Data logging
First Claim
1. Apparatus for logging to a storage medium input signal values as a sequence of logged values and respective time periods for which said logged values subsist, said apparatus comprising:
- (i) a trigger-band comparitor for comparing an input signal value with a trigger-band of signal values to determine whether said input signal value is within said trigger-band following a preceding logged value; and
(ii) signal processing logic coupled to said trigger-band comparitor and responsive to said input signal value being outside of said trigger-band to trigger logging of a new logged value with a new time period and setting of a new value for said trigger-band, wherein;
(iii) said signal processing logic detects from said input signal value between said preceding logged value and said new logged value one or more intermediate points having predetermined characteristics;
(iv) said signal processing logic additionally logs said intermediate points;
(v) said logged value includes a rate of change value of said input signal value; and
(vi) said trigger band is updated to change in accordance with said rate of change value.
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Abstract
A logging system 2 is described in which an input signal value is compared by a signal processor 12 to a trigger-band 34 and an inner-band 36 centered about a previously logged value 34 and changing at a previously determined rate of change. When the trigger-band is exceeded at point 40, intermediate points are logged representing the maximum and minimum points since the last logged point and the point at which the inner-band was left. The intermediate points enable a more accurate subsequent reconstruction of the actual signal to be made from the logged values.
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Citations
19 Claims
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1. Apparatus for logging to a storage medium input signal values as a sequence of logged values and respective time periods for which said logged values subsist, said apparatus comprising:
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(i) a trigger-band comparitor for comparing an input signal value with a trigger-band of signal values to determine whether said input signal value is within said trigger-band following a preceding logged value; and
(ii) signal processing logic coupled to said trigger-band comparitor and responsive to said input signal value being outside of said trigger-band to trigger logging of a new logged value with a new time period and setting of a new value for said trigger-band, wherein;
(iii) said signal processing logic detects from said input signal value between said preceding logged value and said new logged value one or more intermediate points having predetermined characteristics;
(iv) said signal processing logic additionally logs said intermediate points;
(v) said logged value includes a rate of change value of said input signal value; and
(vi) said trigger band is updated to change in accordance with said rate of change value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
said signal processuig logic includes an inner-band comparitor for comparing said input signal value an inner-band of signal value to determine whether said signal value is within said inner band; - and
said signal processing logic detects that most recent point at which said input signal value was within said inner-band preceding said new logged value and logs said point as one of said intermediate points.
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3. Apparatus as claimed in claim 1, wherein said signal processing logic detects a maximum signal value point between said preceding logged value and said new logged value and logs said point as one of said intermediate points.
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4. Apparatus as claimed in claim 1, wherein said signal processing logic detects a minimum signal value point between said preceding logged value and said new logged value and logs said point as one of said intermediate points.
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5. Apparatus as claimed in preceding claim 1, wherein said logged value includes an initial signal level value of said input signal value.
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6. Apparatus as claimed in claim 1, said signal processing logic includes an inner-band comparitor for comparing said input signal value an inner-band of signal value to determine whether said signal value is within said inner band;
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said signal processing logic detects that most recent point at which said input signal value was within said inner-band preceding said new logged value and logs said point as one of said intermediate points; and
wherein said inner-band is updated to change in accordance with said rate of change value.
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7. Apparatus as claimed in claim 1, wherein said input signal value is sampled at a predetermined rate.
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8. Apparatus as claimed in claim 7, wherein said predetermined rate is a user set parameter.
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9. Apparatus as claimed in claim 5, wherein said time period is stored as a number of sampling periods for which said logged value subsists.
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10. Apparatus as claimed in claim 1, wherein a time stamp giving an absolute time value is periodically logged.
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11. Apparatus as claimed in claim 1, wherein said new logged value and said new time period represents said input signal value that subsisted from a time corresponding to an immediately preceding logged point to a time corresponding to logging of said new logged value and new time period.
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12. Apparatus as claimed in claim 1, wherein a signal level value, a rate of change value and a number of sampling periods for which said signal value and said rate of change value were valid are logged as a self-contained data unit.
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13. Apparatus as claimed in claim 1, wherein said inner band is centrally located within said trigger band.
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14. Apparatus as claimed in claim 3, said signal processing logic includes an inner-band comparitor for comparing said input signal value an inner-band of signal value to determine whether said signal value is within said inner band;
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said signal processing logic detects that most recent point at which said input signal value was within said inner-band preceding said new logged value and logs said point as one of said intermediate points; and
wherein said inner-band is centrally located within said trigger-band.
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15. Apparatus as claimed in claim 3, said signal processing logic includes an inner-band comparitor for comparing said input signal value an inner-band of signal value to determine whether said signal value is within said inner band;
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said signal processing logic detects that most recent point at which said input signal value was within said inner-band preceding said new logged value and logs said point as one of said intermediate points; and
wherein said inner-band has a width that is user set as a percentage of the width of said trigger-band.
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16. Apparatus as claimed in claim 1, wherein said storage medium is a computer readable medium.
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17. Apparatus as claimed in claim 1, wherein the width of said trigger-band is user set as a percentage of said input signal value.
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18. Apparatus as claimed in claim 1, comprising a sensor linked via a telecommunications link to a computer serving as said trigger-band comparitor and said signal processing logic.
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19. A method of logging to a storage medium input signal values as a sequence of logged values and respective time periods for which said logged values subsist, said method comprising the steps of:
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(i) comparing an input signal value with a trigger band of signal values to determine whether said input signal value is within said trigger-band; and
(ii) in response to said input signal value being outside of said trigger-band, triggering logging of a new logged value with a new time period and setting of a new value for said trigger-band, said logged value including a rate of change value of said input signal value, said method further comprising the step of;
(iii) detecting from said input signal value between said preceding logged value and said new logged value one or more intermediate points having predetermined characteristics;
(iv) additionally logging said intermediate points; and
(v) updating said trigger band to change in accordance with said rate of change value.
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Specification