Abstract: A glass breakage detector includes a cantilever assembly incorporating a base member having a first beam coupled thereto. The base assembly is secured to a pane of glass with the beam extending along an axis determined by the plane contaning the glass. A piezoresistive device is positioned on the beam and adapted to change its resistance upon deflection of the beam due to the breakage of said glass and based upon the application of a vector component of force as deflecting the beam. Other embodiments employ at least another cantilever assembly also having a beam and sensor with the beam directed relatively transverse to the first beam and adapted to respond to force components normal to said vector component.

Abstract: An improved transmitter/receiver for use on a common cable communications system which permits sending and receiving of data at multiple data rates. Each transmitter first transmits a message alerting the intended receiver. The message also informs the receiver of the rate at which data is to be transmitted. This data rate is a function of the available bandwidth between the transmitting transmitter and receiving receiver. Each transmitter includes a memory of such bandwidth for all receivers on the cable.

Abstract: A breakawy fender guide for a vehicle has an upright elongated tube member yieldably mounted to the vehicle bumper by means of a breakaway hinge member attached to the lower portion of the guide. Upon mounting the hinge provides for a selected displacement of the guide from the side of the vehicle to provide a visual marker to the vehicle operator indicating the outboard side thereof. A hinge pin threaded at the ends thereof engages a nut/washer combination in an adjustable bearing relationship against the barrel sections of the respective leaves of the hinge for variously adjusting the force needed to urge the hinge into breakaway movement so as to move the guide from the selected position.

Abstract: A system for monitoring the position of a receptor reradiator in a surveillance zone having a first means for transmitting a first signal through the zone, and a receptor reradiator operable in response to reception of said signal to radiate at least one reply signal which is a function of the first signal and of the position of said receptor reradiator in the zone. There is also a receiver for receiving the reply signal, means controlled by the receiver, dependent upon the reply signal to indicate the position of the receptor reradiator in the zone, and an alarm triggerable by the receiver responsive to the latter for receiving the reply signals.

Abstract: Differential pulse code modulation (DPCM) is used for a fast digital transmission of the analog input signal. In the DPCM modulator, a difference is built between the scaled input signal and the output of a digital/analog converter, which is controlled by a digital integrator. Comparator means generate a DPCM signal with values corresponding to "no change", "up-" or "down-integration" in dependence on the amplitude and polarity of the mentioned difference. The zero-crossings of the input signal itself are detected separately and are converted into a one-bit PCM signal, having the value "reset". The DPCM and PCM signals are combined into a multi-value control signal, which is fed to the integrator and causes it to follow-up the input signal and make a reset at each zero-crossing. The multi-value control signal is coded, transmitted to the receiver side of the link and decoded. The different decoded values control an integrator in the demodulator in the same way, as in the modulator.

Abstract: A liquid flow detecting device incorporates a static member arranged to be fixed within a passage through which flow of an operating liquid is to take place and an active member held captive by the static member but free to move relatively to the static member to a limited extent in one particular direction at least. The active member has an overall specific gravity substantially the same as that of the chosen operating liquid. Proximity sensing apparatus is included to detect movement of the active member relative to the static member in the particular direction and to issue a corresponding signal.

Abstract: In a security alarm system, connections between a local sensor unit or units and a control unit are established by flexible optical light fibre guides, a normal condition of a sensor being indicated by the maintenance of a light signal or signals passing through an associated guide from the sensor unit to the control unit where there is monitoring of at least one parameter of the signal which is dependent on the integrity of the guide.

Abstract: A light detection, signaling and speed measurement system. The system includes a housing having a first photosensitive surface mounted therein for detection of an incident light source approaching the system from any direction. The system further includes at least one light signal device mounted for visibility, along with circuitry responsive to detection of the incident light source for illuminating the light signal device. A second photosensitive surface is also provided to receive largely ambient light and to be nonresponsive to the light of the incident light source, along with circuitry to allow the illumination of the light signal device only when the second photosensitive surface detects the absence of a predetermined level of ambient light. The system further includes circuitry for detecting and indicating the velocity of the incident light source moving with respect to the system.

Abstract: In an audio visual alarm device that can be mounted on a wall or a post an enclosure with an automatic dusk to dawn security light, a selectively energizable rotating signal light and an audible electrically actuated siren. A remotely controlled relay energizes the alarm and a circuit arranged to extinguish the security light upon actuation of the alarm.

Abstract: In an alarm system, differently colored leads of the connection cable between the individual distributors are respectively assigned to different current paths according to a random sequence. By providing this association, targeted manipulations at the connection lines of the signal lines are prevented.