Noise Sidebands

TM 11-6625-2781-14&P-2

Section IV

PERFORMANCE TESTS (cont'd)

4-30. Noise Sidebands

SPECIFICATION:

More than 70 dB below CW signal 50 kHz or more away from signal, with a 1 kHz IF BANDWIDTH setting.

DESCRIPTION:

A stable -40 dBm CW signal is applied to the spectrum analyzer and displayed on the CRT. The amplitude of the noise

associated sidebands and unwanted responses close to the signal are measured.

Figure 4-14. Noise Sideband Test

EQUIPMENT:

Signal Generator................................ ................................ ................................ ................................ ......... HP 606B

BNC Cable Assembly................................ ................................ ................................ .............................. HP 10503A

1. Connect the test setup in Figure 4-14 and make the following control settings:

ANALYZER

RANGE MHz ................................ ................................ ................................ ................................ .................. 0 -110

FREQUENCY ................................ ................................ ................................ ................................ ............... 40 MHz

BANDWIDTH ................................ ................................ ................................ ................................ ................... 1 kHz

SCAN WIDTH ................................ ................................ ................................ ................................ ....PER DIVISION

SCAN WIDTH PER DIVISION ................................ ................................ ................................ ....................... 10 kHz

SCAN TIME PER DIVISION ................................ ................................ ................................ ................... 1 SECOND

INPUT ATTENUATION................................ ................................ ................................ ................................ ...... 0 dB

LOG REF LEVEL ................................ ................................ ................................ ................................ ......... -40 dBm

TUNING STABILIZER................................ ................................ ................................ ................................ .......... ON

VIDEO FILTER ................................ ................................ ................................ ................................ .............. 100 Hz

SCAN MODE ................................ ................................ ................................ ................................ ....................... INT

SCAN TRIGGER ................................ ................................ ................................ ................................ ............ AUTO

LOG/LINEAR ................................ ................................ ................................ ................................ ..................... LOG

606B

FREQUENCY ................................ ................................ ................................ ................................ ............... 40 MHz

ATTENUATOR ................................ ................................ ................................ ................................ ............ -40 dBm

MOD SELECTOR ................................ ................................ ................................ ................................ ................. cw

Tune the analyzer to center the display, and if necessary, adjust HP 606B output vernier so that the signal amplitude

peaks at the top graticule line.

3. Observe the noise level five divisions or greater away from the signal (50 kHz). The average noise level should be

at least 7 divisions below the signal level.

Noise Level >7 div below carrier level:

4-20