In particular, the invention relates to a portable apparatus that can transmit and receive signals along a length of the electrical conductor and which can also measure electrical parameters of a pulse or signal present on the electrical conductor.

Reference through the specification shall now be made to use of the present invention on electric fence systems such as those used for containing animals, or for other purposes such as security applications.

It should be appreciated however that this should not be seen to be a limitation on the present invention in any way as the present invention is equally suited for use with any other form of electrical conductor and electric fence systems are used by way of example only.

BACKGROUND ART Electric fence systems are quite different from other electrical systems.

Electric fence systems generally consist of a large single network with literally kilometres of wire connected to a power source, which is generally in the form of an electric fence energiser.

This type of network can have multiple branches interconnected together.

In contrast to other electrical systems (such as house wiring), there are few if any individual electrical circuits.

Electric fence systems commonly have faults occurring. This is because there is direct access to the wire or tape making up the system.

For example, the wire is exposed to all types of adverse conditions, including weather, animals, machinery such as tractors, falling trees, intruders, and so forth.

Due to the large size of the electric fence systems and the frequency of faults occurring it is desirable to have a device or method by which faults can be readily detected.

Unfortunately, the peculiarities of electric fence systems mean that traditional methods of fault finding cannot be readily used.

One problem is that typically the person trying to find the fault in the electric fence system is an unskilled operator, usually the farmer who owns the electric fence system. Therefore, sophisticated (and usually expensive) electronic devices are unsuitable.

In many situations where an electric fence is employed it can be an advantage that the energiser can be remotely turned on and off.

This can be of particular importance when fault finding the electric fence system as the operator does not wish to travel to and from the energiser each time they wish the energiser to be turned on or off as the energiser is quite often located at quite a distance away from the area where a fault has been discovered.

This problem has been overcome by the advent of various devices that can

transmit control signals to a suitably configured energiser in order to turn on or turn off the energiser from a remote location.

A number of measurement devices have also been developed specifically for use with an electric fence system in order to monitor the pulse characteristics at various points along the fence system in order to assist in fault finding of the electric fence system and also to monitor the performance of the energiser to which the system is connected.

As explained previously, the nature of electric fence systems means that during fault finding the operator will often have to travel significant distances and it is therefore highly desirable that the operator has to carry the minimum equipment.

In order to minimise the equipment that has to be carried by an operator assemblies that contain both measurement equipment and a control transmitter have been developed in order that the operator only has to carry a single piece of fault finding equipment.

These composite devices have both pieces of equipment housed within one enclosure and have two fence connectors, one for each piece of equipment.

Whilst it is recognised that this was a significant improvement over all prior systems it still has significant drawbacks, particularly when the person fault finding an electric fence system is an unskilled operator as it is possible for the measuring circuit connector and the communication circuit connector to be confused by the operator.

This could result in the wrong connector being placed in contact with the electrical fence conductor-which at best would mean the operator is wasting

time as they would have to recognise the error and then correct it, or at worst it could mean the operator receives an electrical shock when they believe they had disabled the energiser but had placed the measurement connector in contact with the fence instead of the transmitter connector.

Another significant problem is that if both connectors are placed in contact with the conductor at the same time it would result in interference between the measurement circuit and the communication circuit and could lead to significant errors in any measurements that were taken due to the communications circuit loading down the fence measurements.

Whilst it is very unlikely that an operator would have both contacts touching the fence simultaneously, this loading effect has precluded the use of a single contact for both communications and measurement.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

It is acknowledged that the term'comprise'may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term'comprise'shall have an inclusive meaning-i. e. that it will be taken to mean an inclusion of not only the

listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised'or'comprising'is used in relation to one or more steps in a method or process.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION According to one aspect of the present invention there is provided a portable apparatus for use with an electric fence, the portable apparatus including at least one measuring assembly that is configured to measure at least one operating parameter of an electric fence, and a transmitter assembly, and a fence contact device that is configured as a single contact terminal characterised in that the measuring and transmitter assemblies are electrically connected to the fence contact device.

According to another aspect of the present invention there is provided a portable apparatus for use with an electric fence, the portable apparatus including,

at least one measuring assembly that is configured to measure at least one operating parameter of an electric fence, and a transmitter assembly, and a receiver assembly, and a fence contact device that is configured as a single contact terminal characterised in that the measuring, transmitter and receiver assemblies are electrically connected to the fence contact device.

It should be appreciated that throughout the present specification the term "measuring assembly"should be understood to mean any device, or combination of devices, for measuring and/or monitoring any of the operating parameters of an electric fence.

It should also be understood that the term"operating parameters"used throughout the present specification should be understood to mean any of the characteristics of any signal that is at any time present on the conductor with which the present invention is in contact.

In some preferred embodiments of the present invention the signal is the pulse from an electric fence energiser.

In some other preferred embodiments of the present invention the signal is a transmission from an ancillary device coupled to the electric fence, an example of which could be a remote transmitter.

Throughout the present specification the term"transmitter assembly"should be

understood to mean an assembly that can transmit a signal to the fence contact device.

In preferred embodiments of the present invention the transmitter assembly is capable of transmitting instructions or data to an electric fence energiser via the electric fence conductor when the fence contact device is brought into physical contact with the electric fence conductor.

In some preferred embodiments of the present invention the transmitter assembly can transmit data or instructions via the electric fence conductor to a remote device that has a receiver that is also in contact with the electric fence conductor.

Preferably the present invention may be adapted to find faults on electric fence systems.

In other embodiments, the present invention may be adapted to control the operation of a device connected to the electric fence involved.

It is envisaged that this facility may be used to assist measurements of fault finding on a large or complex electric fence system where a number of transceivers and/or measuring systems are being used.

The term"receiver assembly"used within the present specification should be understood to mean an assembly that is capable of receiving signals that are present on the electric fence contact device.

Reference throughout this specification will also be made to the present invention also incorporating a receiver assembly. Such a receiver assembly may allow the present invention to be used in a bi-directional communication

scheme to transmit communication signals to a remote location and also to receive communication signals from a remote location. However, those skilled in the art should appreciate that the present invention need not incorporate such a receiver assembly which should not be considered as essential to the implementation of the present invention.

In preferred embodiments of the present invention the receiver assembly may be used to receive signals from an energiser via the electric fence conductor when the fence contact device is in electrical contact with the electric fence conductor.

It should also be appreciated that the receiver assembly of the present invention may also receive signals from any transmitter that is connected to the same electric fence conductor. Preferably such a receiver assembly may be configured to receive instructions or data from any device connected to the electric fence line involved.

It should be understood that the transmitter and receiver can be constructed as a single assembly and can be referred to as such, eg a communications assembly.

Previous devices that encompass both a transmitter and/or receiver assembly and a measurement assembly have had to use separate fence contact devices for each assembly, which as explained in the background art section introduces some significant drawbacks in the operation of these devices.

However, the present invention uses a single fence contact device to connect all the assemblies to an electric fence or other conductor.

In preferred embodiments of the present invention the fence contact device is

configured as a conducting metal probe adapted to be placed in physical contact with an electric fence conductor.

This should not be seen to be a limitation on the present invention in any way as in other embodiments of the present invention the fence contact device may be configured in any way that allows a single point of electrical contact with an electrical fence conductor.

Therefore throughout the specification the term"fence contact device"should be understood to mean a single contact terminal for connecting the assemblies of the present invention to an electric fence conductor.

The term"portable"used within the present specification should be understood to mean that the apparatus can be moved from location to location by an operator in order for the apparatus to be connected temporarily in a sequential manner at a number of different sites along the length of an electric fence conductor.

In some preferred embodiments of the present invention the portable apparatus is a handheld device that is brought into contact with an electric fence conductor in order to undertake at least one of the functions of the present invention.

This also should not be seen to be a limitation on the present invention in any way as in other embodiments the present invention may be placed in contact with the conductor whilst a number of functions are undertaken.

In some embodiments the present invention may be left in contact with a conductor in order to facilitate the undertaking of a number of functions over a period of time.

An example of this might be to measure the pulse characteristics over a period in which vegetation has been removed from the proximity of the fence line.

In order to achieve a single connection point between the present invention and an electric fence conductor it is necessary to have a measuring assembly that does not interfere with the communication assemblies, as well as communication assembly that does not interfere with the measuring assembly.

In a preferred embodiment the transmitter and/or receiver assemblies may have no or minimal loading effect on the measurement assembly, or the parameters measured by the measurement assembly.

In a preferred embodiment the measuring assembly may have no or a minimal loading effect on the transmitter and/or receiver assemblies.

In a preferred embodiment the measuring assembly may include a current measuring circuit.

In further embodiments the measuring assembly may include a voltage measuring circuit.

The measuring assembly may in most embodiments include both a voltage measuring circuit and a current measuring circuit.

In preferred embodiments of the present invention the voltage measuring circuit includes a very high resistance voltage divider, and preferably the current measuring circuit includes an inductive coupling.

It should be noted that the high resistance of the voltage measuring circuit has no loading effect on the communication assembly and the inductive coupling of the current measuring circuit has a low coefficient of inductive coupling to the

fence and therefore has a minimal loading effect on the communications assembly.

In a preferred embodiment low voltage communication transmission signals may be transmitted by the transmitter assembly.

Low voltage transmission signals allows a single terminal (the fence contact device) to be used for both communications and measurement.

A low voltage communication assembly can operate independently of (and may also operate simultaneously with) the measuring circuit, (measuring voltage and current) and at the same time be isolated and protected from the high voltage energiser pulses so that the impedance of the communication assembly does not load and therefore affect the accuracy of the measuring circuit.

However, if high voltage communications were to be used the communication assembly is more difficult to isolate from the energiser pulse and this could affect the measurement accuracy.

Therefore in preferred embodiments of the present invention low voltage communications (transmission and reception) are adopted.

This should not be seen as a limitation on the present invention as an alternative means of enabling a single terminal to function as both a measurement signal terminal and a bi-directional communications terminal is to disable the measuring software routine while communications signals are being sent and this may be used in some embodiments.

It should be appreciated that within the present specification the term"low voltage"means less than 500 volts for the purposes of low voltage communications on an electric fence system.

The more difficult problem to be overcome is to have a communication assembly which does not affect the energiser pulse on the fence to which it is connected and therefore will not alter the characteristics of the pulse being measured.

The communication assembly must therefore present a high impedance to the fence pulse.

In a preferred embodiment a capacitor may be placed in series between the transmitter and receiver assemblies and the fence contact device.

A capacitor (for example in the range of 1-50 pF) placed in series with the communication assembly connection can provide the required high impedance for the energiser pulse ensuring that the transmitter or receiver assembly has no significant effect on the pulse characteristics.

While such a capacitator provides a high impedance for the pulse there is a particular situation that can arise when the communication assembly will need additional protection from the low energy/high voltage pulses.

If the present invention is in the process of being connected to the fence during a pulse from the energiser it is possible to induce a fast transient into the communications circuit wherein the fast transient has been generated by the arcing of the pulse from the fence conductor over to the fence contact device of the present invention.

This fast transient has no significant effect on the pulse characteristics but can lead to a low energy/high voltage pulse being present on the communications input circuit.

This fast transient can pass through the capacitor and apply a potentially damaging high voltage to parts of the communications assembly.

This problem can be overcome by putting in a protection device.

In one preferred embodiment of the present invention a neon lamp (or lamps) is used to clamp the transient voltage to a level that does not damage any part of the communication assembly.

There are many types of devices that can be used to clamp such transients but the neon lamp is considered suitable as the neon lamp has such a small capacitance (less than 1 pF) that it has no significant effect on the communications circuit.

Whereas other devices with a larger capacitance would start to load the communications assembly.

However in other preferable embodiments differing forms of protection devices may be employed in conjunction with the communications assembly. For example, in some instances a tuned frequency filter (such as for example a high pass, low pass, or band pass filter or a resonant circuit) may be employed in a position between the communications assembly and its connection to the fence line involved. With electric fence systems an energiser pulse transmitted along the fence line normally has most of its power between the 1 to 10 kHz frequency range. By filtering out this band of frequencies from the signal which

the communications assembly is exposed to, damage to the communications assembly can be avoided.

In a further preferred embodiment a protection device may be formed by a high pass filter located in series between the communications assembly and its connection to an electric fence line. The frequency of communication signals transmitted (and also preferably received via the communications assembly) may therefore be tuned to signals above those blocked by the filter. The communication signal frequencies employed may be selected so as to present the communications assembly as a low impedance at communication frequencies and a high impedance at energiser or deterrent pulse frequencies.

The communications assembly of the present invention has preferably been designed for bi-directional communications on the fence system. However, also as discussed above the present invention may not necessarily incorporate a receiver assembly and may therefore be employed in mono-directional communications if required. Reference to bi-directional communications throughout this specification should in no way be seen as limiting, as should be appreciated by those skilled in the art.

As stated previously this includes the transmission of data and control signals from the present invention to any other suitable devices connected to the fence, as well as receiving data from any of these or any other suitable devices connected to the fence.

For transmission of signals from the transmitter assembly the circuit has been designed to match the source of the impedance of the present invention to the low fence impedance as well as is possible within the limits of the pulse blocking capacitor.

This allows for the most efficient transfer of the communications signal to the fence.

For received data the circuit has been designed to offer a high impedance so that the maximum signal voltage appears at the receiver assembly input.

In a preferred embodiment the transmitter (and preferably receiver assemblies) may be tuned so as to transmit and receive communication signals between 20kHz and 50kHz. This frequency band is low enough to prevent the fence line attenuating communication signals significantly and high enough to allow for relatively easy differentiation between communication signals and energiser pulses. Furthermore a protection device employed as discussed above consisting of a filter with a band pass region for the frequencies involved would prevent the communications assembly from attenuating the pulses of an energiser and therefore introducing errors into the measurements taken by the measurement assembly. In such embodiments the transmitter and/or receiver assemblies will have no or minimal load on the operation of the measurement assembly.

In a further preferred embodiment communication signals with a frequency of approximately 40kHz may be transmitted by the transmitter assembly and also preferably received by a receiver assembly when integrated into the present invention.

In preferred embodiments of the present invention the signaling method used is 'Continuous Phase'Frequency Shift Keying, as it is considered to be one of the most robust methods of transmitting and receiving data, even in relatively noisy environments. In such instances the transmitter may therefore transmit signals modulated by continuous phase frequency shift keying.

'Continuous Phase'FSK was chosen as this method reduces the transmitted bandwidth by ensuring a smooth transition from one frequency to another.

Throughout the present specification the term"Continuous Phase"should be understood to mean ensuring that the frequencies chosen have an integral number of cycles for the Bit Period that is being used.

In preferred embodiments of the present invention the centre frequency of the FSK signal has been chosen to be between 20kHz and 50kHz in order to provide a balance between the impedance and attenuation of the fence as well as the energiser transformer impedance.

An electric fence can be considered to be largely capacitive to AC signals and therefore the fence impedance will drop as the frequency increases, which can lead to greater signal attenuation.

This indicates that lower frequencies propagate along a fence better than higher frequencies.

The opposite is true however for the energiser transformer, which is of course connected to the fence system.

The transformer is an inductance across the fence which therefore has an impedance which decreases with decreasing frequency.

This indicates that higher frequencies would be less attenuated by the energiser transformer than lower frequencies.

Frequencies in the band between 20kHz and 50kHz are a balance for both of these conflicting requirements.

However, once again this should not be seen to be a limitation on the present invention in any way as in other embodiments different frequencies (or band of frequencies) may be used if desired.

From the aforegoing it is clear that the present invention has significant advantages over all of the systems available to date.

One of the major advantage is that by having only one connection to the fence for all of the functions (both measurement and communications) there can be no error caused by the wrong terminal being in contact with the fence.

This will effectively eliminate measurement errors as the communications assembly will not affect the pulse characteristics.

Another major advantage is that the safety of the operator will not be compromised as they cannot mistakenly have the measurement terminal in contact with the fence instead of the communications terminal when issuing a control function such as to turn off the energiser output, as the same fence contact device is used for all of the functions of the device.

BRIEF DESCRIPTION OF DRAWINGS Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1 is a block diagram of the major assemblies of the present invention in accordance with one embodiment, and Figure 2 is a more detailed view of the assemblies in figure 1, and

Figure 3 is a block diagram of the present invention as implemented in a preferred embodiment.

BEST MODES FOR CARRYING OUT THE INVENTION With reference to the figures there is illustrated a portable apparatus for use with an electrical conductor, generally indicated by arrow 1.

The portable apparatus (1) consists of a fence voltage and current measurement assembly (2) and a fence communications assembly (3), connected to a fence coupling circuit (4). Both the measurement assembly and the coupling circuit of the communications assembly are connected to the fence contact device (5).

The fence measurement assembly (2) and the fence communication assembly (3) are also connected to a keypad (6) and a display device (7).

The key pad (6) is used to select the function of the portable apparatus (1) and the display device (7) is used by the operator to check that the correct function has been requested by the keypad (6), and the display device (7) is also used to determine the output from the fence measurement unit (2).

Figure (2) is a more detailed description of the portable apparatus (1) however the keypad (6) and the display device (7) have been omitted for clarity.

The fence coupling circuit (4) consists of an inductive pickup (8) for use in the current measuring circuit (9), and a pulse limiting impedance circuit (10) that is used for the communications circuit. The fence coupling circuit also includes a high impedance (17) which is connected to a voltage measuring circuit (11).

The output of the pulse limiting impedance unit (10) is connected to fence

communication assemblies (13) (14) (15) (16) through a pulse limiter (12) in order to protect the communication circuits from the energiser pulse.

The output of the pulse limiter (12) is connected to the receiver filter (13), the output of which is fed to the receiver communication assembly (14). The transmitter assembly (15) has its output connected to a tuned drive circuit (16), the output of which is fed to the fence contact device (5) via the pulse limiter (12) and the pulse limiting impedance (10).

Figure 3 is a block diagram of a portable apparatus (21) provided by the present invention as implemented in a preferred embodiment.

In the embodiment shown the portable apparatus (21) includes a current measurement assembly (22) as part of an overall measurement assembly. The current measurement assembly (22) includes an inductive coupling to a fence line (31). The inductive coupling of the current measurement assembly (22) therefore eliminates the need to provide a physical connection to the fence line (31) to measure the current of energiser pulses travelling along the line.

The portable apparatus (21) also includes a fence contact device (23) which is linked to a further subsystem of the measurement assembly, being a voltage measurement assembly consisting of a voltage measurement coupling assembly (27) linked to a voltage measurement circuit (28). The fence contact device (23) is also directly linked to a communications coupling assembly (24) which in turn is linked to a communication assembly (25).

The portable apparatus (21) also includes a processing means, formed in this embodiment by a micro processor (26) which receives inputs signals from the communication assembly (25) as well as the current measurement assembly

(22) and voltage measurement circuit (28). The portable apparatus (21) also includes a keypad (29) allowing a user to enter information or commands into the processor (26), as well as a display (30) which allows information to be presented to a user by the processor (26).

As can be seen from figure 3 both the communication assembly and the voltage measurement portions of the measurement assembly are directly linked to the fence contact device (23). Through each of the coupling assemblies (24,27) these circuits are protected from damage by energiser pulses traversing the fence line (31) in addition to stopping the circuitry of each assembly interfering with the operation of the other.

The communications coupling assembly (24) can includes a high frequency pass circuit or a resonant circuit which presents a low impedance at the frequency of communication signals and a high impedance at the frequency of energiser pulses traversing the fence line (31). Those skilled in the art should appreciate that an arrangement of capacitor (s) or capacitor (s) and inductor (s) can be used to form such a high pass filter or resonant circuit adapted to operate at the frequencies of relevance.

The voltage measurement coupling assembly (27) is configured to present a high impedance at both the communication signal frequencies and also the fence energiser pulse frequencies. This effective high impedance of the voltage measurement coupling assembly ensures that the associated portions of the measurement assembly do not load down either communication signals on the fence line (31) or electric fence energiser pulses to be measured.

In the embodiment shown with respect to figure 3 the voltage measurement coupling assembly (27) may be formed by a voltage divider with a high initial

input impedance to divide down the voltage signal supplied or sent to the actual voltage measuring circuitry (28). For example, in one further preferred embodiment such a coupling voltage divider may have an input impedance of approximately an order of magnitude higher than the impedance of the driving source. The divider resistor is such a value that results in the fence voltage being divided down to a level capable of being processed by low voltage circuits - such as for example of the order of 5 volts.

Alternatively, those skilled in the art should also appreciate that a low value capacitor may also form part of such a voltage coupling measurement assembly to reduce the amount of energy transferred to voltage measurement circuitry employed in conjunction with the present invention.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.