Monitor for RF transmitter

• US 4,274,156 A
• Filed: 01/18/1978
• Issued: 06/16/1981
• Est. Priority Date: 01/18/1978
• Status: Expired due to Term

• Current Assignee: Bird Electronic Corporation (Bird Technologies Group Incorporated)
• Original Assignee: Bird Electronic Corporation (Bird Technologies Group Incorporated)
• Inventors: Trefney, Ralph P.
• Primary Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/870,340
• Time in Patent Office: 1,245 Days
• Field of Search: 325/2, 325/151, 325/152, 325/31, 325/67, 325/133, 325/176, 325/187, 325/150, 343/17.7, 343/703, 343/894, 340/657, 340/660-663, 340/521, 340/517, 455/9, 455/67, 455/115, 455/117
• US Class Current: 455/115.4
• CPC Class Codes: G01R 1/36 Overload-protection arrangements or circuits for electric measuring instruments
• CPC Class Codes: H04B 17/101 for measurement of specific parameters of the transmitter or components thereof
• CPC Class Codes: H04B 17/102 Power radiated at antenna
• CPC Class Codes: H04B 17/103 Reflected power, e.g. return loss
• CPC Class Codes: H04B 17/17 Detection of non-compliance or faulty performance, e.g. response deviations H04B17/18 takes precedence

Abstract

A device for monitoring operating conditions of an RF transmitter, including the RF power output thereof, and the reflected voltage wave on a transmission line therefor, and for promptly switching the transmitter off whenever a faulty condition is detected. The device includes two voltage comparators that receive voltage signals representative of transmitter power output and the magnitude of the reflected voltage wave on an associated transmission line, and which generate an output signal whenever a respective voltage signal varies a predetermined amount from a preset reference voltage level. The two voltage comparators are activated by a relay operated by the carrier wave of the transmitter so that the comparators function only when the transmitter is operating. The output signals from the two comparators are transmitted together with any other signals indicating a faulty condition, to a NAND gate which outputs an alarm signal whenever at least one fault signal is received. The alarm signal is then processed to switch off the transmitter and, if desired, to simultaneously switch on an alternate backup transmitter. A third comparator associated with the amplifier circuit for the meter that indicates the transmitter power output is used to provide a transmitter-on condition indication once the transmitter reaches a power level of 2% of its output power after being switched on.

Claims

1. A device for monitoring operating conditions of an RF transmitter having an output carrier wave, said operating conditions including the RF power output and reflected voltage wave thereof, and for promptly switching off said transmitter when a faulty condition is detected, comprising:

first comparator means comprising solid state circuit elements for comparing an input voltage signal representative of said RF power output with a predetermined reference voltage and for generating a first output signal when said voltage signal varies a predetermined amount from said predetermined reference voltage,

second comparator means comprising solid state circuit elements for comparing another input voltage signal representative of said reflected voltage wave with another predetermined reference voltage and for generating a second output signal when said other voltage signal varies a predetermined amount from said predetermined reference voltage,

relay means operated by the output carrier wave of said transmitter for activating said first and second comparator means,

time delay means operatively associated with said relay means so that said first and second comparator means are actuated only when said transmitter is switched on and has reached a normal operating condition,

a Schmitt trigger for conditioning said output voltage signals from said comparators to provide uniform steady voltage signals for transmission therefrom;

a NAND gate adapted to receive a plurality of voltage signals from said Schmitt trigger, including voltage signals representative of said output signals from said comparators, and to output an alarm signal voltage whenever at least one voltage signal is received whereby said alarm signal voltage may be used to switch off said transmitter.