Technique for the detection of flat wheels on railroad cars by acoustical measuring means
First Claim
1. Apparatus for acoustically detecting the presence of flat wheels on railroad cars, comprisingan electro-acoustic transducer located on the track wayside so as to pick up vibrations generated by a passing train, and to provide a spectrum of electrical signals corresponding to the vibrations;
- means for demodulating and band limiting said spectrum of electrical signals from said transducer;
a sampling analog-to-digital converter connected to said first named means so as to sample signals from the first named means at a predetermined frequency or period;
means for providing a signal indicative of train speed;
a digital first order adaptive filter for receiving sample signals from said converter and a signal from said means for providing a signal indicative of train speed, said adaptive filter having a cutoff frequency which is a function of train speed so as to enhance the signal-to-noise ratio of the signals processed thereby;
an autocorrelator for receiving signals from said adaptive filter and for performing autocorrelation with respect to each of the predetermined signal samples and of the ten signal samples preceding each of the predetermined samples;
a sampling gate, including means for permitting signals from said adaptive filter to be transmitted to said autocorrelator is dependence on the train speed.
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Abstract
Method and apparatus for detecting the presence of flat wheels on railroad cars, comprising an electro-acoustic transducer located on the track wayside so as to pick up the vibrations generated by a passing train. If a flat wheel is present it will generate a periodic clanging sound at a frequency proportional to train speed and wheel diameter. The invention capitalizes particularly on the measurement of train speed to control the response of an adaptive filter so as to enhance the periodic clanging frequency with respect to the background noise, thereby to improve the signal-to-noise ratio; the enhanced signal is further autocorrelated for ten wheel revolutions and if a periodic signal is present in the narrow frequency band of interest, a large periodic autocorrelation output will result and, as a consequence, any wheel flat will be readily detected and will act to trigger an alarm to alert the train crew of the condition.
31 Citations
11 Claims
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1. Apparatus for acoustically detecting the presence of flat wheels on railroad cars, comprising
an electro-acoustic transducer located on the track wayside so as to pick up vibrations generated by a passing train, and to provide a spectrum of electrical signals corresponding to the vibrations; -
means for demodulating and band limiting said spectrum of electrical signals from said transducer; a sampling analog-to-digital converter connected to said first named means so as to sample signals from the first named means at a predetermined frequency or period; means for providing a signal indicative of train speed; a digital first order adaptive filter for receiving sample signals from said converter and a signal from said means for providing a signal indicative of train speed, said adaptive filter having a cutoff frequency which is a function of train speed so as to enhance the signal-to-noise ratio of the signals processed thereby; an autocorrelator for receiving signals from said adaptive filter and for performing autocorrelation with respect to each of the predetermined signal samples and of the ten signal samples preceding each of the predetermined samples; a sampling gate, including means for permitting signals from said adaptive filter to be transmitted to said autocorrelator is dependence on the train speed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification