Distance detecting apparatus

• US 4,905,208 A
• Filed: 08/04/1987
• Issued: 02/27/1990
• Est. Priority Date: 08/04/1987
• Status: Expired due to Fees

• Current Assignee: Garmin Switzerland GmbH (Garmin Limited)
• Original Assignee: Interphase Technologies Incorporated (Garmin Limited)
• Inventors: Dick, Norman R.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Lobo, Ian J.
• Application Number:
  US07/081,330
• Time in Patent Office: 938 Days
• Field of Search: 367/127, 367/118, 367/124, 367/87, 367/88, 367/99, 367/98, 367/101, 367/107, 367/95, 367/97, 367/135, 367/137
• US Class Current: 367/99
• CPC Class Codes: G01S 15/107 using frequency agility of carrier wave
• CPC Class Codes: G01S 7/524 Transmitters
• CPC Class Codes: G01S 7/526 Receivers
• CPC Class Codes: G01S 7/529 Gain of receiver varied automatically during pulse-recurrence period for seismic signals G01V1/245
• CPC Class Codes: G01S 7/56 Display arrangements short-range imaging G01S7/52053

Abstract

A distance detecting apparatus has a transmitter for transmitting a cyclic output signal. The transmitter is digitally controlled to adjust the frequency of the output signal in relatively small increments through a band of frequencies. A receiver receives a cyclic reflected signal and has an adjustable center frequency of response. There is a device for adjusting the center frequency of response to correspond to the frequency of the output signal. The apparatus may have digital control for controlling the power level of the output signal. There may be a digital control for the gain of the receiver. The apparatus may also include a transducer for converting electrical signals to ultrasonic signals and include controls for adjusting the frequency of the output signal according to requirements of the transducer.

Claims

1. A distance detecting apparatus, comprising:

first means for producing a cyclic output pulse;

second means operatively connected to the first means for setting the output pulse at a first frequency and means for connecting the apparatus to a transducer to convert the output pulse to an ultrasonic signal, the first frequency being any of a plurality of transmit frequencies in a bandwidth of frequencies, said transmit frequencies being separated by increments of frequency which are small relative to the bandwidth, thereby allowing the transmit frequency to be tuned for transducers of different resonant frequencies;

third means for receiving a return pulse and having an adjustable centre frequency of response;

fourth means operatively connected to the third means for adjusting the centre frequency of response of the third means, so said centre frequency of response is the same as said first frequency; and

fifth means operatively connected to the first means and the third means for measuring time between an output pulse and a return pulse and thereby a distance.

2. An apparatus as claimed in claim 1 wherein the second means includes a programmable frequency oscillator.

3. An apparatus as claimed in claim 1, wherein the programmable frequency oscillator includes a fixed frequency oscillator, a controllable frequency oscillator, a programmable divider connected to the voltage controlled oscillator and a phase comparator connected to the fixed frequency oscillator and to the programmable divider, the phase comparator being connected to the controllable oscillator to stabilize the frequency of the controllable oscillator.

4. A distance detecting apparatus comprising transmitter means for producing a cyclic output signal, and a transducer means operatively connected to the transmitter means for converting the output signal to an ultrasonic signal, the transmitter means having an output stage and digitally controlled means for adjusting power supply voltage for the output stage and thereby power output of the transmitter to match power output of the transmitter with maximum power input of the transducer, the apparatus further including means for measuring the current of the power supply for the output stage, the means for adjusting the power supply voltage being responsive to the current of the power supply so that the power supply for the output stage and thereby the power of the output signal are at predetermined levels.

5. An apparatus as claimed in claim 4 wherein the means for adjusting includes a programmable power supply.

6. An apparatus as claimed in claim 5, wherein the programmable power supply includes a digital to analog converter connected to the output stage, a latch connected to the digital to analog converter to drive the digital to analog converter, a microprocessor connected to the latch for setting the latch, means for measuring current fed to the programmable power supply, and means for communicating said current measurement to the microprocessor.

7. An apparatus as claimed in claim 4, further including a microprocessor for digitally controlling the second means.

8. A depth sounding apparatus for transmitting an ultrasonic pulse and for receiving back a reflected pulse to indicate the depth of an object, the apparatus having a receiver with an adjustable frequency response extending over a band of frequencies, and means for adjusting the width of said band of frequencies, said means including a switched capacitor filter, and means for setting a centre frequency of response, wherein said means for adjusting the width of said band of frequencies is capable of increasing the bandwidth for a given centre of frequency of response when noise levels are low relative to the reflected pulse and of decreasing the bandwidth when noise levels are high, relative to the reflected pulse.

9. An apparatus as claimed in claim 8, including a plurality of filter stages in the receiver, each having a switched capacitor filter.

10. An apparatus as claimed in claim 9, wherein each said filter stage has a plurality of capacitors, a final said filter stage having a diode connected in series with each said capacitor.

11. An apparatus as claimed in claim 8, further including a microprocessor connected to the receiver for digitally controlling said means for adjusting the width of said band of frequencies.

23. An apparatus as claimed in claim 8, further comprising means for setting the bandwidth independently of the centre frequency of response.

24. An apparatus as claimed in claim 23, further including a microprocessor connected to the receiver for digitally controlling said means for setting the bandwidth independently of the centre frequency of response.

12. A distance detecting apparatus including:

a transmitter for producing periodic cyclic output electrical signals;

a transducer operatively connected to the transmitter for converting the output signals to output ultrasonic pulses, for receiving periodic reflected ultrasonic pulses and for converting the reflected pulses to periodic input electrical signals, each said input signal corresponding to one of the output signals;

a receiver operatively connected to the transducer for receiving the input electric signal, the receiver having a centre response frequency;

digitally controlled means operatively connected to the receiver for adjusting the centre response frequency to correspond to the frequency of the output electrical signals;

means operatively connected to the receiver for measuring time between each periodic output signal and a corresponding said periodic input signal, and for converting said time to a readable form indicating a distance at which the ultrasonic pulse is reflected; and

digitally controlled means operatively connected to the transmitter for adjusting the frequency of the output electrical signal in relatively small increments to a desired level within a band of frequencies generally between 40 kHz and 240 kHz.

13. An apparatus as claimed in claim 12, wherein the digitally controlled means for adjusting the centre response frequency includes a switched capacitor filter.

14. An apparatus as claimed in claim 12, wherein the programmable frequency oscillator includes a fixed frequency oscillator, a controllable frequency oscillator, a programmable divider connected to the controllable oscillator and a phase comparator connected to the fixed frequency oscillator and to the programmable divider, the phase comparator being connected to the controllable oscillator to stabilize the frequency of the controllable oscillator.

15. A distance detecting apparatus including:

a transmitter for producing periodic cyclic output electrical signals;

a transducer operatively connected to the transmitter for converting the output signals to output ultrasonic pulses, for receiving periodic reflected ultrasonic pulses and for converting the reflected pulses to periodic input electrical signals, each said input signal corresponding to one of the output signals;

a receiver operatively connected to the transducer for receiving the input electrical signals;

means operatively connected to the receiver for measuring time between each periodic output signal and a corresponding said periodic input signal, and for converting said time to a readable form indicating a distance at which the ultrasonic pulse is reflected; and

digitally controlled means operatively connected to the transmitter for adjusting the frequency of the output electrical signals in relatively small increments to a desired level within a band of frequencies generally between 40 kHz and 240 kHz, the digitally controlled means including a programmable frequency oscillator.

16. A distance detecting apparatus including:

a transmitter for producing periodic cyclic output electrical signals, said transmitter having an output stage;

a transducer operatively connected to the transmitter for converting the output signals to output ultrasonic pulses, for receiving periodic reflected ultrasonic pulses and for converting the reflected pulses to periodic input electrical signals, each said input signal corresponding to one of the output signals;

a receiver operatively connected to the transducer for receiving the input electrical signals;

means operatively connected to the receiver for measuring time between each periodic output signal and a corresponding said periodic input signal, and for converting said time to a readable form indicating a distance at which the ultrasonic pulse is reflected;

digitally controlled means connected to the transmitter for adjusting power level of the output electrical signals to a safe maximum level for the transducer, the means for adjusting the power level including a programmable power supply including a digital to analog converter connected to the output stage, a latch connected to the digital to analog converter to drive the digital to analog converter, a microprocessor connected to the latch for setting the latch, means for measuring current fed to the programmable power supply and means for communicating said current measurement to the microprocessor.

17. A distance detecting apparatus including:

a transmitter for producing periodic cyclic output electrical signals;

a transducer operatively connected to the transmitter for converting the output signals to output ultrasonic pulses, for receiving periodic reflected ultrasonic pulses and for converting the reflected pulses to periodic input electrical signals, each said input signal corresponding to one of the output signals;

a receiver operatively connected to the transducer for receiving the input electrical signals;

means operatively connected to the receiver for measuring time between each periodic output signal and a corresponding said periodic input signal, and for converting said time to a readable form indicating a distance at which the ultrasonic pulse is reflected; and

digitally controlled means operatively connected to the transmitter for adjusting the frequency of the output electrical signals in relatively small increments to a desired level within a band of frequencies generally between 40 kHz and 240 kHz, the digitally controlled means including means for incrementally increasing the frequency of the output electrical signals and of the output ultrasonic pulses through a preselected bandwidth, means for comparing amplitudes of reflected said ultrasonic pulses for each incremental frequency and means for setting and maintaining the frequency of the output electrical signals and of the output ultrasonic pulses at a frequency within the bandwidth where the reflected ultrasonic signals and the received noise are at optimum levels.

18. An apparatus as claimed in claim 17, wherein the means for incrementally increasing includes a microprocessor.

19. An apparatus as claimed in claim 17, wherein the means for setting and maintaining includes a latch.

20. A distance detecting apparatus including:

a transmitter for producing periodic cyclic output electrical signals;

a transducer operatively connected to the transmitter for converting the output signals to output ultrasonic pulses, for receiving periodic reflected ultrasonic pulses and for converting the reflected pulses to periodic input electrical signals, each said input signal corresponding to one of the output signals;

a receiver operatively connected to the transducer for receiving the input electrical signals, the receiver having a frequency of response extending over a band of frequencies and means for adjusting the bandwidth of said band of frequencies;

means operatively connected to the receiver for measuring time between each periodic output signal and a corresponding said periodic input signal, and for converting said time to a readable form indicating a distance at which the ultrasonic pulse is reflected; and

digitally controlled means operatively connected to the transmitter for adjusting the frequency of the output electrical signals in relatively small increments to a desired level within a band of frequencies generally between 40 kHz and 240 kHz.

21. An apparatus as claimed in claim 20, wherein said means for adjusting the bandwidth includes a switched capacitor filter.

22. An apparatus as claimed in claim 21, further including means for digitally controlling the switch capacitor filter.