Rohde & Schwarz 1145.1010.04/05/06, Operating Manual

Page: 294 / 813

Channel Menu R&S
®
ZVA/ZVB/ZVT
1145.1084.12 4.132 E-6
The characteristics of the high selectivity filter makes it particularly suitable for isolating unexpected
spurious responses or known mixer products.
Remote control:
[SENSe<Ch>:]BANDwidth|BWIDth[:RESolution]
[SENSe<Ch>:]BANDwidth|BWIDth[:RESolution]:SELect
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.
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 bursts measured.
•
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:CLEar