BNC 630 - Manual (Page 24)

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5.6 Internal PM Mode
Introduction
The Internal PM mode generates a phase modulated signal of fixed amplitude. An internally-generated sinusoid is used as a
modulating signal to vary the phase of a carrier sinusoid.
Internal PM Mode Parameters
The Internal PM mode has the following front panel display:
Figure 5.6-1: Internal PM mode display
1. Modulating Frequency
In this field enter the frequency of the modulating sinusoid. You may enter from 0 Hz to 10,000 Hz in 1 Hz steps.
2. Peak Phase Deviation
In this field specify the degree to which the modulating signal is allowed to change the carrier phase. You may enter from 0 (no
change) to 180 degrees in 1 degree steps.
This parameter is a peak value. If the deviation value were 180 degrees, for example, then the output phase will advance to a
maximum of +180 degrees and retard to a minimum of -180 degrees.
To enter a value, type 1 to 3 numeric digits. If you type 3 digits, the value is automatically entered. If you only type 1 or 2 digits,
you can press the MHz key or the KHz key or the Hz key (all are equivalent) to enter the degree value.
Note: FM modulation is equivalent to PM for small frequency deviation values. If you need a larger phase deviation than 180
degrees, go to FM mode and specify an appropriate peak frequency deviation value.
3. Carrier Frequency
In this field enter the frequency of the carrier. You may enter from 0 Hz (DC) to 21.5000000 MHz in .01 Hz steps.
4. Level
In this field enter the output level, from 4 mVp-p to 10 Vp-p in 1 mV steps or from -44.0 dBm to +24.0 dBm in .1 dBm steps.
NOTE: The level specified is a 50 ohm LOADED level. This is the level of the signal which will appear across a 50 ohm load
connected to the SIG Out connector. Into an open circuit, the output swing will be twice the value entered.
Offset
You can enter an offset voltage for the output waveform. For more information on output offsets refer to section 4.4.
Ext Gating Input
(rear panel connector)
This TTL compatible input can be used to gate the output signal on or off. A logic high voltage turns off the output.
For further information on the Ext Gating Input, refer to section 2.0.
Int PM: 1,000 Hz Pk dev: 180 deg
20,000,000.00 MHz -10.0 dBm
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