Signal Resolution With A 10 Khz Resolution Bandwidth; Signal Resolution With A 30 Khz Resolution Bandwidth - HP 8590 E-Series User Manual

3. Set the source to 300.2 MHz, so that the signal is 200 kHz higher than the calibration signal.
Set the amplitude of the signal to -80 dBm (60 dB below the calibration signal).
4. Set the 300 MHz signal to the reference level by pressing
MARKER -+REF LVL .
If a 10 kHz filter with a typical shape factor of 15: 1 is used, the filter will have a bandwidth
of 150 kHz at the 60 dB point. The half-bandwidth (75 kHz) is narrower than the frequency
separation, so the input signals will be resolved.
Figure 3-4. Signal Resolution with a 10 kHz Resolution Bandwidth
If a 30 kHz filter is used, the 60 dB bandwidth will be 450 kHz. Since the half-bandwidth
(225 kHz) is wider than the frequency separation, the signals most likely will not be resolved.
See Figure 3-5. (To determine resolution capability for intermediate values of amplitude level
differences, consider the filter skirts between the 3 dB and 60 dB points to be approximately
straight. In this case, we simply used the 60 dB value.)
Figure 3-5. Signal Resolution with a 30 kHz Resolution Bandwidth
PEAK
LOG
3 0 0 . 0 1 0 MHz
LOG
30 kHZ
C E N T E R 3Ub3.000
- 2 3 8 6 dBm
- 2 3 8 7 dBm
I
S P A N 2 0 0 0 MHz
Making Basic Measurements 3-5