GB2348086A

GB2348086A - Local network with clock back-up

Info

Publication number: GB2348086A
Application number: GB0001186A
Authority: GB
Inventors: Serge Renouard
Original assignee: Sagem SA
Current assignee: Sagem SA
Priority date: 1999-01-22
Filing date: 2000-01-20
Publication date: 2000-09-20
Anticipated expiration: 2020-01-20
Also published as: GB0001186D0; FR2788916A1; DE10001574A1; GB2348086B

Abstract

A base station 1 and associated terminals 2 of a local network each have clocks to provide time of day information. In the event of a power supply failure to either the base station or terminals, the correct time may be downloaded from the terminal or base station respectively. The local network also provides an alarm clock function in which the base station may be programmed from the terminal so as to indicate when a programmed time corresponds to the current time. The base station may send a signal to the terminals to indicate this condition. The local network may operate according to the DECT standard.

Description

2348086

DESCRIPTION LOCAL NETWORK WITH CLOCK BACK-UP

A local telephone network, formed from a base and telephones and which is connected to the switched telephone network, often comprises, in the base, a clock circuit supplied by the mains.

The base comprises a back-up battery to maintain the supply to the clock circuit in the event of a mains power cut. The telephones also comprise a battery if they are portable handsets connected to the base by a wireless link or also if random access memory data is stored therein. The battery in the base creates a problem of bulk and even of cost which is hard to justify, taking account of the small number of mains power cuts which occur.

EP-924 5 8 1 A 1, published after the priority date of this application, discloses a DECT base and an associated terminal, of which the respective clock circuits can assist each other, making it possible to do without the base battery.

The applicant has thought of using these clock circuits, which are still operational, to provide users with other functions linked to the measurement of time.

To this end, the invention relates to a local telephone network comprising a base, which includes a first electronic clock, and at least one telephone terminal, which includes a second electronic clock supplied by a source of stored electrical energy, each of the two clocks being associated with remote-loading means for remotely loading the content of one into the other, and wherein the base comprises 2 signalling circuits controlled by the clock of the base and which are remotely programmable from a terminal of the network in order to signal that the current time corresponds to a programmed time.

The terminal of the network thus has an alarm clock function with a good level of reliability and at a low cost since the corresponding circuits are centralised.

In one particular embodiment, the signalling circuits of the base are deported to the terminal and arranged to be connected to other terminals of the base.

The invention will be better understood with the aid of the following description of a preferred embodiment of the local telephone network of the invention, with reference to the single figure which illustrates it schematically.

The illustrated network comprises a base I linked to an information transmission network and more precisely in this case to a line 3 of the switched telephone network. The base I is in this case connected to a plurality of terminals such as telephone handsets which it manages, of which only the handset 2 is shown, the assembly forming a local network, in this case with wireless connections, between the base I and the handsets 2, according to the DECT radio standard in this example.

The base I comprises an electronic clock 10 comprising an oscillator or clock circuit 100 for supplying periodic clock signals, and a frequency divider 101 controlled by the oscillator 100 and supplying, in particular, time signals for use I 3 of functions based on a time-dating clock (logic function), such as the alarm clock function. The clock 10 clocks the operation of a central microprocessor unit 11 by supplying it with clock signals at various frequencies (physical or material operation) and can transmit, on the radio network via a remote-loading circuit 112 belonging to the central unit 11, the time signals representing the counting state (date, hours, minutes, etc) of the frequency divider 10 1, ie. its contents. Conversely, the divider 10 1 can be remotely loaded via the radio network and via gates 102 controlled by the circuit 112 in order to receive the contents of a frequency divider circuit 201 belonging to a clock 20 of the terminal 2. In other words, the clock 10 constitutes a data terminal of the radio network and the remote-loading circuits 112 and 212 are bidirectional.

In particular, the central unit I I comprises a memory circuit I 10, for storing a date and time supplied by a user locally or from a terminal such as 2, which controls an input of a comparator I I I connected to the divider 10 1 by a second input. The circuits I 10, 111 constitute a signalling assembly controlled by the clock 10 and remotely programmable from a keypad 24 of the terminal 2 and via a radio circuit 13 in order tosignal that the current time corresponds to a programmed time and to transmit, via the radio circuit 13, the corresponding signalling to the terminal 2 or any other which has remotely programmed the memory circuit I 10. Each terminal (2) can thus programme the memory circuit 110 which is arranged simultaneously to process several programming operations and to signal individually to each terminal concerned that the current time 4 corresponds to the time which it has programmed.

The circuit 112 comprises a detector to detect energising. This detector comprises a low-pass filter with series resistance, connected at the input to the positive power supply, and with an integrating capacitor connected to earth on one side. The output of the filter controls a shaping logic gate which thus has a low state for a certain duration controlling the placing of the various circuits of the base I in an initial state. In particular, a sequencing counter for configuration of the base I by the ten-ninal 2 is placed at zero in order, once the pulse has disappeared by reason of the charge of the capacitor, to read a memory of the circuit 112 containing instructions to request remote- loading of the clock 10 by the clock 20 and to exchange the necessary data with the terminal 2.

A line interface circuit 12, for engaging the line and transmitting and detecting dialling, connects the base I to the line 3, while the radio interface circuit 13, for selecting time paths of DECT frames, connects the base I to terminals such as 2. The microprocessor 11 is connected to the various circuits in order to manage and to connect them. A power supply 19, which is itself supplied by the mains in this case, supplies the base I and thus, in particular, the clock 10.

The electronic clock 20, similar to the clock 10, is integrated into the handset 2 and comprises an oscillator or clock circuit 200 for supplying periodic clock signals, controlling the frequency divider 201 supplying time signals. The clock 20 clocks the operation of a central microprocessor unit 21 comprising a random access memory 2 10 connected, at the output, to an input of a comparator I 211, of which another input receives the time signals or the current time from the divider 20 1, and of which the output controls a buzzer 26. The circuits 210, 211 have the same function as the circuits I 10, 111. In the same way as the clock 10, the clock 20 can also have access to the DECT network in a bidirectional manner via a circuit 212 of the central unit 21 and be remotely loaded by this circuit via gates, not shown, the counterparts to gates 102, in order to receive the contents of the divider circuit 10 1.

The time signals of the divider circuits 10 1 and 201 each supply two types of information: clocking information, to make the associated microprocessor and the other circuits (interfaces and others) operate at the rate appropriate to them (material operation), and time reference information, ie. the current time, so that the circuits take the desired decisions at the planned moment (software operation).

Apart from the buzzer 26, the operator-machine interface elements comprise, in this case, the keypad 24 for inputting commands for reminders about meetings or wake-up calls, which are stored in the memory 210, and a screen 25 for checking the commands. The reference 22 designates the standard telephone circuits of such a handset, managed by the microprocessor 21, which is connected to a DECT radio interface circuit 23. A battery 29 supplies the handset 2 and thus, in particular, the clock 20.

The operation of the network will now be explained, in particular, with respect to the clock operation.

The telephone communications of the handset 2 are established in a 6 standard manner and explanation is thus superfluous.

In a minimal configuration the network comprises only the base I and the illustrated handset 2. In such a case, the handset 2 can itself manage the programming of the activation time of the buzzer 26 and the execution of this activation by means of the memory 2 10, of the comparator 211 and of the local clock 20.

In the case of a mains failure, the circuit 112 issues a request by radio to the handset 2 for remote-loading of the clock 10 by the clock 20 when the mains power is restored. If usage circuits for the clock signals I 10, 111 were not provided in the base 1, the clock 10 would then serve only to assist the clock 20 in case of the battery 29 being defective. The handset 2 would thus be master with respect to the use of the clock function and the base I would simply serve as a back-up copy, advancing by itself to keep up to date and to be a copy or image of the clock 20.

However, additional standard terminals can be provided connected to the base 1 by radio and having no time-dating clock but having the alarm clock function but with the corresponding equipment being centralised (110, 111) in the base I or (210, 211) in the terminal 2, the latter then constituting for this function a functional assembly of the base I deported to the terminal 2 and able to be connected by radio, via the base 1, to these standard terminals in order to supply them with the alarm clock function.

If, on the other hand, the circuits 210, 211, locally using the clock 20 of I 7 the handset, were absent or deported to (110, 111) the base I in order to use the clock 10 thereof, the latter would be master, ie. would at least control the remoteloading of its clock 10 by the clock 20. The base I would preferably also ensure the continuity of the clock 20, in the case of a failure or a change of battery 29, by remote-loading the content of the divider 10 1 into the divider 201 in order to have the clock 20 permanently to assist the clock 10.

The remote loading of the clock 10 by the clock 20 will now be described.

In the event of a failure in the mains voltage, the voltage of the source 19 disappears and the clock 10 stops and loses all memory (101). Upon reestablishment of the mains voltage, the circuit 112 launches a programme to reload the clock 10, consisting of occupying a channel of the radio network to transmit a remote-loading request message to the counterpart circuit 212 of the handset 2. The circuit 212, which is connected to all the outputs of the divider circuit 201, transmits the current binary state of the divider circuit 201 to the circuit 112 on the return radio channel.

The circuit 112 applies all the bits, an image of the state of the divider circuit 20 1, to the inputs of the counterpart stages of the divider circuit 10 1 by opening the row of gates 102 by means of a remote- loading forcing signal applied to an input cable 103 common to all the gates 102. In this example in order to avoid any incorrect operation the remote-loading signal is synchronised with the clock signal issuing from the oscillator 100, which is also supplied to the circuit 112. In particular, the remote-loading signal falls, closing the forcing gates 102, in 8 phase opposition with the active leading edge of the clock signal above, causing the divider 10 1 to advance. As a result of this, any simultaneity, which is a possible source of poor operation, between this active leading edge and the unlocking of the divider 10 1 during closure of the gates 102 is avoided, which pennits activation of the divider 10 1 by the active leading edge.

It will have been understood that the remote-loading of the clock 20 from the clock 10 is carried out under conditions similar to those of the remote-loading in the opposite direction which has just been described.

In the case of the presence of a plurality of handsets with clocks, such as the handset 2, these handsets can, in the same way, each act as a timedating clock back-up in order, apart from the clock 10 of the base 1, to remotely load the clock (20 1) of the others via the radio network.

I

Claims

9 CLAIMS

1. A local telephone network comprising a base which includes a first electronic clock, and at least one telephone terminal, which includes a second electronic clock supplied by a source of stored electrical energy, each of the two clocks being associated with remote-loading means for remotely loading the content of one into the other, and wherein the base comprises signalling circuits controlled by the clock of the base and which are remotely programmable from a terminal of the network in order to signal that the current time corresponds to a programmed time.

2. A network according to claim 1, wherein the signalling circuits controlled by the base clock are arranged to transmit their signalling to said terminals.

3. A network according to claim I or 2, wherein each of said remoteloading means is bidirectional.

4. A network according to claims 1, 2 or 3, wherein the base is connected to the terminal by a wireless link.

5. A network according to any of claims I to 4, wherein the signalling circuits of the base are deported to the terminal and arranged to be connected to other terminals of the base.

6. A local telephone network, substantially as hereiribefore described, with reference to and as illustrated in the accompanying drawing.