More specifically, this invention relates to improvements to a device and method for testing lines such as telephone lines or communication lines or power lines. The lines may be of fibre-optic or copper construction.

However, one skilled in the art should appreciate that the principles of the present invention may be applied to testing in other context.

BACKGROUND ART Telecommunications are an essential part of today's residential and business activities.

Telecommunication lines are used to communicate many types of data between points, including voice, data, and video.

Because many consumers in residential and business situations rely on telecommunications, it is important that any faults resulting in a hindrance to the use of the telecommunication are detected and remedied quickly.

A number of devices exist to assist in detecting the source of faults in telephone lines.

One such class of device is known as a Far End Device (FED).

Another such class of device is known as a Premises Isolation Device (PID).

FEDs were developed to improve the efficiency of maintenance and commisioning work on telephone lines. The use of the FED overcomes the necessity of positioning a technician at the end of the telephone line where the FED now is located, and having a second technician located somewhere along the telephone line, transmitting signals to be interpreted by the first technician. Alternatively, the FED saves a single technician the onerous task of travelling back and forth to each end of the line.

These previous techniques were clearly an inefficient use of labour.

FEDs are placed on one end of the telecommunication line. A technician at the other end of the line then sends signals down the telephone lines which are received and processed by the FED. The output from the FED and switching configurations of the FED can be used to determine the types of faults and the source of faults and the location of faults along the telephone. A typical FED is capable of sending a trace tone, shorting the line, isolating the line beyond the FED, sending a tone, measuring the amplitude of a tone (and reporting back by DTMF), sending a tracing tone to allow a probe to identify the same pair at a distance along the cable.

PIDs were developed to enhance the automatic and remote controlled testing systems in telephone subscriber loop networks. In other respects, the functionality of PIDs is the same as for FEDs.

Whereas FEDs are normally battery powered, the PIDs are usually, but not always, line-powered in that they derive their power from the telephone line. Alternatively, PIDs may be mains-powered. PIDs are usually permanently or semi-permanently installed at or near the subscriber premises, which is in contrast to the portable nature of a FED.

A PID enhances a remote controlled or automatic testing system by providing remote controlled testing functionality at one end of the telephone line. More accurate and detailed test results are made possible, and two-ended testing of the line is possible without the necessity of manual connections of testing equipment on one or both ends of the line.

FEDs and PIDs of this nature have been disclosed in US Patent No. 4,862,491 (Lasalle Et Al), US Patent No. 5,357,556 (Dresser), and US Patent No. 5,528,662 (Stephens).

FEDs and PIDs commonly use Dual Tone Multi Frequency (DTMF) signalling as a remote control mechanism, enabling commands and responses to be communicated end to end.

DTMF tones are commonly used to transmit information along phone lines between the customer and the exchange, for example, interactive voice response systems, and dialling numbers. Information using these tones enables commands to be sent to the FED. One problem associated with using such signals are that DTMF receivers use relatively large amounts of power in operation.

Due to the requirement of portability for the FEDs, a battery is desirable, as a power outlet is not always available.

Consequently, DTMF receivers quickly deplete battery operated FEDs of power. It would be desirable for the DTMF receiver to be deactivated when not in use, and therefore there is a need for remote re-activation.

A typical sequence in the operation of an FED may be as follows: The FED is connected at one end of the line, and is manually switched on. A technician travels to a chosen test point such as a roadside cabinet or the main distribution frame. The FED transmits a tracing tone, which allows the correct pair to be identified at the test point. A second device is used to send a DTMF command, which may be to isolate the line for further testing such as loss testing, and earth fault location.. The FED may be sent a command to reconnect the line.

The cable may then be repaired. Typically, the FED is not used during this repair time, and consequently the battery is drained unnecessarily.

It would be inefficient for the technician to travel all the way to the FED to manually switch it off, travel back to the repair point, and then travel to the FED to switch it on, when it is necessary to perform further tests on the repaired line.

Furthermore, a FED is required to be relatively compact. This is necessary for convenience of carrying, and for the FED to be able to fit inside small enclosures, or access points, required to reach to the cable.

Consequently, the battery supply for the FED must also be compact. This results in the battery having a lower capacity, making the need to conserve battery power during times when the FED is not in use, even more paramount.

What would be of great advantage is a device that allowed for longer battery life on an FED, and consequently allowed the FED to be compact and more practically applicable.

Line-powered PIDs are also required to have a low power consumption. The current drawn by a PID requires power from the Central Office or Exchange equipment, and this power is a cost to the telephone company. Furthermore, the power drawn causes a voltage drop on the line, and less power is available for the subscriber equipment which could result in loss of service in the case of long subscriber loops. Another problem is that testing systems will determine that there is a fault on the line if the PID is drawing too much current.

For each of the above reasons, it would be of great advantage to be able to minimise the DTMF receiver activity in the PID.

FEDs or PIDs may deploy signalling for remote control other than DTMF. Other signalling may be pure tones, or combinations of more than one pure tone. This circuitry may be able to be depowered, or placed in a low power state. It would be of great advantage to minimise the activity of this circuitry for the same reasons as previously explained for the DTMF receiver.

The FEDs or PIDs may also incorporate additional processing circuitry which offers a lower power consumption when it is put into a low power or disabled state. Once more, it is highly desirable to minimise the activity of this circuitry.

FEDs and PIDs commonly are designed to receive pure tones or combinations of pure tones to provide a transformation from a relatively low power or dormant state to a relatively high power or active state. The FED or PID is required to use a narrow band receiver to detect each or any of the pure tones.

The disadvantage of such a method is that a tuned receiver must be set to receive a specific signal. Furthermore, there is often a limitation of frequencies available for this function, and there may easily be a conflict between different devices connected to the same network and which are sensitive to the same frequencies.

It would be of great advantage if the narrow band receiver could be simplified, and could be made more flexible so that the remote controlled transformation from dormant state to active state is flexible, cheap and easy to implement, and compatible with normal telephone networks.

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 testing device for testing a line including; a receiver, the testing device having a dormant state and an active state, the testing device characterised in that on receipt of a coded signal by the receiver, the testing device changes from one state to the other state.

According to a further aspect of the present invention, there is provided a method of operating a testing device characterised by the step of sending of a coded signal to the receiver of the testing device to cause the testing device to change from a dormant state to an active state.

In further preferred embodiments, the testing device may be a FED or a PID, which are devices commonly used to test and locate faults along telecommunication lines.

Reference to the testing device in this fashion should not be seen to be limiting the scope of the present invention's manufacture or use, as one skilled in the art will appreciate that the principles of the present invention may be used in the context of using other parameters-for example, power lines.

The testing device may be remote controlled with (Dual Tone Multi Frequency) DTMF tones, sent by the technician with a device that can generate DTMF tones.

It should be appreciated however, that in other embodiments of the present invention other signalling formats may be used and DTMF tones is just one preferred example.

The receiver which forms part of the FED or PID may be any device with means responsive to a stimulus, such as a radio frequency, electrical signal, mechanical movement, on/off switch, or a combination of these.

Preferably, the receiver may be any unit in the transmission system unit where received information is stored, recorded or converted into the necessary form.

In preferred embodiments, the receiver may take the form of a wide band receiver.

Preferably there may be associated with the receiver, a processor and the necessary power supply.

Typically, the power supplies in the FED are batteries, but should not be seen to be limited to batteries, as other sources of power may be used such as mains power, photovoltaic cells, or other sources of electric power. Similarly the power supply in the PID should not be seen to be limited to line-power.

Preferably, the processor associated with the receiver may be any electronic circuit that suitably processes the information received by the receiver. The processor may comprise an analogue circuit, discrete componentry, an integrated circuit, a microprocessor or a microcontroller, or a programmable logic array. In preferred embodiments the processor may be an integrated circuit.

The active state of the testing device or in preferred embodiments, the FED, may have a relatively high power consumption, being that of an FED or a PID (or testing device) in normal operation.

The dormant state may preferably be a state of relative low power consumption, that being at a level sufficient to maintain a FED or a PID (or testing device) in an alert state, but not in full operation.

For example, the testing device may be capable of more than two levels of power consumption.

In preferred embodiments, the coded signal may be any coded radio frequency, electronic, audio, mechanical or other signal capable of receipt by the receiver.

For example the coded signal may be a particular radio frequency, a vibration sequence, a conducted electrical signal such as a voltage variation, a current variation, a fibre-optically transmitted signal, or a combination of these.

The coded signal may be an on/off amplitude modulation sequence of a tone. In preferred embodiments, the tone falls within a wide frequency band for the advantages described on page 5 associated with using a wide band receiver.

The coded signal may preferably be modulated on a 577 Hz or 1000 Hz carrier signal which are commonly used tracing tone frequencies. It may take the form of an on/off amplitude modulation tone sequence signal with a predetermined on/off timing pattern.

The use of a single carrier frequency should not be seen to be limiting however, as other signal types and frequency ranges may be used. For example, more than one carrier frequency may be present. A DTMF signal can be modulated on/off to have the same effect, or a random noise signal with many frequency components can be used as a carrier. The fundamental property of the coded signal is the on/off timing.

The on/off timing or cadence of the wakeup signal may conform to a general pattern, and not just to a specific pattern. More specifically, the FED or PID may be designed to respond to any number of different on/off patterns, provided that a recognisable pattern does exist in the on-off cadence. In this fashion, the FED or PID is compatible with many different standard tracing tone sources, all of which have slightly different on/off cadences.

Preferably, the testing device enters the dormant state, upon detecting a predetermined condition. Preferably, the predetermining condition may be an inactivity time-out due to the lack of receipt of DTMF signals at the receiver. This should not be seen to be limiting however as the predetermined condition may take other forms such as a particular coded signal, heat, light, sound or vibrational stimulation, or a particular battery power level. Another predetermining condition may be a DTMF command, or activation of an on/off switch.

Preferably, the coded signal may cause the change of state from dormant to active.

This has the advantage that the device may be shut down actively, or shut down automatically, and may be reawakened when further required.

Preferably, the coded signal may be sent from a location remote from the testing device. This has the advantage that the testing device may be used from a remote location, removing the need to have one operator at the device in order to operate it.

This results in savings of labour costs and time efficiency.

Preferably, the dormant state of the testing device may be one where the testing device draws a very small current. This results in a low power consumption while maintaining an alert electronic state.

While in the dormant state, the testing device maintains a vigilance for the coded signal to turn the device back on to full operational features and corresponding active power consumption.

In the low power state, the receiver may use a time based sampling method to detect the pulse with modulated or otherwise coded signal, which will cause the Far End Device to go into the active state.

The 3M Dynatela 965/965MC/965DSP Subscriber Loop Analysers (the 965s), are line testing devices capable of sending DTMF tones. In preferred embodiments, the coded signal is the standard interrupt cadence tone of one of these devices.

Alternatively, an industry standard tracing tone source (interrupted-tone) may be used.

One advantage of this is that the equipment for generating this tone is already in existence, thus reducing the need to produce a device for this specific purpose.

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 shows a flow diagram of the activity of a preferred embodiment of the present invention, and Figure 2 shows operation of the FED with the 965DSP for telephone line testing, and Figure 3 shows operation of the PID with an automatic line testing system.

BEST MODES FOR CARRYING OUT THE INVENTION With reference to Figure 1, there is shown an algorithm of the preferred embodiment in operation.

In operation, the present invention is sourced to power at stage 1. This may be by the insertion of a battery (not shown).

The device automatically reverts to a dormant state of low power consumption using the wide band receiver. The dormant state is indicated at stage 2.

A coded wake up signal is received at 2 by a wide band receiver. This signal may be as a result of the touch pad or the interrupted tracing signal from the 3M DynatelTM 965DSP Subscriber Loop Analyser. The device is then reawakened on the condition that the coded wakeup signal is valid. The detection of the correct wakeup signal results in a transition from stage 2 to stage 3. If the coded signal is invalid then the device remains dormant.

If a DTMF digit is received as part of a command, there is a transition to stage 4.

The desired commands are executed at stage 5, dictated by the DTMF signals received at stage 4 and interpreted by the command parser46. After these are executed, and ifthe DTMF receiver does not receive digits for a predetermined time period, the DTMF receiver relinquishes control and initiates dormant state (2).

For background informality Figures 2 and 3 illustrate the operation of FED's and PID's.

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 of the appended claims.