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EP0586256A2
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EP
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Time measurement system
Assignee: Nokia Oyj
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Filing: 1993-09-03
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Granted: —
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Expires: 2013-09-03
Abstract
Abstract A time measurement system for measuring time accurately with an inaccurate clock, in which two clock oscillators are compared and the momentary error of the slower clock oscillator is measured. When the error change rate of the slower clock oscillator is slow enough the fast clock oscillator can be switched off for longer time intervals. With the help of this apparatus and method of operation power can be saved in portable equipment which requires accurate time measurement.
Inventors
- 👤 Harri Jokinen
- 👤 Sakari Jorri
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 13:03
CPC Classifications
G; G04; G04G; G04G7/00; G04G3/00; G04G3/02; G04G3/027; H; H04; H04W; H04W52/00; H04W52/02; H04W52/0209; H04W52/0261; H04W52/0287; H04W52/0293; Y; Y02; Y02D; Y02D30/00; Y02D30/70
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
131 words
An apparatus for producing pulses comprising a first clock oscillator (1) for outputting a relatively high frequency signal (f₂) and a second clock oscillator (3) for outputting a relatively low frequency signal (f₁), an error calibrating means (5) for measuring a deviation of the relatively low frequency signal (f₂) from a predetermined frequency, and control means (6) for selectively coupling the relatively high frequency signal (f₁) and the relatively low frequency signal (f₂) to a counter means (2) for outputting said pulses, wherein the control means (6) couples the relatively high frequency signal to the counter means (2) for a time period (T₁₁,T₃₁) dependant upon the deviation of the relatively low frequency signal (f₂) from the predetermined frequency and controls the counter means (2) according to the signal (f₁,f₂) coupled thereto.
Claim 2
Dependent Claim
27 words
An apparatus as claimed in claim 1, wherein the relatively low frequency signal (f₂) is coupled to the counter means (2) for a predetermined number of cycles.
Claim 3
Dependent Claim
42 words
An apparatus as claimed in claim 1 or claim 2, wherein the error calculating means (5) measures the deviation of the relatively low frequency signal (f₂) by periodically comparing the relatively low frequency signal (f₂) with the relatively high frequency signal (f₁).
Claim 4
Dependent Claim
60 words
An apparatus as claimed in claim 3, wherein the relatively low frequency signal (f₂) is compared with the relatively high frequency signal (f₁) for a time period T err such that T err = n f₁ = m f₂ , where n and m are the number of cycles of the relatively high and relatively low frequency signals (f₁,f₂) respectively.
Claim 5
Dependent Claim
19 words
An apparatus as claimed in claim 4, wherein T err is a minimum time period for measuring the deviation.
Claim 6
Independent Claim
30 words
An apparatus as claimed in any preceding claim, wherein the first clock oscillator (1) is controllable by an Automatic Frequency Control (AFC)means responsive to an Automatic Frequency Control (AFC) signal.
Claim 7
Independent Claim
79 words
An apparatus as claimed in any preceding claim, wherein said pulses output from the counter means (2) have a time period T derived from the relatively high frequency signal (f₁) being respectively coupled to the counter means (2) for time periods T₁₁ and T₃₁ at one or other end of the time period T and the relatively low frequency signal (f₂) being coupled to the counter means (2) for a time period T₂₁ such that a pulse width T=T₁₁+T₂₁+T₃₁.
Claim 8
Independent Claim
31 words
An apparatus as claimed in any preceding claim, wherein the first clock oscillator (1) is turned off when not required by the counter means (2) or the error calculating means (5).
Claim 9
Dependent Claim
20 words
An apparatus as claimed in claim 7, wherein the first clock oscillator is turned off during the time interval T₂₁.
Claim 10
Independent Claim
31 words
An apparatus as claimed in any one of claims 6 to 9, wherein the AFC signal is derivable from a signal transmitted by a base station of a radio telephone network.
Claim 11
Dependent Claim
11 words
A radio telephone comprising apparatus as claimed in any preceding claim.
Claim 12
Dependent Claim
45 words
An apparatus as claimed in claim 7, wherein during the time interval T₂₁ the first clock oscillator (1) is switched off from a high frequency oscillator, from fast dividers of the counter means (2) and from a D/A converter, the clock oscillator (1) being AFC-controlled.
Claim 13
Dependent Claim
29 words
An apparatus as claimed in claim 12, wherein during the time interval T₂₁, part of the fast dividers and the D/A converter required by the AFC-function are switched off.
Claim 14
Independent Claim
92 words
A method of producing pulses wherein a relatively high frequency signal (f₁) and a relatively low frequency signal (f₂) output from a first clock oscillator (1) and a second clock oscillator (2) respectively are compared for detecting a deviation of the relatively low frequency signal (f₂) from a predetermined frequency and selectively coupled to a counter means (2) for respective time periods dependant upon the deviation of the relatively low frequency signal (f₂) from the predetermined frequency, and wherein the counter means (2) is controlled according to the signal (f₁,f₂) coupled thereto.
References Cited (Backward Citations)
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