R&S ZVB - Page 264

R&S
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ZVA / R&S
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ZVB / R&S
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ZVT GUI Reference
Channel Menu
Operating Manual 1145.1084.12 – 30 249
In general, the system error correction is no longer valid after a change of the IF filter bandwidth. The
message Cal? appears in the trace list.
Remote control:
[SENSe<Ch>:]BANDwidth|BWIDth[:RESolution]
[SENSe<Ch>:]BANDwidth|BWIDth[:RESolution]:SELect
[SENSe<Ch>:]BANDwidth|BWIDth[:RESolution]:DREDuction
Average Factor
Opens the numeric entry bar to define the number of consecutive sweeps to be averaged.
An average over several sweeps reduces the influence of random effects in the measurement and
therefore minimizes the noise level. The effect increases with the average factor, however, obtaining an
averaged result requires several sweeps and therefore increases the measurement time.
In contrast to the sweep count (for single sweep mode), averaging is always channel-specific. Both
features are completely independent from each other.
The average factor is also valid for calibration sweeps: The calculation of system correction data is based
on the averaged trace.
Smoothing is an alternative method of compensating for random effects on the trace by averaging
adjacent measurement points. Compared to the sweep average, smoothing does not significantly increase
the measurement time but can eliminate narrow peaks and thus produce misleading results.
The sweep average is not frequency selective. To eliminate a spurious signal in the vicinity of the
measurement frequency, alternative techniques (e.g. a smaller filter bandwidth) must be used.
Calculation of sweep average
The average trace is obtained as follows:
Let c be the Average Factor and assume that n sweeps have been measured since the start of the
average cycle (start of the measurement or Restart Average). The following two situations are
distinguished:
 n < c: At each sweep point, the average trace no. n is calculated from the average trace no. n 1
and the current trace no. n according to the following recurrence:
The average trace represents the arithmetic mean value over all n sweeps.
 n > c: At each sweep point, the average trace no. n is calculated from the average trace no. n 1
and the current trace no. n according to:
The formulas hold for Average Factor n = 1 where the average trace becomes equal to the current trace.
Remote control:
[SENSe<Ch>:]AVERage[:STATe] ON | OFF
[SENSe<Ch>:]AVERage:COUNt
[SENSe<Ch>:]AVERage:COUNt:CURRent? (query current sweep)