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BK Precision 4070A User Manual Rev.2.2
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5.6 Internal PM Mode
Introduction
Internal PM mode generates phase-modulated signal of fixed amplitude. It used internally generated signal to
modulate phase of carrier signal. Modulated and modulating frequency, output level, deviation, and DC offset values
could be manually entered on the keypad in this mode. External signal gating options is available in this mode.
Internal PM mode could be entered by pressing “Mode”> “PM” >”1” key at any time.
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 21.5 MHz in 0.1 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
0.1 dBm steps.
NOTE: The level specified is a 50O loaded level. This is the level of the signal, which will appear across a 50O
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 signal. For more information on output offsets refer to section 4.4.
Ext Gating Input
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.
I
nt PM: 1,000 Hz
Pk dev: 180 deg
1,000,000.00 Hz -10.0 dBm
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