Swimming pool alarm

A method of detecting entry of an object into a body of water, comprising the steps of:

• transmitting a controlled sound wave into the body of water to set up a standing wave;
• detecting a sound wave having a predetermined frequency that is expected to occur when the object enters the body of water, the predetermined frequency being different than the frequency of the controlled sound wave;
• filtering the controlled sound wave from the detected sound wave;
• producing two electrical signals having amplitudes related to the amplitude of the detected sound wave, at least one of which represents an average of the amplitude of the detected sound wave;
• detecting when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount;
• and thereafter
• generating an alarm signal that is used to activate an alarm.

A method of detecting entry of an object into a body of water, comprising the steps of:

• establishing a standing wave in the body of water;
• separating from the standing wave a sound wave having a component in a predetermined range of frequencies expected to occur when the object enters the body of water;
• producing two electrical signals having amplitudes related to the amplitude of the sound wave, at least one of which represents an average of the amplitude of the sound wave;
• detecting when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount;
• and thereafter
• generating an alarm signal that is used to activate an alarm.

A method of detecting entry of an object into a body of water, comprising the steps of:

• transmitting a controlled sound wave into the body of water to set up a standing wave;
• detecting a sound wave having a component in a predetermined range of frequencies expected to occur when the object enters the body of water, the predetermined range of frequencies excluding the frequency of the controlled sound wave;
• producing two electrical signals having amplitudes related to the amplitude of the detected sound wave in the predetermined frequency range, at least one of which represents an average of the amplitude of the detected sound wave;
• filtering the controlled sound wave from the detected sound wave;
• detecting when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount;
• and thereafter
• generating an alarm signal that is used to activate an alarm.

An apparatus for detecting entry of an object into a body of water, comprising:

• a transmitter to establish a standing wave in the body of water;
• a sound wave detector for separating from the standing wave a sound wave having at least one predetermined frequency expected to occur when the object enters the body of water and for producing an electrical output waveform representing the detected sound wave;
• a rectifier electrically connected to the sound wave detector for rectifying the electrical output waveform;
• an integrator/comparator electrically connected to the rectifier for producing two electrical signals having amplitudes related to the amplitude of the electrical output waveform, at least one of which represents an average of the amplitude of the electrical output waveform, and for generating an alarm signal when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount;
• and
• an alarm electrically connected to the integrator/comparator that is activated in response to the alarm signal.

An apparatus for detecting entry of an object into a body of water, comprising:

• a signal generator for transmitting a controlled sound wave into the body of water to set up a standing wave;
• a sound wave detector for receiving a sound wave having at least one predetermined frequency expected to occur when the object enters the body of water, the predetermined frequency being different than the frequency of the standing wave, and for producing an electrical output waveform representing the detected sound wave;
• a rectifier electrically connected to the sound wave detector for rectifying the electrical output waveform;
• a filter for removing the controlled sound wave from the electrical output waveform;
• an integrator/comparator electrically connected to the rectifier for producing two electrical signals having amplitudes related to the amplitude of the electrical output waveform, at least one of which represents an average of the amplitude of the electrical output waveform, and for generating an alarm signal when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount;
• and
• an alarm electrically connected to the integrator/comparator that is activated in response to the alarm signal.

An apparatus for detecting entry of an object into a body of water, comprising:

• a transmitter to establish a standing wave in the body of water;
• a sound wave detector for separating from the standing wave a sound wave having at least one predetermined frequency expected to occur when the object enters the body of water and for producing an electrical output waveform representing the detected sound wave;
• a processing means electrically connected to the sound wave detector for producing two electrical signals having amplitudes related to the amplitude of the electrical output waveform, a first one of which represents an average of the amplitude of the electrical output waveform, and for producing an alarm signal when amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by predetermined amount;
• and
• an alarm electrically connected to the processing means that is activated in response to the alarm signal.

An apparatus for detecting entry of an object into a body of water, comprising:

• a transmitter to establish a standing wave in the body of water;
• sound wave detecting means for separating from the standing wave a sound wave having at least one predetermined frequency expected to occur when the object enters the body of water;
• signal output means connected to the sound wave detecting means for producing an electrical output waveform representing the detected sound wave;
• averaging means connected to the signal output means for producing two electrical signals having amplitudes related to the amplitude of the electrical output waveform, at least one of which represents an average of the amplitude of the electrical output waveform, and for producing an alarm signal when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount;
• and
• alarm activation means connected to the averaging means for activating an alarm in response to the alarm signal.

A method of detecting entry of an object into a body of water, comprising the steps of:

• transmitting a sound wave into the body of water to set up a standing wave that is disturbed when the object enters the body of water;
• detecting the disturbed sound wave and producing an electrical output waveform indicating the amplitude and frequency of the disturbed sound wave;
• producing two electrical signals having amplitudes related to the amplitude of the electrical output waveform, at least one of which represents an average of the amplitude of the electrical output waveform;
• generating an alarm signal when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount, indicating the entry of the object into the body of water;
• and
• activating an alarm in response to the alarm signal.

An apparatus for detecting entry of an object into a body of water, comprising:

• means for transmitting a sound wave into the body of water to set up a standing wave that is disturbed when the object enters the body of water;
• means for detecting the disturbed sound wave and for producing an electrical output waveform representing the disturbed sound wave;
• means for producing two electrical signals having amplitudes related to the amplitude of the electrical output waveform, at least one of which represents an average of the amplitude of the electrical output waveform;
• means for generating an alarm signal when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount, indicating the entry of the object into the body of water;
• and
• means for activating an alarm in response to the alarm signal.

An apparatus for detecting entry of an object over a predetermined size into a body of water, comprising:

• a signal generator for transmitting a sound wave into the body of water to set up a standing wave that is disturbed when the object enters the body of water;
• a sound wave detector for receiving the disturbed sound wave and producing an electrical output waveform indicating the amplitude and frequency of the disturbed sound wave;
• processing means electrically connected to the sound wave detector for producing two electrical signals having amplitudes related to the amplitude of the electrical output waveform, at least one of which represents an average of the amplitude of the electrical output waveform, and for detecting when the amplitude of one of the electrical signals exceeds the amplitude of the other electrical signal by a predetermined amount, indicating the entry of the object into the body of water;
• and
• an alarm electrically connected to the processing means that is activated in response to the alarm signal.