Specifications

Using the Markers R&S FSH
1145.5973.12 4.32 E-10
Marker functions
Apart from displaying the level and frequency at the marker position (NORMAL setting), the R&S FSH
can also perform other forms of analysis at the marker position. For example, the R&S FSH can
calculate the noise power density referred to 1 Hz bandwidth (NOISE function) or measure the
frequency of a signal at the marker position (FREQ COUNT function).
Measuring the noise power density
The NOISE function is used to calculate the noise power density at the marker position. The R&S FSH
calculates the noise power density in dBm/(1 Hz) from the trace pixel values, the selected resolution
bandwidth, the detector and the level display mode (absolute or relative). To stabilize the noise power
display, the R&S FSH uses the pixel on which the marker is positioned and the four pixels to the right
and the four pixels to the left of the marker pixel. Noise power density can provide useful information
when measurements are made on noise or digitally modulated signals. However, valid results are
obtained only if the spectrum in the vicinity of the marker has a flat frequency response. The function
gives incorrect results if measurements are made on discrete signals.
Operating sequence:
¾ Press the MARKER key.
¾ Press the MARKER MODE softkey.
¾ Using the cursor keys or the rotary knob, select the
NOISE menu item.
¾ Confirm the selection with the ENTER key or by
pressing the MARKER MODE softkey again.
The R&S FSH now indicates the marker level in
dBm/Hz. If the delta marker is the active marker, it
displays the result in dBc/Hz. The reading is referred to
the main marker.