IES81283B2 - A communications device - Google Patents

Abstract

A communications device (101) for use with an electric fence (102) of the type having a pulse generator (100) has a transmitter for remotely switching the pulse generator (100) and a probe (2). The probe (2) has an associated signalling device (3) for measuring and indicating pulse amplitudes to denote the operational status and strength of the fence pulse at the remote location of the fence.

Description

APPLICATION N«. - 1 P7763.IES A COMMUNICATIONS DEVICE The present invention relates to a communications device and in particular to a communications device for use with an electric fence.

A variety of communications devices are known and are most commonly used with electric fence systems having electric fence energisers. These electric fence energisers emit a high voltage pulse approximately every second and the intensity of the pulse acts as a deterrent to livestock from touching the fence. One of the main advantages of the electric fence is that it can cover a large area of a farm with a small amount of equipment thereby reducing the cost. However if the farmer is at a remote location from the energiser unit and wishes to turn the electric fence off, then he or she has a considerable distance to walk, considering electric fences of this type can cover distances of the order of seven kilometres.

U.S Patent specification no. 4270735 discloses a product that can operate the energiser of an electric fence from a remote location. The product consists of a battery, connected between the fence and the ground, supplying a D.C signal to the fence. This signal is received by a receiver that turns the energiser between an off position and an on position. The operation of the device causes a large drain on the batteries and reduces the efficiency of the product dramatically.

European Patent specification no. 514222/A discloses a device which comprises a means for sending a coded signal down an electric fence line in order to switch a further receiver between an off position and an on position.The coded signals are separated from the normal pulses - 2 produced by the energiser. In this application the device is included in the energiser unit.

There are also general problems associated with sending signals along an electric fence line. It is common for electric fence lines to have signals from other electric fence lines or power lines induced on them. This has the effect of attenuating the signal. A further problem of poor connections on the system could also mean that the emitted signal may not reach the energiser or pulse generator.

The object of the present invention is to alleviate the above disadvantages .

Accordingly there is provided a communications device for use with an electric fence of the type including a pulse generator, the communications device having a transmitter for remotely switching the pulse generator and a probe with an associated signalling device for measuring and indicating pulse amplitudes to denote the operational status and strength of the fence pulse at the remote location of the fence.

Advantageously, the transmitter for remotely switching the pulse generator between an off position and an on position comprises: a switching means; a microcontroller for generating a modulated frequency signal in response to the switching means; a H-bridge amplifier for transmitting the FM signal and to provide a voltage to a step-up transformer, the step up transformer delivering the voltage to the fence. - 3 Preferably, the signalling device incorporates means for generating a control signal in proportion to a measured pulse amplitude.

Conveniently, the signalling device incorporates a microcontroller for receiving a signal in response to a fence pulse.

Beneficially, the communications device is provided as a hand held portable unit and the dual features of the device are operable with or without a grounding probe.

Advantageously, the switching means is provided by a push button whereby pressing the button switches the pulse generator to an alternate position. The push button control means reduces the number of parts on the control box and thus the overall cost of design and manufacture of the device.

Additionally, the control signal can be broadcast by a number of visual and audio methods, for example: (1) An L.E.D array can be used to display the peak pulse amplitude in a visual bar graph indication manner. (2) An LCD display can display the peak pulse amplitude in the relevant range. (3) An internal buzzer can sound once per second with a tonal frequency that is proportional to the peak pulse amplitude .

The display means is beneficial for observing the value of the peak fence voltage and also for ensuring that the pulse generator has been switched to the correct position.

Additionally, the communications device can be activated from a dormant state to an operational state by engaging it with the electric fence while the pulse generator is operating.

This is a further method of determining the operational status of the electric fence.

Alternatively, the communications device can be activated by pressing the push button for one second.

Beneficially, the communications device will accept a fence pulse for one minute after the push button is pressed and will remember the status, operational or dormant, of the pulse generator.

It will be understood that continuous tone combinations could be used in order to remotely switch the pulse generator between an off position and an on position.

The invention will now be described with reference to the following drawings which show, by way of example only, one embodiment of the communications device.

Figure 1 is a schematic diagram of a typical electric fence incorporating a communications device.

Figure 2 shows a simplified block diagram of the measurement section of the communications device.

Figure 3 shows a simplified block diagram of the receiver Figure 1 shows an electric fence energiser 100 attached to a switch unit 101 in order to pulse the fence with a 10 KV signal. The communications device 1 rests in contact with the fence 102 and works in conjunction with the switch unit 101. In use the switch unit 101 receives signals from the communications device 1 and disconnects or reconnects the mains 103 to the energiser 100.

Figure 2 shows a simplified block diagram of the measurement section of the communications device 1. A series resistor and VDR included in the communications device interface 2 protect the handset from the high voltage transients. The fence voltage is then transferred to the measurement electronics via a step down transformer included in the communications device interface 2. For the operation without a ground probe earthing is provided by capacitive coupling through the communications device handle wall to the operator's hand using the hand communications device 3. The high value series resistor and/or capacitor 4 swamps the effect of variations in the impedance of this capacitive earth as well as dividing down the input voltage.

A peak detector 5 is used to hold the peak pulse value.

An RC pair is charged up to a value proportional to the fence pulse amplitude and transferred to a microcontroller 7 where an analogue to digital conversion is made.

The on/off control of the energiser is carried out using the push button 8 sending one of two modulated frequencies. The signals are continuous tones of either 129 KHz for on or 117 KHz for off. This signal is generated within the microcontroller 7 and fed to a Η-Bridge amplifier 9 to drive the fence with an 80 volt peak-peak voltage. This signal is delivered to the fence via a step up toroidal transformer that is included in the communications device interface 2.

The visual display of the fence pulse amplitude is provided by the microcontroller 7 along bus lines 10 to a two digit, seven segment display 11, an audible indicator 12 or an LED array 13.

As the frequency is relatively high then the hand capacitance is sufficient in most cases to provide a ground return to the receiver earth.

The battery 14 is a 9V supply and is connected to a 5V regulator 15.

The microcontroller 7 functions include:1. Converting the input signal on the microcontroller to an energiser on/off control signal. 2. Protecting the electronics from the fence's high voltage.

Figure 3 shows a simplified block diagram of the receiver 21. The energiser output 22 is fed into the primary of a toroid transformer included in the fencer interface 23 and then to the fence 24. The toroid isolates the high voltage pulse from the receiver electronics but still allows the line signal to pass to the receiver. The toroid secondary drives two circuits. 1. A voltage divider, bridge rectifier and resistor are all included in the peak detector 25, the resistor combining with the capacitor 26 to provide an RC pair.

This circuit divides down the ten KV fence voltage to a 10 V pulse that is then rectified and charges an RC pair each time the fence is energised. This pulse is taken to an input pin of the microcontroller 27 to allow a pulse width (time domain) to voltage amplitude conversion. 2. A series resistor and voltage clamp protection diodes included in the peak detector 25 ensure that the receiver is protected from the fence pulse 22 and other high voltage transients.

The receiver is a direct conversion mixer that takes the low amplitude 129KHz and 117 KHz signals from the fence, amplifies them and mixes them with the 125 KHz local oscillator. The mixed signal is either a 4KHz signal for an on command or 8KHz for an off command. The local oscillator signal is derived from the microcontroller clock of 8MHz. It is divided by a six stage divide by two IC. The digital signal is then rounded off and attenuated to ensure the correct waveform. These functions are carried out in the bandpass filter and input protection 28.

The output of the amplifier/mixer is fed to a low pass filter with 50db's of gain and then to a second unity gain op amp acting as a low pass filter with a 10 KHz roll off. This ensures that signals outside of the bandwidth 115 KHz to 135 KHz are rejected. These components are housed in the voltage receiver converter 29. This is very important as the electric fence acts as a very good antenna to low radio frequencies.

The data out signal goes directly to the micro pin.

The microcontroller 27 has the following outputs:1. Relay drive 30 to turn the electric fence on or off for separate fencer. 2. Digital drive 31 to turn on the electric fence control line on or off - integrated fencer. 3. Bussed lines 32 that drive a 2 digit LCD display 33 to enable the fence pulse amplitude to be displayed to the user.

Additional filtering and noise suppression are provided by the operating software.

The following sequence of operations show the various uses of the communications device :1. Fence off, communications device off, communications device is engaged with fence - nothing happens and no display. 2. Fence on, communications device off, communications device engaged with fence - communications device activates and indicates fence voltage. 3. Fence on, communications device on and engaged with fence, button pressed - pulse generator is turned off. 4. Fence off, communications device on, and engaged with fence, button pressed - pulse generator is turned on.

. Fence on, communications device off, communications device not in contact with fence, button pressed and then engaged with fence - communications device activates and indicates fence voltage.

It will of course be understood that the invention is not limited to the specific details as herein described, which are given by way of example only, and that various alterations and modifications may be made without departing from the scope of the invention.

MACLACHLAN & DONALDSON Applicants' Agents 47 Merrion Square

Claims (5)

CLAIMS:

1. A communications device for use with an electric fence of the type including a pulse generator, the communications device having a transmitter for remotely switching the pulse generator and a probe with an associated signalling device for measuring and indicating pulse amplitudes to denote the operational status and strength of the fence pulse at the remote location of the fence.

2. A communications device as claimed in Claim 1, in which the transmitter for remotely switching the pulse generator between an off position and an on position comprises:a switching means; a microcontroller for generating a modulated frequency signal in response to the switching means; a H-bridge amplifier for transmitting the FM signal and to provide a voltage to a step-up transformer, the step up transformer delivering the voltage to the fence; optionally the signalling device incorporates means for generating a control signal in proportion to a measured pulse amplitude; optionally the signalling device incorporates a microcontroller for receiving a signal in response to a fence pulse; and optionally the communications device is provided as a hand held portable unit and the dual features of the device are operable with or without a grounding probe.

3. A communications device as claimed in Claim 1 or Claim 2, in which the switching means is provided by a push button means, whereby pressing the button switches the pulse generator to an alternate position; optionally the control signal is broadcastable by a number of visual and audio methods, such as an L.E.D array which can be used to display the peak pulse amplitude in a visual bar graph indication manner, or an LCD display which can display the peak pulse amplitude in the relevant range or - loan internal buzzer operational to sound periodically with a tonal frequency that is proportional to the peak pulse amplitude.

4. A communications device as claimed in any one of the preceding claims, in which 5 the communications device is activatable from a dormant state to an operational state by engaging it with the electric fence while the pulse generator is operating; alternatively, the communications device is activatable by pressing the push button for a first period of time and optionally, the communications device is adapted to accept a fence pulse for a second period of time 10 after the push button is pressed and is provided with a memory means to remember the status, operational or dormant, of the pulse generator.

5. A communications device substantially as herein described, with reference to, and as shown in the accompanying drawings.