SYSTEM AND METHOD FOR ELECTRONICALLY SIGNALLING ALONG A FENCE LINE

Abstract: A system for electronically signalling along a fence line, comprising one or more transmitter device(s) for connection to the fence line from which control signals or information may be sent along the fence line and one or more receiver device(s) for connection to the fence line to receive control signals. Each transmitter device includes transmission means arranged to form the control signal(s) or information as one or more data blocks, generate a carrier frequency, and phase modulate the carrier with the signal and apply the phase modulated carrier to the fence line. Each receiver device includes means arranged to demodulate the transmitted signal to recover the data block(s) and process the data block(s) to recover the control signal(s) or information. The system is adapted to work with both electric and non-electric fence lines.

Description: SYSTEM AND METHOD FOR ELECTRONICALLY SIGNALLING ALONG A FENCE LINE FIELD OF INVENTION The invention comprises a method and system for electronically signalling along either an electric or non-electric fence line. BACKGROUND Electric fences are used in agricultural and pastoral applications, for containing stock within a defined area, or to deter them from entering an area of crops or similar, and also in agricultural and industrial security fencing of installations such as for example power stations, prisons, and similar. An electric fence system comprises an energiser which is typically connected to mains power at a base station but may be battery powered, and which is connected to a fence line and emits a high voltage pulse approximately every second to the fence line. The intensity of the pulse is such that it deters animals and persons from touching the electric fence. An electric fence may often be many kilometres in length, particularly in agricultural and pastoral applications. At least one system is now available which includes a remote control unit which may be carried by a farmer and which enables the farmer to energise or de-energise the fence from any point on the fence line, by remotely turning the energiser off and on. The remote control unit is applied to the fence line and transmits a coded signal along the fence line to the energiser. NZ patent specification 258240 describes such a system in which the control signal sent from the remote unit to a receiver in the energiser is a coded digital signal. SUMMARY OF INVENTION The present invention provides an improved or at least alternative method and system for electronically signalling along a fence line, for example from a hand held remote control unit to a base station, or from a hand held remote control unit or a base station to one or more devices along the fence line, or to otherwise transmit control signals or information along the fence line. In broad terms in one aspect the invention comprises a system for electronically signalling along an electric or non-electric fence line, comprising: (a) one or more transmitter device (s) comprising a hand held remote control unit and/ or other device for connection to the fence line from which control signals or information may be sent along the fence line and including transmission means arranged to form the control signal(s) or information as one or more data blocks, generate a carrier frequency, and phase modulate the carrier with the signal and apply the phase modulated carrier to the fence line, and (b) one or more receiver device(s) for connection to the fence line to receive control signals or information transmitted along the fence line and including receive means arranged to demodulate the transmitted signal to recover the data block(s) and process the data block(s) to recover the control signal(s) or information. Where the system is used on an electric fence line a receiver device may be interfaced to a switching means arranged to disconnect or reconnect the electric fence energiser from or to the fence line or turn the electric fence energiser on or off, or may be interfaced to a switching means connected in series between the energiser and the fence line to disconnect or reconnect the electric fence energiser from or to the fence line. In addition one or more receiver devices may be interfaced to a switching means to form an isolator enabling disconnection or reconnection of a part of the fence line from or to the electric fence energiser. As another example a receiver device may be interfaced to a gate controller arranged to control opening or closing of a gate, or to any other device for controlling any function or for signalling along the fence line for any purpose. The system may also or alternatively comprise a fence line voltmeter as a transmitter device, for transmitting signals indicative of voltage at a point on the fence line, either on receiving a control signal polling the voltmeter or on the occurrence of a predetermined voltage condition on the fence line. Preferably the or each receiver device (s) is/ are arranged to transmit a response signal or information along the fence line on receipt of a control signal or information by the receiver device. Most preferably the system includes a hand held remote control unit, including a contact part adapted to be touched to the fence line for transmission of control signals or information along the fence line and a display for displaying transmitted or received signals or information. A base station may comprise a receiver and a transmitter. The base station may be capable of sending signals to a hand held control unit or to other devices and or/ of polling the status of the other devices. The base station may be adapted to be connected to a computer and may itself be based on a microcontroller or microprocessor. In the system and method of the invention, a carrier frequency is phase modulated by data comprising control signals or other information to be transmitted along the fence line and the modulated carrier is applied to the fence line and at the receive end is demodulated. In particular an electric fence line is a unique signalling medium, in that it is also carrying a continuous series of discrete high voltage pulses which can make use of the fence line as a signalling medium extremely difficult, and because the fence line is not an electrically robust signalling medium - a fence line can often be tens of kilometres long and include electrically defective joints along the fence line or vegetation touching the fence line. It is believed that the method and system of the invention will provide improved performance relative to systems currently available. For the purposes of this specification "electric fence line" includes both fence lines which carry a continuous series of high voltage pulses and also fence lines which while not carrying high voltage pulses at all times can be triggered for example by a person touching the fence Une or a part of a multi-stranded or wire netting fence Une for example, to then immediately electrify the fence. Use of a non-electric fence Une as a signalling medium is also problematic. The non-insulated wire forming the fence Une is attached directly to the fence posts or standards or similar. Typically these are formed from wood (which may have a significant moisture content) or concrete for example, and the fence Une is not an electrically robust signalling medium. Again the fence Une can be long and include electrically defective joints along the fence Une. It is beUeved that the method and system of the invention will provide acceptable signalling performance even on such non-insulated fence lines. For the purposes of this specification "non-electric fence Une" includes single strand fence lines, multi-strand fence lines, fence netting and any other types of fence Une not connected to an electric fence energiser. BRIEF DESCRIPTION OF THE DRAWINGS Preferred forms of the system of the invention are described by way of example and without intending to be limiting, with reference to the accompanying drawings wherein: Figure 1 schematically shows a preferred form system of the invention for signalling on an electric fence Une, comprising an energiser base station, a number of other devices connected to the fence Une, and a hand held remote control unit, Figure 2 is a block diagram of transmit-only electronics for implementing any device which is to be connected to the fence Une where transmit-only functionaUty is required, to transmit control signals or information over the fence Une, Figures 3 and 4 are block diagrams of receive and transmit electronics in the base station of the preferred form system for receiving control signals or information sent along the fence Une and also able to transmit control signals or information along the fence Une from the base station, and which may be implemented in any other device which is to be connected to the fence Une where both transmit and receive functionaUty is required, Figure 5 is a block diagram of receive and transmit electronics for implementation in any device to be connected to a non-electric fence Une for signalling over the fence Une, and Figure 6 illustrates the format of the control signals in the preferred form systems. DETAILED DESCRIPTION OF PREFERRED FORMS The preferred form system for signalling on an electric fence Une of Figures 1 to 4 is described with reference to electric fencing in an agricultural or pastoral appUcation, by way of example, but the invention and the preferred form system described is equaUy appUcable to electric security fencing and other electric fencing appUcations. Referring to Figure 1, an electric fence energiser 1 which is typically positioned at a house or building on a farm and is mains powered but may be a battery powered energiser, is connected through a base station 2 which is a component of the system of the invention, to a fence Une which defines a number of paddocks or similar. The base station 2 may be physicaUy incorporated in the energiser housing, or may be a separate module which is connected in series between the energiser and the fence Une as shown and may be sold as an after market item which can be retrofitted to an existing fence Une for example. The base station 2 comprises a receiver which can receive control signals and other information transmitted along the fence Une, for example from a hand held remote control unit 4 carried by a farmer. In the preferred form the base station 2 incorporates both receive and transmit electronics as shown in Figures 3 and 4, and a switch 15 (see Figure 4) such as a solenoid activated switch, a motor driven or electronic switch, or other suitable form of switch within or associated with the base station, through which the energiser is connected to the fence Une. The switch in the base station 2 may be operated on receipt of a remotely transmitted control signal to disconnect or reconnect the energiser from and to the fence Une. The hand held remote control unit 4 or other transmit device may optionaUy comprise only transmit electronics as shown in Figure 2, but preferably has both transmit and receive functionaUty using similar transmit-receive electronics of Figures 3 and 4 as in the base station 2, so that the remote control unit may be used not only to send a control signal to the base station 2 to disconnect or reconnect the energiser to the fence Une for example, or to any other device connected to the fence Une, but may also receive a signal sent back along the fence Une from the base station (or other device) to verify receipt of the transmitted control signal. The remote control unit 4 may incorporate a small display in addition to a keypad by which the user may send control or other signals or poU any device connected to the fence Une to return transmit data or information, as may the base station 2. In the system described above the remote control unit or other transmit device may be used to signal over the fence Une to the base station 2 to cause the base station to disconnect the energiser from and reconnect the energiser to the fence Une. In an alternative embodiment the receive electronics may be associated with the energiser and incorporated within the energiser housings and may operate to turn the energiser off or on by controlling a switch in the power supply to the energiser for example. Alternatively again the receive electronics may be incorporated in a separate unit positioned between the power supply and the energiser which may be sold as an after market item which can be used with an existing energiser to enable turning on and off the energiser. Instead of or in addition to a hand held remote control unit, signals may be transmitted to the base station 2, or along the fence Une from one device to another connected to the fence Une for any reason, from a remote device which may be in a fixed physical position such as at a gate, building, etc and from which a control signal may be sent to disconnect or reconnect the energiser from or to the fence Une or turn the energiser on and off, or a control signal or signals or information may be sent to any other device or for any other purpose using the fence Une as the signalling medium. Figure 1 shows a number of isolators 3 provided at points along the fence Une as shown. Each isolator 3 may comprise receive electronics and an associated switch enabling individual sections of the fence Une to be disconnected and subsequently reconnected, by signalling from the hand held remote control unit 4 when a farmer wishes to repair a particular section of the fence Une without de- energising the entire electric fence system for example, or alternatively by signalling from a transmitter in the base station 2 for example, again using the fence Une as the signalling medium. The isolator(s) may also comprise transmit electronics for sending a verification signal on receipt of a disconnect or reconnect signal to the isolator over the fence Une, or to enable the isolator to send a status signal to the remote control unit or base station if poUed by a signal from the remote control unit or base station as to the status of the isolator. Also as shown in Figure 1 as another example, a transmitter 5 associated with a water trough 6 incorporating a level monitoring device may use the fence Une as a signalling medium to transmit a signal to the base station or to the hand held remote control unit indicating if the water level in the water trough is low, or indicating the water level in response if poUed by a signal from the remote control unit or base station. Further, the hand held remote control unit or base station may be used to transmit a control signal along the fence Une to a gate controller 7 of an electric opening gate to command the gate controUer to open or shut an electric gate. Again electronics at the gate controUer may be both receive and transmit electronics to enable sending of a verification signal or a signal indicating gate status in response to a poU signal sent along the fence Une. As yet a further example voltage sensing devices positioned along the fence Une may incorporate transmit and receive electronics to transmit a signal to the base station if the fence voltage at a distant part of the fence Une is reduced below a predetermined threshold, caused by vegetation growing against the fence Une or similar, or to transmit a voltage level signal or low voltage signal if poUed from the hand held remote control unit or base station or any other device connected to the fence Une. As described above, devices connected to the fence Une may comprise transmit or receive only electronics, or both. Thus, the system of the invention may use the electric fence Une as a signalling medium for controlling various devices and transmitting and receiving information to provide a farm management system with a high degree of functionaUty for multiple appUcations. Figure 2 is a block diagram of a preferred form transmit only hand held remote control unit. The unit comprises an external casing with a contact part such as a metal probe or ear which is touched against the fence Une in use, and one or more buttons or a keypad and preferably a small display. Data blocks comprising control signals or other information are transmitted, between energiser pulses in an electric fence system, and energiser pulse detector 20 provides timing information to the CPU 21 for data synchronisation. Electric fence interface 23 protects transmit driver 24 from the high voltage energiser pulses and at the same time couples the transmitter to the electric fence. The CPU 21 encodes the data blocks which are then used to phase modulate a carrier frequency. The carrier frequency generation as weU as the modulation of the digital data stream to a phase encoded pseudo sine wave is in the preferred form all done in software. If a " 1" is transmitted the carrier phase is advanced by 90 degrees and if a "0" is transmitted the phase is retarded by 90 degrees. Figure 3 is a block diagram of a preferred form of receive electronics, which may be implemented in an energiser base station, hand held control unit 4, or other device connected to the fence Une. Electric fence interface and input protection circuit 30 matches the fence to input amplifier 31 and protects the receiver from the energiser pulses. The input protection circuitry is on a virtual earth of the amplifier and operates when the output of the first amplifier saturates. Band-pass filter 32 provides some rejection of mains and broadcast band interference. The filter has two identical low Q stages. The low Q prevents the output ringing at the signalling frequency due to impulse noise, and reduces the sensitivity of the design to component variation. Oscillator and clock generator 33 provides switching signals to both in phase and quadrature phase detectors 34 and 35. In the preferred form circuitry described the clock signal is not phase locked to the transmitted carrier (but this is possible in an alternative configuration) but both the clock generators must be accurate to for example 200ppm. The band-limited signal is demodulated by the phase detectors 34 and 35 and subsequently low pass filtered by filters 36 and 37. The output of each phase detector is inverted and attenuated providing, in the preferred form, six outputs to an analogue to digital conversion stage 38 comprising four phase state comparators. The four outputs of the comparators are combined to represent 8 phase differences between the incoming signal and the local clock (0°, ±45°, ±90°, ±135° and 180°). The outputs of the comparators are suppUed to and compared in a CPU (not shown in Figure 3 but see below with reference to Figure 4) with the output during the previous data period and the phase difference calculated. If a phase advance is detected the data bit is a " 1" otherwise it is a "0". Referring to Figure 4, the decoded data block is suppUed to the CPU 40. Figure 4 shows implementation in an energiser base station and solenoid activated switch 15 is controUed by the CPU to, on receipt of a control signal, disconnect or connect the energiser from or to the fence Une. In other cases the CPU 40 output wiU control other devices where the receiver stage is associated with other devices connected to the fence Une. Figure 4 includes a transmit stage associated with the energiser base station. Again control signals or information is formatted into data blocks which are phase modulated with a carrier frequency in CPU 40. The data blocks are transmitted between energiser pulses and energiser pulse detector 41 provides timing information to the CPU 40 for data synchronisation. Electric fence interface 42 protects transmit driver 43 from the high voltage energiser pulses and at the same time couples the transmitter to the electric fence. Referring to Figure 6 in the preferred form system the data blocks consist of a pseudo random noise sequence 51 foUowed by the data bits 52 and then a BCH error correction code 53. Upon initiaUsation the CPU reads the address of the base station which is also the farm address. The address is basicaUy one of several pseudo random noise (PRN)-sequences of maximal length which is used for message synchronisation. The CPU encodes the data by calculating the BCH error correction code from the data to be transmitted and appends both the data and the BCH code to the PRN sequence. The receiver synchronises only to the selected PRN sequence and when a vaUd data packet arrives the block of data is decoded checked for errors and if necessary corrected. Figure 5 is a block diagram of receive-transmit electronics for implementation in any device to be connected to a non- electric fence Une for signalling over the fence Une. In a non-electric fence system there is no energiser. The signalling system of the invention may be used for signalling on a non-electric fence Une to send information from a base station or hand held remote control unit to devices connected to the fence Une such as gate controUers or any other devices connected to the fence Une, or simply for use of the fence Une as a transmission medium between different locations on a farm or any other installation or appUcation where it is desired to use the fence Une as a signalling medium. Each device may comprise receive electronics, transmit electronics or both receive and transmit electronics. Because in a non-electric fence appUcation the fence Une does not carry high voltage pulses the pulse detector and input circuitry is not required. Otherwise the operation of the receive and transmit electronics is similar to that of Figures 2 and 3. CPU 60 encodes control signals or other information for transmission as data blocks, which in the preferred form again consist of a pseudo random noise sequence followed by the data bits and then a BCH error correction code, which are then used to phase modulate a carrier frequency to a phase encoded pseudo sine wave. Fence interface 61 connects transmit amplifier 62 to the fence Une. Fence interface 61 also matches the fence to an input amplifier and band-pass filter 32. OsciUator and clock generator 33 provides switching signals to both in phase and quadrature phase detectors. The band-limited signal is demodulated by the phase detectors and subsequently low pass filtered. The output of each phase detector is inverted and attenuated providing six outputs to an analogue to digital conversion stage 38 comprising four phase state comparators. The outputs of the comparators are suppUed to and compared in the CPU 60 with the output during the previous data period and the phase difference calculated. The decoded data block is suppUed to the CPU 60. The receiver synchronises only to the selected PRN sequence and when a vaUd data packet arrives the block of data is decoded checked for errors and if necessary corrected. As indicated above the invention and the preferred form transmit and receive electronics described above are equally appUcable to transmission of control signals or information along a fence Une which is electrified for security purposes, including a fence Une which is not electrified unless first touched by a person in which event electrification of the fence Une by voltage pulses is immediately triggered. A security fence Une may be used for transmitting information from hand held control units or communication units carried by persons such as security guards for example, each of which has a unique code. The foregoing describes the invention including a preferred form thereof. Alterations and modifications as will be obvious to those skiUed in the art are intended to be incorporated in the scope hereof.

Claims: CLAIMS 1. A system for electronically signalling along a fence Une, comprising: (a) one or more transmitter device (s) comprising a hand held remote control unit and/ or other device for connection to the fence Une from which control signals or information may be sent along the fence Une and including transmission means arranged to form the control signal(s) or information as one or more data blocks, generate a carrier frequency, and phase modulate the carrier with the signal and apply the phase modulated carrier to the fence Une, and (b) one or more receiver device (s) for connection to the fence Une to receive control signals or information transmitted along the fence ne and including receive means arranged to demodulate the transmitted signal to recover the data block(s) and process the data block(s) to recover the control signal(s) or information. 2. A system according to claim 1 wherein the fence Une is an electric fence Une. 3. A system according to claim 2 wherein a receiver device is interfaced to a switching means arranged to disconnect or reconnect an electric fence energiser from or to the fence Une or turn an electric fence energiser on or off. 4. A system according to claim 2 wherein a receiver device is housed in a base station unit adapted to be connected in series between an electric fence energiser and the fence Une and incorporating a switching means arranged to disconnect or reconnect the electric fence energiser from or to the fence Une. 5. A system according to any one of claims 2 to 4 including a receiver device interfaced to a switching means to form an isolator enabling disconnection or reconnection of a part of the fence Une from or to the electric fence energiser. 6. A system according to any one of claims 1 to 5 including a receiver device interfaced to a gate controUer arranged to control opening or closing of a gate. 7. A system according to any one of claims 2 to 6 including a transmission means associated with the or each receiver device, arranged to transmit a response signal or information along the fence Une on receipt of a control signal or information by the receiver device. 8. A system according to any one of claims 2 to 7 including a fence Une voltmeter as a transmitter device, for transmitting signals indicative of voltage at a point on the fence Une, either on receiving a control signal polling the voltmeter or on the occurrence of a predetermined voltage condition on the fence Une. 9. A system according to claim 1 wherein the fence Une is a non-electric fence Une. 10. A system according to any one of claims 1 to 9 including a transmitter device which is a hand held remote control unit including a contact part adapted to be touched to the fence Une for transmission of control signals or information along the fence Une. 11. A system according to any one of claims 1 to 10 including a transmitter device which is a hand held remote control unit and also incorporating receive means arranged to demodulate signals received over the fence Une to recover signals or information. 12. A system according to claim 10 or claim 11 wherein the hand held control unit includes a display for displaying transmitted or received signals or information. 13. A system according to any one of claims 1 to 8 wherein said transmission means of the transmitter device (s) comprises and energiser pulse detector means, a central processing unit, an address select unit, an electric fence interface, and a transmit amplifier. 14. A system according to any one of claims 1 to 8 and 13 wherein the receive means comprises an electric fence interference and input protection means, a fence input amplifier, a band pass filter, at least one low pass filter, osciUator and clock generation means, at least one attenuation means, analogue to digital conversion means, and a central processing unit. 15. A system according to any one of claims 9 to 12 wherein the transmission means of the transmitter device (s) comprises a central processing unit, an address select unit, a fence interface, and a transmit amplifier. 16. A system according to any one of claims 9 to 12 and 15 wherein the receive means comprises a fence interface means, a fence input amplifier, a band pass filter, at least one low pass filter, osciUator and clock generation means, at least one attenuation means, analogue to digital conversion means, and a central processing unit. 17. A system according to any one of claims 1 to 16 wherein the transmitter device(s) is/are arranged to format the data block(s) as a pseudo random noise sequence, data bits, and an error correction code. 18. A system according to claim 17 wherein the error correction code is a BCH code. 19. A method of electronicaUy signalling along a fence Une comprising in a transmitter in a hand held control unit or other device connected to the fence Une, forming the signal as one or more data blocks and phase modulating a carrier frequency with the signal and applying the phase modulated carrier to the fence Une, and at a receiver also connected to the fence Une, demodulating the transmitted signal to recover the data blocks and processing the data block(s) to recover the control signal.

Inventors: DEUSS EBERHARD JUERGEN, GREAGER DAVID CRISTEN, TEAL PAUL, DEUSS, EBERHARD, JUERGEN, GREAGER, DAVID, CRISTEN, TEAL, PAUL
Applicants: DEUSS EBERHARD JUERGEN, GREAGER DAVID CRISTEN, TEAL PAUL, ULLRICH HOLDINGS LTD, DEUSS, EBERHARD, JUERGEN, GREAGER, DAVID, CRISTEN, TEAL, PAUL, ULLRICH HOLDINGS LTD.
Application year: 1999
Main classification: H04B3
IPC codes: H04B3, H05C3