B&K 4071 user manual External PM Mode, External PM Pk dev 180 deg 000,000.00 Hz 10.0 dBm

5.7 External PM Mode

Introduction

External PM mode generates phase-modulated signal of fixed amplitude were externally supplied signal is used as a modulating signal to vary phase of the carrier signal. Modulated frequency, level, peak deviation and DC offset values could be manually entered from the front panel keypad in this mode. External signal gating options is available in this mode. External PM mode could be entered by pressing “Mode”> “PM” >”2” key at any time.

External PM Mode Parameters

The External PM mode has the following front panel display:

	External PM	Pk dev: 180 deg
	1,000,000.00 Hz	-10.0 dBm
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Figure 5.7-1: External PM mode display

1. Peak Phase Deviation

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3

In this field specify the degree to which the modulating signal is allowed to change the carrier phase. You may enter from 0 degrees (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 for a 1 Vp -p input signal.

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 phase deviation 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.

2. Carrier Frequency

In this field enter the frequency of the carrier. You may enter from 0 Hz (DC) to 31.5 MHz in 0.01 Hz steps.

3. Level

In this field enter the output level, from 4 mVp -p to 5 Vp -p in 1 mV steps or from -44.0 dBm to +18.0 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.

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BK Precision 4071 User Manual Rev.2.2