R&S PR100 User Manual
High receiver sensitivity, high signal resolution
The R&S® PR100 features an IF bandwidth of up to 10 MHz. This allows even very
short signal pulses to be captured since the receiver displays the large bandwidth of
10 MHz in a single spectrum about the set center frequency without any scanning
being required. The widest IF bandwidth of 10 MHz yields the widest spectral display;
the narrowest IF bandwidth of 10 kHz yields maximum sensitivity. The IF spectrum is
digitally calculated by means of a Fast Fourier Transform (FFT). The use of FFT
computation at the IF offers a major advantage: The receiver sensitivity and signal
resolution are clearly superior to those of a conventional analog receiver at the same
spectral display width.
IF spectrum
FFT calculation of the IF spectrum is performed in a number of steps. These are
described below in simplified form for an IF bandwidth of 10 kHz (BWIF spectrum =
10 kHz), which yields maximum sensitivity. Due to the finite edge steepness of the IF
filter, the sampling rate fs must be larger than the selected IF bandwidth BWIF
spectrum. The quotient of the sampling rate and the IF bandwidth is thus a value >1
and is a measure of the edge steepness of the IF filter. This relationship is expressed
by the following two formulas:
const
B
f
IFspectrum
s
=
or
constBWf
IFspectrums
*=
The value of the constant is dependent on the selected IF bandwidth, i.e. it may vary
as a function of the IF bandwidth. For an IF bandwidth of BWIF spectrum = 10 kHz,
the constant has a value of 1.28. To display a 10 kHz IF spectrum, therefore, a
sampling rate of fs = 12.8 kHz is required.
To Next Page
Loading...
