Siemens Aktiengesellschaft

Peer Thilo

Otto W Moser

Karla Oberstein

Uwe Metzner

Peter Kupec

Karlheinz Schreyer

Herbert Foissner

Bernd Josef Siepmann

Klaus Drebinger

Wolfgang Kratzer

Hartmut Scherer

At a security fence comprising a plurality of electrodes disposed in parallel, a transmitter applies an alternating voltage to at least one of the electrodes. Remaining electrodes are grounded as receive electrodes. An ammeter measures electrode current and a measured value corresponding to an operating capacitance of this electrode is acquired and provided in every electrode circuit. Disruption factors are compensated on the basis of these measured values by means of comparison to earlier measured values of the same or of the other electrodes and by means of comparison to specific measured value patterns. An alarm is triggered only given non-compensatable measured values.

Method and arrangement for measuring changes of capacitive state at a

An electrode arrangement for capacitive guard fences wherein the conductor is horizontally stretched substantially parallel to the ground has a shape for preventing formation of water droplets which may collect as a result of precipitation from generating a false alarm and which also deters small animals from perching on the electrode. In one embodiment the electrode has a rectangular cross-section with the longest sides of the electrode being disposed substantially vertically. In another embodiment the electrode consists of two conductors having circular cross-sections which may be disposed parallel to one another or twisted. A further electrode embodiment has at least three conductors having very small circular cross-sections disposed at equal intervals from one another around a circular circumference. Means for facilitating water droplet runoff are provided at equal intervals which simultaneously serve as spacers for the conductors. Another electrode embodiment has a single line wire in the shape of a stretched helical spring.

Electrode arrangement for capacitive guard fences

A method and apparatus for monitoring an alarm system such as a fire alarm system having a plurality of alarms connected to a central station determine the amount of departure of measured alarm values from a rated quiescent value and calculate a fluctuation value therefrom, the fluctuation value then being compared at selected time intervals with a rated limiting value. If the result of the comparison shows that the fluctuation value is less than the rated limiting value, a malfunction signal is displayed.

Method and apparatus for monitoring an alarm system

A method and apparatus for inspecting a danger alarm system, such as a fire alarm system, having a plurality of discrete alarm units which are connected to a central station having a means for cyclically sampling and connecting the alarm units to a like plurality of evaluators permits the alarm units to be connected individually or in groups to an inspection display without suppressing the display of an actual alarm signal which may be received during the inspection. A first report of an alarm unit to be inspected is evaluated as an inspection report and an actual alarm report from the same alarm unit arriving after the inspection report is evaluated and displayed as an alarm report. Given alarm units which emit multi-level or analog signals, the alarm unit signals are evaluated in the central station with two threshold circuits, the evaluator at the central station being switched during an inspection to a less sensitive state and the inspection signals being evaluated by a lower threshold stage and a true alarm signal which may occur during an inspection being evaluated as such by an upper threshold stage.

Method and apparatus for inspecting a danger alarm system

A method and apparatus for increasing the response sensitivity and the interference resistance in an alarm system such as a fire alarm system which cyclically samples a plurality of alarm units in the system for obtaining a series of measured values from each alarm unit, the measured values being utilized to form a quiescent value which is stored in a quiescent value memory. With each sampling cycle a current comparison value is formed from the alarm measured value, the stored quiescent value, and a comparison value from a previous sampling cycle stored in a comparison value memory. The current comparison value is then written in the comparison value memory as the new comparison value. The current comparison value is compared with a rated limiting value, and if the comparison value is greater than or equal to the rated limiting value, a display unit is activated indicating an alarm. If the comparison value is less than the rated limiting value, a new quiescent value is formed from the measured value and the stored quiescent value and written into the quiescent value memory.

Method and apparatus for increasing the response sensitivity and the

In order to measure a magnetic field, an exciting current rising in small increments is applied to a measuring probe so that the coil of the probe traverses the entire range from the negative saturation up to the positive saturation. At the secondary side, respective voltage pulses which decay according to an e-function are measured at the coil. The time constant of the voltage pulses corresponds to the respective coil inductance. Since the coil inductance is shifted relative to the zero point of the exciting current due to an external magnitude field, more voltage pulses with a high time constant are produced on one side of the zero point than on the other side. By means of digital counting of all voltage pulses whose time constant exceeds a minimum value both given a negative exciting voltage as well as given a positive exciting voltage, one obtains two measured values whose difference directly produces a measured value for a strength of the external magnetic field.

Method and circuit arrangement for measuring a magnetic field

In a correction system for a magnetic field probe, the probe is first moved in a circle for calibration such that respective maximum and minimum values of a measured magnetic field vector or a respective component thereof is determined. By means of a sum formation and halving of the respective maximum and minimum value, a respective additive correction value is derived which is added to the respective measured values during navigation with the magnetic field probe. By so doing, a noise vector superimposed on the external magnetic field is eliminated.

Correction method and device for a magnetic field probe

A danger alarm system has a plurality of alarm circuits which are operable to provide environmental signals concerning the area about the respective alarm circuits. The alarm circuits are connected to a central exchange by way of respective lines which are terminated in the exchange by respective alarm connection circuits. A write-read memory is provided for storing the busy state of the respective lines, and receives the busy state information via an input multiplexer which is connected to a line state multiplexer through a plurality of logic gates. A comparator gates through alarm and line interrupt signals for each line in response to such signals together with busy condition signals from the memory. An output multiplexer connects the comparator to respective output indicator circuits for alarm conditions and line interrupt conditions.

Danger alarm system

In a danger alarm system, such as a fire alarm system, the availability of the system is increased by decentralization of the system intelligence. For this purpose, the entire system is subdivided into small system modules which are fully functional in and of themselves. Each system module has connection installations for one or more alarm circuits or one or more subordinate system modules, a programmed control for interrogation and evaluation of alarm signals, as well as connections for display operation and registration elements. One of the system modules serves as the central station, as the remaining system modules are subordinate to the central station in one or more hierarchical levels.

A fire alarm system comprises a plurality of alarms which may be operated via an alarm loop and which, being subject to selective interrogation, each alarm transmits an analog value of a particular characteristic of a fire to a central control, the analog value being tapped from a detector for that characteristic. Each alarm comprises an alarm circuit which has a load resistor which can be connected in parallel to the alarm loop by means of a timing element and which amplifies the current which characterizes the alarm at the instant of interrogation.

Fire alarm system comprising a plurality of alarms which may be operated

A fire alarm system has a central control connected to an alarm loop composed of a plurality of fire alarm circuits. Prior to an interrogation of the alarm circuits, the same are disconnected from a supply voltage and supplied by respective capacitors which are charged during connection of a full supply voltage. The individual alarms are subsequently reconnected in the alarm loop in a given sequence by a new voltage change, at a reduced voltage, and each alarm circuit is operable to connect the following alarm circuit to the loop and thus to the line voltage at a time delay corresponding to a measured value of a fire characteristic being monitored by that alarm circuit. In a central analysis device, the relevant alarm circuit address can be derived from the number of preceding increases in line current, and the associated measured value can be derived from the length of the switching delay of the corresponding alarm circuit. Different sequences of applying line voltage may be used such that three line voltage states of 'rest interval--interrogation--capacitor charge' and 'rest interval--capacitor charge--interrogation' and also the different durations of these states in that the line voltage state 'rest interval' is approximately one hundred times greater than is common to the other line states.

Process for generating and transmitting different analog measured values

In a process for fault recognition in a vehicle locating system, measuring signals are emitted from a vehicle which is to be located and are in each case received by a plurality of separately arranged receiving stations and forwarded, via lines, to a central station for analysis. The measuring signals received in the individual receiving stations are each supplied to checking devices which establish signal adulterations and analyze the latter to form fault signals. In the central station these fault signals are employed, by way of logic links, for the acquisition of specific disturbance reports.

Process for fault recognition in a vehicle locating system

A circuit arrangement for a DC to DC converter has at least one switching transistor and one transformer. The transformer includes a primary winding which is connected in the collector circuit of the transistor and a secondary winding from which at least one stabilized DC voltage may be tapped by way of rectifiers. The switching transistor is actuated and blocked by way of a control component in dependence upon load. A voltage comparison device is provided for comparing the collector-emitted voltage of the switching transistor with a predetermined reference value, and upon overshoot of the reference voltage the collector-emitter voltage is analyzed for disconnection of the base current of the switching transistor.

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Munich, Germany

Peer Thilo