune the front-end helical filters until the response is flat in the middle of the lock band and not more than -1 dB at the ends of the band (± 5 MHz). Note: When using the Fine (slow) setting, you may notice a slight delay as the reading from tuning the front-end helical filters takes approximately one second to appear on the graph. 6. Click Finish.
18 Adjusting the Exciter Lock Band MB8100-90-00-806 © TEL 2004
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 ■ Calibrating the TCXO These procedures can be done independently of each other, although it is recommended that you tune the receiver before you calibrate the RSSI. Important: It is recommended that only accredited service centers and Tait engineers perform these procedures.
Calibrating the FCL Modulation This is step two of calibrating the exciter. Once you have auto-tuned the FCL, you should calibrate the FCL modulation. Equipment ■ Tuning tool ■ Calibration test unit (CTU) ■ Modulation meter ■ RF attenuator (only required if you are using a PA) Setup 3 1 2 4 1 Reciter 3 RF attenuator (only required if using a PA) 2 PA (optional) 4 Modulation meter To calibrate the FCL modulation 1. Ensure you are already connected to the reciter. 2.
Calibrating the VCO Modulation This is step three of calibrating the exciter. Once you have tuned and calibrated the FCL, you should calibrate the VCO at frequencies across the band. Equipment ■ Tuning tool ■ Calibration test unit (CTU) ■ Modulation meter ■ RF attenuator (only required if you are using a PA) Setup 3 1 2 4 1 Reciter 3 RF attenuator (only required if using a PA) 2 PA (optional) 4 Modulation meter To calibrate the VCO modulation 1.
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. Note: Ensure that the receiver’s lock band has already been adjusted to the required setting before carrying out this procedure. (See “Adjusting the Receiver Lock Band” on page 15.
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 you are already 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 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.
Equipment ■ Frequency counter ■ RF attenuator (only required if you are using a PA) Important: The accuracy of the calibrated TCXO frequency is only as good as the accuracy of the frequency counter. Setup 3 1 2 4 1 Reciter 3 RF Attenuator pad (optional) 2 PA (optional) 4 Frequency counter To calibrate the TCXO 1. Ensure you are already connected to the reciter. 2. Select the Reciter Calibration tab, and double-click Carrier Freq Offset Adjustment.
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 PA Power ■ Calibrating the Forward and Reverse Detector Bias Voltages Important: It is recommended that only accredited service centers and Tait engineers perform these procedures. Note: The PA is calibrated by the microprocessor via the Calibration Kit. You do not need to make any manual adjustments.
Calibrating the PA Power Important: Before you perform this procedure, you must calibrate the PA bias and the forward and reverse detector bias voltages. The PA power control loop is calibrated at a single frequency, generally in the center of the operating band. Factory calibration is performed at 460 MHz. You perform the calibration procedure to define – for each power level – the reference DAC (Digital-to-Analogue Converter) value and forward detector voltage.
Note: You must perform the calibration in sequence from the lowest to the highest step. The DAC setting must be greater than the previous one otherwise the value will not be stored in the PA, and you cannot move to the next line. 6. When you have completed adjusting the DAC settings, click Finish. When you have finished, the icon this task is complete.
30 Calibrating the Forward and Reverse Detector Bias Voltages MB8100-90-00-806 © TEL 2004
Index A D AC millivoltmeter see equipment Antenna VSWR (Voltage Standing Wave Ratio) 29 audio level calibrating 24, 25 DAC (Digital-to-Analogue Converter) adjusting settings 28 detector diodes 29 detectors forward and reverse 29 directional coupler 28, 29 driver transistor 27 B balanced input calibrating 24 balanced output calibrating 24 band 5 base station connecting to 12 disconnecting from 12 bias current required for each power level 27 RF detectors 29 C calibration test kit see equipment calibrati
G gate bias voltage 27 L lock band definition 15 see exciter see receiver log files application errors 13 commands received and sent 19 Low Pass Filter (LPF) 28, 29 M modulation meter see equipment module number 5 O operating range see switching range P PA calibrating bias current 27 calibrating RF detector bias voltages 29 calibrating transmit power 28 connecting to 12 details 5 faulty gain stage 29 low RF input power 29 PCB module 28, 29 peak deviation measuring 21 power supply see equipment R receiv
version of software 13 VSWR 29 VSWR (Voltage Standing Wave Ratio) 28, 29 TB8100 Calibration Kit User’s Manual W wizards see calibration wizards Index 33
34 Index MB8100-90-00-806 © TEL 2003
