Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
1997-06-25
2001-10-23
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C341S120000, C341S122000, C702S066000
Reexamination Certificate
active
06308139
ABSTRACT:
BACKGROUND INFORMATION
The present invention is directed to a system and process for determining the effective value of a periodic signal.
It is known, that the effective value of a test signal can be determined digitally from samples of a periodic electric test signal using the following equation (1):
I
=
1
N
∑
K
=
0
N
-
1
i
2
(
k
)
(
1
)
See H. Germer and N. Wefers, Electronic Measurements, vol. 2, 2nd edition, 1990.
In this equation, I denotes the effective value of the periodic electric test signal, N denotes the number of samplings per period of the electric test signal and i(k) is the respective sample.
It is also known from the Germer and Wefers book that relatively large errors occur in determining the effective value of a periodic electric test signal when the duration of the sampling interval differs greatly from the period of the test signal. To nevertheless determine the effective value of a periodic electric test signal with a relatively high accuracy when there are differences between the duration of the sampling interval and the period of the test signal, German Patent DE 4,122,399 A1 discloses that the sampling interval can be shifted by one clock cycle with respect to the electric test signal, and corresponding effective values can then be determined from the resulting samples. The effective values thus obtained are used to calculate an average value, which gives the effective value of the test signal, regardless of frequency.
SUMMARY OF THE INVENTION
The present invention discloses a digital process for determining the effective value of a periodic electric test signal, where the test signal is sampled during a sampling interval whose duration is different from the period of the test signal, the samples are subjected to an analog-digital conversion, then squared, added up and averaged in an arithmetic unit, then the root of the resulting average is calculated accordingly, an object of the present invention is to determine quickly (after one period of the test signal) and with a high accuracy the effective value of the periodic electric signal.
With a sampling interval that corresponds in duration to two periods of the electric test signal having an odd number of M samplings with N samples that falling in one period of the test signal, the object of the present invention is achieved by squaring and adding the values up to and including the Nth sample. To the resulting total there is added as a correction factor a value that corresponds to half of the square of a subtotal formed from one quarter of the Nth sample and three quarters of the (N+1)th sample, where N=(M−1)/2, and the average is calculated over the number M/2 samples.
The main advantage of the process according to this invention is that despite a difference in duration between the sampling interval and the period of the test signal, the effective value of the periodic electric test signal can be determined with a high accuracy after just one period of the electric test signal, because the effective value (containing an error) that can readily be calculated from the samples after one period of the electric test signal is corrected. This permits the use of samples to determine the effective value which is formed with regard to other measurement tasks involving the periodic electric test signal such that sampling is performed with a non-integer multiple of the fundamental frequency component of the test signal in order to be able to detect harmonics of a higher order (see German Patent Application P 44 20 348.9).
REFERENCES:
patent: 4527278 (1985-07-01), Deconche et al.
patent: 5265039 (1993-11-01), Curbelo et al.
patent: 5659312 (1997-08-01), Sunter et al.
patent: 32 22 087 A1 (1983-12-01), None
patent: 39 28 083 A1 (1991-02-01), None
patent: 41 22 399 A1 (1993-01-01), None
patent: 44 20 348 (1994-06-01), None
Buch von Germer und N. Wefers, “Messelektronik,” Band 2,2. Auflage, 1990, Seite 15, Reference is described in the Specification.
Reck Thomas
Sezi Tevfik
Hoff Marc S.
Kenyon & Kenyon
Siemens Aktiengesellschaft
Vo Hien
LandOfFree
Digital process for determining the effective value of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Digital process for determining the effective value of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Digital process for determining the effective value of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2567691