Apparatus for Very High Speed Adaptive Spectrum Analysis

摘要

This invention describes a method by which Broadband Spectrum Analysis can be performed in the Rh and Microwave frequency range with significantly higher speed, accuracy, and flexibility than existing RF and Microwave Spectrum Analyzers. This is done by eliminating the need for the filtering of the incoming signal, a process called preselection that needs to track in frequency with the scanning local oscillator in the instrument. By eliminating this requirement, this invention makes possible the identification and analysis of very broadband signals in a single sweep using an Adaptive Sweep Methodology and a Simultaneous Sweep capability that the present invention makes possible.

主权项

1. A Broadband Receiver usable as an Adaptive Sweep Spectrum Analyzer, consisting of:
a. A signal splitter at the input to split the incoming signal into two equal parts. b. Two local oscillators whose output frequencies are symmetrically apart at a selectable frequency separation from the input frequency being scanned, the local oscillators being tuned together through the frequency range of interest for the measurement. c. Two mixers, the local oscillators of which are one of the two symmetrically apart local oscillators, and whose input signals are the split incoming signals. d. Two low pass filters that each filters the output of one of the mixers to output any mixer product signals within the low pass filter bandwidth. e. Two detectors one each at each low pass filter output that detects and outputs a DC voltage proportional to the input power. f. An analog multiplier that multiplies the two low pass filtered and detected mixer outputs. g. A video filter and logarithmic or linear amplifier combination whose input attaches to the analog multiplier output and whose output is connected to a display or to a signal processor or analyzer. Wherein, when used as a spectrum analyzer, the X-axis of the display is a voltage proportional to the position of the input frequency being scanned as a fraction of the total scan bandwidth, and the Y-axis of the display is the detected and amplified output of the analog multiplier. Wherein, if there exists a signal, or if there exists noise at the frequency being scanned at the receiver input, the detected and amplified output of the analog multiplier is proportional to the power of the incoming signal or noise power within the low pass filter bandwidth. Wherein, the need for preselection filters at the input so as not to have spurious images is eliminated by the dual local oscillator and low pass filter combination, allowing much higher speeds of spectrum scanning and digital phase locked accuracy at every frequency. Wherein, the amplitude accuracy can be controlled via programmable attenuators or some closed loop method that corrects any input splitter imbalance as a function of input frequency.