FM monitoring system

Claim 2

Modulation apparatus for monitoring frequency modulated signal transmissions comprising: means for deriving the frequency modulation signal components from said frequency modulated signal transmission; means for generating controlled sequential bursts of continuous wave signals at predetermined frequencies, said bursts bearing a fixed relation to modulation limits for said frequency modulated signal transmission; display apparatus including a visual display screen; and signal processing apparatus operative to alternately apply the frequency modulation signal components from said frequency modulated signal transmissions and the controlled sequential bursts of continuous wave signals to said display apparatus, whereby a visual display is presented to show the relation of the frequency modulation of the signal transmissions to the modulation limits as represented by said sequential bursts of continuous wave signals.

Claim 3

The invention according to claim 1 wherein said display apparatus is a cathode ray oscilloscope including horizontal and vertical input terminals wherein the inputs to the vertical input terminals is derived from said signal processing apparatus and further including horizontal drive circuit means adapted to provide a composite drive signal consisting of a plurality of saw tooth wave signals alternated between sinusoidal signal components of predetermined frequency, said composite drive signal being adapted to be applied to the horizontal input terminals of said cathode ray oscilloscope.

Claim 4

The invention according to claim 1 wherein said means for generating controlled sequential bursts of continuous wave signals at predetermined frequencies comprises: at least a first plurality of crystal controlled logic circuit oscillators, each adapted to provide a continous wave output at a fixed frequency; a circuit clock generator ring counter operative to sequentially activate each of said crystal controlled logic circuit oscillators; and buffer and pulse transformer amplifier means operative to receive the outputs from said crystal controlled logic circuit oscillators and provide a composite output of a repeating sequence of bursts of continous wave signals.

Claim 5

The invention according to claim 3 wherein said plurality of crystal controlled logic circuit oscillators consists of three oscillators, the first providing a signal output at 10.625 mega-hertz, the second providing a signal output at 10.700 mega-hertz and the third providing a signal output at 10.775 mega-hertz.

Claim 6

The invention according to claim 4 additionally comprising a second plurality of two crystal controlled logic circuit oscillators, one providing a signal output at plus 7.5 kilo-hertz and the other providiNg a signal output at minus 7.5 kilo-hertz.

Claim 7

The invention according to claim 1 wherein said signal processing apparatus includes electronic switching means logically controlled to alternately pass the frequency modulation signal components from said frequency modulated signal transmissions and controlled sequential bursts of continuous wave signals.

Claim 8

The invention according to claim 6 wherein said signal processing apparatus additionally comprises: amplifier limiter circuit means adapted to receive the output from said electronic switching means; ratio detector circuit means adapted to receive the output from said amplifier limiter circuit means; and vertical amplifier circuit means operative to receive the output from said ratio detector circuit means and provide a signal output therefrom adapted to be applied to said display apparatus.

Claim 9

The invention according to claim 2 wherein said horizontal drive circuit means comprises: sawtooth generator circuit means operative to provide a continous train of sawtooth wave signals at a predetermined frequency; a source of continous sinusoidal signals of predetermined frequency; a flip-flop circuit having two input terminals, the first adapted to receive the continous train of sawtooth wave signals and the second adapted to receive the continous sinusoidal signals; and gate circuit means operative to sequentially gate said flip-flop circuit to provide a composite output signal consisting of a plurality of sawtooth wave signals alternated between said sinusoidal signal components.

Claim 10

The invention according to claim 8 wherein said sawtooth generator circuit means operates at a frequency of 15 kilo-hertz.

Claim 11

The invention according to claim 8 wherein the frequency of said continous sinusoidal signals is one hundred and 20 hertz.

Claim 12

The invention according to claim 1 additionally comprising means for providing an aural indication of the received frequency modulated signal transmissions.

Claim 13

Apparatus for monitoring the modulation of a transmitted frequency modulation signal including: apparatus operative to receive said signal and generate therefrom an intermediate frequency component of said frequency modulation signal; calibrator apparatus operative to provide sequential bursts of controlled signals at predetermined frequencies; cathode ray display apparatus including horizontal and vertical input terminals adapted to receive signal inputs; amplifier circuit means having output terminals, said output terminals being connected to the vertical input terminals of said cathode ray display apparatus; drive circuit means operative to provide a composite output signal having selected signal components of predetermined form and frequency; means for applying the output signal from said drive circuit means to the horizontal input terminals of said cathode ray display apparatus; electronic switching means having at least first and second input terminals adapted to receive, respectively, the intermediate frequency component of said frequency modulation signal and the sequential bursts from said calibrator apparatus and an output terminal, said electronic switching means being operative to provide an output signal comprising alternate half cycles of the intermediate frequency component of said frequency modulation signal and the sequential bursts from said calibrator apparatus; and means for applying the output signal from said electronic switching means to said amplifier circuit means, whereby a display is generated on said cathode ray display apparatus indicating the modulating signal and the modulation limits and the relation therebetween.

Claim 14

Apparatus for monitoring the modulation of a transmitted frequency modulation signal including: apparatus operative to receive said signal and generate therefrom an intermediate frequency component of said frequency modulation signal; calibrator apparatus operative to provide sequential bursts of controlled signals at predetermined frequencies; cathode ray display apparatus including horizontal and vertical input terminals adapted to receive signal inputs; amplifier circuit means having output terminals, said output terminals being connected to the vertical input terminals of said cathode ray display apparatus; drive circuit means operative to provide a composite output signal having selected signal components of predetermined form and frequency; means for applying the output signal from said drive circuit means to the horizontal input terminals of said cathode ray display apparatus; electronic switching means having at least first and second input terminals adapted to receive, respectively, the intermediate frequency component of said frequency modulation signal and the sequential bursts from said calibrator apparatus and an output terminal, said electronic switching means being operative to provide an output signal comprising alternate half cycles of the intermediate frequency component of said frequency modulation signal and the sequential bursts from said calibrator apparatus; and means for applying the output signal from said electronic switching means to said amplifier circuit means, whereby a display is generated on said cathode ray display apparatus indicating the modulating signal and the modulation limits and the relation therebetween.