Wideband Data Deviation Measurement Description

Last updated: September 16, 2009

How is a Wideband Data Deviation measurement made?

Wideband data is 10 kbps Manchester-encoded data that is used for cellular system signaling and control. The wideband data stream is used to modulate the 8 kHz transmitter carrier using direct binary frequency shift keying (FSK).

Wideband Data Deviation measurement measures the frequency deviation of an RF carrier that is modulated by a wideband data burst. When the wideband data measurement is initiated, the test set samples the input signal for the time period specified by the gate time. When the sample is complete, the measurement analyzes the sample' s frequency deviation and attempts to find the wideband data burst. If the wideband data burst is detected, the frequency deviation of the wideband data is measured and the positive and negative peaks are reported.

NOTE

The wideband data deviation measurement returns the peak deviation of the entire wideband data burst. A "settled" result that does not contain any peaks from the first 20 ms of the burst is also provided.

Operating Consideration

This measurement is available in Active Cell operating mode, AVC Test operating mode and CW operating mode.

When in Active Cell, the test set sends the Analog MS TX Level Order Message by changing the Analog MS TX Level setting to trigger the wideband data burst.

If no wideband data burst is detected, an integrity error is generated and other results are 9.91E+37.
If more than one wideband data burst is detected, only the first complete burst is analyzed.
If incomplete wideband data burst that occurs partly outside the gate time is detected, the burst is not analyzed at all.

Wideband Data Deviation Measurement Parameters

The Wideband Data Deviation measurement setup menu provides control over the following parameters.

Gate Time (See SETup:WDDeviation:GTIMe ) - Sets the length of time that the wideband data deviation measurement samples the signal under test.
Trigger Arm (See Trigger Arm (Single or Continuous) Description )
Measurement Timeout (see Timeouts )

Wideband Data Deviation Measurement Results

Maximum Positive Peak Carrier Frequency Deviation (See FETCh:WDDeviation:DEViation:MAXimum:PPEak? )
Maximum Negative Peak Carrier Frequency Deviation (See FETCh:WDDeviation:DEViation:MAXimum:NPEak? )
Settled Positive Peak Carrier Frequency Deviation (See FETCh:WDDeviation:DEViation:SETTled:PPEak? )
Settled Negative Peak Carrier Frequency Deviation (See FETCh:WDDeviation:DEViation:SETTled:NPEak? )
Integrity Indicator (See Integrity Indicator )

A typical measurement result is shown below

Input Signaling Requirements

The input signal is a RF carrier that is direct binary FSK modulated by a 10 kbps data burst. The input signal must be within +/- 2.5 kHz of the test set' s expected frequency, 8 kHz.
The ratio of the input signal' s deviation to residual FM must be greater than 30 dB. The test set can measure the frequency deviation of the carrier in the range from 25 Hz to 50 kHz.
To achieve accurate result, the burst must occur completely within the gate time.

Key TIA/EIA-690 Test Performed Using the Wideband Data Deviation measurement

See Testing 3.3.3 Wideband Data