Charles Bruce Currie

US Patent:

52300978, Jul 20, 1993

Filed:

Mar 9, 1990

Appl. No.:

7/491161

Inventors:

Charles H. Currie - Doraville GA
Owen M. Caldwell - Dunwoody GA

Assignee:

Scientific-Atlanta, Inc. - Norcross GA

International Classification:

H04B 1700

US Classification:

4552261

Abstract:

An offset frequency converter for the intermediate frequency (IF) stages of a multi-channel radio frequency (RF) phase/amplitude measurement receiver, particularly useful for measuring the performance characteristics of antennas. The converter allows use of noncoherent transmitter and receiver local oscillator sources which utilize digital frequency synthesizers and enables harmonic mixing to be employed when the tuning resolution of the receiver local oscillator is incremental. The converter samples an incoming first intermediate frequency signal IF. sub. 1 in a reference channel, which typically is obtained by mixing an LO source in the receiver with an incoming signal from a reference antenna. The IF. sub. 1 sample is then upconverted with an upconversion signal to a higher frequency, filtered, and the downconverted with a downconversion signal to an IF. sub. 1 +IF. sub. 2 signal offset from the IF. sub.