GB2213336A - RDS radio receiver with display of alternate frequencies - Google Patents

Abstract

A radio receiver comprises a broadcast signal tuning section 14 which is operable over at least two frequency bands. A data decoding means 22 is coupled to the broadcast signal tuning section 14 to decode received data signals transmitted with a received audio radio signal, the radio signal being broadcast within a first frequency band, eg. the medium waveband. The data signals comprise data relating to radio signals within the first frequency band and data relating to radio signals within the or each other frequency band, eg the long waveband. Connected to the output of the data decoding means 22 is a means 24 for storing the received data signals relating to signals within the other frequency bands. Means 26 are provided for displaying at least part of the stored data relating to a selected radio signal. <IMAGE>

Description

IMPROVEMENTS IN RADIO RECEIVERS This invention relates to radio receivers for receiving broadcast audio signals.

The Radio Data System (RDS) permits a broadcaster to send data on the same transmissions as his programmes. The system has been described in "Specifications of the Radio Data System RDS for VHF/FM Sound Broadcasting" published by the European Broadcasting Union Technical Centre Brussells, publication Tech. 3244-E, March 1984.

In the system, inaudible data signals are broadcast with the radio signals. The signals may be decoded by a suitably equipped receiver and may also aid automatic tuning of a selected station. Such a VHF/Fn5 receiver is described in our British patent application no.

8521545.

The radio receiver in the above application describes a receiver which will display data about the available signals on a touch sensitive display and will automatically tune into a selected station in response to touching of the display.

RDS only operates on VHF transmissions, and with the increased use of the VHF band is an extremely important aid to the listener when selecting a station to tune into. Typically, RDS receivers will show information about the name of the selected station (Programme Service (PS) name) and the frequency of that station.

There is no equivalent data system in the Medium frequency (MF) and Low frequency (LF) bands. These two bands are even more crowded, and it is difficult to accommodate any data at these frequencies.

The invention is defined in the appended claims to which reference should now be made.

The invention will now be described in more detail by way of example, with reference to the sole figure which shows a radio receiver embodying the invention and additionally musing a touch sensitive display to provide signals to control the receiver.

A broadcaster provides RDS data on his VHF service via the RDS transparent data channel. In addition to the information associated with the VHF radio signals, information about radio signals such as the PS names in the MF and LF bands can also be provided in the RDS signal via the transparent data channel. For example, BBC Bedfordshire is available on 95.5MHz and 103.8MHz in the VHF band and on 630kHz and 116lkHz in the MF band. Therefore, the RDS transmissions from BBC Bedfordshire on 95.5MHz and 103.8MHz would both carry information about the MF transmissions, typically in the form: 630 = BBC Beds and 1161 = BBC Beds or some other form suitable for use with RDS receivers.The RDS transmissions may also contain information about the alternative VHF frequency of BBC Bedfordshire and also about other available stations in the VHF, MF and LF bands.

The figure shows a typical RDS receiver which uses the invention. The radio signal and RDS signal are received via an antenna 12 and are selected by a broadcast tuning section 14 which is operable over at least two tuning bands, in this case the VHF, MF and LF bands. The output of the tuning section is fed through an audio amplifier 16 to a loudspeaker 18 in the conventional manner.

A data decoder 22 which decodes the received RDS data is also coupled to the output of the tuning section 14.

The output of this data decoder is connected in this embodiment to a control and storage microprocessor 24. The function of the microprocessor is to store the data relating to radio signals available in at least the MF and LF bands since RDS is not available in these bands. A display 26 shows the user the received RDS data when the receiver is receiving a signal in the VHF band, and shows the stored data when the receiver is operating in the MF or LF bands. In this example, the display 26 is touch sensitive and can be used to provide signals to the microprocessor 24 to automatically control the broadcast tuning section 14 as described in our British patent application no. 8621545.

Another problem with MF and LF reception is that the same frequencies are used for transmitting different radio stations in different parts of the country. For example, in the MF band 630KHz and 1161KHz are used for BBC Bedfordshire and are also used at Redruth and Bexhill. The different locations are chosen to be as far as possible mutually exclusively receivable. The same applies to the VHF band. However, a receiver could tune to a VHF station far away and receive RDS information about MF and LF stations which are unlikely to be adequately received at that location. Therefore, to overcome this problem, a signal strength check could be carried out to determine whether or not the RDS data was to be stored or not.Thus the receiver will only store information about a limited geographical area of MF and LF transmissions when acquiring RDS data over the VHF band.

The above strength check could be carried out by a signal strength detector 28 coupled to the output of the tuning section 14.

This would provide signals to prevent the received RDS data being stored by the microprocessor 24 when the signal strength drops below a predetermined level. This could be done by disabling the microprocessor from storing data which is not relevant at that location. The tuner in the receiver illustrated in the figure takes the form of a microprocessor-controlled synthesiser tuner and it will tune exactly to the relevant MF or LF transmission by manual tuning or by selecting MF or LF frequencies provided to the receiver when tuned to a VHF RDS station which provides alternative frequencies directly or within other Networks information. A "lookup" process can then be used to compare the data in memory with the tuning frequency and if an exact match of frequency occurs the stored PS name can be used to display the station name.

There is of course some ambiguity with MF and LF transmissions and it is therefore advantageous for an RDS receiver tuned to MF or LF to display both the PS name and the frequency.

The display 26 could also be made to change colour when an MF or LF signal is being received. This would indicate to the user that the PS name displayed is one stored in the microprocessor 24 and not one being received directly.

The above description is one example only of a embodiment of the invention and many other possible embodiments exist. For example, the tuner section 14 need not be controlled by the microprocessor 24 and could be manually operated. The display 26 in that case could be an LCD display of, for instance, 8 digits to display either the PS name or the frequency. Other variations and modifications are possible.

Claims (7)

1. A radio receiver comprising a broadcast signal tuning section operable over at least two frequency bands, data decoding means coupled to the broadcast signal tuning section to decode received data signals transmitted with a received audio radio signal, the radio signal being broadcast within a first frequency band, the data signals comprising data relating to radio signals within the first frequency band and data relating to radio signals within the or each other frequency band, means connected to the output of the data decoding means for storing the received data relating to signals within the other frequency band(s) and means for displaying at least a part of the stored data relating to a selected radio signal.

2. A radio receiver according to claim 1, including control means coupled to the storage means and the broadcast signal tuning section and responsive to the stored data 0 automatically control the tuning section in accordance with the selected radio signal.

3. A radio receiver according to claim 1 or 2, in which the data signals relating to the first frequency band are also stored in the storage means.

4. A radio receiver according to claims 1, 2 or 3, including means for testing the strength of a received radio signal in the first frequency band and for providing a signal relating to the said strength to determine whether or not the signal strength is above or below a pre-determined level.

5. A radio receiver according to any preceding claim, in which the display means displays both the name and the frequency of the selected radio signal when the receiver is operating in the or each other frequency band.

6. A radio receiver according to any preceding claim, in which the display means changes colour when the receiver is receiving a radio signal in the or each other frequency band.

7. A radio receiver substantially as herein described with reference to the drawing.