Phase Accuracy Experiments with a Direct-Sampling Coherent Detector
Abstract
The full potential of digital radar and communications signal processing may be realized only after errors in converting received signals to digital sample values are minimized. Coherent methods of analog-to-digital (A/D) conversion that preserve phase information fall into two classes-baseband and direct-sampling methods. As modern A/D converters have become faster, interest in direct-sampling approaches has grown; this report focuses on a direct- sampling digital coherent detector (DCD). The main advantage claimed for direct sampling over baseband detectors is improved phase accuracy. In the baseband case this is due to difficulties in matching separate I and Q channels. Data taken from the DCD demonstrate operation at carrier frequencies to 11.25 MHz with phase errors less than 0.8. At frequencies less than 4 MHz, phase errors are less than 0.3; this corresponds to time-measurement accuracy better than 230 picoseconds. A brief review of the rules of direct sampling proceeds descriptions of the approach, hardware implementation instrumentation test results, and conclusions. Keywords: Analog to digital converters; Signal processing; Digital communications; Digital radar; Direct sampling; Phase measurement.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 10, 1989
- Accession Number
- ADA205458
Entities
People
- B. R. Jarrett
- G. J. Linde
- W. M. Waters
Organizations
- United States Naval Research Laboratory