Technical data

Programming Fundamentals 28
Agilent N8201A Performance Downconverter Synthetic Instrument Module, 250 kHz to 26.5 GHz 593
You may 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 Table 13 to see how these value relate.
The parameters for this GSM example are MEAN,9,197,1730.
• 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 (25μs/sample interval)
• 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
(526μs/sampleInterval).
• 1730 is how much data you have before you repeat the process. For this example it is 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
(576.9μs*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 13 GSM Parameters for 1 Slot/Frame Measurement Requirements
Resolution
Bandwidth
Filter Type Decimation Aperture Start Length Repeat
500 or 300 kHz Flat or
Gaussian
4 or 1 dependent on
settings
24 μsec 526 μsec 576.9 μsec
500 kHz Gaussian 1 0.2 μsec 124 2630 2884.6
500 kHz Gaussian 4 0.8 μsec 31 657 721.15
500 kHz Flat 1 0.4 μsec 61 1315 1442.3
500 kHz Flat 4 1.6 μsec 15 329 360.575
300 kHz Gaussian 1 0.2667 μsec 90 1972 2163.1
300 kHz Gaussian 4 1.07 μsec 22 492 539.16
300 kHz Flat 1 0.6667 μsec 36 789 865.31
300 kHz Flat 4 2.667 μsec 9 197 216.33