HP 8642A Operation And Calibration Manual page 161

Model 8642A/B
Operation
Modulation, <PM (cont'd)
Related
Operating
Instructions
113. Modula tion Frequency Correction Off. This special function disables the
single-band calibration of the modulation frequency oscillator that normally occurs
whenever the modulation oscillator frequency is set or the internal modulation oscillator
is put into use, When this calibration is disabled, the typical modulation frequency
switching time is decreased by approximately 200 ms. For more information, refer to
"Speeding Up Modulation Switching Time", page 3-132.
213. Modulation Frequency Correction On. This special function re-enables the
modulation frequency correction disabled with Special Function 113.
114. Negative <PM Polarity. This special function causes a positive voltage applied to
the external FM/<PM INPUT to cause a phase lag and a negative voltage applied to cause
a phase lead,
214. Positive.pM Po]al'ity. This special function causes a positive voltage applied to
the external FM/<pM INPUT to cause a phase lead and a negative voltage applied to
cause a phase lag.
119. Disable Settling, This special function allows the Signal Generator's
microprocessor to respond to new commands without waiting for the internal circuitry to
settle. When using this special function, it's possible to select a function before the
previous function has finished settling. When settling is disabled, response time is
improved by up to 40 ms. Special Function 119 disables out-of -lock messages
219. Re-enable Settling. This special function re-enables the settling that is disabled
when Special Function 119 is selected.
248. Calibrate the Modulation Frequency Bands Again. This special function enables
you to initiate the calibration sequence that normally only occurs during instrument
power-up, This function can be used, for example, to recalibrate the modulation
oscillator frequency bands if normal modulation frequency correction has been disabled
with Special Function 11 3. Calibration typically takes one to two seconds.
Refer to Modulation Oscillator (page 3-131) for more information
OIl
the internal
modulation oscillator that is the common source for all internal modulation as well as for
the MOD OUTPUT connector.
Refer to Knob (page 3-141) and Step, Increment Set (page 3-149) for information on
using these to modify settings.
Refer to Operating Messages (page 3-177) if the instrument displays a message you want
clarified,
Refer to Special FUllctions (page 3 -165) for inforrna tion a bou t t he way these are
accessed.
3-125