Spectrum analyzer using multiple intermediate frequencies and multiple clock configurations for residual, spurious and image signal reduction

摘要

A spectrum analyzer for measuring an RF signal over a selected frequency span configured to use multiple Intermediate Frequencies (IFs) for residual, spurious and image signal reduction. The spectrum analyzer has both a primary IF path and a secondary IF path configured to provide band pass filtering of the IF signals. A master clock synthesizer is configured to reduce residual noise by providing from a single Voltage Controlled Oscillator, a master clock signal and a Local Oscillator (LO) signal. The spectrum analyzer has a microcontroller configured to change the frequency of the master clock signal and the LO signal if the center frequency of the selected span is sufficiently close to a known spurious signal.

主权项

1. A spectrum analyzer system for measuring an RF signal over a selected frequency span comprising:
a Radio Frequency/Intermediate Frequency (RF/IF) hardware section configured to convert the RF signal to a first IF signal using a first Local Oscillator (LO) signal with a first LO frequency; the RF/IF hardware section further configured to convert the RF signal to a second IF signal using a second LO signal with a second LO frequency different from the first LO frequency; the RF/IF hardware section further configured to select one of a primary IF path and a secondary IF path to filter the first IF signal, the primary IF path having a different pass band center frequency than the secondary IF path and select one of the primary IF path and the secondary IF path to filter the second IF signal; the RF/IF hardware section further configured to convert the first IF signal to a first set of digitized IF signal samples then convert the second IF signal to a second set of digitized IF signal samples; a processor configured to convert the first and second set of digitized IF signal samples to first and second sets of frequency domain samples; the processor further configured to combine the first and second set of frequency domain samples into a combined set of frequency domain samples; and a display configured to visually present the combined set of frequency domain samples.