Personal object detector

A personal object detector apparatus including a CTFM ranging system which transmits a frequency-swept pressure wave, receives a reflected frequency-swept pressure wave from each of at least one object, and forms an audio signal based upon a frequency difference between the frequency-swept pressure wave and each reflected frequency-swept pressure wave, the ranging system comprising:

• an FM sweep generator which generates the frequency-swept signal;
• a first transducer which generates the frequency-swept pressure wave;
• a second transducer which receives the reflected frequency-swept pressure wave and generates a reflected signal based thereupon;
• a summer which combines the reflected signal and the frequency-swept signal to form a combined signal;
• a detector which forms the audio signal by extracting a beat envelope contained in the combined signal;
• a signal filter in communication with the detector for producing a filtered audio signal having only a portion of frequency content of the audio signal;
• a reverberator in communication with the signal filter for adding reverberation to the filtered audio signal to produce a filtered reverberated audio signal;
• and
• a summer in communication with the detector and in communication with the reverberator for combining the audio signal with the filtered reverberated audio signal.

A personal object detector apparatus comprising:

• a housing which permits handheld use of the detector;
• a CTFM ranging system disposed within the housing, the ranging system transmitting a frequency-swept pressure wave, receiving a reflected frequency-swept pressure wave from each of at least one object, and forming an audio signal based upon a frequency difference between the frequency-swept pressure wave and each reflected frequency-swept pressure wave;
• and
• an audio output device disposed within the housing, the audio output device producing an acoustic pressure wave in dependence upon the audio signal.

A personal object detector comprising:

• a CTFM ranging system which transmits a frequency-swept pressure wave using a first transducer which generates the frequency-swept pressure wave based upon a frequency-swept signal generated by an FM sweep generator, the CTFM ranging system receiving a reflected frequency-swept pressure wave from each of at least one object, and forming an audio signal based upon a frequency difference between the frequency-swept pressure wave and each reflected frequency-swept pressure wave;
• and
• an audio output device which produces an acoustic pressure wave in dependence upon the audio signal;
• wherein the FM sweep generator includes a counter for receiving sweep parameters which control frequency of the FM sweep generator, a memory having a plurality of sine function values stored therein, the memory in communication with the counter for retrieving at least one of the plurality of sine function values based on counter output, a modulator in communication with the memory for receiving the at least one of the plurality of sine function values retrieved from the memory and producing a bit stream output, and a filter in communication with the modulator for converting the bit stream output to the frequency swept signal.

A method of detecting at least one object, the method comprising the steps of:

• transmitting a frequency-swept pressure wave;
• receiving a reflected frequency-swept pressure wave from each of the at least one object;
• and
• producing an acoustic pressure wave in dependence upon a frequency difference between the frequency-swept pressure wave and the reflected frequency-swept pressure wave, the acoustic pressure wave containing a tone for each of the at least one object wherein each tone has an intensity dependent upon a size of the corresponding one of the at least one object.

A personal object detector apparatus comprising:

• a first CTFM ranging system which transmits a first frequency-swept pressure wave, receives a first reflected frequency-swept pressure wave from an object, and forms a first signal dependent upon a frequency difference between the first frequency-swept pressure wave and the first reflected frequency-swept pressure wave;
• a second CTFM ranging system which transmits a second frequency-swept pressure wave, receives a second reflected frequency-swept pressure wave from the object, and forms a second signal dependent upon a frequency difference between the second frequency-swept pressure wave and the second reflected frequency-swept pressure wave;
• and
• a pair of audio output devices which produces a tone within a stereo sound image based upon the first signal and the second signal, wherein the tone is positioned within the stereo sound image in accordance with the lateral position of the object.