B&K 4071 user manual Internal PM Mode, Int PM 1,000 Hz Pk dev 180 deg 000,000.00 Hz 10.0 dBm

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:

1
	Int PM: 1,000 Hz	Pk dev: 180 deg
3	1,000,000.00 Hz	-10.0 dBm

Figure 5.6-1: Internal PM mode display

1. Modulating Frequency

2

4

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 31.5 MHz in 0.1 Hz steps.

4. 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