Agilent Technologies E4406A VSA manual MEAN,25us,526us,579.6us,8, Requirements

Programming Fundamentals

Improving the Speed of Your Measurements

There are two versions of this command depending on your firmware revision. Earlier revisions require the optional variables be entered in terms of their position in the trace data array. Versions after A.05.00 allow the variables to be entered in terms of time.

For early firmware revisions you need to know the sample interval. In the waveform measurement it is equal to the aperture value. Query :WAVeform:APERture? to find the sample interval. (Note: the WAV:APER? command always takes decimation into account.) The sample interval (aperture value) is dependent on the settings for resolution bandwidth, filter type, and decimation. See the following table to see how these value relate.

The parameters for this GSM example are:

MEAN,9,197,1730 (or with later firmware:

MEAN,25us,526us,579.6us,8)

•MEAN calculates the mean of the measurement points indicated

•9 is how many points you want to discard before you look at the data. This allows you to skip over any “unsettled” values at the beginning

of the burst. You can calculate this start offset by (25∝s/sampleInterval)l

•197 is the length of the data you want to use. This would be the

portion of the burst that you want to find the mean power over. You can calculate this length by (526∝s/sampleInterval)

•1730 is how much data you have before you repeat the process. For this example it’s the time between the start offset point on the burst in the first slot (first frame) to the same spot on the burst in the first

slot (second frame). You can calculate this by

(576.9∝s*N/sampleInterval) where N is the number of data items that you want. In this case it is the number of slots in the frame, N=8.)

Table 2-1 GSM Parameters for 1 Slot/Frame Measurement

Requirements

Resolution	Filter	Decimation	Aperture	Start	Length	Repeat
Bandwidth	Type
500 or 300	Flat or	4 or 1	dependent	24 ∝seca	526 ∝seca	576.9 ∝seca
kHz	Gaussian		on settings
500 kHz	Gaussian	1	0.2 ∝sec	124	2630	2884.6
500 kHz	Gaussian	4	0.8 ∝sec	31	657	721.15
500 kHz	Flat	1	0.4 ∝sec	61	1315	1442.3
500 kHz	Flat	4	1.6 ∝sec	15	329	360.575
300 kHz	Gaussian	1	0.2667 ∝sec	90	1972	2163.1
300 kHz	Gaussian	4	1.07 ∝sec	22	492	539.16

Chapter 2 73