Electromagnetic noise source locator

• US 4,214,210 A
• Filed: 01/09/1978
• Issued: 07/22/1980
• Est. Priority Date: 01/09/1978
• Status: Expired due to Term

• Current Assignee: Sprague Electric Company
• Original Assignee: Sprague Electric Company
• Inventors: O'Shea, Martin W.
• Primary Examiner(s): Bookbinder, Marc E.
• Application Number:
  US05/868,020
• Time in Patent Office: 925 Days
• Field of Search: 325/27, 325/29, 325/43, 325/67, 325/363, 325/364, 325/325, 325/377, 325/379, 325/386, 325/313, 324/72, 324/72.5, 324/102, 343/701, 343/703, 340/540, 340/659
• US Class Current: 455/282
• CPC Class Codes: G01R 19/145 Indicating the presence of current or voltage
• CPC Class Codes: G01R 29/26 Measuring noise figure; Measuring signal-to-noise ratio
• CPC Class Codes: G01R 31/12 Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing G01R31/08, G01R31/327 and G01R31/72 take precedence; measuring in plasmas G01R19/0061; measuring dielectric constants G01R27/2617; ESD, EMC or EMP testing of circuits G01R31/002

Abstract

An electromagnetic noise source locator is comprised of an audio amplifier which is connected to drive a speaker and to which is connected at the input a series circuit that includes a very small antenna loop of area less than 1 in², a diode and a capacitor. This apparatus responds only to bursts of radiated energy and furthermore responds only to such bursts having frequency components over about 1 GHz. It is therefore particularly suitable for the selective sensing and location of sparking gaps as may occur on power lines.

Claims

1. An apparatus for locating the source of sparking electromagnetic noise radiation comprising:

(a) an indicator means for producing an indication of the presence of an electrical signal;

(b) an audio amplifier, an output thereof being electrically connected to said indicator means; and

(c) an r.f. antenna-detector means comprising a conductive loop, a diode, a capacitor and a coaxial cable that has a center conductor and a cylindrical outer conductor, said loop having an area of less than 1 square inch and being connected between said conductors at one end of said cable with said diode forming a part of said loop;

said loop, said diode, said capacitor and said cable conductors forming a series circuit which is connected across the input of said audio amplifier.

2. The apparatus of claim 1 wherein said amplifier and the portion of said antenna-detector means that is connected between said amplifier input and said cable are enclosed in a metal case.

3. The apparatus of claim 1 wherein said amplifier is comprised of a plurality of audio amplifier stages being connected in tandem, said amplifier including a gain adjusting means for permitting manual adjustment of the gain of said amplifier.

4. The apparatus of claim 1 additionally comprising a pulse stretching means for widening signal pulses that pass through said amplifier.

5. The apparatus of claim 1 wherein said indicator means is an electro-acoustic transducer.

6. The apparatus of claim 1 additionally comprising a signal threshold means in said amplifier for passing only signals having a magnitude greater than a certain threshold voltage.