VXI 3002 manual AM depth and distortion, Figure recorded in 5 20 log10 Figure recorded

(6)Using the figure recorded in (4) as a reference, calculate the change in response at each modulation frequency using the formula:

￿ Figure recorded in (5) ￿ 20 log10 ￿￿ Figure recorded in (4) ￿￿

Check that the results are within the specifications shown in Table 5-29.

Amplitude modulation

Specification

Range		0 to 99.9%.
Resolution		0.1%.
Accuracy		For carrier frequencies less than 500 MHz (usable to 2 GHz): ±5% of set depth at 1 kHz
		rate at +17°C to 27°C ambient temperature.
		Temperature coefficient <0.02% per °C.
Bandwidth (1 dB)		DC to 30 kHz (DC coupled),
		10 Hz to 30 kHz (AC coupled),
		20 Hz to 30 kHz (AC coupled with ALC).
Distortion		Less than 2.5% at 1 kHz rate for modulation depths up to 80%,
		Less than 1.5% at 1 kHz rate for modulation depths up to 30%.
Test equipment
	Description		Minimum specification	Example
	Modulation meter		AM accuracy ±1% at 1 kHz modulation frequency	IFR 2305 with
				distortion option
	DVM		DC voltage measurement	Solartron 7150+
	50 Ω load		1 W 50 Ω nominal impedance, DC to 2.4 GHz	Lucas Weinschel
	(termination)			M1404N
	Audio analyzer		Capable of measuring THD of 0.01% from 100 Hz	Rohde &
			to 20 kHz	Schwarz UPA3
	Function		DC to 30 kHz sine, ±0.6 dB flatness	Agilent 3325B
	generator

AM depth and distortion

Test procedure

(1)Connect the test equipment as shown in Fig. 5-7.

(2)On the UUT set:

Carr Freq	1.5 MHz
RF Level	−4 dBm
Mod Mode	AM Internal
Source On
Mod On
AM1 Level	30%

(3)On the modulation meter, select CAL, AM, 300 Hz ￿ 3.4 kHz LF filter.

(4)Measure the AM accuracy and distortion at the frequencies shown in Table 5-30 checking that the results are within specification.

(5)Set the UUT AM1 level to 80% and repeat (4).

(6)Set the UUT to RF level +7 dBm and repeat (2) to (5) using Table 5-31.

(7)Set the UUT to RF level +13 dBm and repeat (2) to (5) using Table 5-32.

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