WO2003034570A2

WO2003034570A2 - Improvements relating to remote control

Info

Publication number: WO2003034570A2
Application number: PCT/GB2002/004701
Authority: WO
Inventors: Phillip Thomas Foxley; Neil Morris
Original assignee: Technical Support & Supplies Limited
Priority date: 2001-10-17
Filing date: 2002-10-17
Publication date: 2003-04-24
Also published as: AU2002339057A1; GB0124922D0; WO2003034570A3

Abstract

A system capable of controlling a number of apparatus, the system comprising a command station (2) capable of broadcasting a signal to one or more base stations (26, 28; 200-210). Each base station (26, 28; 200, 202) is arranged to control one or more apparatus (30-40, 212-226) in receipt of a predetermined command from the command station. The apparatus (30-40, 212-226) may be street lighting.

Description

IMPROVEMENTS RELATING TO REMOTE CONTROL

This invention relates to an apparatus for the remote control of apparatus, and also related methods. Primarily, but not exclusively, the apparatus and methods relate to the remote control of lighting.

The remote control of remote of lighting is a known and well developed field. Examples of systems for such remote control are shown in many patent applications, including PCT/GB97/01870. However, prior art remote control apparatus is limited on the number of apparatus that can be controlled.

Previously, the use of mains borne signalling has been proposed. Such an arrangement has a limited range due to the degradation of the signal on the mains supply. Although it is possible to boost the signal this requires complex circuitry and is not a cost effective option.

Bus based systems have been proposed, which allow a larger number of apparatus to be controlled. However, such systems require a bus cable to be connected to each apparatus that it is desired to control. Clearly, if the number of lights is high, or the distances large, the amount of cabling required becomes prohibitive.

It is known to provide system that rely on dial up access over a telephone network. However, if large numbers of apparatus are being controlled then such system are not practical. For example, a dial up connection may take 20 seconds to run, including the dial up time. To control 1000 pieces of apparatus using such communications techniques would take on the order of 5.5 hours, which is too slow for some applications. It is an aim of the present invention to solve, or at least reduce, the problems associated with the prior art.

According to a first aspect of the invention there is provided a system capable of controlling a number of apparatus, the system comprising a command station capable of broadcasting a signal to one or more base stations, each base station being arranged to control one or more apparatus on receipt of a predetermined command from the command station.

An advantage of such a system is that it can control a large number of apparatus, which may be considerable distances from the command station.

The command station may be arranged to use any one or more of the following mediums to broadcast said signal: radio signal, television signals, Short Message Service (SMS) text messages, GSM wireless network, paging network, a mesh communication network. Each of these mediums is convenient because it allows a large number of base stations to be contacted by signals from the command station. In particular the mediums may allow a single signal to be broadcast to a large number of base stations at any one time.

The system may be arranged to send a signal over inband, or out-of-band frequencies of a radio network. It will be appreciated that radio networks are well established, and it may be possible to make use of an established radio station to transmit the signal. If the signal is transmitted within the frequencies that the radio network generally transmits then this is an inband frequency. Radio networks may have frequency bands that they do not generally use but which are reserved, and transmitting the signal in such a reserved band used an out-of-band frequency. If a radio signal is used the command station may be arranged to make use of an Radio Data Service (RDS) signal. Such an arrangement is advantageous because it may allow the signal to be compensated for regional variations.

In some embodiments the signal may be added to a television transmission. The signal may be in an inband, or out-of-band frequency range, much in the same way as the radio signal discussed above. The system may be arranged to incorporate the signal much in the same way as teletext signals are encoded into a television transmission.

In alternative, or additional embodiments, SMS text messaging may be advantageous. It is convenient because it allows messages to be sent to a large number of base stations at any one time. However, the use of SMS messages relies on a network provider being able to provide enough band width to send the required number of messages at any one time.

The command station may be arranged to make use of a variety of media in order to deliver the signal.

Preferably, each base station communicates with one or more remote stations. Each remote station may be arranged to control one or more pieces of apparatus, which may be electrical. In the preferred arrangement each base station is not directly connected to the controlled apparatus, but controls the apparatus via remote stations connected thereto. The advantage of such an arrangement is that a single base station may control a plurality of apparatus. The base station may be connected to the remote stations via any known communication means, such as mains borne signalling, bus connections, etc. In the preferred embodiment, the base stations are arranged such that they do not send a response to the signal during normal operation. In such an arrangement the command station assumes that the each base station has correctly received the signal. It will be appreciated that this is advantageous because if the command station sends out a large number of signals at any one time, it is likely to require more bandwidth, and processing power, than is available to receive and process a large number of responses to the command station.

The base stations may be arranged to send a response to the command station if an error occurs. Examples of errors that may cause the base station to send a response include any one or more of the following: a corrupted signal, a fault detected in one of the apparatus that it controls, or the like.

The command station may comprise a database arranged to maintain details of base stations and/or remote stations and/or apparatus controlled thereby. The details may include the status (i.e. on/off, functioning correctly, or any other relevant parameter) , contact number (may be a mobile telephone number, etc. to which an SMS message should be sent, may be a unique identity to which a radio signal could be transmitted) .

Conveniently, the command stations and the or each base stations are arranged to have two modes of operation: a normal mode and an emergency mode.

In the normal mode the base station may be arranged control apparatus controlled thereby in a predetermined manner at predetermined times. For example, it may be arranged to turn the apparatus on/off at said predetermined times. Such an arrangement is convenient in arrangements such as street lighting, in which the lights are turned on in the evening and off again in the morning. The time at which the lights are to be turned on/off may be held as default values accessible by the base station.

If a signal is not received before the default value for the time occurs then the action may occur. For example, the base station may cause lights controlled thereby to come on at a predetermined time unless it receives a signal to the contrary. The skilled person will appreciate that because in the preferred embodiment a signal is being broadcast, and no response is being made, that there is a chance that the broadcast signal may not be received by all of the base station. Therefore, an advantage of having the default times for the action to occur is that the apparatus controlled by the base station is likely to be operated as desired.

In the normal mode of operation, the command station may be arranged to send the signal at a time just before the predetermined time at which the apparatus would otherwise be controlled. Just before may mean a few minutes, or perhaps tens of minutes, or may be seconds, or tens of seconds. For example, roughly any one or more, or any time in between of the following times may be suitable: 5 seconds, 10 seconds, 20 seconds, 30 seconds, 1 minute, 2 minutes, 3 minutes, 5 minutes, 10 minutes, 20 minutes .

In an emergency mode, the command station may send the signal at any time. Thus, if it were desired to turn on apparatus connected controlled by the command station due to an extraordinary situation this could be achieved with a single command.

The system may be arranged to control apparatus over a wide geographical area. The apparatus may be separated from the command station by roughly any of the following distances, or roughly any distance in between the following distances: 100m, 500m, 1km, 5km, 10km, 50km, 100km, 500km, 1000km, 5000km. The skilled person will appreciate that when a medium such as SMS messaging is used to deliver the signal the system is relying on a medium that can transmit the signal between countries, which may be on opposite sides of the globe.

Preferably, the apparatus is an electrical apparatus. In the most preferred embodiment the apparatus comprises lighting and in particular street lighting and/or tunnel lighting.

The base station may be connected to other base stations, and arranged such that a signal received by a base station may be passed to other base stations.

According to a second aspect of the invention there is provided a method of controlling a number of apparatus comprising broadcasting a signal from a command station which is capable of being received by one or more base stations, and causing the base stations to control the apparatus in response to the signal.

The method may comprise corresponding steps to any of the features described in relation to the system of the first aspect of the invention.

According to a third aspect of the invention there is provided a computer readable data carrier carrying instructions to cause a computer to carry out the method of the second aspect of the invention.

According to a fourth aspect of the invention there is provided a computer readable data carrier carrying instructions arranged to cause a computer to provide the system according to the first aspect of the invention. According to a fifth aspect of the invention there is provided a command station capable of broadcasting a signal and transmitting suitable for use in a system according to the first aspect of the invention.

According to a sixth aspect of the invention there is provided a base station capable of receiving a signal from a command station and being suitable for use in a system according to the first aspect of the invention.

There now follows by way of example only a detailed description of the invention with reference to the accompanying drawings of which:

Figure 1 schematically shows one possible network arrangement for realising the present invention;

Figure 2 shows an alternative network embodiment; and

Figure 3 shows schematically a system for monitoring and controlling the operation of a number of street lights . ;

Figure 4 shows a monitoring system;

Figure 5 shows a schematic of a light unit in accordance with the invention; and

Figure 6 shows an isometric view of a housing means suitable for use with a street lamp.

A command station 302 comprises a first computer 304, and a second computer 306, which would typically be of the kind referred to as a PC, but could be any other type of computer. The first computer 304 is primarily used to control the system, and the second computer 306 is used as a backup in case the first computer should fail for any reason.

The computers 304,306 are connected to a transmission network 310. Two possible ways of connecting to the network 310 are shown in the Figure. Firstly, the computers 304,306 are connected thereto using a modem 308. Secondly, the computers 304,306 are connected by a network connection 312 to a satellite dish 314. The satellite dish 314 can be used to establish a satellite link 316 with a second satellite dish 318, giving the possibility of sending a signal from the command station 302 over great distances.

The transmission network 310 can comprise a variety of different transmission media. Figure 1 shows the following transmissions: a national/local television, radio, or wireless network using "in-band" or "out-of-band" data frequencies 320; a GSM wireless network, or SMS service provider 322; and a wireless pager network 324. Each of these transmission media 320,322,324 provides a two way data link with the command station 302.

A plurality of base stations 326,328 (although only two base stations are shown there may in fact be 10's, 100's, or even 1000's of base stations in communication) are arranged to accept messages from one or more of the transmission media 320,322,324.

The base stations 326,328 are arranged such that they can transmit response signals to the command station 302. In the case of the radio/television transmission medium 320 the base station 326 communicates with the command station 302 via a telephone, SMS link or similar (It will be appreciated that the transmission medium 320 is a one way medium) . In the case of the GSM, SMS, or Wireless paging transmission media 322,324 the base station 326,328 may be arranged to send response signals back to the command station using the same media (since these are two way communication mediums) .

Each base station 326,328 is arranged to communicate with, and control a plurality of apparatus, in this case electrical apparatus comprising street lamps 330,332,334,336,338,340.

The computers 304,306 have access to a database, which holds unique access number for each of the base stations 326,328 in communication with the command station, together with status information for the apparatus connected to that particular base station 326,328. For example, the database may comprise an entry for base station 326 comprising an access number (e.g. 12345678) together with a status of on/off. The base stations 326,328 may be arranged such that response signals sent therefrom to the command station 302 contain the access number so that the command station knows from where the response signal arose.

Each of the lamps 330-440 contains a remote station capable of communicating with the base station 326,328. The remote station monitors the status of the street lamp 330-340 and reports this information to the base station, and is also arranged to respond to signal received from the base station 326,328 (for example light on/off, dim light to 50% power, full power, etc.) The network of base stations, and remote stations may be as described in PCT/GB97/01870, and the description of the communication between the base station and remote stations are hereby incorporated by reference. The skilled person is directed to read PCT/GB97/01870 and understand its teachings).

In use, if it is desired to send a signal to any one of the base stations 326,328 then the command station looks up the access code for that base station 326,328 from the database, and then transmits via a transmission media 320,322,324 a signal giving an appropriate instruction.

When a base station 326,328 receives a signal transmitted from the command station 302 it actions the instructions contained in the signal. The base station 326,328 do not make a response to the signal unless an error occurs. However, if an error does occur (perhaps the signal had errors within it, the street lamps 330-340 do function as instructed, etc.) then a signal is returned to the command station 302.

Each base station 326,328 contains processing circuitry allowing it to respond to the signal as appropriate. The base stations 326,328 may be arranged to monitor the status of any apparatus connected thereto, and may further be arranged to transmit this information to the command station 302.

In a normal mode of operation the base stations 326,328 are arranged to switch on the street lamps 330-340 connected thereto at a predetermined time at dusk, and switch the lamps off at a predetermined time in the morning. For example, the base station 326,328 may be arranged to switch the street lamps on as a default at 20:00, and off again at 08:00. The command station 302 may be arranged to transmit a lamp on signal at 19:50, and a lamp off signal at 07:50. If any of the base stations 326,328 do not receive this signal then they will come on 10 minutes later by default. Transmission of the signal from the command centre allows the database to be updated correctly.

In an emergency mode of operation the command station 302 can be arranged to send a signal to the base stations 326,328 at any time. The system may provide an event driven reporting function, in which response signals received from a base station 326,328 highlighting a fault are stored in the command station 302, possibly within the database. These fault responses can later be browsed according to their classification, or simply browsed through in order, etc.

Figure 2 shows an alternative network arrangement in which a command station 302 communicates via a transmission medium 310 with base stations 200,202. Each of these base stations 200,202 communicates with further base stations: base station 200 communicates with base stations 204,206 and base station 202 communicates with base stations 208,210. The base stations 204,206,208,210 are arranged to control a plurality of aρparatus:212,214,216,218,220,222,224,226.

The base stations 200, 202 could be directly connected to apparatus.

Specific notable points of the system described in relation to Figure 1 or 2 include:

• central control computer • global command functions for apparatus/lighting control

• central database for system addressing and location

• sql database browser for event driven reporting

• network communication monitoring

• automatic data base back up and recovery • redundancy slave computer for system failure protection.

Other notable points about the system are as follows:

General Broadcast mode communication features: The base stations have the capability of operating in a specific broadcast mode. This mode comprises two main elements:

First mode: Base station to command station ^'

Once installed and commissioned the base station unit will immediately begin an internal, cyclic self-diagnostic and status checking routine. This routine is software programmable and would include standard as well as non-standard routines, to suit the final end-user application.

Typical default scanned Fault/status parameters are Errors

1. mains voltage supply

2. mains fuse 3. CPU fault

4. circuit 1-3 over /under current

Status

1. circuit 1-3 contactor 2. operating mode (normal or emergency)

3. 10 digital input/output channels

4. 5 analogue input/output channels

Should the cyclic routine detect any error event, an appropriate error message would be instantly generated and transmitted (usually via wireless SMS) to the command station for further analysis. This error message would generally contain the unique base station address, together with a relevant error code describing the nature of the fault.

station id ^uni(l^{ue area/} zone address id

The above error code has had data encryption algorithms omitted for the 0 sake of clarity, but these may be used.

Second Mode: command station to base station.

The command station would be capable of connecting to a multitude of 5 current and future wireless data transport technologies e.g. UMTS, GSM, SMS, GPRS, local radio/t.v. in/out band, standard radio, etc.

When the command station is set to broadcast mode, a single specific command string would be generated and transmitted via the selected 0 medium to all (tens/hundreds/thousands) of base stations .

On receipt of this command string, the base station units would instantly action the command string instruction. Typical default command strings would result in the following actions : 5

1. normal mode - all lamps on

2. normal mode - all lamps off

3. normal mode - circuits no 1-3 on/off

4. emergency mode - all lamps on 0 5. emergency mode - all lamps off

6. update time / data values 7. update lamp on/off backup times

The command station operating software would include a system database, containing detailed records of all base stations e.g. unit address, location, service history, etc. The command station operating software would be pre-programmed to automatically search and present the relevant record to the end-user, based on the error message information received from the base station unit.

The command station may also be set to Direct Connection Mode as required. This mode would allow direct data connection (typically via GSM) to an individual base station, for the purpose of retrieving data logs or performing programme updates, etc.

An example of an embodiment which provides remote control of remote lighting is now described in relation to Figures 3 to 6. Although the remote station is described as being within the luminaire in the following example, this need not be the case and is described by way of example only.

Figure 3 shows a schematic of an embodiment of a monitoring system for light units. The system comprises a command station 2 which is connected to one or more base stations 3. Each base station controls the operation of one or more street lamps 4,5,6 each provided with a remote station. Each street lamp comprises a lamp post 7,8,9 and a housing means 10, 11 ,12 (commonly referred to as a luminaire) . The street lamps 4,5,6 are supplied with electricity by mains power supply cables 1.

The housing means 10,11,12 is shown in more detail in Figure 5. The housing means comprises a light source 13 and associated starter circuit 14, a monitoring means 15 and control means 16. A local processing means 17 is also provided. The housing means 10,11,12 contains all the necessary apparatus for running the light source contained within. The monitoring means 15 comprises a plurality of sensors. Figure 6 shows an overall view of a typical housing means 10.

In use, the base station 3 sends out a power-up signal to the local processing means 17 of the remote station over the mains power supply line 1. In other embodiments a bus cable, or any other communication medium may be used between the base station 3, and the remote station/processing means 17. This signal is received by the local processing means 17 within the housing means. The local processing means then switches on and waits for a set period, perhaps three minutes after it switches on before sending a signal back to the base station 3 to record its operation or status. Thus, when a base station 3 is connected to a plurality of street lamps 4,5,6, the base station will receive a series of status signals. Only those signals indicating a fault condition are stored in a memory provided in the base station (not shown) i.e. the fault/error signals are logged. The time at which the fault signals were received, and which street lamp issued the fault signal are also recorded.

After the reply signals have been sent to the base station 3, the local processing means 17 at the street lamp awaits further instruction. At this point the street lamps 4,5,6 are not yet on.

The base station 3 may contain a photocell which measures when the street lamps 4,5,6 need to be turned on, or alternatively, a control signal issued by the main controller 5 can be used to decide when the street lamps 4,5,6 are to be turned on. In either case, when the lamps are required to be turned on, the base station 3 issues a light source 13 "on" signal to the local processing means at each street lamp 4,5,6. This is done in sequence to avoid a large spike being generated. The local processing means 17 and the control means 16 at each street lamp 4,5,6 will then switch the lamp on. A predetermined period is allowed to elapse, say 10 minutes, in order to allow the light source 13 to warm up to its correct operating temperature. Once this time has elapsed, the processing means 17 at each street lamp 4,5,6 then sends further signals back over the mains power supply cables 1. The signals are obtained by processing parameter signals generated by the monitoring means 15. The monitoring means 15 are adapted to measure the actual physical status of the lamp. For example, the monitoring means 15 may include sensors for measuring lamp current, and lamp voltage.

Once the light source 13 is on, and has reached equilibrium (i.e. the parameters do not fluctuate substantially) the local processing means 17 sends a signal back to the base station 3 in the event that one of the parameters changes. This may indicate that a fault has occurred in the street lamp 4,5,6.

The housing means may also incorporate means (perhaps the control means) for controlling the light output. This may then switch the light source 13 between full output and a dimmer output in response to a signal sent from the base station 3 to the local processing means 17. As an example, dimming may be such that the output current is reduced by 50% which results in a 35% saving in power. This results in a significant saving when a large number of street lamps 4,5,6 are provided. We may for example want to turn lights to their dim setting after a watershed time at night (e.g. 1.00am) .

Because each street lamp 4,5,6, is individually controlled by the base station 3, it is possible to selectively dim one or more of a set of street lamps 4,5,6 provided at each base station 3, or even selectively turn some off. The light control system unit described above is advantageous in that it is event driven. A signal is only sent back to the base station 3 and logged if it is an error signal. One particular case of interest is when a street lamp 4,5,6 continually switches between an ON and an on OFF state. This may occur if there is a fault in the street lamp 4,5,6. In this case, it is possible to cause the local processing means in the housing means to monitor the fault signal, and if more than a given number of fault signals occur within a predetermined period of time, the local processing means 17 may send an error signal to the base station 3 and shut down the particular, faulty, street lamp 4,5,6 until it is repaired.

The signals sent back to the base station 3 provide for many possible improvements over the prior art method of monitoring street lamps. For example, the local processing means 17 may send a signal to the base station 3 indicating when a light source 13 actually turns on and when it actually turns off. The amount of time that a light source 13 is on is then recorded, and a cumulative total can be built up which is representative of the "burn time" of the light source 13. This is only possible by using the monitoring means which measures the actual amount of time a light source 13 is on, as distinct from the amount of time a light source 13 is instructed to be on. Obviously, the control means 16 in the housing means may have switched a light source 13 on, but if the light source 13 is not monitored to check that it is operating, a correct check of light source 13 "burn time" cannot be made.

By monitoring the actual "burn time" of the light source 13 before failure, street lamp 4,5,6 providers can then ask for a refund or may complain if a light source 13 does not burn for the correct number of hours before failure, for example if lamps are warranted to last for 5,000 hours yet they only last 4,000 hours . Because individual street lamp 4,5,6 control is provided, an override can be provided for individual lamps 4,5,6. For example, to meet safety codes, street lamps 4,5,6 at major junctions and roundabouts must be fully illuminated at all times. However, it is desirable to dim street lamps 4,5,6 during periods of low road use to reduce power consumption (e.g. after midnight). Using this control method, a base station 3 may switch some street lamps 4,5,6 to dim (or to turn off) yet retain some at full power.

The housing means may also include a visual indicating means in the form of a set of LED's 18,19,20. The LED's 18, 19,20 are illuminated in response to the output signals from the local processing means 17 provided with the housing means, or may be operated by sensors remote from the housing means. A first LED 18 shows that the light source contactors are switched ON, the second LED 19 shows that the light source is dimmed, and the third LED 20 shows that the light source is fully on. The LED's 18, 19,20 can be used by maintenance staff to determine if the street lamp 4,5,6 is operating correctly.

A number of diagnostic tools may also be provided with this street lamp monitoring system. The base station 3 may send a test signal to the local processing means 17, and the local processing means 17 may also be adapted to send a status check signal back to the base station 3 in response to this test signal. In this way, the integrity of the system can be checked.

Also, the ability to measure the actual status of the street lamp 4,5,6 in real time provides several additional operational advantages. Because the base station 3 can record the time in which signals are received and logged, the efficiency of repair work can be checked. In one example, where three street lamps 4,5,6 in a row on a motorway are all at fault, repairs must be carried out within two hours of the fault occurring. This is known as a category one fault as it represents a severe hazard. After the repair has been carried out, the local processing means 17 at the street lamp 4,5,6 will send a signal back to the base station 3 indicating that the street lamp 4,5,6 is now functioning, and the time that this signal is received can be logged. Thus it is possible to check that repair work is carried out in the correct time. For example, with street lighting, the replacement of lights and general repair work is usually contracted out by the provider of the street lamps and so this system allows the street lamp provider to penalise the contractors if standards are not met.

To summarise, we provide a self monitoring light unit for use with a street lamp 4,5,6 or any other suitable mounting. Importantly, the housing means is self contained and incorporates its own monitoring means 15. This monitoring means 15 senses a parameter such as the current or voltage at the light and may sense when a fault occurs. There may also be provided all the control means 16 and local processing means 17 required to implement a complete remote street lamp 4,5,6 monitoring system suitable for remote interrogation over a mains power supply cable 1. This system brings with it cost savings over providing a separate housing and processing/control unit such as has been provided in the past. Also, it offers the beneficial feature of being easy to install and more secure from vandalism than prior art systems. Previously systems allowing a street lamp to be remotely monitored have been fitted at the base of lamp-posts 7,8,9 once all the lamp posts have been erected and wired up. This is a separate operation and is not as attractive as simply fixing the head of a lamp-post to its pole or post.

The monitoring means 15, the control means 16 and the local processing means 17 may be provided in a single module. Each module comprises a microcontroller 72, an associated conversion circuit, and an identifying circuit 32 embedded in an epoxy resin block. A variety of input sensors SI, S2, S3 monitor suitable physical characteristics in the electronic circuit of the lamp post, for example SI might monitor the voltage of a certain point, S2 might monitor the current at a certain point and S3 might monitor the voltage at another point, and so on. The sensors SI , S2 and S3 measure signals SI, S2 and S3 respectively.

Microcontroller72 emits its own report signals back down the power supply line, to the base station 3. The microcontroller has a memory (not shown) and is programmed by the base station 3 to report in a desired way. For example, in this particular embodiment, the base station 3 programs the microcontroller so that it records in its memory the performance, at 5 second intervals, of signals SI to S3 for the first 30 minutes of the operation of the lamp post and then stops recording them

(because we believe that most lamp failures occur during the first 30 minutes following start up of a lamp) . The microcontroller then polls the base station 3 to ask for permission to down load its memory to the base station 3. If the base station 3 sees that there is no other signal traffic then the microcontroller 72 sends out a carrier signal and dumps its acquired date to the base station 3.

The microcontroller 72 identifies itself by including in the transmitted data an identifying code. The identifying code may be set by switches, a code key (as in PCT/GB97/01870), programmed into non- volatile memory, or the like.

The individual local processing means 17 provided in the street lamps 4,5,6 are also programmed by the base station 3 to keep a record of any signals which are outside of an allowable range. Although the signals SI to S3 are recorded as a matter of course in the memory of the microcontroller 72 for the first 30 minutes, and not thereafter (as a matter of course) , the microcontroller is programmed to monitor the signals continuously (say at 5 second intervals) and to keep a record of signals which are outside of an allowable error band. The microcontroller 72 may also be set up to transmit such unusual signals to the base station 3 periodically, or even substantially immediately (when the polling enquiry receives instructions to proceed) .

It will be appreciated that the base station 3 could be arranged to vary the operational conduct of the microcontroller 72, for example, the command station 2 could be used to tell the base station 3 to change the period of sampling of the signals from once every 5 seconds to once every 10 seconds, or ten times a second, or any other period. Similarly, the initial recording period could be varied.

It will be appreciated that because a microcontroller is a powerful tool it can simply be reprogrammed once by the command station 2 and then left alone to get on with the job of monitoring/reporting. Because so much processing is done at the local processing means 17, the volume of signal traffic to the base station 3, and to the command station 2 is kept low, and this avoids confusion between the signals.

It will be appreciated that one of the benefits of the present system is that each of the blocks 33, and each of the microcontroller 72, is identical (or substantially identical) . This means that we can mass produce the blocks 33 and use some and store some conveniently. If there is then a problem with one of the blocks 33 an engineer can take a replacement from our store and visit the lamp post that is having trouble (as detected by the base station 3, and as interrogated by the command station 2) . He can then simply unplug the key 34, disconnect the broken base unit of the resin block 33 and exchange it for a new base unit resin block 33, and reconnect the same key 34 to the new resin block. This will guarantee that the new resin block will generate the same identity signal (since the identity signal is generated in response to the configuration of the key 34) and the base station 3 will be able to correlate incoming signals with a particular lamp post. This avoids the need to have special programming of replacement chips, and reduces the down time involved in maintaining the unit.

Figure 4 shows an embodiment of a monitoring system represented in a block diagrammatic form. A computer 62 (providing a base station) running the system has dedicated software for data analysis and control. The computer 62 is connected to a monitor 64 (provided by a remote station) by means of a communication link 66. Mains communication buffers 68 and 70 are provided at each end of the link 66. Buffer 68 is connected to the computer 62 by an RS232 or 488 serial link. Buffer 70 is connected to a microcontroller 72 through a decoder 74.

The communication link 66 between the two buffers 68 and 70 is a half duplex link over a mains supply. Information passes along the link 66 to or from the computer 62 on a phase locked loop carrier for data integrity. Transmission can be in a frequency band 90- 145kHz as opposed to the mains which is between 40 to 60Hz. For further data integrity, an automatic error correction routine is incorporated in the software in the computer 62 to replace any bits of information which are lost. The communication stream between the buffers 68 and 70 can be in a digital form or any other suitable form.

The monitor 64 is provided with an independent power supply 76, which can be a mains supply separate from the main supply providing the link 66. The microcontroller 72 is fed with information concerning the operation of a piece of street furniture through a number of analogue inputs. We prefer eight analogue inputs although only four inputs 78,80,82 and 84 are shown in Figure 4. Each input 78,80,82,84 is provided with a signal conditioner 86 and an opto-isolator 88. The inputs may include signals relating to an A.C. signal (such as mains supply) , a D.C. signal, other current signals, or signals representative of absolute temperature or temperature change for example atmospheric temperature or temperature change. The signal conditioners 86 scale the signal up or down to be in a range suitable for the microcontroller 72 to receive. This would be, for example, in the range 0-5V. The opto-isolators 88 provide a potential cut out in case of power surges or other signals which can harm the microcontroller 72.

The microcontroller 72 has at least three outputs. In the Figure three outputs 90,92 and 94 are shown. These may be volt free outputs for external use, pulse width modulation outputs for analogue control of external loads (for example power supply to a lamp) or standard analogue D.C. voltage outputs.

The microcontroller may be provided with a plurality of further input/output ports for monitoring and control as required. In this embodiment two eight bit ports, making sixteen digital input/output ports can be used.

As has been discussed in the foregoing, the invention is not to be considered to be limited to the field of monitoring street furniture. It may be applied as a metering or control system to a diverse range of electrical devices or apparatus. There may be provided a photodetector to sense whether a door at the base portion of the lamp post is open or closed. Obviously these doors should be closed when the lamp is in use and it is important to know if the door has inadvertently been left open so that it can be closed.

Claims

1. A system capable of controlling a number of apparatus, the system comprising a command station capable of broadcasting a signal to one or more base stations, each base station being arranged to control one or more apparatus on receipt of a predetermined command from the command station.

2. The system of claim 1, wherein the command station is arranged to use any one or more of the following mediums to broadcast said signal: radio signal, television signals, Short Message Service (SMS) test messages, GSM wireless network, paging network, a mesh network.

3. The system of claim 1 or claim 2 in which the system is arranged to send a signal over inband or out-of-band frequencies of a radio network.

4. The system of claim 3 in which the command station is arranged to make use of a Radio Data Service (RDS) signal.

5. The system according to any preceding claim in which the signal is added to a television transmission.

6. The system according to any preceding claim in which the or each base station communicates with one or more remote stations arranged to control one or more pieces of apparatus.

7. The system of any preceding claim in which the or each base station is arranged to send a response to the command station if an error occurs .

8. The system according to any of the preceding claims in which the command station comprises a database arranged to maintain details of base stations and/or remote stations and/or apparatus controlled thereby.

9. The system according to any of the preceding claims in which the command station and/or the or each base station is arranged to have two modes of operation: a normal mode and an emergency mode.

10. The system according to any preceding claim in which the base station is arranged to control apparatus controlled thereby in a predetermined manner at predetermined times .

11. The system according to claim 10 wherein if the signal is not received by the base station before the f the predetermined time occurs then the apparatus is controlled, by the base station, in the predetermined manner.

12. The system according to any of claims 10 or 11 as they depend directly or indirectly from claim 9 wherein, while in normal mode of operation, the command station is arranged to send the signal at a time before the predetermined time at which the apparatus would otherwise be controlled.

13. The system according to any of claims 10 to 12 as they depend directly, or indirectly, from claim 9 wherein, while in emergency mode, the command station sends the signal at any time.

14. The system according to any preceding claim in which the apparatus is electrical apparatus.

15. The system according to any preceding claim in which the apparatus comprises lighting and in particular street, and/or tunnel lighting.

16. The system according to any preceding claim, in which the or each base station is connected to other base stations, and arranged such that a signal received by a base station is capable of being passed to other base stations .

17. A method of controlling a number of apparatus comprising broadcasting a signal from a command station which is capable of being received by one or more base stations, and causing the base stations to control the apparatus in response to the signal.

18. A computer readable data carrier carrying instructions to cause a computer to carry out the method of claim 17.

19. A computer readable data carrier carrying instructions arranged to cause a computer to function as the system according to any of claims 1 to 16.

20. A system for controlling a number of apparatus substantially as described herein and as illustrated in the accompanying figures.

21. A method of controlling a number of apparatus substantially as described herein and as illustrated in the accompanying figures.

22. A command station capable of broadcasting a signal and transmitting it suitable for use in a system according to any of claims 1 to 16.

23. A computer readable data carrier carrying instructions arranged to cause a computer to function as a command station according to claim 22.

24, A base station capable of receiving a signal from a command station and being suitable for use in a system according to any of claims 1 to 16.

25. A computer readable data carrier carrying instructions arranged to cause a computer to function as the base station according to claim 24.