Spectrogram Display

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The Spectrogram view can be used with the Interference ID or the Occupied BW measurements and standard spectrum. Troubleshooting a transmitter system is often aided by examining the time evolution of the power distribution.
This view provides a history of the spectrum. You can use it to:

• locate intermittent signals.
• track signal levels over time.

You may set the following parameters for this view:

• The Update Interval is the interval, measured in whole seconds, between successive records displayed on the spectrogram. In other words, if you set the update interval to 5 seconds, the spectrogram display will not update until the after the first complete measurement following a gap of five seconds. Alternatively, you can set the update interval to provide the maximum data collection speed by pressing [Max Speed], or by setting the update interval to 0 (zero) seconds.

NOTE It is not always possible for the analyzer to match the update interval you specify. It is possible, for example, to set your update interval to zero seconds (the maximum speed), and then to find that the analyzer can not update any faster than once every two seconds.

• A data sample is taken every n seconds for display on the spectrogram. Increasing the update time allows data capturing over a longer period of time in the spectrogram. However, it is a sampling technique that allows intermittent events, which may occur between samplings, to be lost. Therefore, if you are searching for intermittent signals, consider using Group Max average type in conjunction with increasing the capture time (see "Setting Average, Sweep, and Restart")

Approximate Times Taken to Display the Spectrogram

Update Interval	Time for a Full Screen Display
Max. Speed	34 seconds
1 second	3 minutes
2 seconds	6 minutes
4 seconds	12 minutes
30 seconds	90 minutes (1.5 hours)
60 seconds (1 minute)	180 minutes (3.0 hours)
300 seconds (5 minutes)	900 minutes (15.0 hours)
600 seconds (10 minutes)	1800 minutes (30.0 hours)

• The frequency indicator is at the bottom right corner of the screen, the time reference indicator at the bottom left. For each indicator the text indicates which reference you have chosen. A green LED indicates a locked condition. A red "X" indicates an unlocked condition.

Frame Skip: Allows you to set the number of frames you would like to skip when capturing data. You may set this value from skip 0 to 2147,483,647 frames. Increasing the frame skip value causes the display to redraw the spectrum every n^th trace and a block of lines is shown at once instead of a single line at a time. Higher frame skip values are for use with fast measurements.
Palette: Allows you to set the display to full color or grayscale.