Circuit arrangement for the transmission of measurements to a central, especially in a fire alarm system
First Claim
1. Apparatus for the transmission of alarm signals to a detector, comprisinga signaling channel,means for energizing said signaling channel,means for applying monitoring signals to said channel at a first frequency,means for applying alarm signals to said channel at a second frequency greater than that of said first frequency, andmeans connected to said channel for detecting the monitoring and alarm signals,wherein the duration of said monitoring signals is no longer than the interval between said alarm signals.
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Accused Products
Abstract
Several arrangement in which several measurement sources (fire alarms) are connected in parallel to a two-wire line. The supply voltage for the measurement sources is simultaneously fed through this line. Here, a measurement is formed by switching a measurement shunt circuit into the two-wire line, to generate measurement pulses, where the switch-in process is controlled by a local pulse generator. Each measurement source is provided with a pulse generator, and all these pulse generators operate at frequencies of the same order of magnitude. A monitoring circuit, at the far end of the two-wire line, is switched through by a pulse generator whose frequency is significantly lower. The pulse duration of the monitoring pulses is no longer than the pulse pauses of the measurement pulses.
15 Citations
8 Claims
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1. Apparatus for the transmission of alarm signals to a detector, comprising
a signaling channel, means for energizing said signaling channel, means for applying monitoring signals to said channel at a first frequency, means for applying alarm signals to said channel at a second frequency greater than that of said first frequency, and means connected to said channel for detecting the monitoring and alarm signals, wherein the duration of said monitoring signals is no longer than the interval between said alarm signals.
Specification