JPH11262053A - Digital cordless system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overlap a radio area of each master set on a radio area of other master sets when plural master sets are contained in a master device and to eliminate the need for a temperature compensated crystal oscillator(TCXO) which is a small-sized device when a master set is contained in a master device. SOLUTION: A voice signal is sent between a master set data transmission section 12 and a radio section 13 in a form of analog signals. Furthermore, call control data between them are sent by an asynchronous transfer system. A radio section 13 uses a clock from a TCXO 17 as it is when no synchronizing signal is available and uses the clock from the TCXO 17 synchronously with the synchronizing signal, when the synchronizing signal is available.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital cordless system, and more particularly to a digital cordless system in which a main unit of a key telephone device accommodates a base unit of a digital cordless telephone.

[0002]

2. Description of the Related Art As a digital cordless system, there is a system in which a main unit of a digital cordless telephone is housed in a main unit of a key telephone device.

In this type of system, a plurality of master units can be connected to one main unit, and a slave unit of a digital cordless telephone can communicate with any master unit. Therefore, in this system, by arranging the plurality of base units such that the wireless areas of the plurality of base units are continuous with each other, it is possible to provide a service area considerably larger than the wireless area of the single base unit. it can.

Here, in order to make the wireless areas of a plurality of master units continuous, it is necessary to make a part of these wireless areas overlap. And the child device which exists in the area where a plurality of wireless areas overlap,
In order to communicate properly with any one of the master units, the master units in the overlapping wireless areas must be synchronized with each other.

Therefore, conventionally, as shown in FIG. 2A, a high-precision oscillator (TCXO: Temperatur
An e-Compensated Crystal Oscillator (22) is provided, and a synchronization signal is transmitted from the main device 21 to all the master units 23 to establish synchronization between the master units.

Each master unit 23 has a data transmission unit 24 for transmitting and receiving data to and from the main unit 22, and a slave unit (not shown).
And a radio unit 25 for transmitting and receiving signals to and from the built-in TCXO 26. The built-in PLL (Phas
e Locked Loop) 27 to synchronize with a synchronization signal from the main unit.

Incidentally, between main device 21 and master device 23,
A PCM signal is used, and ADP is used between the master unit and the slave unit.
Since the CM signal is used, the PCM is transmitted to the main device data transmission unit 24 or the radio unit 25 as shown in FIG.
An / ADPCM conversion unit 28 is provided to perform code conversion.

[0008]

In a conventional digital cordless system, a plurality of master units are accommodated in a main unit, and a synchronization signal is transmitted from the main unit to all the master units, thereby synchronizing all the master units. Thus, a large service area can be provided.

However, in such a system,
All signal exchanges between the main unit and the main unit data transmission unit of the master unit and between the main unit transmission unit and the wireless unit of the master unit are performed in synchronization with the synchronization signal from the main unit. I have. Therefore, there is a problem that an expensive TCXO for generating a synchronization signal must be provided on the main device side even when the main device accommodates only one master device.

Here, when only one master unit is accommodated in the main unit, as shown in FIG. 3, if the main unit and the master unit are connected by an analog interface, the master unit becomes: Since operation is possible using its own TCXO, there is no need to provide a TCXO in the main device. However, in this configuration, when a master unit is subsequently added, synchronization between the master units cannot be obtained, and thus a problem arises in that the wireless areas must be arranged so as not to overlap with each other.

According to the present invention, when a plurality of master units are accommodated in the main unit, these master units can be arranged so that the wireless area of each master unit overlaps the wireless area of another master unit. However, when one main unit is accommodated in the main unit, it is an object to provide an inexpensive digital cordless system without the necessity of providing a TXCO in the main unit.

[0012]

According to the present invention, a master unit including a main unit, a main unit data transmission unit connected to the main unit, and a radio unit connected to the main unit data transmission unit. When,
In the digital cordless system having the above, transmission of voice data between the main device data transmission unit and the radio unit is performed by an analog signal, and transmission of call control data between the main device data transmission unit and the radio unit. Is performed by an asynchronous transfer method, thereby obtaining a digital cordless system.

According to the present invention, when the radio unit receives a synchronization signal transmitted from the main device, the radio unit operates in synchronization with the synchronization signal, and receives the synchronization signal from the main device. If not, a digital cordless system characterized in that it operates in synchronization with a signal transmitted from a built-in oscillator.

Still further, according to the present invention, when one master unit is connected to the master unit, the master unit does not transmit a synchronization signal to the master unit, and the master unit transmits the synchronization signal to the master unit. When a plurality of master units are connected, a digital cordless system is obtained in which the main unit transmits the same synchronization signal to the plurality of master units.

[0015]

The transmission of the audio signal between the main unit data transmission unit and the radio unit in the master unit is performed by an analog signal. Further, transmission of a call control signal between the main unit data transmission unit and the radio unit is performed using an asynchronous transfer method. Thus, the wireless unit does not need to synchronize with the main device data transfer unit, and can transmit an audio signal to the slave unit without a synchronization signal from the main device.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. FIG.
As shown in (a), the digital cordless system according to the present embodiment includes a main device data transmission unit 12 connected to a main device 11 of a key telephone device, and a main device data transmission unit 12.
And a base unit 14 of a digital cordless telephone device having a wireless unit 13 connected to the base unit 14. The wireless unit 13
Is a TCXO (high precision oscillator:
PLL (Phase Locked Loop) to which a synchronization signal from Temperature Compensated Crystal Oscillator (15) is input
) 16 and a TCXO1 for generating a clock signal in the base unit
7 is provided.

The main unit data transmission unit 12 transmits data (digital data) including a voice signal and a call control signal to and from the main unit 11 via an extension interface (I / F). Further, the main unit data transmission unit 12 includes a radio unit 13.
The transmission of the voice signal and the transmission of the call control signal are performed through different paths.

At this time, the audio signal is converted between a PCM signal and an analog signal by the PCM encoding / decoding section 18 in the main apparatus data transmission section 12, as shown in FIG. 1B. . On the wireless unit 13 side, A
An analog signal and an AD signal are output by the DPCM encoding / decoding unit 19.
Conversion to and from PCM signals is performed. The PCM encoding / decoding unit 18 is very inexpensive as compared with the conventional PCM / ADPCM conversion unit 28, and the same ADPCM encoding / decoding unit 19 as that used in the slave unit can be used. So economical.

On the other hand, as shown in FIG. 1C, the call control signal is transmitted between the CPU controlling the main unit data transmission section 12 and the CPU controlling the radio section 13 by a serial asynchronous transfer system (start-stop synchronization system). The connection is made by the following. In the serial asynchronous transfer method, since the two CPUs transmit signals at timings independent of each other, there is no need to synchronize the CPUs. Note that such a function is provided by a UART (Universal
Asynchronous Receiver Transmitter) function. Further, the same can be realized by providing a common memory that can be accessed from the two CPUs at independent timing.

As described above, the main unit data transmission unit 12 and the radio unit 13 are analog signals for audio signals,
Since the call control data is exchanged by the asynchronous transfer method, they need not be synchronized with each other. In other words, even when the synchronization signal is not input from main device 11, main device data transmission unit 12 and radio unit 13
And can communicate.

When only the clock signal from the TCXO 17 is input, the PLL 16 outputs the clock signal to the radio unit 13 as it is. As a result, the wireless unit 13
When a synchronization signal is not input from the main device 11, the voice signal and the call control data are processed using a clock signal generated by the built-in TCXO 17, and communicate with a slave unit (not shown).

When the clock signal from the TCXO 17 and the synchronizing signal from the main unit 11 are input, the PLL 16 synchronizes the phase of the clock signal from the TCXO 17 with the synchronizing signal and outputs it. As a result, the wireless unit 13
Operate with a clock signal synchronized with the synchronization signal.

As described above, in the present embodiment, the base unit 14
When no synchronization signal is input from the main device 11,
It runs on the basis of a clock signal from the TCXO 17 and, when a synchronization signal is input from the main unit 11, operates in synchronization with a clock signal synchronized with the synchronization signal. Therefore, when only one parent device 14 is accommodated in main device 11, parent device 14 operates normally without installing expensive TCXO 15 in main device 11. When a plurality of parent devices 14 are accommodated in main device 11, TCXO
If the base station 15 is installed, each base unit 14 can normally communicate with the slave unit even when the wireless areas of the base units 14 overlap. That is, a plurality of base units 14 can be installed such that the wireless areas overlap.

[0025]

According to the present invention, the base unit of the digital cordless telephone device connected to the main device of the key telephone device,
The transmission of the audio signal between the main unit data transmission unit and the radio unit is performed by an analog signal, and the call control signal is performed by the asynchronous transfer method, so that the main unit accommodates one master unit. It is not necessary to install an expensive TCXO in the main unit, and when accommodating a plurality of master units, it is possible to install a plurality of master units so that their wireless areas overlap by providing a TCXO. become.

[Brief description of the drawings]

1A is a block diagram showing an embodiment of the present invention, FIG. 1B is a diagram for explaining audio signal transmission in FIG. 1A, and FIG. 1C is an asynchronous signal in FIG. FIG. 9 is a diagram for explaining transfer.

FIG. 2A is a block diagram of a conventional digital cordless system, and FIG. 2B is a diagram for explaining audio signal transmission in FIG.

FIG. 3 is a block diagram of another conventional digital cordless system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 Main device 12 Main device data transmission unit 13 Radio unit 14 Master device 15 TCXO 16 PLL 17 TCXO 21 Main device 22 High-precision oscillator 23 Master device 24 Data transmission unit 25 Radio unit 26 TCXO 27 PLL

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Ishioka, Inventor 3-192-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Sadasuke Michimoto 3-19, Nishishinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A digital cordless system comprising: a main unit; a main unit including a main unit data transmission unit connected to the main unit and a wireless unit connected to the main unit data transmission unit; The transmission of the audio signal between the device data transmission unit and the radio unit is performed by an analog signal, and the transmission of the call control data between the main device data transmission unit and the radio unit is performed by the asynchronous transfer method. Digital cordless system characterized by the following. 2. The radio section operates in synchronization with a synchronization signal transmitted from the main device, and operates when the synchronization signal cannot be received from the main device. 2. The digital cordless system according to claim 1, wherein the digital cordless system operates in synchronization with a signal transmitted from an oscillator. 3. When one main unit is connected to the main unit, the main unit does not transmit a synchronization signal to the main unit, and a plurality of the main units are connected to the main unit. Wherein the main unit transmits the same synchronization signal to the plurality of master units.
Digital cordless system.