Multi-Tone Audio Measurement Description

Downlink Audio Mode

The downlink audio mode (selected from Multi-Tone Audio Setup menu) is intended to test the audio reproduction abilities of the mobile station (such as decoder, speaker, etc.). You should select a voice service option (SO1, SO3, SO17, SO68, SO70 or SO32768) (see Service Option ) and set the Voice SO Mode to Multi-Tone (see Voice SO Mode ) to perform the downlink multi-tone audio measurement. This causes downlink audio generator tones to be encoded and gets placed on the F-Traffic/F-FCH channel.

A Simplified Diagram for Speaker Test with Downlink Audio Mode shows an example of the speaker test. The tones generated from the Downlink Audio Generator of the test set are encoded into the digitized speech frame and sent to the mobile station over the RF link. The mobile station decodes the received speech frame into an analog signal and sends it to the speaker. The audio signal travels through an acoustic coupler (or a test interface connection) to the AUDIO IN port of the test set, where frequency response is computed by the multi-tone audio analyzer. Measurement results, such as audio level, frequency response, and distortion (if a single tone present) results are available. See Multi-Tone Audio Measurement Results .

A Simplified Diagram for Speaker Test with Downlink Audio Mode

Uplink Audio Mode

The uplink measurement mode (selected from Multi-Tone Audio Setup menu) is intended to test the audio capture and encoding functions of the mobile station (such as the microphone, encoders, etc.). You should select a voice service option (such as SO1, SO3, SO17, SO68, SO70 or SO32768) (see Service Option ) and set the voice SO mode to Null Frames (see Voice SO Mode ) to perform the uplink multi-tone audio measurements. Setting the voice SO mode to Null Frames ensures minimal energy signal sent on the downlink, which would reduce the leakage in the mobile station to interfere with the test.

A Simplified Diagram for Microphone Test with Uplink Measurement Mode shows an example of microphone test. The tones generated from the Uplink Audio Generator of the test set are sent to the AUDIO OUT port. An acoustic coupler (or a test interface connection) is used to connect the AUDIO OUT port to the mobile station's microphone. The mobile station encodes the audio signal into digitized speech frames and transmits it back to the test set via the RF link. The test set decodes the received speech frames and sends it to the multi-tone audio analyzer, where frequency response is computed. Measurement results, such as audio level, frequency response, and distortion (if a single tone present) results are available.

A Simplified Diagram for Microphone Test with Uplink Measurement Mode

SINAD/Distortion Measurements

When the SINAD/Distortion (on Audio Tone 1) State is set to On (see Multi-Tone Audio Setup ), the test set returns the SINAD, Distortion, Audio Level, and Audio Frequency results for the first audio tone. See Multi-Tone Audio Measurement Results .

In this mode, it is also possible for you to measure a distortion level when no tone is being generated. This allows you to detect spurs from the mobile station.

Multi-Tone Audio Setup

• Multi-Measurement Count ( SETup:CMAudio:COUNt[:SNUMber] ) - See Statistical Measurement Results .
• Measurement Mode ( SETup:CMAudio:MEASurement:MODE ) - Controls whether audio measurements are made on the downlink or uplink. See Downlink Audio Mode and Uplink Audio Mode .
• Analyzer 0dB Reference Mode ( SETup:CMAudio:REFerence:MODE )- Controls the reference mode to be used when making audio level measurements. If Relative is selected, the Analyzer Reference Tone is used to specify a tone as the reference. If Absolute is selected, the Analyzer Downlink Reference Level or the Analyzer Uplink Reference Level is used to specify a reference level.
• Analyzer Reference Tone ( SETup:CMAudio:REFerence:RELative:TONE ) - Specifies which tone (1 to 20) is to be used as the reference when making relative measurements. The Analyzer 0dB Reference Mode must be set to Relative for this parameter to be active.
• Analyzer Downlink Reference Level ( SETup:CMAudio:REFerence:ABSolute:LEVel:DOWNlink ) - Specifies the reference level used when making absolute measurements on the downlink. The Analyzer 0dB Reference Mode must be set to Absolute and the Measurement Mode must be set to Downlink Audio for this parameter to be active.
• Analyzer Uplink Reference Level ( SETup:CMAudio:REFerence:ABSolute:LEVel:UPLink ) - Specifies the reference level (in percentage of the full DAC range) to be used when making absolute measurements on the uplink. The Analyzer 0dB Reference Mode must be set to Absolute and the Measurement Mode must be set to Uplink Audio for this parameter to be active.
• Expected Audio In Peak Voltage ( SETup:CMAudio:PEAK:VOLTage ) - Specifies the absolute peak voltage of the audio signal expected at the AUDIO IN port of the test set. The Measurement Mode must be set to Downlink Audio for this parameter to be active. It must be in the range of 1 mV _peak to 20 V _peak . Note that measuring a 1 V _rms sinewave input signal would require a 1.414 V _peak expected voltage value to avoid clipping (over-driving) the input.
• Device Settling Time ( SETup:CMAudio:SETTling[:TIME] ) - Specifies how long the multi-tone audio measurement will wait to start the measurement after each measurement request. This setting applies to both the uplink and downlink measurement mode. A setting of 0.0 seconds will let the multi-tone audio measurement run at maximum speed. Note that this setting provides a variable delay for the settling of audio transients, but will decrease the measurement speed since this delay is applied to each measurement including those measurements in which a generator transient is not expected to be present.
  
  It is recommended that you set the Device Settling Time to approximately 600ms to allow for the settling of audio transients when operating in the uplink measurement mode. For the downlink measurement mode, set the Device Settling Time to zero and use the setting of the Downlink Encoder Settling.
  
• SINAD/Distortion (on Audio Tone 1) State ( SETup:CMAudio:SDIStortion:STATe ) - Selects On or Off to enable or disable the SINAD and Distortion measurements. When it is enabled (On), the Distortion, SINAD, Audio Level, and Frequency results for the first audio tone are available and displayed on the measurement result screen replacing the default bar graph results of frequency response. See Multi-Tone Audio Measurement Results .
     

  NOTE

  The SINAD and Distortion measurements are made on the first audio tone. It is recommended that you set the downlink or uplink audio generator to produce single tone (see Multi-Tone Audio Generator Parms ) when making the SINAD and Distortion measurements. If multi-tone is selected, all other tones will be measured as noise resulting in bad SINAD and Distortion results.

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• Downlink Encoder Settling ( SETup:CMAudio:ANALyzer:DOWNlink:SETTling ) - Specifies the time (in frames) that the downlink multi-tone audio measurement should be held off to ensure that transients have settled in the vocoders in the test set's transmitter and the mobile station's receiver. The hold-off period begins with any change to the downlink generator parameters. This settling time is only applied in downlink measurement mode when a call is connected and the Voice SO Mode is set to Multi-Tone.
  
  It is recommended that you use the Downlink Encoder Settling setting for the downlink mode measurement and set the Device Settling Time to zero.
  
• Trigger Arm ( SETup:CMAudio:CONTinuous ) - See Trigger Arm (Single or Continuous) Description .
• Measurement Timeout ( SETup:CMAudio:COUNt[:SNUMber] ) - See Timeouts .

• Expected Uplink Signal Bandwidth - Specifies the signal bandwidth (fixed or in percentage of the Audio Tone 1 uplink frequency) to be used when making SINAD/Distortion measurement on the uplink.

  • Fixed - 100Hz
  • Narrow - 20% of the Audio Tone 1 uplink frequency
  • Medium - 40% of the Audio Tone 1 uplink frequency
  • Wide - 60% of the Audio Tone 1 uplink frequency

Multi-Tone Audio Generator Parms

The Downlink Frequencies ( F1 ) is used to configure the tones' frequencies/states generated by Downlink Audio Generator :

• Preset Frequencies To - Allows you to configure all of the 20 available tones' frequencies/states based on the selected preset. See SETup:CMAudio:GENerator:FREQuency:DOWNlink:PRESet for details on the preset configurations.

The Downlink Levels ( F3 ) is used to configure the tones' power levels generated by Downlink Audio Generator :

• Multi-Tone Audio Total Level - Sets the total audio output level (in percentage of the full DAC range) to be distributed evenly among the tones whose states are on. The range of this setting is from 10% to 50% in 20% increment. See also SETup:CMAudio:GENerator:LEVel:DOWNlink:ALL:TOTal[:SAMPlitude] .

The Uplink Frequencies ( F2 ) is used to configure the tones' frequencies/states generated by Uplink Audio Generator :

• Preset Frequencies To - Allows you to configure all of the 20 available tones' frequencies/states based on the selected preset. See also SETup:CMAudio:GENerator:FREQuency:Uplink:PRESet .
• Audio Tone <n> Frequency - Allows you to specify the frequencies for each of the 20 available tones individually as required for your test situation. Making any change to these settings will automatically set the Preset Frequencies To to None . See also SETup:CMAudio:GENerator:FREQuency:Uplink:ALL[:SVALue] .

The Uplink Levels ( F4 ) is used to configure the tones' power levels generated by Uplink Audio Generator :

• Multi-Tone Audio Total Level - Sets the total average audio output level (in RMS) to be distributed evenly among the tones whose states are on. See also SETup:CMAudio:GENerator:LEVel:UPLink:ALL:TOTal[:SAMPlitude] . When this parameter is set to Off, you can turn on each audio tone individually and specify the level associated with it by Audio Tone <n> Level settings.
• Audio Tone <n> Level - Allows you to specify the levels for all of the 20 available tones individually as required for your test situation. The Multi-Tone Audio Total Level must be set to Off for these parameters to be active. See also SETup:CMAudio:GENerator:LEVel:UPLink:ALL[:SAMPlitude] .

Multi-Tone Audio Measurement Results

Depending upon the setting of the SINAD/Distortion (on Audio Tone 1) State (see Multi-Tone Audio Setup ), different results are available for the multi-tone audio measurements.

• For multi-tone audio measurement results when the SINAD/Distortion (on Audio Tone 1) State is set to Off (default value), see Bar Graph Measurement Results .
• For multi-tone audio measurement results when the SINAD/Distortion (on Audio Tone 1) State is set to On , see SINAD/Distortion Measurement Results

Bar Graph Measurement Results

When the SINAD/Distortion (on Audio Tone 1) State is Off (default value), a bar graph (see Bar Graph for Multi-Tone Audio Measurement Results ) will be displayed to provide the following results.

• Integrity Indicator ( FETCh:CMAudio:INTegrity? ) - See Integrity Indicator .
• Multi-Tone Audio Levels - The measurement reports the average level for all of the 20 available tones that are turned on. The results are displayed in a bar graph on the measurement screen (see Bar Graph for Multi-Tone Audio Measurement Results ) The measured level for each of the 20 tones can be queried with FETCh:CMAudio:LEVel? .
• Multi-Tone Audio Pass/Fail Result - Indicates a pass or fail for all of the 20 available tones that are turned on. If any tone is outside of its specified level limits (see Multi-Tone Audio Level Limits ), a Fail result occurs resulting in the corresponding bar for the failed tone displayed in red. If the audio tone is within the valid mask, then the bar will displayed in yellow. You can query the overall pass/fail result with FETCh:CMAudio:LEVel:LIMit:FAIL? .

Bar Graph for Multi-Tone Audio Measurement Results

You can control the graph view by the softkeys accessed from Graph Control ( F6 ):

• The y-axis on the graphical display is scaled as 10 divisions (4dB/div) and defaults to be ranged from -30 dB to 10 dB. You can view the levels of particular interest such as above +10 dB or below -30 dB by adjusting the scale with the Graph Reference ( F2 ) and Span ( F3 ) softkeys.
• The x-axis on the graphical display is labeled with the bar numbers 1 to 20 corresponding to the audio tones 1 to 20.
• The power level measured for each tone that is on is displayed as a bar. The color of the bar may be yellow, red, or blue.
  • Pass/fail limit lines for each tone are superimposed on the graph in green line. These lines are set from the Multi-Tone Audio Level Limits menu (see Multi-Tone Audio Level Limits ). If the measured level for any given tone is outside its limit lines, the corresponding bar is in red. If the measured level for any given tone is within its limit line, the corresponding bar is in yellow.
  • When the Analyzer 0dB Reference Mode is set to Relative (see Multi-Tone Audio Setup ), the tone whose state is on if specified as a reference tone by Analyzer Reference Tone will be displayed as blue bar.
• The marker can be positioned on any of the 20 tone bars by the Marker Position ( F1 ). The frequency/level settings for that tone, as well as the measured level are then displayed at the top of the graph.

SINAD/Distortion Measurement Results

   

NOTE

The SINAD and Distortion measurements are made on the first audio tone. It is recommended that you set the downlink or uplink audio generator to produce single tone (see Multi-Tone Audio Generator Parms ) when making the SINAD and Distortion measurements. If multi-tone is selected, all other tones will be measured as noise resulting in bad SINAD and Distortion results.

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When the SINAD/Distortion (on Audio Tone 1) State is set to On , the Distortion, SINAD, Audio Level, and Frequency results for the first audio tone will be displayed (see SINAD/Distortion Results for Audio Tone 1 )

• Distortion - The measured distortion of audio tone one. The SINAD/Distortion state must be turned on for this measurement result to be available (see SINAD/Distortion Results for Audio Tone 1 ). You can also get the results by sending FETCh:CMAudio:DISTortion[:AVERage]? .
• SINAD - The measured SINAD for audio tone one. The SINAD/Distortion state must be turned on for this measurement result to be available (see SINAD/Distortion Results for Audio Tone 1 ). You can also get the results by sending FETCh:CMAudio<:SINad|:SNDRatio>[:AVERage]? .
• Audio Level - The measured audio level for audio tone one. The SINAD/Distortion state must be turned on for this measurement result to be available (see SINAD/Distortion Results for Audio Tone 1 ). You can also get the results by sending FETCh:CMAudio:VOLTage[:AVERage]? .
• Frequency - The measured frequency for audio tone one. The SINAD/Distortion state must be turned on for this measurement result to be available (see SINAD/Distortion Results for Audio Tone 1 ). You can also get the results by sending FETCh:CMAudio:FREQuency[:AVERage]? .

SINAD/Distortion Results for Audio Tone 1

Related Topics

Measuring a Multi-tone Digital Audio

Programming a Multi-Tone Audio Measurement

Multi-Tone Audio Troubleshooting