VSWR alarm system

Claim 2

A voltage standing wave ratio alarm system comprising: first means to detect a forward voltage and a reflected voltage on a transmission line; second means coupled to said first means to amplify said reflected voltage by a given value dependent upon the desired voltage standing wave ratio; third means coupled to said first means and said second means to compare the amplitude of said amplified reflected voltage to the amplitude of said forward voltage and to produce an alarm indication when the amplitude of said amplified reflected voltage is greater than the amplitude of said forward voltage; a source of transmit ready signal, said transmit ready signal being present at the output of said source only when a transmitter associated with said system is transmitting on said transmission line; and fourth means coupled to said third means and said source responding to the simultaneous presence of said transmit rEady signal and said alarm indication to produce an alarm.

Claim 3

A voltage standing wave ratio alarm system comprising: first means to detect a forward voltage and a reflected voltage on a transmission line; second means coupled to said first means to amplify said reflected voltage by a given value dependent upon the desired voltage standing wave ratio; third means coupled to said first means and said second means to compare the amplitude of said amplified reflected voltage to the amplitude of said forward voltage and to produce an alarm indication when the amplitude of said amplified reflected voltage is greater than the amplitude of said forward voltage; a source of transmit ready signal, said transmit ready signal being present at the output of said source only when a transmitter associated with said system is transmitting on said transmission line; and fourth means coupled to said third means and said source responding to the simultaneous presence of said transmit rEady signal and said alarm indication to produce an alarm.

Claim 4

A voltage standing wave ratio alarm system comprising: first means to detect a forward voltage and a reflected voltage on a transmission line; second means coupled to said first means to amplify said reflected voltage by a given value dependent upon the desired voltage standing wave ratio; third means coupled to said first means and said second means to compare the amplitude of said amplified reflected voltage to the amplitude of said forward voltage and to produce an alarm indication when the amplitude of said amplified reflected voltage is greater than the amplitude of said forward voltage; a source of transmit ready signal, said transmit ready signal being present at the output of said source only when a transmitter associated with said system is transmitting on said transmission line; and fourth means coupled to said third means and said source responding to the simultaneous presence of said transmit rEady signal and said alarm indication to produce an alarm.

Claim 5

A system according to claim 1, further including fifth means coupled between said first means and said third means to amplify said forward voltage by a predetermined amount; and sixth means coupled between said first means and said second means to amplify said reflected voltage said predetermined amount.

Claim 6

A system according to claim 2, wherein each of said fifth and sixth means includes an operational amplifier having a gain equal to said predetermined amount.

Claim 7

A system according to claim 1, further including fifth means coupled to the output of said third means to store said alarm indication and provide a voltage standing wave ratio alarm when said alarm indication is present in said fifth means; sixth means coupled to said fifth means to activate a fault lamp; and seventh means coupled to said fifth means and said sixth means, said seventh means being activated in response to activation of said fault lamp to reset said fifth means after a given time interval.

Claim 8

A system according to claim 4, wherein said first means includes a directional coupler coupled to said transmission line to detect said forward and reflected voltage.

Claim 9

A system according to claim 4, wherein said second means includes an operational amplifier having an adjustable gain to amplify said reflected voltage by said given value.

Claim 10

A system according to claim 4, wherein said third means includes an operational amplifier coupled to said first means and said second means to operate as an amplitude comparator, said forward voltage being employed as a reference voltage by said operational amplifier.

Claim 11

A system according to claim 4, wherein said fourth means includes a NAND gate responding to the simultaneous presence of said alarm indication and said transmit ready signal from said source.

Claim 12

A system according to claim 4, wherein said fifth means includes a pair of cross coupled NAND gates coupled to the output of said fourth means.

Claim 13

A system according to claim 4, wherein said sixth means includes a transistor having its base coupled to the output of said fifth means, its emitter grounded and its collector coupled to said fault lamp.

Claim 14

A system according to claim 4, wherein said seventh means includes a timer circuit having three interconnected transistors coupled between the output of said sixth means and a reset input of said fifth means.

Claim 15

A system according to claim 4, wherein said first means includes a directional coupler coupled to said transmission line having a first output providing said forward voltage and a second output providing said reflected voltage; said second means includes a first operational amplifier having an adjustable gain to amplify said reflected voltage by said given value and having its non-inverting input coupled to said second output of said directional coupler; said third means includes a second operational amplifier having its inverting input coupled to said first output of said directional coupler and its non-inverting input coupled to the output of said first operational amplifier; said fourth means includes a first two input NAND gate having one of its inputs coupled to the output of said second operational amplifier and its other input coupled to said source of said transmit ready signal so that said alarm is produced only during the simultaneous presence of said transmit ready signal and said alarm indication; said fifth means includes a second two input NAND gate, a third two input NAND gate having one input connected to the output of said second NAND gate and an output to provide said alarm when said alarm indication and said transmit ready signal are present, said output of said third NAND gate being connected to one input of said second NAND gate, and the other input of sAid second NAND gate being connected to the output of said first NAND gate; said sixth means includes a first transistor having its base connected to the output of said second NAND gate, its emitter grounded and its collector coupled to said fault lamp; and said seventh means includes a timer circuit having a second transistor with its base coupled to the collector of said first transistor and its emitter grounded, a third transistor with its emitter connected to the collector of said second transistor, its base connected to the other input of said third NAND gate, and a fourth transistor with its base connected to the collector of said third transistor, its emitter grounded and its collector connected to the other input of said third NAND gate.