Making Basic Measurements Using Spectrum Analyzer Mode

Resolving Signals of Equal Amplitude Using the Resolution Bandwidth Function

PEAK

LOG

10

dB/

RES BW

WA SF!

SC FC

CORR

EM1 BW

Men”

 

CENTER 300.000

MHZ

 

SPAN

2.000

MHZ

I

#RES BW 100

)tHZ

“BW 30 km

SWP

20.0

nlsec

Figure 4-2. Resolving Signals of Equal Amplitude

As the resolution bandwidth is decreased, resolution of the individual signals is improved and the sweep time is increased. For fastest measurement times, use the widest possible resolution bandwidth. Under preset conditions, the resolution bandwidth is “coupled” (or linked) to span.

Since the resolution bandwidth has been changed from the coupled value, a I‘#” mark appears next to RES EW in the lower-left corner of the screen, indicating that the resolution bandwidth is uncoupled. (Also see the CAUTO COUPLE_) key description in Chapter 6.)

N O T E

To resolve two signals of equal amplitude with a frequency separation of 200 kHz, the resolution bandwidth must be less than the signal separation, and resolution of 100 kHz must be used. The next larger filter, 300 kHz, would exceed the 200 kHz separation and would not resolve the signals.

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