EP0399610A2
Expired / Lapsed
EP
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Improvements in or relating to digital cordless telephone systems
Assignee: Philips Electronics UK Ltd
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Filing: 1990-05-22
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Granted: —
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Expires: 2010-05-22
Abstract
Abstract A digital cordless telephone system which comprises a primary station (PS) controlled by a system controller (14 or 15) and a plurality of secondary stations (SS) capable of communicating with the primary station by way of a time division duplex radio link, the primary and/or secondary station having means to generate a beacon signal which is receivable by a secondary station outside the range of normal speech communication and the beacon signal comprising a low bit rate signal which is transmitted at a power comparable to the digitised speech signal. In one embodiment the beacon signal is recovered using a narrowband filter and a demodulator. In another embodiment direct sequence spread spectrum techniques are used to send the beacon signal and a correlator/matching circuit is used to recover the low bit rate data representative of the beacon signal.
Inventors
- 👤 Frank Charles Gwyn Owen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 20:16
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/24; H04B7/26; H04W; H04W48/00; H04W48/08; H04W48/12; H04M; H04M1/00; H04M1/72; H04M1/725; H04M1/72502; H04M1/72516; H04M1/733
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
63 words
A digital cordless telephone system comprising a primary station and a secondary station, each said station comprising a transceiver whereby digitised speech communication is established on a time division duplex channel, and means in at least the primary station for producing a beacon signal comprising a data signal having a net data rate substantially less than the digitising rate of the speech signal.
Claim 2
Dependent Claim
63 words
A digital cordless telephone system comprising a primary station and a secondary station, each said station comprising a transceiver whereby digitised speech communication is established on a time division duplex channel, and means in at least the primary station for producing a beacon signal comprising a data signal having a net data rate substantially less than the digitising rate of the speech signal.
Claim 3
Dependent Claim
20 words
A system as claimed in Claim 1, characterised in that the secondary station comprises means for producing a beacon signal.
Claim 4
Dependent Claim
34 words
A system as claimed in Claim 1 or 2, characterised in that the bit rate of the beacon signal is a factor of at least 100 times less than that of the digitisation rate.
Claim 5
Dependent Claim
31 words
A system as claimed in Claim 1, 2 or 3, characterised in that the output power of the beacon signal is comparable to the output power of a digitised speech signal.
Claim 6
Independent Claim
42 words
A system as claimed in any one of Claims 1 to 4, characterised in that the primary station transmits signalling information in a physical channel and in that a beacon signal is transmitted in the physical channel in place of signalling information.
Claim 7
Independent Claim
41 words
A system as claimed in any one of Claims 1 to 5, characterised in that the receiver section of the transceiver of at least the secondary station includes a narrowband filter for recovering the data signal representative of the beacon signal.
Claim 8
Dependent Claim
26 words
A system as claimed in Claim 6, characterised by a demodulator coupled to the digital filter for demodulating the data signal representative of the beacon signal.
Claim 9
Independent Claim
37 words
A system as claimed in any one of Claims 1 to 5, characterised in that at least the primary station comprises means for applying direct sequence spread spectrum techniques to the data representative of the beacon signal.
Claim 10
Dependent Claim
33 words
A system as claimed in Claim 8, characterised in that means are provided for applying respective orthogonal pseudo-random codes to the "1" and "0" bits of the data representative of the beacon signal.
Claim 11
Dependent Claim
43 words
A system as claimed in Claim 9, characterised in that at least the secondary station includes a demodulator for demodulating the spread spectrum signal and a correlator/matching circuit for deriving the "1" and "0" bits of the data representative of the beacon signal.
Claim 12
Dependent Claim
72 words
A secondary station for use in a digital cordless telephone system as claimed in any one of Claims 1 to 10, characterised by a transceiver, a CODEC for encoding speech to be transmitted and decoding received encoded speech, means for recovering a low data rate signal having a data rate substantially less than that of the digitised speech and means for deriving a beacon signal from the recovered low data rate signal.
Claim 13
Dependent Claim
54 words
A secondary station as claimed in Claim 11 for use in the system as claimed in any one of Claims 1 to 7, characterised by a narrowband filter for recovering the low data rate signal received by the transceiver, and a MODEM for deriving a beacon signal from the recovered low data rate signal.
Claim 14
Dependent Claim
50 words
A secondary station for use in the system as claimed in any one of Claims 8 to 10, characterised by demodulating means for demodulating the spread spectrum low data rate signal and a correlator/matching circuit for deriving the "1" and "0" bits of the data representative of the beacon signal.
References Cited (Backward Citations)
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