FR2760923A1 - Telephone installation providing digital answerphone service with multiple handsets - Google Patents

Abstract

The installation comprises a base (1) to which several portable handsets (C1,C2) may be linked. This base comprises a digital data processing unit (20) which processes information for the handsets. The digital data processing unit also forms a responder consisting of a flash type memory (30) which is intended to hold messages, operating without supplementary resources. The data processing unit comprises a differential coding / decoding system for effecting this coding in one format for the handsets, and one format for the responder. The message quality may be switched between high and low quality, with an identifier being stored to indicate the message quality in operation.

Description

Description
The invention relates to a telephone apparatus comprising at least one digital processing device for processing digital speech signals and a digital type answering device.

 The invention also relates to a method implemented in such an apparatus.

 The invention finds important applications in particular in the field of telephones comprising a digital type answering device, for example those meeting the DECT standard. These digital answering devices are becoming more and more important because of their ease of use combined with their great robustness.

 In DECT type telephones that include digital processing devices, the answering device must have its own converter so that the data, whether it provides or receives, is suitable for storing messages for the longest possible duration for a reasonable memory capacity while respecting the criteria of acceptable intelligibility.

 The present invention provides a device of the kind mentioned in the preamble which provides the answering machine function without requiring a lot of equipment.

 For this, such a device is remarkable in that it includes processing control means so that said processing member also processes the speech signals for said answering device.

 The idea of the invention consists in taking advantage of the presence of the converter already used in the device and in making it work so that the requirements of duration and intelligibility of the messages recorded in the answering device can be satisfied.

 The following description given with reference to the attached drawings, all given by way of nonlimiting example, will make it clear how the invention can be implemented.

 Figure 1 shows an apparatus according to the invention.

Figure 2 shows an operating diagram of
the device of figure 1.

 In Figure 1, the device shown is a device meeting the DECT standards. Reference 1 shows the basic circuit to which a plurality of handsets C1, C2, etc. can be attached by radio. This basic circuit includes, among other things, a line circuit 10 which allows it to be connected to a telephone line 12 and a radio circuit 14 which allows dialogue with the various handsets C1, C2, ..., by transmitting and by receiving waves via an antenna 16. To process all the information which passes inside the basic circuit, there is provided a digital processing member 20. This member is composed, in the usual way - a signal processor 22 which cooperates with a random access memory 24 and with a read-only memory 26 containing operating instructions, - an interface circuit 27 which organizes the digital data according to DECT standards so that they are transmitted via the radio circuit 14, - a codec 28 to code in digital form the speech signals which are, by nature, analog and - a microcontroller 29 to manage all the functions of this organ.

This member 20 is formed from an integrated circuit registered PCX5O9x manufactured by the company "PHILIPS
Semiconductors ". The basic circuit 1 also includes a memory 30 of a type known as flash memory constituting the main part of the answering device. It is therefore intended to contain the messages necessary for the answering function.

Still within the framework of the example described, this memory has a capacity of 4 Megabits organized in bytes. This memory provides a message duration of approximately 5 minutes.

The operation of the device is explained with the aid of FIG. 2. In this figure, the different blocks represent tasks to be processed by the processing unit 20, in particular by the unit 22. These tasks are executed according to the data path. Thus, according to the path T1, T2, the processing is carried out for the data which go from the telephone line 12 to the handsets C1, C2, ..., passing through the radio circuit 14. The paths T3 and T4 relate to the data going from the above-mentioned handsets to line 12. In the path T1, there is box K1 which indicates processing on the level of the signals which come from line 12 and which are in the form of linear samples on 16 bits (PCM coding ) supplied by codec 28. These signals, before being transmitted to circuit 14, are converted into differential codes
ADPCM (box K2) in the T2 route. This code is defined by the CCITT standard G726. In the path T3, the signals originating from the circuit 14 in the form of ADPCM are coded in binary code by decoding shown in box K4 and are also subjected to processing of "silent" in box K5. In path T4, the level is adjusted in box K6 before transmission on line 12 via line circuit 10 after a conversion to analog carried out by codec 28.

 According to one aspect of the invention, the data are recorded in the memory 30, after an ADPCM coding indicated in box K10 and the data originating from this memory are linearly encoded by the decoding indicated in box K11. So that the memory does not have too much capacity, this ADPCM coding / decoding is a processing providing fewer bits than for the handsets. The aforementioned standard G726 provides any indication for this kind of processing according to several formats of differential codes. Thus, are shown in FIG. 2 - an ADPCM16d decoding (respectively ADPCM24d) to signify a transcoding of a differential code whose bit rate is 16 kbit / s (respectively 24 kbit / s) to a linear code having a bit rate of 64 kbit / s , - ADPCM16e coding (respectively ADPCM24e) for the reverse operation, i.e. the transition from a linear code at 64kbit / s to a differential code at 16kbit / s (respectively at 24kbit / s), - a ADPCM32d decoding to signify a transcoding of a differential code whose bit rate is 32 kbit / s to a linear code with a bit rate of 64 kbits, - ADPCM32e coding for the reverse operation, i.e. passing a linear code at 64kbit / s to a differential code at 32kbit / s.

 In what follows, we will only mention, for reasons of clarity, the 16kbit / s differential code. But it goes without saying that the 24kbit / s code can be used without departing from the scope of the invention.

 In summary, the paths T1, T2, T3 and T4 represent an operation which does not involve the answering device, that is to say therefore involving a 32kbit encoder and a 32kbit decoder.

 The paths T1 and T6 represent the operation in the event of recording of a message coming from the line 12 which implies a 16kbits coding operation.

 The paths T5 and T2 represent the operation when a message recorded in the memory 30 is listened to from a handset, this implies a 16kbit decoding operation and a 32kbit coding operation.

 The paths T3 and T7 represent the operation when a message from a handset is recorded. This implies a 32 Kbits decoding and a 16 kbit coding.

 The paths T8 and T4 represent the operation when a message is sent on the line. This implies a 16 kbit decoding.

 All these routes are determined by referral tasks represented by boxes K20, K21, K22 and K23.

 Thus, according to the measures recommended by the invention, one realizes that the presence of the answering device brings practically no work overload for the processing member 22.

Claims (4)

CLAIMS. 1) Telephone apparatus comprising at least one digital processing device for processing digital speech signals and a digital type answering device, characterized in that it includes processing control means so that said processing device also processes the signals speech for said answering device. 2) Telephone apparatus according to claim 1 to which is attached at least one handset, characterized in that the processing member comprises coding / decoding means of differential type for performing differential coding / decoding according to a first format for said handsets and according to a second format relating to the answering device. 3) Telephone apparatus according to claim 2, characterized in that, at most, two encodings / decodings are used in the processing. 4) Method implemented in a telephone apparatus according to one of claims 1 to 2, connected, on the one hand, to a telephone line transmitting inter alia speech signals and, on the other hand to telephone handsets, characterized in that it involves the following steps  - putting in the form of first linear digital samples of the speech signals coming from said line,  - putting in the form of differential samples, according to a first format, of said first linear samples for transmission to said handsets,  - putting in the form of differential samples, according to a second format of said samples, of said first linear samples for storage in the answering device,  - putting in the form of second linear digital samples of differential samples having according to said first format,  - Putting in the form of third linear digital samples of differential samples having according to said second format, coming from said answering device.