EARLY FIRE DETECTION METHOD AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2017 - IPC G08B17/00 

FIELD: fire safety.

SUBSTANCE: early fire detection method based on measuring the current value of the air concentrations of gas components selected from the group consisting of hydrogen, carbon monoxide, carbon dioxide and aromatic hydrocarbons released during the smoldering of combustible materials. The ratio of the measured concentrations of the gas components is determined and compared with the predetermined value thereof, if the values indicated coincide, an alarm is generated. Along with the alarm signal, a high-frequency oscillation and a modulating code that displays the identification number of the fire safety object and its coordinates are formed. The high-frequency oscillation in phase is modulated by the modulating code, amplifies the generated complex signal with phase manipulation in power, radiates it on the air, is captured at the control center and/or in the fire service. Strengthening the voltage, converting the frequency using the voltage of the local oscillator. Isolating the intermediate frequency voltage and searching for signals in a given frequency range by periodically tuning the local oscillator frequency, and then doubling the phase of the intermediate frequency voltage, measuring the width of the spectrum of the received signal at the intermediate frequency and its second harmonic. Converting the value of the spectral width into the corresponding amplitudes, determine the difference of these amplitudes, compare it with the threshold level and, in case of exceeding it, making a decision to detect a complex signal with phase shift keying, stopping the tuning of the local oscillator frequency for a time τ_Z, necessary for synchronous detection of the detected complex signal with phase manipulation, resolution of its further processing, during which it is divided into two phases, a harmonic oscillation at a frequency ω_p/2, double the phase, allocate the oscillation at the intermediate frequency ω_etc, are phase-shifted by 90° and used as the reference voltage for synchronous detection of the received signal with phase shift keying at the intermediate frequency. A low-frequency voltage proportional to the modulating code is isolated and recorded, after the expiration of the time T_z continue the tuning of the local oscillator frequency and search for signals in a given frequency range. In the process of converting the frequency of the received signal, the total frequency voltage is extracted, it is detected and the detected voltage is used to allow processing of the received signal by selection and detection of a complex signal with phase manipulation, allocating a false signal (interference) received on the forward transmission channel at an intermediate frequency ω_etc, invert it in phase by 180°, adding up with the received false signal (interference) and compensate it. A device for early detection of a fire is used to implement the method.

EFFECT: increasing the noise immunity and reliability of reception of alarm signals.

2 cl, 6 dwg