Agilent Technologies 11970-90031 manual Signal Identification

Operation

Operation

Using the Mixers with the E4407B Spectrum Analyzer (Option AYZ)

Signal Identification

The IF output of a harmonic mixer will contain a signal at the intermediate frequency of the analyzer whenever the harmonic frequency of the LO and the frequency of the RF differ by the intermediate frequency.

As a result, within a single harmonic band, a single input signal can produce multiple responses on the analyzer display, only one of which is valid (see Figure 2-3.). These responses come in pairs, where members of the valid response pair are separated by 642.8 MHz and either the right-most (for negative harmonics) or left-most (for positive harmonics) member of the pair is the correct response.

Figure 2-3.

Identification of valid responses is achieved by simply turning on the signal-identification feature. (instrument preset selects the Image Suppress signal identification mode.) Press Input/Output, Input Mixer, Signal Ident (On) and note that now only the valid response (35 GHz) remains.

Press Peak Search to place a marker on the remaining response. The signal-identification routine can introduce slight amplitude errors which is indicated by the message Signal Ident On, Amptd Uncal. Refer to Figure 2-4..

After identifying a signal of interest, press Signal Ident (Off) before making final amplitude measurements. Note that Image Suppress should only be used to identify the fundamental signal and not for accurate amplitude measurements.

24 Chapter 2