Method and Apparatus for a SuperSpeed USB Bus Powered Real-Time Spectrum Analyzer

摘要

An RF processing module that when coupled to a computer having appropriate signal processing software will function as a spectrum analyzer. The RF processing module has a first stage mixer and a switch that allows either port of the first stage mixer to be selected as the input and receive the RF signal. The RF processing module has a sample packing buffer that packs digitized signal samples into a fewer number of longer words and loads the words into a circular buffer and from thence to one of two DMA channels on a USB link. The circular buffer can be emptied faster than it can be filled, allowing the sample packing buffer to create time intervals for a USB controller to switch DMA channels. LO leakage through the mixer-to-IF path is used to self-calibrate the filter's frequency response as temperature and other environmental factors change.

主权项

1. A device comprising:
a mixer configured to convert a Radio Frequency (RF) signal to an Intermediated Frequency (IF) signal using a local oscillator signal, the mixer having a first port, a second port, and a local oscillator input, wherein the mixer is double balanced; a Transmit/Receive (T/R) switch configured to route the RF signal to the first port of the mixer when the T/R switch is in a first T/R switch position and configured to route the RF signal to the second port of the mixer when the T/R switch is in a second T/R switch position; and an IF-to-bits module configured to receive the IF signal and generate a stream of digital signal samples of the IF signal.