GB2258118A - Remote telephone switch - Google Patents

Abstract

A switch for remote management of electrical equipment using a telephone line. The switch connects to the Public Switched Telephone Network (PSTN) and has a number of input and output channels for control of equipment. This remote switch can be called from any telephone. The user issues instructions to the switch, using Dual Tone Multi Frequency (DTMF) signals. These are generated from the telephone keypad or a hand held tone pad. Instructions are formed using the digits 0 to 9 and the and '#' characters available on telephone keypads. The switch replies using simple audible tones. The switch has a Personal Identification Number (PIN), set within the switch as a security feature. This PIN must be entered by the caller, before control functions may be carried out. <IMAGE>

Description

REMOTE TELEPHONE SWITCH This invention relates to remote management of electrical apparatus using the Public Switched Telephone Network.

Many control applications require management of electrical equipment from a remote location. When access to a telephone line can be gained at the remote location, data communication modems are used to provide the control. This method is expensive and cannot be simply controlled from any telephone, without the use of additional equipment.

This invention allows the user to control electrical equipment and enquire about the status of equipment, by use of a telephone line. The invention connects to the Public Switched Telephone Network (PSTN) and has a number of input and output channels.

This remote switch can be called from any telephone. The user issues instructions to the switch using Dual Tone Multi Frequency (DTMF) signals. These are generated from the telephone keypad or a hand held tone pad. The instructions are used to switch output channels and enquire about the status of input channels. The switch replies using simple audible tones. This method of communication can thus be achieved, from any telephone connected to the Public Switched Telephone Network.

A specific embodiment of the invention will now be described.

The remote switch consists of five main sections of electronics which are shown in Figure 1. These are described below: Referring to the diagram in Figure 1, the switch comprises a power supply (5) which accepts mains supply voltage and provides low voltage to drive the circuitry. A microprocessor (2) provides overall control of the switch, allowing commands over the telephone line to be interpreted and carried out using the input / output interface circuitry (3). The PSTN interface circuitry (1) provides the interface with the telephone line and the decoding of DTMF tones. This interface will inform the microprocessor of incoming calls via the 'Ring Detect' line. The microprocessor uses the 'Answer' line to instruct the PSTN interface to answer the call. The 'Tone' lines from the PSTN interface (1) are used to communicate to the microprocessor (2), the decoded DTMF tones.The 'Sound' line is used to communicate outgoing sounds from the microprocessor to the PSTN interface.

This circuitry must conform to the relevant safety regulations which apply to the PSTN.

There are also four rotary switches forming the configuration (4). These are configured by the user, to set a Personal Identification Number (PIN). This number must be entered by the caller, as a password, before control actions may be carried out.

The configuration circuitry (4) contains a reset switch to locally set output channels to the default state. The Input / Output interface circuitry (3) contains four output relays for controlling equipment and two digital input sensors for monitoring equipment.

The remote switch is installed by connecting it to a telephone line and wiring the inputs and outputs to the equipment being controlled. The Personal Identification Number is configured using the four rotary switches.

The user calls the remote switch from a telephone. When the switch answers, the Personal Identification Number (PIN) is entered using either the telephone keypad or a tone pad.

Instructions are then sent to the remote switch again using the telephone keypad or tone pad. These are formed using the digits O to 9 and the '*' and '&num;' characters available on telephone keypads. The remote switch replies to commands using simple audible tones for a "YES" or "NO" response. Instructions can be issued for each of the following functions: Switch an output channel on Switch an output channel off Enquire about the status of an output channel Enquire about the status of an input channel Thus the remote switch can be used to provide a simple control and monitoring function.

Claims (6)

1A remote telephone switch for controlling output channels and monitoring input channels using a telephone line.

Communication to the remote switch is achieved using standard Dual Tone Multi Frequency (DTMF) signals, generated from a telephone keypad or a hand held tone pad. A means for security is provided by the use of a Personal Identification Number (PIN).

2 A remote telephone switch as claimed in claim 1, wherein the switch replies to the caller using either simple audible tones or computerised speech.

3 A remote telephone switch as claimed in claim 1, wherein a Personal Identification Number 'PIN' for security, is set within the remote switch and is entered by the user, over the telephone line before control functions may be carried out.

4 A remote telephone switch as claimed in claim 1, wherein a reset button is provided locally to set output channels back to their default state.

5 A remote telephone switch as claimed in claim 1, wherein connection is made to an internal exchange telephone line or to the external Public Switched Telephone Network (PSTN).

Connection to either type of line may be in parallel with existing equipment.

6 A remote telephone switch substantially as described herein with reference to Figure 1 of the accompanying drawing.