Ku-band receiver and transmitter for breadboard DSP scatterometer

The design and test results for the Radio Frequency (RF) portion of a breadboard polarimetric scatterometer operating at 13.402 GHz are presented. An integrated breadboard has been developed at the Jet Propulsion Laboratory (JPL) to evaluate the feasibility of a programmable Digital Signal Processing (DSP) approach for a follow-on scatterometer similar to SeaWinds (scheduled for launch in winter 2002). Early breadboards of an integrated system have been identified as valuable assets in developing effective subsystem requirements for the eventual flight instrument. Many compatibility and partitioning issues between the RF and DSP hardware are addressed with empirical results derived from the aforementioned breadboard. The RF portion of the breadboard consists of a dual channel receiver, heterodyning the received signal of 13.402 GHz down to an IF of 37 MHz prior to the analog to digital conversion, and a single channel transmitter, that converts the I/Q baseband transmit waveform up to Ku band. The breadboard makes provision for emulating capabilities such as programmable attenuators, loop-back calibration, and saturation effects in an actual instrument's power amplifier. It also provides control interfaces to allow early verification of software control algorithms.