NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Ground Isolation Circuit for Isolating a Transmission Line from Ground InterferenceThis invention relates generally to a system for isolating ground interference from a transmission line, e.g., a ground isolation circuit for isolating a wideband transmission signal (such as a video signal) from ground by modulating the base signal on a carrier signal to permit the transmission signal to be isolated. In one embodiment, the circuit includes a pair of matched mixer circuits, each of which receives a carrier signal from the same oscillator circuit. The first mixer circuit also receives the baseband signal input, after appropriate conditioning, and modulates the baseband signal onto the carrier signal. In a preferred embodiment the carrier signal has a predetermined frequency which is at least two times the frequency of the baseband signal. The modulated signal (which can comprise an rf signal) is transmitted via an rf transmission line to the second mixer, which demodulates the rf signal to recover the baseband signal. Each port of the mixer connects to an isolation transformer to ensure isolation from ground interference. The circuit is considered to be of commercial value in that it can provide isolation between transmitting and receiving circuits, e.g., ground isolation for television circuits or high frequency transmitters, without the need for video transformers or optical isolators, thereby reducing the complexity, power consumption, and weight of the system.
Document ID
19970018522
Acquisition Source
Johnson Space Center
Document Type
Other - Patent Application
Authors
Davidson, Craig A.
(Hernandez Engineering, Inc. Houston, TX United States)
Date Acquired
September 6, 2013
Publication Date
February 1, 1996
Subject Category
Communications And Radar
Report/Patent Number
NAS 1.71:MSC-22521-1
Accession Number
97N20478
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
NASA-Case-MSC-22521-1
Patent Application
US-Patent-Appl-SN-595312
No Preview Available