EP0162646A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Ground speed sensor
Assignee: Deere and Co
•
Filing: 1985-05-13
•
Granted: —
•
Expires: 2005-05-13
Abstract
Abstract The sensor comprises an ultrasonic transmitter and receiver and a processing circuit in which a phase-locked loop tracks the received frequency in order to indicate the speed of a vehicle over the ground. A circuit (18) provides an attenuated and phase-shifted replica of the transmitted signal. This is combined in a circuit (20) with the received signal (14) to cancel out a cross-talk component in the received signal. A low pass filter (26) and squaring circuit (28) provide a signal (30) for the phase locked loop which is substantially pure at the reflected and received signal frequency. It is therefore possible to compare this with a reference frequency corresponding to zero speed to provide an output signal with sign and magnitude indicating respectively the direction (forwards or reverse) and speed of movement of the vehicle.
Inventors
- 👤 James Joseph Phelan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 04:57
CPC Classifications
G; G01; G01P; G01P13/00; G01S; G01S15/00; G01S15/02; G01S15/50; G01S15/58; G01S15/60; G01S13/00; G01S13/02; G01S13/50; G01S13/58; G01S13/60
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
166 words
A Doppler ground speed sensor for a vehicle, comprising a transmitter (12) for transmitting a signal with a given transmit frequency, a receiver (14) for receiving a reflected signal having a shifted frequency dependent on the speed and direction of movement of the vehicle, and a processing circuit (30) responsive to the received signal to provide a signal (Vv) representing the speed of the vehicle, characterised by a circuit (18) for producing an attenuated and phase-shifted replica of the transmitted signal, means (R9, RIO) for combining the received signal and the replica signal so as to cancel a transmitted signal cross-talk component in the received signal, thereby to provide an unmixed signal with substantially the pure reflected frequency, and in that the processing circuit (15) generates an output signal (Vv) with an amplitude proportional to the difference between the reflected frequency of the unmixed signal and a predetermined constant frequency, whereby the output signal indicates both the speed and the direction of movement of the vehicle.
Claim 2
Dependent Claim
166 words
A Doppler ground speed sensor for a vehicle, comprising a transmitter (12) for transmitting a signal with a given transmit frequency, a receiver (14) for receiving a reflected signal having a shifted frequency dependent on the speed and direction of movement of the vehicle, and a processing circuit (30) responsive to the received signal to provide a signal (Vv) representing the speed of the vehicle, characterised by a circuit (18) for producing an attenuated and phase-shifted replica of the transmitted signal, means (R9, RIO) for combining the received signal and the replica signal so as to cancel a transmitted signal cross-talk component in the received signal, thereby to provide an unmixed signal with substantially the pure reflected frequency, and in that the processing circuit (15) generates an output signal (Vv) with an amplitude proportional to the difference between the reflected frequency of the unmixed signal and a predetermined constant frequency, whereby the output signal indicates both the speed and the direction of movement of the vehicle.
Claim 3
Dependent Claim
18 words
A speed sensor according to claim 1, characterised in that the transmitter (12) continuously transmits the transmit frequency.
Claim 4
Dependent Claim
31 words
A speed sensor according to claim 1 or 2, characterised in that the output signal (Vv) has a sign and magnitude corresponding to the direction and speed respectively of vehicle movement.
Claim 5
Dependent Claim
52 words
A speed sensor according to claim 1, 2 or 3, the combining means comprises a summing amplifier (IC3), a first input resistor (R9) for the replica signal and a second input resistor (RIO) for the received signal, the first input resistor being a variable resistor for amplitude adjustment of the replica signal.
Claim 6
Dependent Claim
50 words
A speed sensor according to claim 4, characterised by a lowpass filter (26) having an input coupled to the output of the summing amplifier (IC3), a squaring circuit (28) having an input coupled to the output of the low pass filter and an output coupled to the processing circuit (30).
Claim 7
Dependent Claim
35 words
A speed sensor according to any of claims 1 to 5, characterised by a low pass filter (42) receiving the output signal generated by the processing circuit (30) for eliminating noise from the output signal.
Claim 8
Dependent Claim
22 words
A speed sensor according to any of claims 1 to 6, characterised in that the processing circuit (30) comprises a phase-locked loop.
Claim 9
Dependent Claim
22 words
A speed sensor according to any of claims 1 to 7, characterised in that the transmitted and reflected signals are ultrasonic signals.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.