System for measuring the transfer time of a sound-wave in a gas and thereby calculating the temperature of the gas

A system for measuring the transfer time of a sound wave in a gas, the velocity of said sound wave in the gas and thus the temperature of the gas using the relation between the temperature of the gas and the velocity at which said sound wave propagates through the gas, and, to this purpose, consisting of a current controlled emitter (T2) stimulated by a first electric signal to generate sound at a specific point in the gas, a receiver (T1) to receive said sound after the sound has traveled a given distance through the gas, a transducer for converting said sound into a second electric signal, a means of comparing said first and second electrical signals by means of a suitable algorithm and thus defining the transfer time of said sound, an indicator of the temperature of said gas being a function of the transfer time, wherein:

• the current controlled emitter (T2), generates a sound of coherent phase and substantially of a single or a group of frequencies;
• the receiver (T1) is followed by a self-correlating decoder, both associated to said emitter in order to send the sound received to a band-pass filter system with narrow band and extremely high stability FI;
• said system further comprising an electronic circuit breaker (K), that acts on the signal entering the filter system FI and which is driven by a microprocessor (MP) by means of an iterating algorithm so as to allow always a pre-set number of n first waves of the signal entering the filter system (FI);
• and wherein the signal out-going from the filter system FI forms a Hamming wave shape within a Time-Amplitude diagram, which is processed by said microprocessor (MP) in order to find the absolute maximum of the oscillations making up said Hamming wave shape, so as to determine therefrom the transfer time and, by reference to known characteristics of the gas, calculate the temperature of the gas.