Security alarm transmission of radio frequency coded pulses

Claim 2

A security alarm system for transmitting and receiving coded signals, said system comprising: A. Radio transmitter means for generating an RF signal, said radio transmitter means being adapted to be carried camouflagedly by a person and including modulator means for modulating said RF signal with an audiofrequency signal itself modulated with a pulse code signal having short and long marks and spaces, said modulator means including:

Claim 3

A transistor multivibrator means for generating said audiofrequency signal, said transistor multivibrator means being connected by a supply conductor to a power supply with compensating diode means being inserted into said supply conductor for stabilizing the frequency of said transistor multivibrator means against changes in ambient temperature and power supply voltage;

Claim 4

A transistor multivibrator means for generating said audiofrequency signal, said transistor multivibrator means being connected by a supply conductor to a power supply with compensating diode means being inserted into said supply conductor for stabilizing the frequency of said transistor multivibrator means against changes in ambient temperature and power supply voltage;

Claim 5

A bistable multivibrator means and a slowly oscillating multivibrator means coupled together to generate said pulse code signal and connected to said transistor multivibrator means to switch the same in accordance with said pulse code signal; and B. Radio receiver means tuned to said RF signal for receiving the same, said radio receiver means including an intermediatefrequency stage, a detector means, an audiofrequency filter means, and pulse-decoding means, said pulse-decoding means including a plurality of delay circuit means controlled by changes in level of the received audiofrequency signal, and a plurality of bistable circuit means actuated by said delay circuit means for distinguishing between short and long intervals between the pulses and for detecting predetermined sequences of pulses, and an alarm triggering circuit means controlled by said decoding means, said alarm triggering circuit means being provided with a delay circuit means whereby an alarm device is actuated in response to the decoded signals.

Claim 6

A bistable multivibrator means and a slowly oscillating multivibrator means coupled together to generate said pulse code signal and connected to said transistor multivibrator means to switch the same in accordance with said pulse code signal; and B. Radio receiver means tuned to said RF signal for receiving the same, said radio receiver means including an intermediatefrequency stage, a detector means, an audiofrequency filter means, and pulse-decoding means, said pulse-decoding means including a plurality of delay circuit means controlled by changes in level of the received audiofrequency signal, and a plurality of bistable circuit means actuated by said delay circuit means for distinguishing between short and long intervals between the pulses and for detecting predetermined sequences of pulses, and an alarm triggering circuit means controlled by said decoding means, said alarm triggering circuit means being provided with a delay circuit means whereby an alarm device is actuated in response to the decoded signals.

Claim 7

A bistable multivibrator means and a slowly oscillating multivibrator means coupled together to generate said pulse code signal and connected to said transistor multivibrator means to switch the same in accordance with said pulse code signal; and B. Radio receiver means tuned to said RF signal for receiving the same, said radio receiver means including an intermediate-frequency stage, a detector means, an audiofrequency filter means, and pulse-decoding means, said pulse-decoding means including a plurality of delay circuit means controlled by changes in level of the received audiofrequency signal, and a plurality of bistable circuit means actuated by said delay circuit means for distinguishing between short and long intervals between the pulses and for detecting predetermined sequences of pulses, and an alarm triggering circuit means controlled by said decoding means, said alarm triggering circuit means being provided with a delay circuit means whereby an alarm device is actuated in response to the decoded signals.

Claim 8

A bistable multivibrator means and a slowly oscillating multivibrator means coupled together to generate said pulse code signal and connected to said transistor multivibrator means to switch the same in accordance with said pulse code signal; and B. Radio receiver means tuned to said RF signal for receiving the same, said radio receiver means including an intermediate-frequency stage, a detector means, an audiofrequency filter means, and pulse-decoding means, said pulse-decoding means including a plurality of delay circuit means controlled by changes in level of the received audiofrequency signal, and a plurality of bistable circuit means actuated by said delay circuit means for distinguishing between short and long intervals between the pulses and for detecting predetermined sequences of pulses, and an alarm triggering circuit means controlled by said decoding means, said alarm triggering circuit means being provided with a delay circuit means whereby an alarm device is actuated in response to the decoded signals.

Claim 9

A security alarm system as defined in claim 1, wherein said delay circuit means of said alarm triggering circuit means delays actuation of said alarm device until several sequential correct code are detected.

Claim 10

A security alarm system as defined in claim 1, wherein said receiver means further comprises means coupled therewith controlling said receiveR such that the receiver only responds to a predetermined lowest input voltage, whereby no alarm triggering occurs in the event of a lower input voltage.

Claim 11

A security alarm system as defined in claim 3, wherein said receiver means includes inverter means for inverting incoming coded pulses, and wherein said delay circuit means responsive to changes in level of said audiofrequency signal comprises a first delay means triggered by the trailing edge of a mark, said first delay means being coupled to a first bistable circuit means for sampling the length of the spaces, and a second delay means triggered by the trailing edge of an inverted mark, said second delay means being coupled to a second bistable circuit means for sampling the length of the marks.

Claim 12

A security alarm system as defined in claim 4, wherein said receiver means includes a third bistable circuit means biased from the outputs of one of said first and second bistable circuit means respectively coupled to said first and second delay means, said third bistable circuit means storing information relating to the pulse immediately preceding the pulse which actuated said one of said first and second bistable circuit means.