GB2052077A

GB2052077A - Monitoring Electrical Signals

Info

Publication number: GB2052077A
Application number: GB8015930A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-06-21
Filing date: 1980-05-14
Publication date: 1981-01-21
Also published as: GB2052077B

Abstract

The apparatus comprises a probe for the reception and sampling of the electrical signal, a logic system to process the digital signals so sampled, and means operable by the processed signal. The means operable by the processed signals may be, for instance, display logic to store and prepare signals in a format suitable for display and visual display means to display the resulting information. Instead of or in addition to the visual display means, the apparatus may include some form of feedback arrangement for effecting a change in the conditions giving rise to the original electrical signal. The display logic is preferably that used in Teletext, Viewdata, Antiope, Canadian Viewdate or the like. <IMAGE>

Description

SPECIFICATION Monitoring of Electrical Signals This invention relates to methods of monitoring, including measuring, electrical signals.

According to the present invention there is provided apparatus for monitoring an electrical signal, the apparatus comprising a probe for the reception and sampling of the electrical signal, a logic system to process the resultant digital signals and means operable by said processed signals.

Preferably the logic system is a minicomputer, microcomputer, microprocessor or other programmable system.

Preferably the means operable by said processed signals include display logic to store and prepare the signals in a format suitable for display and visual display means to display the resulting information. More preferably the apparatus includes interface logic which adapts the signals from the logic system to a speed suitable for the display logic. The visual display means is preferably a low cost display, a low cost colour display, a visual display unit, a video monitor or a television receiver. Preferably the display logic is that used in Teletext, Viewdata, Antiope, Canadian Viewdata or any other commercially available display logic system.

In addition or instead of the visual display means, the means operable by said processed signals may include means for effecting a change in the conditions giving rise to the original electrical signal. Thus the apparatus may include some form of feedback arrangement.

Preferably the sampling probe includes means for sampling the electrical signal at several times the frequency of said signal.

Preferably the apparatus includes means allowing access to the logic system by an operator, for instance by means of a control keyboard.

The present invention also provides a system comprising a plurality of sets of apparatus of the invention, the sets being interconnected by means of, for instance, telephone lines.

Further the present invention also provides a method of monitoring an electrical signal comprising receiving and sampling the signal, processing the resultant digital signals by means of a logic system and feeding signals to means operable thereby.

Apparatus in accordance with the present invention allows electrical signals to be monitored, using digital techniques to give greater accuracy, flexibility and simplicity of display than was available hitherto. The apparatus can be produced cheaply and can easily be operated.

The sampling of the electrical signal can be carried out at low or high speed (depending upon the requirements) either synchronously or asynchronously.

The interpretation of the results of the sampling by digital techniques could involve, for instance: 1. The corrolation of the signal against timing and amplitude standards, related or unrelated to clock signals present within the microprocessor, microcomputer or other digital system.

2. The programming of the microprocessor, microcomputer or other digital system to execute and display measurements related to signals derived from the sampling.

3. The storage of the digital information ready for translation into the appropriate format used in a display system employed, such storage possibly involving the use of alpha-numeric ROMs.

4. The read-out of the stored information by means of suitable display processors which contain appropriate timing generators.

5. The transmission of the signals to a display or tqequipment for carrying out the functions (for instance, the control of some mechanism), such transmission being over short or long distances without the accuracy of the results being affected.

6. Utilisiation of non-specialised displays, offering low cost and high resolution, in order to display the required information.

Embodiments of the present invention will now be described, by way of examples only.

Example I Figures 1 and 2 of the accompanying drawings of block diagrams are two possible ways of embodying the present invention.

The sampling probe or probes 1 contain a sampling pulse generator which operates at several times the frequency of the signals under measurement. The sampling pulse generator can be locked to the microprocessor, microcomputer or logic system clock or could be unrelated to it.

The sampling pulse generator could also be locked to the microprocessor, microcomputer or logic system but running at a frequency several orders of magnitude to that of the clock. In this case a frequency divider and a phase locked loop is used to lock both frequencies. The sampling pulse frequency can also be locked to the signal under measurement by means of a programmable divider and a phase locked loop.

The output of a signal probe 1 (Figure 1) contains information related to the amplitude and frequency of the signal under test. This output is fed to the microprocessor, microcomputer or logic system 3 which interprets the output in accordance with the appropriate command received from a control keyboard 5. Thus microprocessor, microcomputer or logic system 3 will interpret the command from control keyboard 5 in accordance with the complexity of the required measurement and the software implementation.

In the case where there are a plurality of sampling probes 1 (Figure 2) the output of the probes can be related to voltage, current, power, instantaneous power, phase, amplitude and phase distortion, frequency etc. and all the results can be made available at the same time in the display.

Sampling probe or probes 1 can contain other subsystems for the analogue reproduction of the waveform in the display in a suitable graticule, amplitude control, locked modes, etc, which can be programmed or manually controlled.

Interface logic 7 is capable of adapting the signals from the logic system buses to the speed of the display logic, thereby avoiding the need for high speed logic systems.

A display format memory 9 is of such magnitude as that required for the elements of resolution in the display, without affecting the accuracy of the measurements.

The apparatus of Figures 1 and 2 includes display processor and timing 11 which feeds a video signal to the display elements. As shown in Figure 1 the video signal may be fed to display 13 and/or via encoder and R.F. modulator 1 5 to a mono or colour set 17. In the Figure 2 embodiment the video signal is fed to low cost colour display 19.

The display logic can be identical to that used in Teletext, Viewdata or Antiope systems, in which case it is capable of presenting the information related to the signal measurements in twenty-four rows of forty characters per row.

However, formats of finer resolution can be used such as those presently being considered for the Canadian Viewdata or for fine graphic systems.

The results of the measurements can be displayed in different forms, for instance 1. Analogue representation of the electrical signal undermeasurement on a calibrated graticule, in one or a plurality of colours.

2. Alpha-numeric read-out, in monochrome or colour, stating the results of each measurement.

Alternatively a complete tabulated table may present all the results obtained in accordance with the commands entered in the keyboard.

3. Other variations of alpha-numeric or graphic formats or a combination of both.

In addition the results can be printed out or stored on magnetic tape or discs or other storage media.

Example II An embodiment of the present invention, similar two one of the embodiments described in Example I, can be used to replace specialised or general purpose osciiloscopes or general purpose measurement instruments. Such an arrangement in accordance with the present invention will have improved accuracy and there will be a low possibility of error in the interpretation of the results. It will be possible to display instantaneously information such as slew rate, peak power, average values, r.m.s. or peak parameters, frequency, phase and distortion.

Such information would take a considerable amount of time to calculate using standard methods.

Such apparatus in accordance with the present invention could be produced at much lower cost than the specialised equipment as a result of the use of low cost displays, display logic (such as the logic manufactured for Teletext, Viewdata, Antiope, etc.) and standard microprocessor or microcomputer boards or even single chip microcomputers. Thus it is possible to produce effective apparatus in accordance with the present invention utilising a single chip microcomputer together with a low cost television receiver and a low cost display processor. Even with such a system the results obtained can be transmitted over long distances without affecting their accuracy.

The following Examples Ill to VII involves the use of viewdata decoders including line terminating units, modems and displays. The logic system may be a central viewdata computer or alternatively a dedicated minicomputer, microcomputer or microprocessor for the particular application. In all cases normal telephone lines can be employed and the terminal can contain a programme with subroutines which can initiate automatic dialling to operate an overall feedback system in real time.

Example III A plurality of power stations are interconnected up and down the country with auxilliary stations which can come into operation when the load demand so requires, so that load sharing can be accomplished.

Each power station has a viewdata station terminal connected to a telephone line as well as several sampling probes monitoring power demand and other waveforms for auxilliary monitoring. The viewdata terminal contains a programme enabling a watch to be kept on key outputs from the sampling probes. Outputs which indicate readings can be displayed using standard displays and recorded on, for instance, audio tape, printers and floppy discs.

When a sampling probe indicates that some action is required, for example, the switching-on of an auxilliary station, the viewdata terminal, through its own programme, will start the following sub-routine: a. Automatic dialling of the substation.

b. Initiation of the substation start up.

c. The switching of the substation into the required grid.

d. The monitoring of the results.

e. The termination of the sub-routine and the disconnection of the telephone line.

The appropriate information is sent to a central computer dedicated for this purpose, being part of the centralised viewdata computer, thereby enabling a check to be kept on the whole grid as a result of this information and that received from other terminals.

Example IV A system similar to that described in Example lli can be used to monitor water levels in different reservoirs. Automatic dialling along telephone lines is used to operate other manually or automatically operable gates to transfer water according to the levels of the reservoirs and the demand for water.

Example V A system similar to that described in Example Ill may be operated within one manufacturing installation. Thus sampling probes situated in containers may monitor the levels of liquids or solids in those containers in a chemical plant or oil refinery. Because of the low cost of viewdata terminals, each set of pumps is connected to a telephone network via a viewdata terminal. Each terminal contains a programme with a number of sub-routines which come into operation as signals from the sampling probes and indicate that action needs to be take.

Where action only needs to be taken infrequently, a single telephone line is used to interconnect a number of terminals to a central viewdata computer.

When action needs to be taken, for instance, as a result of the level in a container being too high, a sub-routine is initiated by the terminal which stops the particular product being manufactured.

This sub-routine initiates another sub-routine in the central computer which redirects the production in the plant to a different product.

Advantages of using viewdata terminals in such a system are the low cost involved and the sharing of one common telephone network.

Example VI A retailing organisation has a large number of outlets spread throughout the country. There is a need to send information about stock levels to a stock distribution centre and apparatus in accordance with the present invention can allow the information to be sent at the end of the day, when the telephone network is not busy and the cost is at a minimum.

The stock levels are monitored by information collected from point of sales terminals and as a stock level falls below an acceptable figure, information is sent to a viewdata terminal which contains a memory where all the data is entered.

At a particular time of the night, which is different for each retail outlet, the viewdata terminal initiates a sub-routine as follows:- a. The central depot is dialled.

b. The information is sent with regard to the stock levels of all products for which further stock is required.

c. The fact that the information has been acknowledged is verified.

d. The sub-routine is terminated and the telephone line disconnected.

Example VII Apparatus in accordance with the present invention may be used to monitor signals obtained in unmanned weather stations. Thus the apparatus allows sampling and monitoring of electrical signals relating to wind speed, rainfall, pressure, etc. The information is stored in the viewdata memory and at regular intervals the following sub-routine is initiated:- a. Automatic dialling of the central computer bureau.

b. The unloading of all information stored since the last transfer of information.

c. The verification that the information has been sent.

d. The termination of the sub-routine and the disconnection of the line.

Such apparatus is of low cost. Furthermore a normal telephone line can be used although the amount of use is relatively small.

Claims

1. Apparatus for monitoring an electrical signal, the apparatus comprising a probe for the reception and sampling of the electrical signal, a logic system to process the resultant digital signals and means operable by said processed signal.

2. Apparatus according to claim 1 wherein the logic system is a minicomputer, microcomputer, microprocessor or other programmable system.

3. Apparatus according to claim 1 or claim 2 wherein the means operable by said processed signals include display logic to store and prepare the signals in a format suitable for display and visual display means to display the resulting information.

4. Apparatus according to claim 3 wherein the apparatus includes interface logic which adapts the signals from the logic system to a speed suitable for the display logic.

5. Apparatus according to claim 3 or claim 4 wherein the display means is a low cost display, low cost colour display, visual display unit, video monitor or television receiver.

6. Apparatus according to any of claims 3 to 5 wherein the display logic is that used in Teletext, Viewdata, Antiope, Canadian Viewdata or any other commercially available display logic system.

7. Apparatus according to any of the preceding claims wherein the means operable by said processed signals include means for effecting a change in the conditions giving rise to the original electrical signal.

8. Apparatus according to any of the preceding claims wherein the sampling probe includes means for sampling the electrical signal at several times the frequency of said signal.

9. Apparatus according to any of the preceding claims wherein the apparatus includes means allowing access to the logic system by an operator.

10. Apparatus according to claim 9 wherein the accessing means is a control keyboard.

11. Apparatus according to claim 1 and substantially as described herein.

1 2. Apparatus for monitoring an electrical signal substantially as described in any one of the specific Examples.

1 3. A system comprising a plurality of sets of apparatus as claimed in any of the preceding claims, the sets being interconnected by means of telephone lines.

14. A method of monitoring an electrical signal comprising receiving and sampling the signal, processing the resultant digital signals by means of a logic system, and feeding the processed signals to means operable thereby.

1 5. A method according to claim 1 and substantially as herein described.

1 6. A method of monitoring a signal substantially as described in any-of the specific Examples.