Marker & peak search Page 41
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* Differing from base band at which the up-conversion of input frequency is done with a frequency mixer, the
spurious response peculiar to band 1- and band 1+ is generated because the down-conversion is done at those
two bands.
* About SPURIOUS FREE mode
1. SPURIOUS FREE mode is a mode by which the spurious response peculiarly caused at band
1+ is simply deleted.
2. SPURIOUS FREE mode is especially effective in the measurement of a stationary wave.
3. If SPURIOUS FREE mode is used in measurement of a signal with level change or frequency
change, the phenomenon that the level goes down will occur.
4. The noise level goes down a little in case of a noise changing at random. In short, the same
phenomenon as MIN HOLD function happens.
* How to judge SPURIOUS response at band 1- and band 1+
The procedure for judging SPURIOUS response at band 1- and band 1+ is as follows.
1. Set the center frequency to < (current setting value) + f >.
2. The spectrum shifting left by f is a correct spectrum, but another spectrum shifting such as left
by 2f, left by 3f, right by f, right by 2f or right by 3f is a spurious response.
* “f ” should be changed according to SPAN for easy judgment. For reference;
f = SPAN / (10 to 50) (corresponding to 0.2 to 1 div)
Example: judging a spectrum displayed at 6.92 GHz
(setting : center frequency 6.92 GHz and SPAN 500 MHz)
1. Set the center frequency to < 6.92 GHz + 500 MHz/25 > = 6.94GHz.
2. A spectrum at 6.92 GHz (shifting left by f from 6.94 GHz) is correct. A spectrum at 6.98 GHz (shifting
right by 2f from 6.94 GHz) is spurious.
* Additionally, a spurious response mentioned above shifting right by 2f at band 1+ is largest, and other
spurious response are about 25 to 50 dB smaller than that.
17. Marker & Peak Search
When is pushed, the following function menu is displayed.
● Main menu of marker function
F1
F2
F3
F4
F5
F6
CONV
dBm
→W
NORMAL
MARKER
DELTA
OFF
CENTER FREQ
NORMAL
ZONE
MKR