Rohde & Schwarz 1145.1010.04/05/06, Operating Manual

Page: 227 / 813

R&S
®
ZVA/ZVB/ZVT Trace Menu
1145.1084.12 4.65 E-6
Windows in the Frequency Domain
The finite sweep range in a frequency domain measurement with the discontinuous transitions at the
start and stop frequency broadens the impulses and causes sidelobes (ringing) in the time domain
response. The windows offered in the
Define Transform dialog can reduce this effect and optimize the
time domain response. The windows have the following characteristics:
Window Sidelobe
suppression
Relative impulse width Best for...
No Profiling (Rectangle) 13 dB 1 –
Low First Sidelobe
(Hamming)
43 dB 1.4 Response resolution: separation of
closely spaced responses with
comparable amplitude
Normal Profile (Hann) 32 dB 1.6 Good compromise between pulse
width and sidelobe suppression
Steep Falloff (Bohman) 46 dB 1.9 Dynamic range: separation of
distant responses with different
amplitude
Arbitrary Sidelobes
(Dolph-Chebychev)
User defined between
10 dB and 120 dB
1.2 (at 32 dB sidelobe
suppression)
Adjustment to individual needs;
tradeoff between sidelobe
suppression and impulse width
Remote control: CALCulate<Ch/Tr>:TRANsform:TIME:WINDow
CALCulate<Ch/Tr>:TRANsform:TIME:DCHebyshev
Low Pass Settings
The Low Pass Settings dialog defines the harmonic grid for low pass time domain transforms.
Harmonic grid
A harmonic grid is formed by a set of equidistant frequency points f
i
(i = 1...n) with spacing f and the
additional condition that f
1
= f. In other words, all frequencies f
i
are set to harmonics of the start
frequency f
1
.
If a harmonic grid, including the DC value (f = 0) is mirrored to the negative frequency range, the result
is again an equidistant grid.
The point symmetry with respect to the DC value makes harmonic grids suitable for lowpass time
domain transformations.