GB2267005A

GB2267005A - Data transmission

Info

Publication number: GB2267005A
Application number: GB9210402A
Authority: GB
Inventors: Michael William David Hammond; Ross Stuart Henderson
Original assignee: Delta Technical Services Ltd
Current assignee: Delta Technical Services Ltd
Priority date: 1992-05-15
Filing date: 1992-05-15
Publication date: 1993-11-17
Also published as: GB9210402D0

Abstract

Data transmission in utility meter reading such as water meter reading is achieved by means of a fibre optic cable 16 disposed between an encoder associated with the water meter 10 and a remote reader 12 within a building. In order to avoid the need for structural alteration to the building, the fibre optic cable 16 passes through a sealed connector into the water pipe 14 at the water meter end of the pipe, and out of another sealed connector at the remote reader end of the pipe. Meter reading data transmission can be achieved either by the encoder generating a serial data stream signal indicative of the meter reading in response to an interrogation signal from the remote reader 12, or by using a light interrupter at the encoder, the remote reader 12 then including a photoemitter and photodetector arrangement. The cable 16 can be installed within the pipe 14 by propelling a soluble member along the pipe under fluid pressure so as to lay a line inside the pipe 14 between the two openings in the pipe, and then pulling the cable 16 through by means of the line. After cable installation, the member will dissolve avoiding the need to remove the member. <IMAGE>

Description

DATA TRANSMISSION This invention relates to data transmission, and in particular but not exclusively to data transmission in utility meter reading and associated techniques.

In various applications, such as meter reading and in particular remote water meter reading, a number of problems can arise. One difficulty is encountered when a water meter is fitted outside the building to which the water is supplied, for example in a meter pit at the boundary of the property. It is then difficult to install any communication link between the meter and a reading device inside the building without disruption or damage to the property. Another difficulty can arise when a meter is located far from a source of electrical power, as in the above case of a water meter fitted outside the building in a meter pit. It is then not readily possible for certain data transmission techniques, such as radio transmission, to be implemented for remote reading purposes without providing a dedicated electrical power source.If this is to be a mains electricity connection, complex and disruptive wiring of a waterproof nature would be required, whereas power from a battery supply would be vulnerable to battery run-down and hence require frequent checking.

According to a first aspect of the invention there is provided a system for connecting a fluid meter to a remote reading device, the system comprising an encoder associated with the meter for providing a signal indicative of the meter reading, a cable connected between the encoder and the remote reading device for conveying the signal to the remote reading device, and first and second connecting means for allowing the cable to pass from outside to within a fluid supply pipe connected to the meter, the first connecting means providing access for the cable to the meter and the second connecting means providing access for the cable to the remote reading device such that the cable passes through the supply pipe between the first and second connecting means.

According to a second aspect of the invention there is provided a system for providing remote reading of a fluid meter, the system comprising an encoder associated with the meter for providing a signal indicative of the meter reading, a remote reading device for receiving the signal from the encoder and for providing a corresponding reading, a cable connected between the encoder and the remote reading device for conveying the signal to the remote reading device, and first and second connecting means for allowing the cable to pass from outside to within a fluid supply pipe connected to the meter, the first connecting means providing access for the cable to the meter and the second connecting means providing access for the cable to the remote reading device such that the cable passes through the supply pipe between the first and second connecting means.

Preferably the cable is a fibre optic cable, and the encoder is an optical encoder for converting the meter reading to an optical signal. The fluid meter may be a water meter in which case the fibre optic cable is installed within the water pipe connected between the water meter and the water consumer premises. Thus the reading device may be installed within a building without having to provide a separate cable passage through a wall of the building, entry being provided by the existing water pipe itself.

According to a third aspect of the invention there is provided a method of forming a signal conveying path between two points connected by a fluid supply pipe, the method comprising passing a cable capable of conveying a signal into the supply pipe via first and second sealed connecting means such that the cable extends within the supply pipe between the first and second connecting means.

According to a fourth aspect of the invention there is provided a system for providing remote reading of a utility meter, the system comprising an optical encoder associated with the meter for providing an optical signal indicative of the meter reading, a remote reading device for receiving the optical signal from the optical encoder and for providing a corresponding reading, and a fibre optic cable connected between the optical encoder and the remote reading device for conveying the optical signal to the remote reading device.

In remote reading of a meter such as a water meter not provided with an electrical power supply, the need for such a power supply for the optical encoder can be obviated by using the fibre optic cable as a bidirectional link. A photoemitter and photodetector arrangement is suitably connected, such as via a beamsplitter, to the remote reading device end of the cable. The water meter end of the cable is associated with a light interrupter such as an alternately light reflective/absorbent segmented disc connected to the water meter mechanism. Rotation of the disc, as a result of operation of the metering mechanism, causes light transmitted down the cable from the photoemitter to be reflected back via the cable as a series of pulses according to the disc rotation.Rather than provide a continuous beam of light, the photoemitter can be pulsed with a short duty cycle signal at a frequency sufficient to detect the fastest rate of change of the detector. This provides a measure of power saving.

According to a fifth aspect of the invention there is provided a system for providing remote reading of a utility meter, the system comprising an encoder associated with the meter for providing a signal indicative of the meter reading, and a remote reading device connected to the encoder, wherein the encoder generates a serial data stream signal indicative of the meter reading in response to an interrogation signal from the remote reading device.

According to a sixth aspect of the invention there is provided a method of installing a cable within a pipe, the method comprising inserting in a first opening in the pipe a member of a dimension smaller than the diameter of the pipe with a line attached to the member, propelling the member down the pipe by fluid pressure to a second opening in the pipe, removing the line through the second opening, attaching the cable to the line, and drawing the cable through the pipe by means of the line, wherein the member is soluble in a liquid so that the member may be removed from the pipe by being dissolved in the liquid.

In a water meter installation, the member can be made of a substance soluble in water. Either air or water can be used as the propulsion fluid. When water is used, the rate of solution of the member should be slower than the time required for cable installation.

The invention will now be described by way of example with reference to the accompanying drawings, throughout which like parts are referred to by like references, and in which; Figure 1 is a partially-schematic cross-sectional view of a water meter and remote meter reading installation; Figure 2 is an enlarged view of the water meter and encoder of Figure 1; Figure 3 is an enlarged view of the remote meter reading device of Figure 1; Figure 4 is a schematic representation of one data reading transmission method; Figure 5 is a schematic representation of another data reading transmission method; Figure 6 shows interrogation waveforms in one type of reading technique; and Figure 7 is a partially-schematic cross-sectional view of a cable installation method.

Referring to Figure 1, there is shown a water meter/remote reader installation including a water meter portion 10 and a remote reader portion 12. The portions 10 and 12 are connected by a water pipe 14 having a fibre optic cable 16 within the pipe 14.

Figure 2 shows the water meter portion 10 in greater detail.

This includes a water meter 20 with associated encoder head 22. A cable 24 connects the encoder head 22 to an electro-optical interface 26 (used in one embodiment) from which the fibre optic cable 16 emerges and enters the water pipe 14 via a sealed pipe entry gland 28. As shown in Figure 2, the water meter portion 10 can be installed in a water meter pit at the boundary of the premises.

Figure 3 shows the remote reader portion 12 in greater detail.

This is installed within the building and includes a pipe exit gland 30 for the fibre optic cable 16 to pass outside the water pipe 14, a remote display 32 connected to the cable 16, and a telemetry connection 34 for providing remote reading data via a telephone link. The sealed entry and exit glands 28,30 are conveniently in the form of glanded tee-pieces.

In operation, the fibre optic cable 16 acts as a data link.

Traditionally it has been difficult to install any communication link without causing disruption or damage to the property. This system avoids all such problems by containing the fibre optic cable 16 within the water pipe 14 connecting the meter 20 to the building. At the meter end, the cable 16 enters the pipe 14 through the glanded teepiece (entry gland 28) which is fitted between the meter assembly and the consumer supply pipe. Meter assemblies often contain a stopcock and a non-return valve; the tee-piece is fitted downstream of these obstructions such that there is an unobstructed length of the pipe 14 leading into the building. A similar arrangement is used to extract the fibre optic cable 16 from the pipe upstream of the stopcock 36 fitted inside the building.

Two methods of recovering the data are possible. One uses an encoder meter, which is a water meter fitted with an electronic system (including the encoder head 22 and the interface 26) which transmits serially the actual data as displayed on the meter 20. Such meters are readily available, all using the same system of data transmission. The interface 26 is fitted between the meter communication cable 24 and the fibre optic cable 16. This interface 26, which is powered from a long life battery, responds to an incoming optical signal by interrogating the meter and sending the resultant data as light pulses through the optical link. The duration of communication is fixed by the parameters of the meter transmission system, and is typically less than 0.5 second. The interface 26 is a totally sealed unit with a nonreplaceable battery, which has sufficient power for 25,000 communications.Even assuming 10 reads per day, this provides nearly seven years of operation. An optical arrangement for this system is schematically shown in Figure 5.

The remote reader for this system operates on a demand principle.

When a reading is required, the reader sends the interrogating signal to the interface 26 fitted to the meter 20 and receives the returned data stream. This data is then decoded and displayed.

Interrogation/reply waveforms as used in this system are shown in Figure 6. Enhancements may be added, such as a lockout circuit to prevent data being read too frequently.

Another method, schematically shown in Figure 4, avoids the requirement for a source of power at the water meter 20 by using light produced from the remote end as the transmission medium. The meter 20 is fitted with a segmented disc 40, alternate segments being reflective and absorbent, which rotates as water flows through the meter 20. The fibre optic cable 16 is used as a sensor, with its end normal to the surface of the disc 40; at the remote end, a beamsplitter 42 allows the light to travel towards the meter and separates the light reflected from the segments of the disc 40.

The remote reading instrument contains a simple incremental counter with a facility to enable the count to be set to the initial value recorded by the water meter 20. The count is incremented by detecting the change in reflected light, as sensed by the fibre optic cable 16. In order to conserve power, as this instrument is powered by a long-life battery, the light source may be pulsed with a short duty cycle at a frequency sufficient to detect the fastest rate of change produced by the meter 20. Circuitry then uses the received pulse train to detect rotation of the reflective disc 40 fitted to the meter 20.

The remote reader in both embodiments has a display to indicate the count value. Various security arrangements are incorporated to prevent tampering and to detect breakage of the fibre optic cable 16.

A connection to allow electronic reading of the value can be added, as shown in Figure 3, with the effect that data can be retrieved locally or transmitted over the telephone network using the telemetry connection 34. An extension to such a system can allow remote reading of the data by radio or other communication means.

The choice of which reading method is used depends on several parameters. By regulations, only the value indicated on the meter can be used in any revenue operation, and thus this is the method to be used for billing systems. However, there is extra cost involved in both the encoder head 22 and the meter interface 26, which is avoided by the incremental system of Figure 4. The incremental system, however, has the possibility that the counts on the meter and on the display may differ if the optical link malfunctions.

Referring again to Figures 5 and 6, it should be noted that encoder heads are available which are designed to produce a serial pulse train when supplied with a suitable clock signal. The interface 26 thus supplies the clock when it recognises the remote interrogation command (shown, as an example, by three regular pulses), and the encoder output is applied directly to the output light emitting diode to transmit the meter data to the remote reading device which decodes the data and displays (and/or transmits by telemetry or radio link) thedecoded meter reading data.

A method of installation of the cable 16 is now discussed, with reference to Figure 7.

The principle of installation is to disconnect the pipe 14 at the tee-pieces and to force a strong cable 50 through the length of the pipe 14 by attaching it to a ball 52 which fits within the pipe 14.

The ball 52 is blown through the pipe 14 using compressed air, although water is an alternative. The fibre optic cable 16 is subsequently drawn through the pipe 14 by disconnecting the cable 50 from the ball 52, attaching the optical fibre cable 16 to the free end of the drawing cable 50 and retracting the cable 50, thereby pulling the optical fibre cable 16 through the pipe 14.

The drawing cable 50 must feed freely when the ball 52 is being blown through the pipe 14, and it may accordingly be fed from a reel 54 similar to a casting reel" as used in angling. The cable 50 may be nylon-covered stainless steel wire, again similar to that used in angling.

The shape is chosen as a ball to provide the best tolerance of irregularities within the pipe 14, and to negotiate any bends which may be encountered. Depending on the nature of the obstructions in the pipe 14, the ball 52 may be obstructed. It would then generally be necessary to extract the ball 52 by using the cable 50, then repeating the operation using a smaller ball. However, it may happen that the ball 52 cannot be extracted by tension on the cable 50.

If the ball 52 is made of a material soluble in water, then the problem may be resolved. Such a material does not prevent the propulsion of the ball 52 by water, provided that the rate of solution is sufficiently slow. There are various arrangements which may be used; it would be effective, for example, to provide some small holes through the ball 52, such that there is effectively virtually total obstruction to flow when the ball 52 is free, but some flow of water can be achieved under pressure when the ball 52 becomes jammed. Such an arrangement will result in faster dissolution of a jammed ball because of the flow of water through the holes causing improved dissolution and erosion.

Figure 7 also shows the reel 54 attached to a water chamber 56 which has a tapering end 58 for insertion in the pipe 14. An injection nozzle 60 in the tapering end 58 allows water to flow into the pipe 14 and also the cable 50 to be fed through via a cable feed tube 62. A water pipe 64 from a pressurised source (not shown) is connected to the water chamber 56 by means of a control valve 66.

Claims

1. A system for connecting a fluid meter to a remote reading device, the system comprising an encoder associated with the meter for providing a signal indicative of the meter reading, a cable connected between the encoder and the remote reading device for conveying the signal to the remote reading device, and first and second connecting means for allowing the cable to pass from outside to within a fluid supply pipe connected to the meter, the first connecting means providing access for the cable to the meter and the second connecting means providing access for the cable to the remote reading device such that the cable passes through the supply pipe between the first and second connecting means.

2. A system for providing remote reading of a fluid meter the system comprising an encoder associated with the meter for providing a signal indicative of the meter reading, a remote reading device for receiving the signal from the encoder and for providing a corresponding reading, a cable connected between the encoder and the remote reading device for conveying the signal to the remote reading device, and first and second connecting means for allowing the cable to pass from outside to within a fluid supply pipe connected to the meter, the first connecting means providing access for the cable to the meter and the second connecting means providing access for the cable to the remote reading device such that the cable passes through the supply pipe between the first and second connecting means.

3. A system according to claim 1 or claim 2, wherein the fluid meter is a water meter monitoring flow through a water pipe, and the cable passes through the water pipe between the first and second connecting means.

4. A system according to claim 1, claim 2 or claim 3, wherein the cable is a fibre optic cable and the encoder is an optical encoder for converting the meter reading to an optical signal.

5. A system according to claim 4, wherein the remote reading device includes a photoemitter and photodetector arrangement, and the encoder includes a light interrupter operable to modulate light from the photoemitter in response to fluid flow, the modulated light being detected by the photodetector.

6. A system according to claim 5, wherein the light interrupter comprises an alternately light reflective and light absorbent segmented disc.

7. A system according to claim 5 or claim 6, wherein the photoemitter is pulsed with a relatively short duty cycle signal having a frequency sufficient to detect the fastest possible rate of change of the photodetector.

8. A system according to any one of claims 1 to 4, wherein the encoder is operable to generate a serial data stream signal indicative of the meter reading in response to an interrogation signal from the remote reading device.

9. A system for connecting a fluid meter to a remote reading device, the system being substantially as hereinbefore described with reference to the accompanying drawings.

10. A system for providing remote reading of a fluid meter, the system being substantially as hereinbefore described with reference to the accompanying drawings.

11. A method of forming a signal conveying path between two points connected by a fluid supply pipe, the method comprising passing a cable capable of conveying a signal into the supply pipe via first and second sealed connecting means such that the cable extends within the supply pipe between the first and second connecting means.

12. A method according to claim 11, wherein the cable is installed within the pipe by the steps of inserting in a first opening in the pipe a member of a dimension smaller than the diameter of the pipe with a line attached to the member, propelling the member down the pipe by fluid pressure to a second opening in the pipe, removing the line through the second opening, attaching the cable to the line, and drawing the cable through the pipe by means of the line, wherein the member is soluble in a liquid so that the member may be removed from the pipe by being dissolved in the liquid.

13. A method of forming a signal conveying path between two points connected by a fluid supply pipe, the method being substantially as hereinbefore described with reference to the accompanying drawings.

14. A method of installing a cable within a pipe, the method comprising inserting in a first opening in the pipe a member of a dimension smaller than the diameter of the pipe with a line attached to the member, propelling the member down the pipe by fluid pressure to a second opening in the pipe, removing the line through the second opening, attaching the cable to the line, and drawing the cable through the pipe by means of the line, wherein the member is soluble in a liquid so that the member may be removed from the pipe by being dissolved in the liquid.

15. A method according to claim 14, wherein the pipe is a water pipe and the member is made of a substance which is soluble in water.

16. A method of installing a cable within a pipe, the method being substantially as hereinbefore described with reference to the accompanying drawings.

17. A system for providing remote reading of a utility meter, the system comprising an optical encoder associated with the meter for providing an optical signal indicative of the meter reading, a remote reading device for receiving the optical signal from the optical encoder and for providing a corresponding reading, and a fibre optic cable connected between the optical encoder and the remote reading device for conveying the optical signal to the remote reading device.

18. A system according to claim 17, wherein the remote reading device includes a photoemitter and photodetector arrangement, and the encoder includes a light interrupter operable to modulate light from the photoemitter in response to fluid flow, the modulated light being detected by the photodetector.

19. A system according to claim 18, wherein the light interrupter comprises an alternately light reflective and light absorbent segmented disc.

20. A system according to claim 18 or claim 19, wherein the photoemitter is pulsed with a relatively short duty cycle signal having a frequency sufficient to detect the fastest possible rate of change of the photodetector.

21. A system for providing remote reading of a utility meter, the system comprising an encoder associated with the meter for providing a signal indicative of the meter reading, and a remote reading device connected to the encoder, wherein the encoder generates a serial data stream signal indicative of the meter reading in response to an interrogation signal from the remote reading device.

22. A system for providing remote reading of a utility meter, the system being substantially as hereinbefore described with reference to the accompanying drawings.