Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Parameter related to the reproduction or fidelity of a...
Patent
1994-08-16
1996-03-12
Regan, Maura K.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Parameter related to the reproduction or fidelity of a...
324 95, G01R 2728
Patent
active
054989680
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates to measuring electromagnetic emission from component or circuit boards mounted in racks, i.e. in the usual way in parallel to each other with a common connection plane, on one side of which the connections to the boards are located. The invention also relates to measuring interference sensitivity to electromagnetic radiation coming from the outside in such an individual component or circuit board, i.e. the influence of the radiation on the signal transmission between the electronic circuits on the board and therefrom to the connections of the board in the connection plane.
Authorities in different countries make ever harder demands on the amount of electromagnetic radiation which is allowed to be emitted by electronic equipment. Emission of electromagnetic radiation thus must be restricted as much as possible. For electronic equipment, in which several component or circuit boards are mounted in parallel in a common connection plane, there is for natural reasons particular difficulties in measuring the emitted radiation from each individual board.
From the document AT & T Technologies, Technical Digest No. 73, January 1984, "Circuit Pack Adaptor for High-Speed Circuit Packs", it is, in the testing of electronic equipment previously known to mount an individual circuit board on the rear side of the backplane or connection plane conventionally used in a computer. This mounting of the individual board makes the conductors on the board accessible for connection to electric testing equipment. The device mentioned in this document can however not be used for the measurement of the electromagnetic radiation which is emitted from the circuit board connected at the rear side, since radiation emitted from this card is mixed with the radiation emitted from the other boards. Nor is this device suited to be used for testing the interference sensitivity of an individual board, since a possible fault appearing in the electronic device, as a whole, of which an individual board is a part, not securely can be traced to have appeared in this board.
SUMMARY
For measuring the emission from and radiation effects on an individual board a method and a device are provided, the more detailed characteristics of which appear below.
Thus a backplane or connection plane is used being principally of the kind disclosed in the document cited above. In addition however, all other component or circuit boards than that to be tested, are enclosed by suitable electrical and/or magnetic shieldings. Hereby the measurement is not disturbed by radiation emitted from the other component or circuit boards. Nor will faults appear in the shielded boards except possibly in the board which is tested and which protrudes from the rear side of the connection plane. The board which is tested then suitably protrudes through a slot in the shielding, which in the simplest embodiment is an electrically conducting, grounded housing.
On one side of this housing, which is located adjacent to the board which is tested, ferrite material may be arranged to provide also a magnetic shielding. Also the slit area itself, through which the board protrudes from the housing, can be covered by a ferrite plate. It is then provided with appropriate openings for connection pins or connection leads to the component or circuit board which is to be tested.
For some boards also advantageously a lower and/or an upper ground plane may be arranged, which are located in an angle perpendicular to the surface of the board. This or these extra ground planes are further advantageously also coated by ferrite material on the side facing the tested board.
Further the device should in the testing operation be operated by a battery power source, possibly supplemented by an appropriate voltage converting assembly for production of various suitable supply voltages.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described with reference to the accompanying drawings, in which
FIG. 1 shows a perspective view of a device for the measurement o
REFERENCES:
patent: 2509045 (1950-05-01), Salisbury
patent: 4463309 (1984-07-01), Crochet et al.
patent: 4939446 (1990-07-01), Rogers
patent: 5006788 (1991-04-01), Goulette et al.
G. F. Eminger, "Circuit Pack Adaptor for High-Speed Circuit Packs," AT&T Technologies Technical Digest, No. 73, pp. 7-8 (Jan. 1984).
Derwent's Abstracts Nr. 84-157 004/25, SU 1 045 430.
Regan Maura K.
Telefonaktiebolaget LM Ericsson
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