GB2282686A - Monitoring and/or controlling electrically controlled equipment - Google Patents

Abstract

Apparatus for controlling and/or monitoring from a base station (Fig.1) electrically-controlled equipment at a site remote from the base station comprises means 3 - 5 for generating electronic signals representative of commands to be passed from the base station to the remote station, means 7 for encoding these electronic command signals as audio tone pulses, radio transmitting means 9 operable to transmit such encoded audio pulses to receiving means, means for decoding the audio tone pulses received as electronic command signals, and means for transmitting these decoded signals to electrically-controlled equipment whose function is to be controlled or monitored. Transmission may be via repeaters which each respond to part of the remote station address in the signals to send on only signals intended for remote stations served by that repeater. <IMAGE>

Description

Apparatus for Monitoring and/or Controlling Electrically Controlled Equipment This invention relates to apparatus for controlling and/or monitoring from a base station electrically controlled equipment at a site remote from the base station. The invention also relates to a method of controlling and/or monitoring such equipment.

More especially, the invention concerns apparatus which operates to send and receive encoded audio pulses via a two-way radio or other suitable transmission system from a base station to a remote receiving station at which the pulses are decoded to produce command signals to control and/or monitor equipment on site at the remote receiving station. The invention has particular application in situations in which it is necessary frequently to visit distant sites to operate and monitor equipment, eg water pumps, and to ensure that the equipment is operating properly.

It is, of course, possible to control the operation of equipment located at a remote site by electronic signals transmitted by cables or the like. The apparatus and cabling required would, however, be extremely costly to produce and install.

It is an object of the present invention to provide apparatus for controlling and monitoring the performance of electrically controlled equipment at such remote locations using readily available and approved sending and receiving equipment.

According to the present invention in one aspect there is provided apparatus for controlling and/or monitoring from a base station electrically controlled equipment at a site remote from the base station, the apparatus comprising means for generating electronic signals representative of commands to be passed from the base station to the remote station, means for encoding these electronic command signals as audio tone pulses, transmitting means operable to transmit such encoded audio pulses to receiving means, means for decoding the audio tone pulses received as electronic command signals, and means for transmitting these decoded signals to electrically controlled equipment whose function is to be controlled or monitored.

In a preferred arrangement, the audio pulse transmitting and receiving means comprise two way radios.

The encoding and decoding means may comprise add-on accessories for such two way radios and decoded data may be transmitted to an equipment controller on site at the remote station.

These two way radios can be of standard "typeapproved" design and do not have to be modified. The audio tone pulses are typically fed through a microphone input socket of the transmitting radio and are typically recovered from a loudspeaker or headphone connector of the receiving radio. An acoustic coupler may alternatively or additionally be used. As the radios are not modified in any way they still retain their "Type Approval" in their country of origin. The use of an indigenous radio link enables the remote control system to be used in all countries of the world.

In another aspect, there is provided a method for controlling and/or monitoring from a base station electrically controlled equipment at a site remote from the base station, the method comprising the steps of generating electronic signals representative of commands to be passed from the base station to the remote station, encoding these electronic signals as audio tone pulses, transmitting these audio tone pulses by a two way radio from the base station to the remote station, decoding the audio tone pulses received as electronic command signals and transmitting these decoded pulses to electrically controlled equipment to control or monitor the same.

The invention will now be described by way of example only with reference to the accompanying drawings in which Figures 1 and 2 are circuit diagrams of apparatus in accordance with the invention.

The apparatus illustrated in Figure 1 is for location at a base station and that in Figure 2 at one of several stations remote from the base station at which equipment is installed which requires, for example, to be switched "on" or "off" on a frequent or infrequent basis and/or whose state and/or condition and/or operation needs to be monitored. In one application, the base station comprises a farm building, the remote station being sited some distance from the farm building (typically in excess of 10 miles and possibly up to 100 miles) and including pumpoperated water towers which provide water for livestock.

Many other applications are, of course, possible.

The circuit diagram illustrated in Figure 1 comprises a base unit encoder which includes a sequencer 1, an address encoder 2 and three data encoders 3, 4 and 5. The encoders 2 to 5 essentially comprise dedicated integrated circuits. The address encoder 2 is programmed manually through a manual address 6 including two or more rotary switches to enable the address of the remote site to which commands are to be sent selectively to be entered into the address encoder 2. The rotary switches of the manual address 6 essentially select the electrical signals to be applied to the address pins (typically nine in number) of the address encoder. Trinary logic is used on the first eight of these address pins; the electrical states being high, low or floating. The ninth address pin is designed to accept binary logic.Thus, with the arrangement described it is possible to program up to 13122 different addresses with the nine available "bits" of address data.

Only the address encoder 2 is used to select the appropriate address for a required site, the other encoders 3, 4 and 5 using standard addresses common to equivalent decoders at all remote sites. This method of addressing reduces the number of discrete addresses required, simplifies the address switching and increases the total number of remote sites that can be allocated a unique address.

Each of the data encoders 3, 4 and 5 are programmed to receive from a store a plurality of (typically four) data commands for transmission to a selected remote site whose address is determined by the address encoder 2. The data encoders are connected to transmit this data sequentially to a modem 7 via the sequencer 2 when instructed so to do.

A manually operated SEND button 8 is provided to cause required sequences of command signals to be sent to a selected remote site.

On operation of the SEND button 8, a monostable integrated circuit is triggered to operate a relay which in turn operates a PTT (Press To Transmit) circuit of the radio 9. The radio 9 is held in its transmit state by a PTT TIME OUT gate 11 for sufficient time for all of the required data from the address and data encoders to be sent. The signal which operates the PTT circuit also holds an RTS (Request To Send) line of a modem 7 "low". After approximately 0.2 seconds a CTS (Clear To Send) line of the modem 7 also goes "low". This triggers the address encoder 2 to send the address data to the modem 7. Data is sent as two identical data trains for error checking purposes.

Triggering of the address encoder 2 initiates a further delay, through a third monostable integrated circuit in the sequencer 1 to allow the address encoder 2 to send its data. At the end of this delay period another integrated circuit of the sequencer 1 triggers data encoder 3 to send its data to the modem 7. Depending on the number of encoders used, this sequential triggering process continues via data encoders 4, 5 through further monostable delay circuits included in the sequencer 1 until all the data encoders have sent their data to the modem 7. The modem 7 converts the data received into audio pulses for transmission via the two way radio 9. At the end of the transmission the PTT relay releases to turn off the transmitter in the base station two way radio 9. As a precaution against the radio transmitter remaining "on" after the end of data transmission, a further "Time Out" delay circuit is provided. This acts as a backup, through integrated circuits to release the PTT relay after a set time interval, thus preventing the radio transmitter remaining permanently on.

The modem 7 is typically a standard asynchronous Frequency Shift Keying (FSK) voice band modem, this generating the required sequence of audio tones which modulate the radio transmitter. Such a modem can handle up to 1200 bits of data per second; thus the total transmission time for a twelve bit data system (three data encoders) is approximately 1 second (0.2 second delay before sending data +0.2 second for each encoder to send its data).

As will be seen from Figure 2, a two way radio 11 and modem 12 similar or identical to radio 9 and modem 7 of the base station are provided at the remote station and operate to receive tone pulses from the base station, the audio pulses being typically extracted via a loudspeaker/ headphone socket of the radio 11, or through an acoustic coupler. These audio pulses are sent to the receiving part of an integrated circuit of the modem 12 where they are converted into a stream of digital electronic signals usable by an address decoder 14 and data decoders 16, 17 and 18. The address decoder 14 receives digital data direct from the output of the modem 12 and, provided that the address data received is correct and that the two transmitted address words are identical, a VT pin of the address decoder 14 goes "high" for a short period of time determined by a gate timer 19.This triggers a monostable delay circuit which opens a signal gate formed by two Nand gates 21. The signal gate routes the digital data from the modem 12 to the three Data Decoders 15, 16 and 17.

Additionally, at the remote site only, the valid transmission signal which operates the signal gate 21 also triggers a first monostable delay circuit of a sequencer 22. The data decoders 15 to 17 at all remote sites have the same standard address for executing a specific function of electrically controlled equipment at these sites. Thus only one unique decoder integrated circuit is used at a remote site, this being to recognise the correct address for a particular remote site. This simplifies address generation at the base station.

On receipt of the two correct data bit words validated by address decoder 14 each decoder 15, 16 and 17 latches the received data bits onto its data pins for use by the equipment logic and control circuits.

The circuits of the sequencer 22 include three dual monostable integrated circuits each with positive or negative triggering. These are identical to those of sequencer 1 at the base station, although some of the time delays may vary. The VT positive pulse from the address decoder 14 is fed to the first monostable of the sequencer 22 to provide a delay to allow the remote site equipment to respond to any change in command. This delay can be preset at between 2 to 10 seconds, depending on the equipment being controlled at the remote site. At the end of this period the second monostable of the sequencer 22 sends a signal to the PTT relay and the Request to Send (RTS) pin on the modem 12. This initiates a 0.2 second delay within the modem 12 before a Clear To Send (CTS) pin goes "low".

The resulting pulse triggers the address encoder 23 to send its address data which corresponds to the address of the base station to the modem 12 and also initiates the monostable cascade of encoded data as described previously with reference to Figure 1. This sequences the data transmissions from each of three data encoders 24, 25, 26 in turn. The 0.2 second delay before the CTS pin goes low also allows the transmitter to stabilise before data is sent. The data from the data encoders 24, 25, 26 is routed to the transmit side of the remote site modem 12 which converts the data pulses into audio tone pulses. These are then sent to the two way radio transmitter 11 for broadcast to two way radio 9 of the base station. By the use of further monostables in cascade, the data encoders 24 to 26 are triggered to transmit in turn to the modem 12.At the end of the transmission sequence the PTT relay releases to turn off the transmitter. A further "Time Out" delay circuit similar to the one at the base station, running in parallel with the sequencer 22, is used to prevent the transmitter from remaining "on" due to a fault in the sequencer circuit.

The data encoders 24 to 26 at the remote station each have a standard address to transmit to data decoders 27, 28 and 29 at the base station. The first data encoders 24 at all remote sites will transmit to the first data decoder 27 at the base station; similarly, the subsequent data encoders 25, 26 at all remote sites will transmit to the appropriate data decoders 28, 29 at the base station. The encoders at a remote site operate in the same way as the encoders at the base station. However, at the base station the operator dictates the data to be sent, whereas at the remote site it is the operational state of the remote equipment which dictates the data to be sent back. The equipment control logic circuits dictate the electrical state of the data pins on each encoder integrated circuit and thus the information which is sent back to the base station.

If the system is being used automatically to send an alarm to the base station, the last five or six bits of data are preprogrammed to encode the site number so that either 32 or 64 different sites may be identified. With this type of operation the first six or seven data bits would be used to encode the details of the particular fault that caused the alarm.

In use, an operator at the base station sends by pressing the SEND button 8 a series of commands, selected by switches, to the chosen remote site. These are then actioned by the equipment at the remote site and, after a short delay to allow the commanded equipment to start up or shut down, the remote site automatically sends a signal back to the base station reporting on the state of its operation. This signal may typically be representative of water level in a tank - up to 8 levels r water pump running and producing pressure + mode of operation of the equipment - automatic or manual + fuel level in the water pump diesel tank - up to 8 levels. Any type of equipment could be controlled by the system. If required, periodic reports back to the base station could be made automatically or alarm warnings given in the event of a malfunction.

In cases where it is not possible to obtain a satisfactory signal path between the base station and a group of remote sites, the system can include a repeater unit. In its simplest form the repeater unit simply receives an incoming radio frequency signal, converts this to audio tone pulses, and after a short delay retransmits a radio frequency signal corresponding to the received signal.

However, it is preferred if an individual repeater unit is associated with a selected number of remote sites and filters out signals not intended for those remote sites. Thus, signals are only retransmitted if appropriate. In this arrangement, the audio tone signal is received from the two-way radio and the address part of the signal decoded. The data part of the signal are fed to a suitable latch. The address signal is then interpreted, and if appropriate the address signal and latched data signal are fed to an encoder in the repeater for retransmission to the remote site. Only the remote site whose unique address corresponds with the transmitted signal can be activated, of course. The remote site will act upon the remaining data bits in the normal way and in due course will return its operating data to the repeater for onward transmission back to the base station.

In a preferred embodiment the repeater station only decodes the first five bits of a transmission as an address, thus avoiding wasting time. It therefore responds to sixteen different nine bit addresses. Since one address is reserved for the base station receive decoders, fifteen different remote sites may be controlled through one repeater unit.

It will be appreciated that the apparatus described is merely exemplary of apparatus for controlling and/or monitoring electrically controlled equipment in accordance with the invention and that modifications can readily be made thereto without departing from the scope of the invention.

Claims (6)

1. Apparatus for controlling and/or monitoring from a base station electrically controlled equipment at a site remote from the base station, the apparatus comprising means for generating electronic signals representative of commands to be passed from the base station to the remote station, means for encoding these electronic command signals as audio tone pulses, transmitting means operable to transmit such encoded audio pulses as radio frequency signals to receiving means, means for receiving the radio frequency signals and converting them to audio tone pulses, means for decoding the audio tone pulses as electronic command signals, and means for transmitting these decoded signals to electrically controlled equipment whose function is to be controlled or monitored, wherein the radio frequency signal pulse transmitting and receiving means comprise two way radios.

2. Apparatus as claimed in Claim 1 wherein the encoding and decoding means comprise add-on accessories for the two way radios and decoded data is transmitted to an equipment controller on site at the remote station.

3. Apparatus as claimed in Claim 1 or Claim 2 whereinte audio tone pulses are fed through a microphone input socket of the transmitting radio and are recovered from a loudspeaker or headphone connector of the receiving radio.

4. Apparatus according to any preceding claim wherein the audio pulse transmitting and receiving means comprise a loudspeaker and/or a microphone.

5. A method for controlling and/or monitoring from a base station electrically controlled equipment at a site remote from the base station, the method comprising the steps of generating electronic signals representative of commands to be passed from the base station to the remote station, encoding these electronic signals as audio tone pulses, transmitting these audio tone pulses as radio frequency signal by a two way radio from the base station to the remote station, decoding the audio tone pulses received as electronic command signals and transmitting these decoded pulses to electrically controlled equipment to control monitor the same.

6. Apparatus for controlling and/or monitoring electrically controlled equipment substantially as herein described and as described with reference to Figures 1 and 2 of the accompanying drawings.