Calibrating the Test Set

Calibrating the Test Set

Last updated: January 16, 2009

Description

Various calibration routines must be run periodically to ensure measurement accuracy, source accuracy and allow the most robust demodulation of the device-under-test's signal. This document describes the various calibrations available in the test set and when they should be performed.

Calibration Process Requirements

   
IMPORTANT
Before performing any calibrations on your test set:

  • Ensure that the calibration is necessary - running calibrations more often than necessary wastes your time and effort, and if the calibration is performed incorrectly, could actually result in degraded test set performance.
  • Ensure that the test set is in its ambient operating environment - in other words, ensure that the test set has warmed up (at least 30 minutes) and is in a location similar to the one it will be used in. For example, if you are going to be using the test set in a racked test system, then you must calibrate the test set while it is in that test system, and all of the equipment has reached a stable operating temperature.
  • Ensure that no power is present at the front panel RF connectors - remove any cables or connectors from the RF IN/OUT and RF OUT ONLY connectors. If you are operating in a high RF environment, it is recommended that you also terminate the RF connectors with a 50 Ohm load.
       

    

Recommended Calibration Intervals

This section indicates when the test set calibrations should be performed. Procedures are given for test sets that include Option 003: Flexible Radio Link and test sets that do not. Refer to Calibration Descriptions for details about the calibrations and how to perform them.

   
IMPORTANT
Ensure that your test set has warmed up at least 30 minutes and that no power is present at the front panel RF connectors before performing any calibrations.
   

Calibration Procedure for Test Sets with Option 003

Calibration Procedure for Test Sets without Option 003    

Calibration Descriptions

If any of the following calibrations fail, ensure that you have followed the Calibration Process Requirements and have performed the calibrations in the order prescribed by Recommended Calibration Intervals . If the calibration still fails, contact your local Keysight Sales Representative for assistance.

IQ Calibrations

When performed from a GSM/GPRS/EGPRS or AMPS/136 application or format, the First IQ Modulator calibration sends a signal from the Baseband Generator 1 module to the RF Source 1 module to optimize the phase accuracy of RF Source 1 as a function of frequency. The optimization data is then stored in the test set and accessed whenever the RF Source frequency is set. The Second IQ Modulator calibration performs a similar procedure for RF Source 2 (RF Source 2 is only present if the test set includes option 002: RF Source 2).

When performed from a W-CDMA/HSPA, cdma2000/IS-95/AMPS or 1xEV-DO application or format (which require option 003: Flexible Radio Link), the IQ calibrations perform the same phase optimizations explained above. Additionally, a signal is sent from the Flexible Radio Link Subsystem to the RF sources to calibrate phase accuracy for those alternative paths as well. This additional calibration data is written to the same calibration data file as above, but in a different area of the calibration table.

The IQ calibrations ensure that the test set accurately generates IQ-modulated signals. If the test set's IQ modulators have not been properly calibrated, the test set's output power (when producing an IQ-modulated signal) will be inaccurate, which may result in degraded receiver test results.

If you perform the IQ calibrations from a W-CDMA/HSPA, cdma2000/IS-95/AMPS or 1xEV-DO application or format, you do not need to perform them from any other application or format. However, note that if you perform the IQ calibrations from a GSM/GPRS/EGPRS or AMPS/136 application/format, you must still perform them once from a W-CDMA/HSPA, cdma2000/IS-95/AMPS or 1xEV-DO application or format.

The IQ calibrations do not need to be run frequently. See Recommended Calibration Intervals .

To initiate the IQ calibrations from the front panel, press SYSTEM CONFIG , press the right More ( 1 of 2 ) key, select Service ( F7 ), then select Cal. first IQ Modulator or Cal. second IQ Modulator . To initiate the IQ calibrations from a remote program, use the CALibration:IQ[1]|2? queries.

Each IQ calibration takes 5-6 minutes to execute.

Burst Mod Offset 1 Calibration

This calibration is only applicable to W-CDMA/HSPA, cdma2000/IS-95/AMPS, and 1xEV-DO applications and formats. This calibration is only required when using the test set to generate an AM or DSB-SC test signal (select ( F9 ) Test Signal when in CW Operating Mode ). These test signals are used for calibrating Zero Intermediate Frequency (Zero IF) devices which utilize Qualcomm's radioOne™ architecture.

You do not have to perform the Burst Mod Offset 1 calibration for each application/format in your test set; performing it from one application/format provides calibration data to all relevant applications and formats.

The Burst Mod Offset 1 calibration does not need to be run frequently. See Recommended Calibration Intervals .

The Burst Mod Offset 1 calibration calibrates the noise and signal level of RF Source 1 (as a function of frequency) to most accurately produce the AM and DSB-SC test signals required for Zero IF device calibration. The calibration is performed by generating the modulated test signals and adjusting RF Source 1 to optimize gain and minimize the noise floor. The optimization data is then stored in the test set and accessed whenever the RF Source frequency is set.

To initiate the Burst Mod Offset 1 calibration from the front panel, press SYSTEM CONFIG , press the right More ( 1 of 2 ) key, select Service ( F7 ), then select Cal. Burst Mod Offset 1 . To initiate the Burst Mod Offset 1 calibration from a remote program, use the CALibration:BMOFfset? query.

The Burst Mod Offset 1 calibration takes less than 1 minute to execute.

Thermal Power Null Adjustment

The Thermal Power Null Adjustment is only applicable to the cdma2000/IS-95/AMPS, 1xEV-DO and W-CDMA/HSPA applications/formats.

The Thermal Power Detector is calibrated at the factory and temperature controlled for stability. However, it is still possible for the auto-null circuit within the detector to drift over time. The Thermal Power Null Adjustment re-centers the auto-null circuit to provide optimum accuracy for the affected measurements.

You only need to perform the Thermal Power Null Adjustment once to re-center the auto-null circuit (you do not have to perform it from each application/format in your test set).

   
NOTE
Older application releases loaded on your test set may not include the Thermal Power Null Adjustment feature. Any applications that do not include the Thermal Power Null Adjustment feature (in the Utilities menu of the System Config screen) do not use the re-centering data and thus do not achieve the accuracy optimization that results from re-centering the auto-null circuit. You must upgrade those applications if you wish to achieve the accuracy optimization that results from running the Thermal Power Null Adjustment .
   

The Thermal Power Null Adjustment does not need to be run frequently. See Recommended Calibration Intervals .

This adjustment affects the Thermal Power (W-CDMA/HSPA) measurement, as well as all measurements that are calibrated by the Digital Average Power Calibration (cdma2000/IS-95/AMPS, 1xEV-DO) and Calibrate Measurements (W-CDMA/HSPA) routine.

To initiate the Thermal Power Null Adjustment from the front panel, press SYSTEM CONFIG , press the right More ( 1 of 2 ) key, and select Thermal Power Null Adjust ( F9 ). To initiate the Thermal Power Null Adjustment from a remote program, use the SYSTem:INSTrument:THERmal:POWer:NULL:ADJust? query.

The Thermal Power Null Adjustment takes between 30 seconds and 3 minutes.

The Thermal Power Null Adjustment can also be used to help verify your test set. See "Verifying the Test Set" in the Related Topics below.

Digital Average Power Calibration

The Digital Average Power calibration is only applicable to the cdma2000/IS-95/AMPS and 1xEV-DO applications/formats.

You do not have to perform the Digital Average Power calibration for each application/format in your test set; performing it from one application/format provides calibration data to all relevant applications and formats.

The Digital Average Power calibration does not need to be run frequently. See Recommended Calibration Intervals .

   
IMPORTANT
You must cycle the test set's power after the Digital Average Power calibration is complete in order to complete the calibration (the calibration data is not available to the test set until it has been restarted).
   

The Digital Average Power calibration generates calibration data for the Fast Power Detector for use by cdma2000/IS-95/AMPS and 1xEV-DO applications and formats. This calibration improves the accuracy of the Fast Power Detector when used to measure IS-95 and reverse RC-1 and RC-2 signals.

The calibration generates a CW signal at a given power level, measures it using the Fast Power Detector, generates a CDMA-modulated signal at the same power level, measures it using the Fast Power Detector and notes the difference. The calibration then generates a CW signal at a given power level, measures it using the Thermal Power Detector, generates a CDMA-modulated signal at the same power level, measures it using the Thermal Power Detector and notes the difference. Calibration data is then created by comparing these results. This is repeated for several power levels.

The Digital Average Power calibration provides calibration data for the following measurements:

  • Digital Average Power
  • Maximum/Minimum Power

To initiate the Digital Average Power calibration from the front panel, press Measurement selection , select Digital Average Power , then select Calibrate Digital Avg Pwr (F4) . To initiate the Digital Average Power calibration from a remote program, use the CALibration:DAPower? query.

The Digital Average Power calibration takes approximately 9 minutes to execute.

Spectrum Monitor Calibration

Performing the Spectrum Monitor calibration from one application/format does not provide calibration data to all relevant applications and formats. The calibration data files are shared as follows:

  • cdma2000/IS-95/AMPS and 1xEV-DO share the same Spectrum Monitor calibration data file.
  • W-CDMA/HSPA has its own Spectrum Monitor calibration data file.
  • GSM/GPRS/EGPRS and AMPS/136 share the same Spectrum Monitor calibration data file.

Thus, if you perform the Spectrum Monitor calibration from a 1xEV-DO application/format, you do not need to perform it from a cdma2000/IS-95/AMPS application/format. However you do still need to perform it from a W-CDMA/HSPA application/format and then again from either a GSM/GPRS/EGPRS or AMPS/136 application/format.

The Spectrum Monitor calibration should be run monthly, or whenever the test set's operating environment changes. See Recommended Calibration Intervals .

Performing the Spectrum Monitor calibration from a cdma2000/IS-95/AMPS or 1xEV-DO application/format executes the same routine as performing the Channel Power Calibration .

Performing the Spectrum Monitor calibration from a W-CDMA/HSPA application/format executes the same routine as performing the Calibrate Measurements routine.

Performing the Spectrum Monitor calibration from a GSM/GPRS/EGPRS or AMPS/136 application/format calibrates the IF signal path in the Measurement Downconverter, using a CW signal.

To initiate the Spectrum Monitor calibration from the front panel, press Instrument selection , select Spectrum Monitor , select Trigger Setup ( F4 ), then select Calibrate Measurement ( F11 ). To initiate the Spectrum Monitor calibration from a remote program, use the CALibration:SMONitor? query.

The Spectrum Monitor calibration takes between 45 seconds and 3 minutes to execute, depending upon which application/format it is executed from.

Channel Power Calibration

The Channel Power calibration is applicable to the cdma2000/IS-95/AMPS and 1xEV-DO applications/formats.

You do not have to perform the Channel Power calibration for each application/format in your test set; performing it from one application/format provides calibration data to all relevant applications and formats.

The Channel Power calibration should be run monthly, or whenever the test set's operating environment changes. See Recommended Calibration Intervals .

The Channel Power calibration calibrates the signal paths through the Measurement Downconverter and Demod Downconverter using both a CW signal and a modulated signal. The calibration is performed by comparing measured signals through the MDC and DDC to measurements made using the Fast Power Detector (which is calibrated at the factory and temperature controlled for stability). During the Calibrate Measurements calibration, the internal temperature of the test set is measured and stored with the calibration data. If the internal temperature of the test set drifts by more than +/- 10 C since the last calibration, measurements utilizing this calibration will return integrity indicator 19 ( Uncalibrated Due to Temperature ).

The Channel Power calibration provides calibration data for the following measurements:

  • Access Probe Power
  • Channel Power
  • Code Channel Time/Phase Error
  • Fast Device Tune ( lab application or feature-licensed test application only )
  • Gated Power
  • Graphical Access Probe Power ( lab application only )
  • Handoff Waveform Quality
  • Maximum/Minimum Power
  • Time Response of Open Loop Power Control
  • TX Dynamic Power
  • TX Spurious Emissions
  • Waveform Quality + Code Domain
  • Spectrum Monitor

Performing the Channel Power calibration executes the same routine as performing the Spectrum Monitor Calibration from a cdma2000/IS-95/AMPS or 1xEV-DO application/format.

To initiate the Channel Power calibration from the front panel, initiate any of the measurements listed above and select Calibrate Channel Power (F4) . To initiate the Channel Power calibration from a remote program, use the CALibration:CPOWer? query.

The Channel Power calibration takes approximately 2 minutes to execute.

Calibrate Measurements

The Calibrate Measurements routine is only applicable to W-CDMA/HSPA applications/formats.

The Calibrate Measurements routine should be run monthly, or whenever the test set's operating environment changes. See Recommended Calibration Intervals .

The Calibrate Measurements routine calibrates the signal paths through the Measurement Downconverter and Demod Downconverter using both a CW signal and a modulated signal. The calibration is performed by comparing measured signals through the MDC and DDC to measurements made using the Fast Power Detector (for CW signals) and the Thermal Power Detector (for modulated signals). Both of these detectors are calibrated at the factory and temperature controlled for stability. During the Calibrate Measurements calibration, the internal temperature of the test set is measured and stored with the calibration data. If the internal temperature of the test set drifts by more than +/- 10 C since the last calibration, measurements utilizing this calibration will return integrity indicator 19 ( Uncalibrated Due to Temperature ).

The Calibrate Measurements routine provides calibration data for the following measurements:

  • Adjacent Channel Leakage Ratio
  • Channel Power
  • Change of TFC ( lab application only )
  • Code Domain
  • Dynamic Power Analysis
  • Extended Range Dynamic Power
  • Fast Device Tune ( lab application or feature-licensed test application only )
  • Inner Loop Power
  • IQ Tuning
  • Occupied Bandwidth
  • Phase Discontinuity
  • PRACH Preamble Analysis ( lab application only )
  • PRACH Transmit On/Off Power
  • Spectrum Emission Mask
  • Spectrum Monitor
  • TX Dynamic Power
  • Waveform Quality

Performing the Calibrate Measurements routine executes the same routine as performing the Spectrum Monitor Calibration from a W-CDMA/HSPA application/format.

To initiate the Calibrate Measurements routine from the front panel, initiate any of the measurements listed above and select Calibrate Measurements (F4) . To initiate the Calibrate Measurements routine from a remote program, use the CALibration:MEASurements? query.

The Calibrate Measurements routine takes approximately 3 minutes to execute.