VSWR monitor and alarm

• US 20020113600A1
• Filed: 12/28/2000
• Published: 08/22/2002
• Est. Priority Date: 12/28/2000
• Status: Abandoned Application

• Current Assignee: Bird Electronic Corporation (Bird Technologies Group Incorporated)
• Original Assignee: Bird Electronic Corporation (Bird Technologies Group Incorporated)
• Inventors: Swank, John D. II
• Application Number:
  US09/750,478
• Publication Number:
  US 20020113600A1
• Time in Patent Office: Days
• US Class Current: 324/637
• CPC Class Codes: G01R 27/06 Measuring reflection coefficients; Measuring standing-wave ratio
• CPC Class Codes: G01R 27/28 Measuring attenuation, gain, phase shift or derived characteristics of electric four pole networks, i.e. two-port networks; Measuring transient response in line transmission systems H04B3/46

Abstract

A VSWR meter and alarm device that produces an alarm when an undesirable VSWR is sensed on an RF transmission line. This device uses a single-arm directional coupler and detectors operating at least 15 dB into the “square law region” at full power. The single-arm directional coupler is capable of sensing the forward voltage wave and reflected voltage wave from a transmission line. The coupler isolates the forward and reflected voltages and each is converted into a direct current (dc) signal by a full-wave detector. Attenuator circuits are utilized between the coupler and detectors so that the detectors operate at least 15 dB into the “square-law region” at full power. The dc signals representing the forward and reflected voltages are then amplified and transformed into respective digital signals by a digital-to-analog converter. The digital signals are then transmitted to a microprocessor which operates an alarm system.

Claims

1. ) an instrument for measuring the forward and reflected voltages on an RF transmission line and for activating an alarm when an excessive VSWR is detected, comprising;

directional coupler means for measuring the forward voltage wave and reflected voltage wave on an RF transmission line and for generating voltage signals representative thereof, the respective signals being isolated from one another;

means for processing each of said signals to generate respective dc voltage signals;

means for amplifying each of said dc voltage signals;

means for converting each of said amplified signals to a digital signal; and

a microprocessor for determining the VSWR from said digital signals and for comparing said VSWR to a selected maximum ratio so as to activate an alarm when said selected maximum ratio is exceeded;

2. ) A process for measuring the forward and reflected voltages on an RF transmission line and for activating an alarm when an excessive VSWR is detected comprising the steps of;

sensing the forward voltage level on said RF transmission line using a first directional coupler and generating a first voltage signal representative thereof;

simultaneously sensing the reflected voltage level on said RF transmission line using a second directional coupler isolated from said first directional coupler and generating a second voltage signal representative thereof and isolated from said first signal;

attenuating each of said signals;

amplifying each of said attenuated signals;

converting each of said amplified signals to a digital signal;

determining the VSWR on said RF transmission line by processing said amplified signals, and;

comparing said VSWR to a preselected maximum ratio to detect a VSWR that exceeds the preselected maximum, and;

generating an alarm when said excessive VSWR is detected.