FM Frequency Response

FM frequency response verifies that a selected FM deviation remains constant within ±1 dB as the FM rate is varied from 20 Hz to 100 kHz, and the UUT CW frequency is varied from 500 MHz to 1.0 GHz. If the UUT meets the frequency response specification in this CW frequency range, frequency response in all other frequency ranges will be assured.

FM deviation is set to 100 kHz at an FM rate of 1 kHz. The actual deviation is measured with a measuring receiver and stored as the reference deviation. While the deviation setting remains at 100 kHz, actual deviation is measured for FM rates between 20 Hz and 100 kHz. If the measured deviation at any test rate is more than 1 dB different from the reference deviation at 1 kHz, the test fails.

Required Test Equipment

This test supports two equipment setups using either a spectrum analyzer or a measuring receiver. The spectrum analyzer is the preferred solution.

1. The preferred solution uses a spectrum analyzer with Analog Demodulation Measurement Application to demodulate the signal and measure the deviation.

   Test Equipment	Critical Specifications for This Test	Recommended Models	Alternate Models
   Spectrum Analyzer	FM Deviation Accuracy	N9030B Opt 5xx1, N9063EM0E Analog Demodulation Measurement Application	N9030A Opt 5xx1 and N9063EM0E Analog Demodulation Measurement Application2 E444xA3 Opt 233

   Select any option of PXA spectrum analyzer (503, 508, 513, 526, 543, 544, 550) that has a maximum frequency greater than or equal to the maximum frequency of the unit under test. To use the PXA N9030A with N9063EM0E analog demodulation measurement application functionality above 3.5 GHz, the N9030A must be upgraded with either Option MTU or TES. For more information, see the main Required Equipment table. Select any model of PSA spectrum analyzer (E4440A, E4443A, E4445A, E4446A, E4447A, E4448A) that has a maximum frequency greater than or equal to the maximum frequency of the unit under test.

2. The alternate solution uses an 8902A measuring receiver to demodulate the signal and measure the deviation.

   Test Equipment	Critical Specifications for This Test	Recommended Models
   Measuring Receiver	FM Deviation Accuracy	8902A

Connections and Setup Procedures

1. Connect all test equipment as shown.
2. Connect GPIB cables to all GPIB-controlled test equipment.
3. While performing this test, follow all instructions on the controller display.

Spectrum Analyzer Test Setup

Measuring Receiver Test Setup

Calibration Setup

FM Frequency Response Test Setup

In Case of Difficulty

If this performance test fails, perform the following steps in order:

1. Check the equipment setup (see above). If the setup is incorrect, make the necessary corrections and rerun the performance test.

2. If this test fails with the equipment set up properly, refer to the troubleshooting section of the signal generator's service guide. If you do not have a printed copy of the service guide (Option OBW), one is available either on the CD-ROM that came with your signal generator shipment or on the Keysight Website.

3. If you cannot correct the problem using the troubleshooting procedures in the Service Guide, obtain service from Keysight Technologies. Refer to Contacting Keysight Technologies.