EP0125108A2
Expired / Lapsed
EP
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Radar ground speed sensing system
Assignee: Deere and Co
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Filing: 1984-05-03
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Granted: —
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Expires: 2004-05-03
Abstract
Abstract A vehicle carries a radar transmitter (12) and receiver (14) which provides a Doppler signal representing vehicle ground speed. The Doppler signal is processed by a Schmitt trigger (18) and a flip-flop (20)to generate a symmetrical square wave whose instantaneous pulse-width is the reciprocal of the Doppler frequency. A microprocessor is interrupted by edges of the square wave and processes the pulse-width to produce a symmetrical output square wave (23). The processing steps comprise: (1) Input pulse widths exceeding a threshold value set by a timer are ignored (2) When the input pulse width INVAL is within 12½% of the output pulse width OUTVALthe latter is updated in accordance with a weighted average, OUTVAL = (15 OUTVAL + INVAL)/16 (3) When the input pulse width INVAL deviates more than 12;% from the output pulse width OUTVAL no updating occurs unless this situation has persisted for 8 or more input pulses, whereupon more abrupt updating occurs in accordance with a second weighted average OUTVAL = (3 OUTVAL + INVAL)/4 where INVAL is the average INVAL over 8 input pulses when the second weighted average is first used but is the latest input width when the situation has persisted for more than 8 input pulses.
Inventors
- 👤 Robert John Hoffa
- 👤 Carl Martin Burde
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 13:14
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/58; G01S13/585; G01S13/60
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
175 words
A radar ground speed sensing system for a vehicle comprising means (14, 16, 18, 20) responsive to a radar return signal reflected from the ground to provide an input pulse signal with a pulse-width inversely proportional to Doppler frequency, and processing means (22) operative to effect an averaging operation, characterised in that the processing means provide an output pulse signal with a pulse-width (OUTVAL) determined from the input signal pulse widths by the following processing steps: (1) Input pulse widths (INVAL) exceeding a threshold value are ignored (2) When an input pulse width (INVAL) does not deviate from the output pulse width (OUTVAL) by more than a predetermined amount the output pulse width is updated by the input pulse width in accordance with a first averaging algorithm (3) When a predetermined number of input pulse widths have deviated from the output pulse width by more than the predetermined amount, the output pulse width is updated by an average value derived from the predetermined number of input pulse widths in accordance with a second averaging algorithm.
Claim 2
Dependent Claim
175 words
A radar ground speed sensing system for a vehicle comprising means (14, 16, 18, 20) responsive to a radar return signal reflected from the ground to provide an input pulse signal with a pulse-width inversely proportional to Doppler frequency, and processing means (22) operative to effect an averaging operation, characterised in that the processing means provide an output pulse signal with a pulse-width (OUTVAL) determined from the input signal pulse widths by the following processing steps: (1) Input pulse widths (INVAL) exceeding a threshold value are ignored (2) When an input pulse width (INVAL) does not deviate from the output pulse width (OUTVAL) by more than a predetermined amount the output pulse width is updated by the input pulse width in accordance with a first averaging algorithm (3) When a predetermined number of input pulse widths have deviated from the output pulse width by more than the predetermined amount, the output pulse width is updated by an average value derived from the predetermined number of input pulse widths in accordance with a second averaging algorithm.
Claim 3
Dependent Claim
29 words
A system according to claim 1, characterised in that the first averaging algorithm is a weighted average of the output pulse width (OUTVAL) and the input pulse width (INVAL).
Claim 4
Dependent Claim
24 words
A system according to claim 2, characterised in that the output pulse width (OUTVAL) is weighted more heavily than the input pulse width (INVAL).
Claim 5
Dependent Claim
30 words
A system according to claim 1, characterised in that the second averaging algorithm is a weighted average of the output pulse width (OUTVAL) and the average input pulse width (INVAL).
Claim 6
Dependent Claim
25 words
A system according to claim 4, characterised in that the output pulse width (OUTVAL) is weighted more heavily than the average input pulse width (INVAL).
Claim 7
Dependent Claim
49 words
6 . A system according to claims 3 and 5, characterised in that the average input pulse width is weighted more heavily relative to the output pulse width in the second algorithm that the input pulse width is weighted relative to the output pulse width in the first algorithm.
Claim 8
Dependent Claim
25 words
A system according to claim 1, characterised in that the second algorithm causes more abrupt updating of the output pulse width than the first algorithm.
Claim 9
Dependent Claim
50 words
A system according to claim 7, characterised in that the second algorithm updates the output pulse width from the latest input pulse width in response to input pulse widths in excess of the predetermined number which continue to deviate from the output pulse width by more than the predetermined amount.
Claim 10
Independent Claim
107 words
A system according to any of claims 1 to 8, characterised in that the step (1) is implemented by generating a data present flag in response to a predetermined transition of the input pulse signal, by timer means for generating a time signal upon expiration of a predetermined time period, by clearing a data dropout flag when a data present flag is generated before generation of the time signal and by setting the data dropout flag when a data present flag is generated after generation of the time signal, and by preventing updating of the output pulse width in step (3) when the dropout flag is set.
Claim 11
Independent Claim
67 words
A system according to any of claims 1 to 9, characterised by an output timer, means for loading the output timer with an output value derived from the first or second algorithm, means for starting the output timer running after it is loaded with a derived output value, and means for producing a transition of the output pulse signal in response to expiration of the output timer.
Claim 12
Dependent Claim
44 words
A system according to claim 10, further characterised by inhibit means for preventing a transition of the output signal when the output timer expires due to the absence of predetermined transitions of the input signal pulse train after expiration of a predetermined time period.
Claim 13
Dependent Claim
27 words
A system according to claim 11, further characterised by means for setting the output signal to a predetermined state when transitions of the output signal are inhibited.
Claim 14
Dependent Claim
50 words
A system according to claim 10, 11 or 12, further characterised by enable means for producing a transition of the output signal when the output timer expires due to the presence of at least one predetermined transition of the input signal pulse train before expiration of a predetermined time period.
References Cited (Backward Citations)
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