EP0045335A1 - Eindringungsmelder nach dem E-Feldprinzip mit balancierter Phase - Google Patents

Eindringungsmelder nach dem E-Feldprinzip mit balancierter Phase Download PDF

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Publication number
EP0045335A1
EP0045335A1 EP80302678A EP80302678A EP0045335A1 EP 0045335 A1 EP0045335 A1 EP 0045335A1 EP 80302678 A EP80302678 A EP 80302678A EP 80302678 A EP80302678 A EP 80302678A EP 0045335 A1 EP0045335 A1 EP 0045335A1
Authority
EP
European Patent Office
Prior art keywords
wires
field
sense
wire
sense wires
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP80302678A
Other languages
English (en)
French (fr)
Inventor
Ronald W. Mongeon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Stellar Systems Inc
Original Assignee
Stellar Systems Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stellar Systems Inc filed Critical Stellar Systems Inc
Priority to EP80302678A priority Critical patent/EP0045335A1/de
Publication of EP0045335A1 publication Critical patent/EP0045335A1/de
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/22—Electrical actuation
    • G08B13/24—Electrical actuation by interference with electromagnetic field distribution
    • G08B13/2491—Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field
    • G08B13/2497—Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field using transmission lines, e.g. cable

Definitions

  • the present invention relates to an improvement in intrusion alarms known as E field alarms and specifically relates to improvements on the intrusion alarms of U.S. Patents 3,237,105 and 4,064,499, the subject-matter of which is incorporated herein by reference.
  • a field wire acts as a transmitting antenna at a relatively low frequency to produce a quasi-stationary electric field.
  • One or more sense antennas are placed in the vicinity of the field wire and connected to filtering and amplifying circuits leading to an alarm.
  • an AM detector is connected to the output of a preamplifier and the output is connected to a low-pass filter and to high-gain amplifying means, including a band pass filter arrangement whereby the output of the high gain amplifier passes only signals within the relatively low frequency range associated with the movement of an intruder in the electric field created between the field wire and the sensing antenna.
  • a system which is much less susceptible to false alarms by providing at least one pair of field wires and at least one pair of sense wires.
  • Each pair of sense wires is connected to opposite terminals of an input circuit for the alarm device in such a manner that if equal voltages of equal phase are developed on the two sense wires, there will be no output. Since both of the sense wires would normally be subject to the same electrical disturbances such as movements of an adjacent fence, trucks or lightning, such disturbances would not cause an alarm. On the other hand, in the case of an intruder, invariably a greater voltage would be developed on one of the sense wires than on the other setting off the alarm. Thus, the system would still remain sensitive to set off an alarm in the case of an intrusion but would be less susceptible to nuisance alarms.
  • circuits would be included for sensing whether or not wires were open or short-circuited.
  • the alarm would include circuits to detect amplitude changes in the field, the rate of change and the time that the intruder is in the field pattern to fit the typical intruder profile.
  • these various features of a practical circuit are well-known to those skilled in the art and form no part of the present invention and therefore are not herein described.
  • a field voltage generator 5 which may be identical with those parts identified as items 11, 12 and 23 in U.S. Patent 4,064,499.
  • the field voltage generator has an output line 7 which feeds an upper field wire 9 and a lower field wire 11.
  • Running parallel to the field wires 9 and 11 are the sense wires 13 and 15. All of these wires are supported on the posts designated 17 and would be insulated from the posts.
  • the sense wire 13 is parallel to the field wire 9 and similarly, the field wire 11 is parallel to the sense wire 15.
  • Sense wires 13 and 15 have output terminals designated S1 and S2 connected to opposite ends 21 and 23 of the primary transformer 19 having a grounded centre tap.
  • the transformer has effectively two primaries wound in the same direction on a common core 25. Although the two primary windings are shown for illustrative purposes as being a single centre tapped winding, in a practical embodiment of the invention, the two primary windings may be separate.
  • the secondary 27 is connected to the input terminals of a tuned probe and alarm circuit 29. Item 29 can be substantially identical with the otems designated 14 to 22 of U.S. Patent 4,064,499.
  • FIG 2 a somewhat similar installation is shown except here the installation is designed for use with an existing fence.
  • the existing fence posts 31 supporting a fence not shown, one provides a plurality of standoff arms 33.
  • These arms can advantageously be made of an insulating material such as fibreglass or they can be made of a conductive material with insulators at the ends.
  • Standoffs 33 support the wires 9, 13, 15 and 11 in exactly the manner previously described.
  • Figure 4 shows how several field and sense wires can be combined to form a curtain array. Note that in the centre of the array, field wire F2 serves two sense wires, namely S4 and S5.
  • FIG 4 a practical filter and probe circuit is shown.
  • a transformer T1 is employed, having equal primary windings 35 and 37 and a secondary winding 39.
  • an ordinary telephone hybrid transformer was employed but it will be understood that the transformer is not critical so long as it is capable of handling the frequencies of the alarm circuit and also matching the impedances of the sensing circuit to the alarm circuit.
  • the sensing wire S1 is attached to one side of the primary 35 while the sensing wire S2 is connected to the opposite terminal of the primary 37 so that voltages developed on Sl and S2 oppose each other.
  • Both of the input lines are advantageously provided with lightning arresters LA1 and LA2.
  • the opposite sides of the primary windings are grounded for AC through the capacitors C5 and C6.
  • the output winding 39 of the transformer is connected to a filter C1, C3 and L1 tuned to the frequency of the field voltage generator.
  • the output of the filter is by-passed to ground for stray RF fields through the capacitor C4.
  • the output signal from the circuit is taken through line 41.
  • R3 forms part of a DC supervisory circuit for detecting an open or short on sense wire S2.
  • line 42 serves to monitor for an open or short on sense wire S1.
  • the circuit shown in Figure 4 is substituted for the tuned probe circuit 14 of Patent 4.064,499 and the output is passed to the preamplifier 15 of said patent so that the further processing of the signal is not herein described.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Burglar Alarm Systems (AREA)
EP80302678A 1980-08-05 1980-08-05 Eindringungsmelder nach dem E-Feldprinzip mit balancierter Phase Withdrawn EP0045335A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP80302678A EP0045335A1 (de) 1980-08-05 1980-08-05 Eindringungsmelder nach dem E-Feldprinzip mit balancierter Phase

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP80302678A EP0045335A1 (de) 1980-08-05 1980-08-05 Eindringungsmelder nach dem E-Feldprinzip mit balancierter Phase

Publications (1)

Publication Number Publication Date
EP0045335A1 true EP0045335A1 (de) 1982-02-10

Family

ID=8187234

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80302678A Withdrawn EP0045335A1 (de) 1980-08-05 1980-08-05 Eindringungsmelder nach dem E-Feldprinzip mit balancierter Phase

Country Status (1)

Country Link
EP (1) EP0045335A1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2137789A (en) * 1983-03-30 1984-10-10 Terrance Michael Hayes Intrusion detector installation
GB2155224A (en) * 1984-03-02 1985-09-18 Shorrock Security Systems Ltd Intrusion detection barrier
GB2259174A (en) * 1991-09-02 1993-03-03 Shorrock Ltd An intruder detector

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4053877A (en) * 1974-12-31 1977-10-11 Plessey Handel Und Investments Ag Method of and apparatus for surveying an area

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4053877A (en) * 1974-12-31 1977-10-11 Plessey Handel Und Investments Ag Method of and apparatus for surveying an area

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2137789A (en) * 1983-03-30 1984-10-10 Terrance Michael Hayes Intrusion detector installation
GB2155224A (en) * 1984-03-02 1985-09-18 Shorrock Security Systems Ltd Intrusion detection barrier
GB2259174A (en) * 1991-09-02 1993-03-03 Shorrock Ltd An intruder detector

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): AT BE CH DE FR GB IT LU NL SE

17P Request for examination filed

Effective date: 19820129

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19840508

RIN1 Information on inventor provided before grant (corrected)

Inventor name: MONGEON, RONALD W.