Flexless telephone system.

The invention relates to a device for cordless telephony, consisting of a fixed part with radio and cable part and multiple handsets with each individual, with the fixed part interchangeable identifier.

In EP 180 178, a cordless telephone is described in which a fixed part associated with multiple handsets. The handsets are distinguished by their device-specific identifier. A main handset are subordinate to a number of neighboring handsets. It is only from the main handset possible to make calls and to accept incoming. Of the secondary handsets only incoming calls can be answered (see page 2 and claim 1). This prevents outgoing calls are made by possibly unsupervised handsets, and the subscriber will be charged fees.

A cordless phone is in Telcom Report 10 (1987), No. 2, page 130-137 describes. It can be integrated into a PBX as extension instead of a string telephone. The technical and financial expenditure increases, however, considerably if more extensions are to be equipped with cordless phones. For each of these participants a special connection module, a fixed and a mobile unit must be provided.

The invention is based, to reduce the outlay in building multiple extensions with cordless phones the task.

This is according to claim 1 achieved in that for each handset a charging station available and the hard part is equipped with a switching matrix, a signal processing path per handset and a Signalsummiervorrichtung the high frequency range as a PBX.

With a high-frequency unit and an antenna in the fixed element may be simultaneously constructed each handset a duplex radio channel, whereby the hard part supplies several handsets. Each handset acts due to the device-specific, different identifier despite its conventional structure as full extension. As an independent from the fixed part charging station requires only a power connection, the site can be changed more easily than at the end connected to the outside line hard part. One or more charging trays can also be formed in the fixed part or releasably connected to him. On line part both trunks and tie lines can be connected to a parent branch exchange system.

To design a home telephone system, at least one subscriber set on a corded phone and / or a door station is connected to the switching network. Thus, an adaptation to different national postal regulations is possible. The functionality of the PBX is increased in that the hard part is equipped with an extension device to the extensions. This feature is an example of the extensibility of the PBX with cordless subscriber terminals.

The invention is further illustrated by an embodiment with drawings. Show it:<ul><li>1 shows the representation of the expansion stage of the embodiment,</li><li>2 shows a block diagram of its continental part,</li><li>3 shows the detailed block diagram of the low-frequency part in the fixed part and</li><li>4 shows the detailed block diagram of the radio part of the hard part.</li></ul>

The Fig.1 shows a PBX, which is connected to two external lines AL. A hard part FT is up to three handsets MT in radio link. Moreover, a cord phone ST and a Doorphone TSS are connected as extension to the fixed part FT. To receive the mobile phones MT are loading shelves LA, which are set up individually or form a part of the fixed part FT. In the loading tray LA of the accumulator for the power supply of the handset MT is charged or held the charge. They can also serve to receive a replacement battery.

As Figure 2 shows, the trunks AL on Office sets AS and the corded phone ST and the door intercom TSS participants sentences TS with a switching network KF connected in the fixed part. The call handler circuits, such as an extension device to the extensions are connected to the switching network KF A door release contact TK complements Doorphone TSS.

A switching control VS not only controls the switching matrix KF, ​​but also the further signal processing in a low frequency and radio part NT, FCT. The RF signals are radiated or received through an antenna AN. Each handset has its own device-specific identifier that is exchanged with the hard part. This process is monitored by the switching control VS. Thus, since each handset is identified, it can be connected via the switching network KF with another extension or one of the official lines AL. With a liquid crystal display in the handset to-date information, such as charges, calling or called number, incoming call can be displayed with line number etc..

The low frequency part shown in Figure 3 includes a signal processing path for each of the three handsets. After switching network KF each signal processing path of an active hook switch GS is constructed on a compander KP follows. A modem M of signal processing path to the switching-oriented data, such as the identifier exchange, taken from the switching control VS and added. He follows mainly the assembly and disassembly of a connection between fixed and mobile part. A band filter BF limits the frequency band to avoid sending interference with an adjacent channel. Moreover, the switching-oriented data transmission end coupled by the modem M via the band filter BF. At the receiving end the modem M is connected directly.

4 shows the continuation of the signal processing paths in the radio part. The transmitting end, the low-frequency signal is modulated onto a carrier signal from the 900 MHz band. This is done in a modulatable frequency synthesizer MFS, which is stabilized by a reference oscillator R0 in the PLL circuit. The modulated frequency synthesizer MFS are connected to switches S, which switch through its output only after the transient effect of about 1 ms. The RF signals of the three signal processing lines are added in a passive Signalsummiervorrichtung SSV. It is built in 50 ohm technology and must be well isolated and adapted. Thus, in the summation effects on the modulatable frequency synthesizer MFS be avoided. This sum signal is amplified by a linearized power amplifier LV, which has to work extra linear and without intermodulation. About a transmit / receive switch SEW the sum signal to the antenna AN is conducted and radiated.

The signals received by the mobile units are fed via the transmit / receive switch and an active SEW signal separator STV. It is composed of three parallel amplifiers, so that the reception signal no additional losses occur. Each of the three high frequency signals is converted back on carrier frequency synthesizer and an intermediate frequency converter TFS ZFUs in a low frequency signal. The carrier frequency synthesizer TFS work parallel to the modulated frequency synthesizers MFS, are not modulated and generate a tuned to the carrier signal frequency.