GB2256346A

GB2256346A - Sub-carrier broadcast system

Info

Publication number: GB2256346A
Application number: GB9108468A
Authority: GB
Inventors: Ali Guryel
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-04-19
Filing date: 1991-04-19
Publication date: 1992-12-02
Anticipated expiration: 2011-04-19
Also published as: GB2256346B; GB9108468D0

Abstract

A broadcast system for transmitting receiving signals particularly suitable for FM radio, in which a sub-carrier carries auxiliary program me material such as background music for use as "music-on-hold" in a telephone PBX system, and data such as electronic advertising, news or the like. The data can be displayed to individual users on the telephone system, by means of displays incorporated in their telephone units or independent display units. Background music, similarly data can be utilised independent of telephone system for general background music and display means in various applications such as reception areas, bank/building society, public areas etc. The signals may include a code which must be decoded in the receiver and validated before proper reception is enabled.

Description

"Sub-Carrier Broadcast System" This invention relates to broadcasting systems, and in particular, to systems suitable for providing programmes of background music, and data channels, from a central source to users such as hotels, stores, and offices.

According to the invention there is provided an FM, AM or UHF broadcasting system in which the main programme material is carried conventionally on a main carrier, whilst a subsidiary programme is transmitted on a sub-carrier. The subsidiary programme may be background music and/or data which can be supplied to loudspeakers or coupled into the control unit of a telephone PBX system so as to provide a source of "music-on-hold".

The subsidiary programme material may be in analogue form or it may be encoded in a digital form, or may comprise superimposed analogue/digital signals. In accordance with a further development of the invention, there is provided a broadcasting system in which a plurality of data signals are interleaved in a "time division multiplex" fashion in the broadcast signal, with each signal including a code which must be decoded in the receiver and validated to enable the signal to be received. The invention also extends to a broadcast receiving system for auxiliary music, data or other programme material broadcast on a sub carrier of a main signal, including a decoding circuit adapted to extract the programme material from the sub-carrier.Preferably, means are provided for remotely enabling the decoding circuit from the transmission, so as to provide a "licensing" or "subscription" system whereby the programme material is inaccessible to unauthorised users.

According to a further feature of the invention the same decoding circuit may be used for retrieving various different services in accordance with a menu selection system, such as (a) retransmission of TELETEXT data (b) electronic advertising with NEWS (c) point-to-point Broadcasting service (d) Closed "Bulletin Board" In a preferred embodiment of the invention, there is provided an FM sub-carrier receiver system including means for decoding data and music signal carried on a subcarrier of an FM signal; authorisation means for enabling the reception by comparing a code in the data stream with a code programmed into the receiver; means for supplying the decoded data to a computer system; and means for applying the music signals to a telephone PBX system, for use a music-on-hold".

Preferably the telephone system also includes telephone sets with alphanumeric displays to which the data or selected parts of it, can be supplied for continuous display.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows the general layout of a transmitter system in accordance with the invention; Figure 2 is a corresponding receiver system; and Figure 3 is a more detailed plan of the transmitter system.

Referring to Figure 1, the transmitter 2 having a main channel input 4 to which a scheduled radio programme is supplied for transmission as entertainment (for example). A sub-carrier generator circuit 6 is additionally provided, whose input is connected to a summing circuit 8 which is supplied with a data signal 10 and a background music signal 12. Referring to Figure 3, the summing circuit may for example comprise a multiplexer 14 for converting a parallel data stream (16) to serial form and interleaving it with a since wave carrier (18) in a "time-division multiplex" fashion, before it is phase-modulated (20) and filtered (22) down to a suitable low frequency band.

The resulting signal is then "amplitude modulated" by applying a background music signal (24) to an AGC circuit (26) before applying both the modulated signal, and the background music signal, to a linear summing network, the audio output of which is in turn supplied to the transmitter (Figure 1).

Figure 2 shows an example of a receiver system in accordance with the invention. As shown the received signal is applied to a sub-carrier detector 30 whose output is applied to "decode authorisation" circuit 32. This may for example, be arranged to enable further transmission of the signal to the output, only if a proper code number has been entered by the user. The output from the decode authorisation circuit is applied to a "data receiver" 34 which is adapted to extract the data signal (by known demodulating techniques) from the signal, and the data stream may include a current value for the "decode authorisation number" which can be fed back (at 36) to the decode authorisation circuit 32. Thus the receiver can be shut down if it has not been properly "licensed" by the entry of the current code number.

The output of the "decode authorisation" circuit is also applied to an audio amplifier 38 whose output is coupled to a telephone PBX. The music signal can then be used as background music to callers place "on hold", for example by means of an extra relay with suitable coupling windings.

The data output of the data receiver may include material such as a newscast, teletext data, or electronic mail messages. These can be applied to a computer network 42 as shown in Figure 2, and additionally or alternatively, may be fed into the telephone PBX (as indicated at 44) for distribution around telephone receivers of the type which include alphanumeric data displays. In this way a continuous stream of "rolling messages" can be displayed on each individual telephone set whilst it is not actually being used to make a call.

Although the circuitry as shown as external to the "computer network" 42, it will be appreciated that the receiver/data decoding circuitry could be contained on a plug-in card adapted to fit in a computer chassis, for example an "EISA" card for a PC.

Claims

1. An FM, AM or UHF broadcasting system in which the main programme material is carried on a main carrier, and at least one programme of subsidiary material is carried on a sub-carrier.

2. A broadcasting system according to claim 1 in which the subsidiary programme material includes background music.

3. A broadcasting system according to claim 1 in which the subsidiary programme material includes data.

4. A broadcasting system according to claim 2 or claim 3 in which the subsidiary programme material is in encoded digital form.

5. A broadcasting system in which the broadcast includes a plurality of data signals interleaved in a time division multiplex form, and in which each signal includes a code which must be decoded in the receiver and validated before proper reception is enabled.

6. A receiving system for use with a broadcasting system according to any preceding claim, the receiving system caffipi-ising a decoding circuit adapted to extract programme material from a sub-carrier.

7. A broadcast receiving system according to claim 6 in which the decoding circuit is automatically enabled by means of a triggering signal in the broadcast material.

8. A broadcast receiving system according to claim 7 further comprising selection means whereby different services can be selected from a plurality of different subsidiary programmes.

9. A broadcast receiving system according to claim 6 or claim 7 further comprising means for supplying music signals extracted from the broadcast, to a telephone PBX system as a source of "music-on-hold".

10. An FM sub-carrier receiver system including means for decoding data and music signal carried on a subcarrier of Kb FM signal; authorisation means for enabling the reception by comparing a code in the data stream with a code programmed into the receiver; means for supplying the decoded data to a computer system; and means for applying the music signals to a telephone PBX system, for use as "music-on-hold".

11. A telephone PBX system including a receiver system according to claim 10.

12. A telephone PBX system according to claim 11 further comprising at least one telephone set incorporating a display for displaying the said data.

13. A system as claimed in claims 2 or 3 in which the background music or data can be utilised for general background music and display news in various applications such as reception areas and public areas of banks, offices and the like.