11
kHz and GHz Keys
The kHz and GHz keys are provided for convenience when entering
frequency; however, the display will only indicate in MHz. Similarly,
the V key can be used for entering input level; however, the display
will indicate in millivolts.
ENTER key
The ENTER key is used for unitless quantities, such as special function
and program numbers.
CLR key
The CLR key is used to recover from errors. Without changing func-
tion, depress the dBm key. The FREQUENCY/LEVEL display will now
indicate Error 9 or 11. This means that an inconsistent units key has
been depressed to terminate a data entry.
Depress the CLR key. The display will return to normal. A list of error
codes is presented in Table 3-8, at the end of the section 3-26 of the
8201A instruction manual.
LEVEL Function key
Depress the carrier LEVEL function key, then the 0 and dBm keys. The
FREQUENCY/LEVEL display will now indicate 0.00 dBm.
mV/MHz key
Depress the mV/MHz key. The display will change to 223.6 m V.
Carrier level may be entered in millivolts, volts, or dBm. The control
program will recalculate or rescale numbers as required.
The DEL and CLR keys are also labeled as up- and down-arrow keys
for scrolling through SPCL function menus.
Getting familiar with Measurement
Control Keys
The measurement control keys consist of the groups of switches
marked FILTERS and DETECTORS. These keys may be operated at any
time and will affect the MODULATION and AUDIO displays. The filter
switches are arranged as self-cancelling groups of four and five keys.
Depressing any high-pass switch will cause the selected filter to be
placed into the measurement channel and cancel any other selected
high-pass filter. Similarly, depressing any low-pass filter will cause
the selected filter to be placed into the measurement channel and
cancel any other selected low-pass filter.
Figure-6: Measurement Control Keys of 8201A Modulation Analyzer
HIGH-PASS Filter keys
Depressing any high-pass switch will cause the selected filter to be
placed into the measurement channel and cancel any other selected
high-pass filter.
LOW-PASS Filter keys
Similarly, depressing any low-pass filter will cause the selected filter
to be placed into the measurement channel and cancel any other
selected low-pass filter.
The maximum low-pass bandwidth selection is a function of carrier
frequency. The control program will automatically adjust the low-
pass filter cutoff frequency as required. The carrier breakpoints and
low-pass filters are:
Carrier
Filter
< 500 kHz
15 kHz max
< 10 MHz
50 kHz max
> 10 MHz
220 kHz max
DE-EMPHASIS Filter Keys
The de-emphasis filters are normally available when measuring FM
only. They are selected in the same manner as the high-pass and
low-pass filters, but are automatically removed from the measure-
ment channel when AM or PM modulation function is selected. The
selected de-emphasis filter will be restored when the FM function is
again selected.
Additionally, the de-emphasis filters may be placed before or after
the modulation display. This is accomplished by selecting SPCL func-
tion 7 for pre-display and SPCL function 8 for post-display de-em-
phasis. SPCL function 9 permits the de-emphasis filters to be selected
in the AM measurement function. This is useful for performance
verification of the filter 3 dB points.
