Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Parameter related to the reproduction or fidelity of a...
Reexamination Certificate
2000-11-24
2003-01-21
Le, N. (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Parameter related to the reproduction or fidelity of a...
C324S628000, C324S613000, C455S067700
Reexamination Certificate
active
06509742
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic noise measurement apparatus, an electromagnetic noise measurement method and a recording medium. More particularly, the present invention relates to an electromagnetic noise measurement apparatus and an electromagnetic noise measurement method for measuring electromagnetic noise radiated from electronic equipment, as well as a recording medium.
2. Description of the Related Art
Recently, as electric equipment and electronic equipment spreads, electromagnetic interference becomes an object of social concern. To deal with this problem, a standard (VCCI or FCC) is set in each country. It is required to satisfy these standards when apparatuses are put on the market.
To judge whether or not electric equipment or electronic equipment conforms to an EMI standard, it is necessary to measure electromagnetic noise radiated from the equipment and to check if a measurement value is below a standard value. The electromagnetic noise measurement is usually made in a range of 30 MH
z
to 1 GH
z
.
A determination as to whether a product conforms to the EMI standard is made based on the result of a quasi-peak measurement. This quasi-peak measurement requires fixed measurement time, and measurement efficiency deteriorates if the measurement is made in a range of 30 MH
z
to 1 GH
z
. For these reasons, the quasi-peak measurement method is not popular.
At an ordinary electromagnetic wave measurement facility (open field test site or the like), a peak is measured by using a spectrum analyzer instead of executing a quasi-peak measurement in a regulated frequency range. During the measurement, it is checked whether or not this peak conforms to a corresponding standard value. As for an interference signal which does not have a sufficient margin of allowable values, a quasi-peak is measured.
In order to measure the maximum value of electromagnetic waves radiated from an apparatus such as electric equipment or electronic equipment, such a measurement facility further requires a means for turning the measurement target apparatus (apparatus to be measured) and a means for elevating an antenna which receives electromagnetic waves radiated from the measurement-target apparatus.
Further, if conventional automatic electromagnetic wave measurement software is employed, the electromagnetic noise of an apparatus is measured while a reception antenna is fixed to a predetermined position based on a calculation formula using an antenna, which formula is referred to as a height pattern, or on an actual measurement value obtained by using a transmission-reception antenna, so as to efficiently carry out the software operation.
However, if an electromagnetic interference wave has a high directivity toward the height direction of the antenna and electromagnetic waves are measured with the antenna set at a fixed height, the electromagnetic interference wave which should be measured sometimes cannot be measured.
An electromagnetic wave measurement apparatus used at the above-stated electromagnetic wave measurement facility is constituted by connecting, with coaxial cables or the like, an antenna for receiving electromagnetic interference waves generated respectively from electric equipment and electronic equipment, an amplifier amplifying the respective electromagnetic waves received by the antenna, a spectrum analysis means for displaying the results of the received electromagnetic waves, a field intensity meter and the like. To check whether or not the electromagnetic interference waves are below a standard value, it has been necessary that electromagnetic interference wave input and output gains and losses (factors) on the respective parts are calculated, and the calculated factors are offset from the electromagnetic waves received on the respective parts to thereby check that each measurement value is less than the standard value. In addition, no consideration has been given to electromagnetic noise signal generation timing which differs according to measurement target apparatuses and to temporarily observed noise.
Moreover, these gains and losses have been measured and managed at a predetermined signal level which is greatly different from the levels of electromagnetic noises emitted from the actual measurement target apparatuses. In this case, output linearity relative to changes in the magnitude of inputs is not examined. While a factor with respect to a certain input is precise, a factor with respect to variable inputs tends to be imprecise, with the result that measurement values cannot be often compared with the standard value.
Meanwhile, according to the standard regarding the above-stated electromagnetic noise, it is required to measure a QP (quasi-peak) and to judge whether or not this Qp measurement value satisfies a standard value. With the above-stated electromagnetic interference evaluation method, radiated noise is measured, electromagnetic wave levels with various frequencies are respectively measured, electromagnetic wave levels corresponding to the harmonic components of a specific repetition signal among a plurality of repetition signals of the apparatus are automatically extracted from the measurement results and a QP measurement is automatically made. If the respective harmonic components of the specific repetition signal overlap those of a different repetition signal with the same frequency or if the harmonic components of the specific repetition signal are adjacent to those of the different repetition signal, the automatic QP measurement of a measurement target harmonic may sometimes cause an error.
Further, if a measurement system receives a signal having an equivalent intensity for the level of electromagnetic noise radiated from a measurement target apparatus, the measurement system does not always exhibit linearity performance and errors may possibly occur to a measurement result.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above-stated disadvantages. It is, therefore, an object of the present invention to provide an electromagnetic noise measurement apparatus, an electromagnetic noise measurement method and a recording medium, which are capable of preventing erroneous measurement of electromagnetic noise and of enhancing measurement efficiency.
To achieve the above object, a first aspect of the present invention is an electromagnetic noise measurement apparatus for measuring electromagnetic noise radiated from an equipment to be measured, the apparatus including: an antenna for receiving the electromagnetic noise; a peak field intensity measuring section which receives the electromagnetic noise from the antenna and measures a peak field intensity of the electromagnetic noise in a predetermined frequency range; a quasi-peak measuring section which receives the electromagnetic noise from the antenna and measures a quasi-peak of the electromagnetic noise at a specific frequency determined in advance; and an informing section which receives measurement results from the peak field intensity measuring section and the quasi-peak measuring section, and, if a difference between a peak field intensity value at the specific frequency and a quasi-peak value at the specific frequency are equal to or more than a predetermined value, informs a predetermined message.
According to this invention, electromagnetic noise radiated from, for example, an electronic equipment (the equipment to be measured) such as, a printer, a copying machine or a facsimile machine or the like, is received by the antenna. When the antenna is to receive the electromagnetic noise, the antenna is moved by an antenna elevating section which elevates the antenna to, for example, a position at which electromagnetic noise is maximized, the electronic equipment is put on a turn table and the electromagnetic noise is received while the turn table turns.
The peak field intensity measuring section measures the peak field intensity of the electromagnetic noise received by this antenna in a predetermined freq
Ebizuka Yasuo
Hirata Masayuki
Matsuzaki Toru
Morita Takaji
Shinozaki Haruo
Fuji 'Xerox Co., Ltd.
Le N.
LeRoux Etienne
LandOfFree
Electromagnetic noise measurement apparatus, electromagnetic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electromagnetic noise measurement apparatus, electromagnetic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic noise measurement apparatus, electromagnetic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3045861