Method and system for detecting a predetermined sound event such as the sound of breaking glass
View Patent ↗A method and system for detecting a predetermined sound event, such as the sound of breaking glass. Data representing monitored sounds is stored, such as in a circular buffer, while a preliminary assessment is made in real time as to whether the monitored sounds potentially include the predetermined sound event. If there is a potential correspondence, the already stored, pre-event data is frozen, and additional data including, and following, the event is stored. Next, the stored pre-event and additional data is retrieved from storage and provided to a processor that applies one or more algorithms to determine, with finality, if the event corresponds to the predetermined sound event.
1. A glass breakage detector comprising:
a microphone to convert incident audio signals to analog electrical signals;
an analog band pass filter with an input coupled to the analog electrical signals, a filtered output therefrom is coupled to detection circuitry which emits as an output signal a varying direct current-type signal defined by tracking band-pass average voltage and band-pass average peak voltage of an output of the analog band pass filter;
a comparator with a reference threshold coupled to a first input port of the comparator and with the output signal coupled to a second input port of the comparator wherein the comparator, responsive to the value of the outputs signal generates a trigger signal and
enables storage of a plurality of samples of the analog electric signals; and
circuitry, responsive to at least the stored plurality of samples to establish the presence of a glass breakage event.
2. The glass breakage detector as in claim 1 which includes pre-trigger signal data storage circuits and post-trigger data storage circuits where the pre-trigger data storage circuits are continually over-written by samples of the analog electric signals until the trigger signal is generated.
3. The glass breakage detector as in claim 2 where the microphone is coupled to an input port of a selected integrated circuit, the integrated circuit carries the filter, the comparator and includes a data ready output port, and a data clock input port.
4. The glass breakage detector as in claim 3 where the integrated circuit carries non-volatile storage which can be used to programmably establish the threshold value.
5. The glass breakage detector as in claim 3 where the data storage circuits are carried by the selected integrated circuit.
6. The glass breakage detector as in claim 5 with control circuits carried on the integrated circuit coupled at least to the data storage circuits and to the comparator.
7. The glass breakage detector as in claim 6 where the integrated circuit carries non-volatile storage which can be used to programmably establish the threshold value.
8. The glass breakage detector as in claim 6 where the control circuits are in a program mode when the threshold value is being programmed.
9. A glass breakage detector comprising:
a microphone;
an integrated circuit with an analog input port coupled to the microphone;
trigger circuits, carried by the integrated circuit and coupled to the analog input port, the trigger circuits establish a DC-type signal indicative of a glass breaking event;
control circuits and storage circuits carried by the integrated circuit with the control circuits coupled to the DC-type signal indicative of the glass breaking event where the storage circuits receive and store both pre-trigger and post-trigger data; and
processing circuits, coupled to a data output port of the integrated circuit to detect the presence of a glass breakage event in response to the stored data.
10. The glass breakage detector as in claim 9 which includes in the integrated circuit programmable reference value establishing non-volatile storage circuits coupled to the trigger circuits.
11. The glass breakage detector as in claim 10 where the trigger circuits include an analog comparator with a reference input coupled to the non-volatile storage circuits and with a signal input for the DC-type signal.
12. The glass breakage detector as in claim 11 where the control circuits are in a program mode when the programmable reference value is being programmed.