GB2137454A - Handsfree telephone system - Google Patents
Handsfree telephone system Download PDFInfo
- Publication number
- GB2137454A GB2137454A GB08305573A GB8305573A GB2137454A GB 2137454 A GB2137454 A GB 2137454A GB 08305573 A GB08305573 A GB 08305573A GB 8305573 A GB8305573 A GB 8305573A GB 2137454 A GB2137454 A GB 2137454A
- Authority
- GB
- United Kingdom
- Prior art keywords
- handsfree
- facility
- control
- call
- lines
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M9/00—Arrangements for interconnection not involving centralised switching
- H04M9/08—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
- H04M9/085—Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic using digital techniques
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0407—Selecting arrangements for multiplex systems for time-division multiplexing using a stored programme control
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Sub-Exchange Stations And Push- Button Telephones (AREA)
- Interconnected Communication Systems, Intercoms, And Interphones (AREA)
- Telephonic Communication Services (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Interface Circuits In Exchanges (AREA)
Description
SPECIFICATION
Handsfree telephone system
This invention relates to automatic telephone exchange systems, especially to such systems for use as PABXs.
In such a system, a number oftelephones are interconnected via a common switching network via which connections between those telephones are set up. Some of the telephones in such a system, especially when it is a PABX have handsfree facilities, i.e.
the subscriber's instrument has a microphone and a loudspeaker with an access button (or switch). When such a button is operated the instrument is converted from its normal handset use to the handsfree condition. When in this condition it is usual to provide a gain control circuit in each of the telephones which adjusts the gain for both incoming and for outgoing calls in such a way as to preventthe acoustic feedback and sidetone signals from generating a feedback oscillation in the system. Such an oscillation manifests itself as a rather vexatious howling noise.
An object of the invention is to provide a system in which the handsfree facility is provided in a relatively economical manner.
According to the invention, there is provided an
automatic telephone exchange system, which
includes a number of telephone subscribers' lines
connected to a switching network via which com
munication connections are set up, wherein the lines
include lines having the handsfree facility available, wherein the provision of the handsfree facility for a
call involves the control of the gain provided for the
lines involved in that call, wherein the switching net
work is centrally controlled, and wherein the handsfree control circuitry', which includes the circuitry for
providing the said gain control in respect of calls for which the handsfree facility is provided is centrally
located so that when it is free it is available for use for
any call for which the handsfree facility is required.
Such a system is especially suited for use in a sys
tem in which the control of the handsfree facility is
effected using microprocessor-controlled digital
hardware. Since the gain control circuitry is central
ised a considerable economy is effected since the
handsfree facility is unlikelyto be needed by all users
at the same time.
Embodiments of the invention will now be
described with reference to the accompanying draw
ings, in which:
Figure 1 is a highly schematic block diagram of a
fully digital telephone system embodying the invention.
Figure 2 is a highly schematic block diagram in
somewhat more detail of a system such as that of
Figure 1 with one central handsfree facility control.
Figure 3 is a diagram similarto Figure 2 for a system
similar to that of Figure 2 but with two centralised
handsfree facility controls.
Figure 1 shows a digital switching network 1 which
serves a number of telephone subscriber's instru
ments, some of which, such as 2, 3, have access to the
handsfree facility. Each such instrument has a mic
rophone and a loudspeaker in addition to the hand
r set, and a push button which is operated when access to the handsfree facility is wanted. Each such instru
ment also has an indicator, such as a small neon lamp or a light-emitting diode, which by its condition tells the user whether the handsfree facility is available.
As already mentioned, when the handsfree facility is used, the enablement of the appropriate channel, transmit or receive, is effected by controlling the gain in those channels. In the arrangement described herein this uses a centralised handsfree gain control circuit 4 which is seized for use for a call when the handsfree facility is needed. Thus the need for separate gain control arrangements at all subscriber's instruments with access to the facility is obviated.
As will be seen from Figure 2, the digital switching network includes a multi-register unit in which each telephone line is allotted an individual address. The digital codes of each speech channel are written into their respective register addresses. Based on signalling information from two lines A and B to be con nected,the PCM code B is then transferred to channel
A and the code A is transferred to channel B under control of the DSN control network 5.
Handsfreefacilityto allow one such call, which may be adequate for a relatively small system, is implemented by the addition of four such memory registers. As will be seen, these registers are for the
A-B transmit, B-A transmit, A from B receive and B from A receive. The use of these registers is controlled by the DSN control 5 such that the call is transferred from the registers used for it to the four registers for handsfree operation. These four registers are controlied by the handsfree control facility circuit 4.
In the arrangement of Figure 2, callerA has "dialled station B and has also requested the handsfree facility. The digital codes from stations A and B, A-Tx and
B-Tx, are therefore diverted to the special addresses in the RAM included in the switching network. These codes are then processed by the handsfree control facility 4 and transferred therefrom to the registers
B-Rx and A-Rx. This processing includes the gain adjustment referred to above. Thus the four registers take the place of the original memory locations A and
B originally in use for the call, and their contents are processed in the normal way.
Figure 3 shows a system with two handsfree facility circuits, although more than two such circuits may be provided. In view ofthe foregoing description it is felt that Figure 3 does not need any detailed description.
1. An automatic telephone exchange system, which includes a number of telephone subscribers' lines connected to a switching network via which communication connections are set up, wherein the lines include lines having the handsfree facility available, wherein the provision of the handsfree facility for a call involves the control of the gain provided for the lines involved in that call, wherein the switching network is centrally controlled, and wherein the handsfree control circuitry, which includes the circuitry for providing the said gain control in respect of calls for which the handsfree facility is provided is centrally-located so that when it is free it is available
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (6)
1. An automatic telephone exchange system, which includes a number of telephone subscribers' lines connected to a switching network via which communication connections are set up, wherein the lines include lines having the handsfree facility available, wherein the provision of the handsfree facility for a call involves the control of the gain provided for the lines involved in that call, wherein the switching network is centrally controlled, and wherein the handsfree control circuitry, which includes the circuitry for providing the said gain control in respect of calls for which the handsfree facility is provided is centrally-located so that when it is free it is available for use for any call for which the handsfree facility is required.
2. A system as claimed in claim 1, wherein the switching network is a digital network which is under the control of digital processing means, and wherein the speech to be conveyed is dealt with in a digital form.
3. A system as claimed in claim 2, wherein the digital network includes a random access memory which provides a number of registers each of which is allocated to one of the lines served, wherein when a call is set up in respect of one said lines that line's one of said registers is used, wherein the random access memory also includes further registers for use for the handsfree facility which are taken into use in place of those allocated to a pair of lines when those lines need the handsfree facility, and wherein the further registers give access to the gain control circuitry.
4. A system as claimed in claim 3, wherein two or more handsfree facility control circuits are provided, each of which is served by a set of said further registers.
5. An automatic telephone exchange system, substantially as described with reference to Figure 1,
Figure 2 or Figure 3 of the accompanying drawing.
New or amended claims:
6. An automatic telephone exchange system, which includes a number of telephone subscribers' lines connected to a switching network via which communication connections are set up, wherein the lines include lines having the handsfree facility available, wherein the provision of the hands free facility for a call involves the control of the gain provided for the lines involved in that call, and wherein the handsfree control circuitry, which includes the circuitry for providing the said gain control in respect of calls for which the handsfree facility is provided, is centrallylocated so that when it is free it is available for use for any call for which the handsfree facility is required.
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08305573A GB2137454A (en) | 1983-03-01 | 1983-03-01 | Handsfree telephone system |
AU25055/84A AU2505584A (en) | 1983-03-01 | 1984-02-27 | Handsfree telephone system |
EP84102044A EP0120324A3 (en) | 1983-03-01 | 1984-02-28 | Circuit arrangement for an automatic telephone exchange with "hands free" phones facility |
BE2/60355A BE899041A (en) | 1983-03-01 | 1984-03-01 | LOUDSPEAKER TELEPHONE SYSTEM |
ES530193A ES530193A0 (en) | 1983-03-01 | 1984-03-01 | AN AUTOMATIC TELEPHONE SYSTEM WITH HANDS FREE POSSIBILITY |
JP3969884A JPS59210760A (en) | 1983-03-01 | 1984-03-01 | Hand-free telephone system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08305573A GB2137454A (en) | 1983-03-01 | 1983-03-01 | Handsfree telephone system |
Publications (3)
Publication Number | Publication Date |
---|---|
GB2137454B GB2137454B (en) | |
GB8305573D0 GB8305573D0 (en) | 1983-03-30 |
GB2137454A true GB2137454A (en) | 1984-10-03 |
Family
ID=10538763
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB08305573A Withdrawn GB2137454A (en) | 1983-03-01 | 1983-03-01 | Handsfree telephone system |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0120324A3 (en) |
JP (1) | JPS59210760A (en) |
AU (1) | AU2505584A (en) |
BE (1) | BE899041A (en) |
ES (1) | ES530193A0 (en) |
GB (1) | GB2137454A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3606516C1 (en) * | 1986-02-28 | 1987-06-19 | Telefonbau & Normalzeit Gmbh | Circuit arrangement for hands-free and loudspeaker devices in telephone sets |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NO134477C (en) * | 1974-10-29 | 1976-10-13 | Manus Max | |
JPS549511A (en) * | 1977-06-24 | 1979-01-24 | Fujitsu Ltd | Digital gain control system using read only memory |
US4329543A (en) * | 1979-09-06 | 1982-05-11 | Southwest Utilities, Inc. | Communication system |
JPS5932943B2 (en) * | 1979-10-17 | 1984-08-11 | 富士通株式会社 | Signal control method |
JPS5657376A (en) * | 1979-10-17 | 1981-05-19 | Fujitsu Ltd | Control system for digital transmission loss insertion |
GB2137049B (en) * | 1983-03-15 | 1986-05-14 | Standard Telephones Cables Ltd | Handsfree telephone |
-
1983
- 1983-03-01 GB GB08305573A patent/GB2137454A/en not_active Withdrawn
-
1984
- 1984-02-27 AU AU25055/84A patent/AU2505584A/en not_active Abandoned
- 1984-02-28 EP EP84102044A patent/EP0120324A3/en not_active Withdrawn
- 1984-03-01 JP JP3969884A patent/JPS59210760A/en active Pending
- 1984-03-01 ES ES530193A patent/ES530193A0/en active Granted
- 1984-03-01 BE BE2/60355A patent/BE899041A/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
EP0120324A3 (en) | 1986-12-03 |
EP0120324A2 (en) | 1984-10-03 |
GB2137454B (en) | |
ES8503906A1 (en) | 1985-03-16 |
ES530193A0 (en) | 1985-03-16 |
JPS59210760A (en) | 1984-11-29 |
BE899041A (en) | 1984-09-03 |
AU2505584A (en) | 1984-09-06 |
GB8305573D0 (en) | 1983-03-30 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |