EP0145097A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Duplex speech transmission method and a system therefor
Assignee: Philips Electronics UK Ltd
•
Filing: 1984-12-05
•
Granted: —
•
Expires: 2004-12-05
Abstract
Abstract The invention relates to a duplex speech transmission method and a system therefor and has particular, but not exclusive, application to cordless telephone systems. A duplex speech transmission method is disclosed wherein a limited bandwitth transmission channel is divided in a plurality of successive time slots, alternate time slots being available for each of two parties to call in Speech signals from either of the parties are divided into time segments with the time segments associated with one of said two parties being offset in time with the time segments associated with the other of said two parties. Segments of speech when present are digitised and stored in digital form. A higher rate of quantisation is used when speech is present in the segments of one party and not in those of the other party, said higher rate quantised signal being transmitted in the other party's time slot and the immediately following time slot of said one party. A lower rate of quantisation is used if both parties have speech in their respective segments, the lower rate quantised signals being time compressed and transmitted in their associated time slots. By the i method being digited throughout the end of a segment coincides substantially with the end of the time slot associated with said segment and thus a delay not exceeding half a segment is incurred. By making the segments have a duration of 2ms then the method complies with PSTN requirements.
Inventors
- 👤 Philip David White
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 09:13
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/38; H04B1/40; H04B1/54; H04B1/56; H04M; H04M1/00; H04M1/72; H04M1/725; H04M1/72502; H04M1/72505; H04M1/72511
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
111 words
A duplex speech transmission method wherein a limited bandwidth transmission channel is divided into time slots, alternate time slots being available for each of the two parties to call in, segments of speech are digitised and stored at a higher mean bit rate if only one party is speaking at any instant, said higher mean bit rate digitised speech being transmitted within the duration of two successive time slots, and wherein segments of speech are digitised and stored at a lower mean bit rate if both parties are speaking, packets of the digitised speech from both parties being time-compressed and being applied to the transmission channel during respective alternate time slots.
Claim 2
Dependent Claim
111 words
A duplex speech transmission method wherein a limited bandwidth transmission channel is divided into time slots, alternate time slots being available for each of the two parties to call in, segments of speech are digitised and stored at a higher mean bit rate if only one party is speaking at any instant, said higher mean bit rate digitised speech being transmitted within the duration of two successive time slots, and wherein segments of speech are digitised and stored at a lower mean bit rate if both parties are speaking, packets of the digitised speech from both parties being time-compressed and being applied to the transmission channel during respective alternate time slots.
Claim 3
Dependent Claim
61 words
A method as claimed in Claim 1 wherein the speech signal from each party is divided into segments and each party signals to the other party whether speech is to be sent in the timeslot associated with its segment and the mean bit rate for digitising and storing the speech in that segment is determined in response to the signal received.
Claim 4
Dependent Claim
20 words
A method as claimed in claim 1 or 2, wherein each segment and its associated time slot terminate substantially simultaneously.
Claim 5
Dependent Claim
179 words
A-duplex speech transmission method wherein a limited bandwidth transmission channel is divided in a plurality of successive time slots, alternate time slots being available for each of two parties to call in; speech signals from either of the parties are divided into time segments with the time segments associated with one of said two parties being offset in time with the time segments associated with the other of said two parties; segments of speech when present are digitised and stored, a higher rate of quantisation being used when speech is present in the segments of one party and not those of the other party, said higher rate quantised signal being transmitted in the other party's time slot and the immediately following time slot of said one party, and a lower rate of quantisation being used if both parties have speech in their respective segments, the lower rate quantised signals being time compressed and transmitted in their associated time slots, and wherein the end of a segment coincides substantially with the end of the time slot associated with said segment.
Claim 6
Dependent Claim
179 words
A-duplex speech transmission method wherein a limited bandwidth transmission channel is divided in a plurality of successive time slots, alternate time slots being available for each of two parties to call in; speech signals from either of the parties are divided into time segments with the time segments associated with one of said two parties being offset in time with the time segments associated with the other of said two parties; segments of speech when present are digitised and stored, a higher rate of quantisation being used when speech is present in the segments of one party and not those of the other party, said higher rate quantised signal being transmitted in the other party's time slot and the immediately following time slot of said one party, and a lower rate of quantisation being used if both parties have speech in their respective segments, the lower rate quantised signals being time compressed and transmitted in their associated time slots, and wherein the end of a segment coincides substantially with the end of the time slot associated with said segment.
Claim 7
Dependent Claim
190 words
A duplex communication system for use on a limited bandwidth transmission channel divided into a succession of time slots, alternate time slots being allocated to each of two parties for transmission, wherein each party has an apparatus comprising means for detecting if speech is to be transmitted by that apparatus in a time slot allocated to said apparatus and for signalling accordingly to the other apparatus, means for digitising and storing a segment of speech, means for determining if the other party has signalled that it has a segment of speech to transmit in its time slot and in response to determining that only one of the apparatus wants to transmit to control the digitising means to digitise its segment of speech at a higher means bit rate and to transmit it in two successive timeslots, and in response to determining that both parties have speech for simultaneous transmission to control the digitising means the segments of speech at a lower mean bit rate, and means for time-compressing the speech digitised at the lower mean bit rate and transmitting the said digitised signal in packets in their respective time slots.
Claim 8
Dependent Claim
190 words
A duplex communication system for use on a limited bandwidth transmission channel divided into a succession of time slots, alternate time slots being allocated to each of two parties for transmission, wherein each party has an apparatus comprising means for detecting if speech is to be transmitted by that apparatus in a time slot allocated to said apparatus and for signalling accordingly to the other apparatus, means for digitising and storing a segment of speech, means for determining if the other party has signalled that it has a segment of speech to transmit in its time slot and in response to determining that only one of the apparatus wants to transmit to control the digitising means to digitise its segment of speech at a higher means bit rate and to transmit it in two successive timeslots, and in response to determining that both parties have speech for simultaneous transmission to control the digitising means the segments of speech at a lower mean bit rate, and means for time-compressing the speech digitised at the lower mean bit rate and transmitting the said digitised signal in packets in their respective time slots.
Claim 9
Dependent Claim
14 words
A system as claimed in Claim 5, wherein each apparatus includes a speech detector.
Claim 10
Dependent Claim
21 words
A system as claimed in Claim 5 or 6, wherein each apparatus comprises an adaptive delta modulator for digitising the speech.
Claim 11
Dependent Claim
21 words
A system as claimed in Claim 5 or 6, wherein each apparatus comprises an adaptive differential PCM for digitising the speech.
Claim 12
Dependent Claim
19 words
A cordless telephone system including the duplex communication system as claimed in any one of Claims 5 to 8.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.