GB2244402A

GB2244402A - A twin-tuner radio receiver

Info

Publication number: GB2244402A
Application number: GB9107298A
Authority: GB
Inventors: Tadashi Kosuga; Koichi Kasa; Kazuhiko Mogi; Yoshiharu Ueki; Shinobu Kawarada
Original assignee: Pioneer Electronic Corp
Current assignee: Pioneer Corp
Priority date: 1990-04-12
Filing date: 1991-04-08
Publication date: 1991-11-27
Also published as: DE4111698A1; GB9107298D0; JPH03293823A

Abstract

A twin-tuner type radio receiver which incorporates two receiver systems. Even when a tuning operation is being executed, the user is able to continue to receive information without waiting period. As shown in Figure 1, the radio receiver comprises at least two radio receivers (TUN1, TUN2), for receiving an RF signal and producing a demodulated voice signal; an output selection circuit (33) for selecting the demodulated voice signal from either of the receivers; and a control circuit (36) for issuing a first command signal to one of the receivers that is not selected by the output selection circuit to cause that receiver to start a tuning operation. the control circuit also issuing a second command signal to the output selection circuit to switch from the demodulated voice signal of the other receiver that is selected by the output selection circuit to that of the receiver that is not selected by the output selection circuit. A best station memory (BSM) function is provided. <IMAGE>

Description

A RADIO RECEIVER The present invention relates to a twin-tuner type radio

receiver which incorporates two receiver systems.

There is a growing demand for enhanced reception quality of demodulated signals in radio receivers. To meet this demand a variety of proposals have been made.

For example, one proposed function automatically selects broadcasting stations in a region which have strong field intensities, writes into a preset memory several of these stations in the order of field strength, and allows the stored stations to be tuned in by the operation of a preset button.

This function is generally called a Best Station Memory -ion, which typically performs the following (BSM) funct control: scanning the reception band from the low end to the upper end to pick up and store reception frequencies whose field strength is higher than a specified value; and presetting the stored frequencies to specified preset buttons in the order of field strength.

One example of the radio receiver with such a function is shown in Figure 3.

In the figure, reference numeral 1 represents a reception antenna. An RF signal received by the antenna 1 i i i i is amplified by an RF amplifier 2 and fed to a mixer 3. The mixer 3 is supplied with a local signal from a local signal oscillator 4, which comp:rises a PLL circuit. The received signal is converted into an intermediate frequency signal by the mixer 3.

The intermediate frequency signal produced by the mixer 3 is selectively amplified by an intermediate frequency amplifier 5 and then demodulated by a detector 6, which is connected to the outDut of the intermediate frequency -ector 6 is amplifier 5. The demodulated output from the dell. further demodulated by a multiplexer 7 to produce a stereo signal, which is supplied through a muting circuit 8 to power amplifiers 9L, 9R, which amplify left and right voice signals.

The demodulated voice signals amplified by the power amplifiers 9L, 9R are reproduced as sound by speakers 1OL, 1OR.

An output from the intermediate frequency amplifier 5 representing the level of the intermediate frequency signal, i.e. an output representing the reception field intensity, is applied to a central processing unit 11 made up of microprocessor.

Connected to the central processing unit 11 are a keyboard 12 from which a desired reception frequency is entered, a display 13 that displays the received frequency, and the local signal oscillator 4 formed of a PLL circuit.

In the above configuration, when the aforementloned BSM function is activated during reception, the central processing unit 11 sends a mute control signal to the muting circuit 8 to interrupt the demodulated output from the multiplexer 7. Immediately after this. the central processing unit 11 sends a command signal to the local signal oscillator 4 to scan the reception frequencies from the low end to the high end of the reception band. According to this command, the receiver performs the scanning and tuning operation on the received frequencies.

At this time, the level signal is produced by the intermediate frequency amplifier 5 and is applied to the central processing unit 11, which, when the level signal is higher than a specified value, stores that level value and the corresponding reception frequency.

With the scanning and tuning operation from the low end to the high end of the reception band completed, the central processing unit 11 presets the stored reception frequencies to specified preset buttons in the order of reception level, sends a control signal to the local signal oscillator 4 to tune in to a frequency with the maximum reception level, and then sends a control signal to the muting circuit 8 to reset the muting operation.

As a result, the receiver receives and reproduces a broadcasting radio signal with the highest reception level in the region.

Figures 4A and 4B show the relationship between the muting control and the reproduced output of the receiver mentioned above.

In the figure, denoted A is a muting control signal that the central processing unit 11 outputs to the muting circuit 8. Designated B is a demodulated voice output.

When for example the BSM function is activated, the muting is brought into action for the duration of xl, say about 10 seconds, during which time the scanning and tuning operation is performed from the low end to the high end of the reception band. During this period the voice signals are muted, as shown by the waveform of B. When the BSM operation is completed, the muting is reset and the broadcasting radio signal with the highest reception level in the region is received and reproduced, as indicated by a period yl. When one wants to choose a frequency other than the currently selected one by pressing a preset button, the muting is again activated until the selected frequency is tuned in for the duration of x2, during which time the voice signals are muted as shown by B. After the selected frequency is tuned in, the demodulated voice signals of the newly selected station are reproduced as shown by y2.

In the conventional receiver, when the BSM function is performed or when the preset recall is executed, the muting must be activated to suppress unwanted reproduction of noise.

During this waiting period, the user therefore receives no information from the radio receiver.

This invention has been accomplished to eliminate this drawback and its objective is to provide a radio receiver which, even when the BSM function or preset recall is being executed, continues to reproduce the demodulated voice output of a frequency that was being tuned in when the BSM function or the Dreset recall was started, thus eliminatina the muted condition as experienced with the conventional radio receivers.

To achieve the above objective, a radio receiver of this invention comprises: a first receiver for receiving an RP signal and producing a demodulated voice signal; a second receiver for receiving an RP signal and producing a demodulated voice signal; an output selection circuit for selecting the demodulated voice signal either from the first - for receiver or the second receiver; and a control circuit issuing a first command signal to one of the receivers that - to cause the is not selected by the output selection circuit receiver to start a tuning operation, said control circuit 4 also issuing a second command signal, after the first command signal, to the output selection circuit to switch from the demodulated voice signal of the other receiver that is selected by the output selection circuit to that of the receiver that is not selected by the output selection circuit.

With the radio receiver of the invention, when for examr)le a command to start the BSM function or the preset recall is issued while the demodulated voice signal from the first receiver is reproduced, these functions are executed by the second receiver. When the second receiver has successfully tuned in to a desired frequency, a switchover is done from the demodulated voice signal of the firs'. receiver to that of the second receiver.

-unction or the preset Therefore, even when the BSM f call is being executed, the demodulated voice output continues to be reproduced, eliminating the abovementioned muted waiting time.

By virture of the above function, the radio receiver of this invention is preferably used for automobiles, as an example.

In the accompanying drawings:

Figure 1 is a block diagram showing one embodiment of a radio receiver according to this invention; Figure 2 is a flowchart showing one example sequence of operation of the embodiment; Figure 3 is a block diagram showing a conventional radio receiver; and Figures 4A and 4B are a timing diagram showing the operation of the radio receiver of Figure 3.

One embodiment of this invention will be described by referring to the attached drawings.

Figure 1 shows one embodiment of the radio receiver according to the invention. In the figure, designated 20 is an antenna, from which an RF signal is applied to an RF amplifier 21 constituting a first receiver TUN1 and to an RF amplifier 22 constituting a second receiver TUN2. The RF signals amplified by the RF amplifiers 21, 22 are fed to mixers 23, 24.

The mixers 23, 24 are each connected with local signal oscillators 25, 26 which mix the received RF signals with local oscillated signals to produce intermediate frequency signals. The intermediate frequency signals are amplified by intermediate frequency amplifiers 27, 28 and then demodulated by detectors 29, 30. The demodulated outputs are then sent to multiplexers 31, 32.

The demodulated outputs fed to the multiplexers 31, 32 are separated into two-channel stereo signals L, R, which are applied to an electronic volume circuit 33.

Under normal condition, the electronic volume circuit 33 selects the stereo signals L, R either from the fIrst receiver TUN1 or the second receiver TUN2 and outputs the selected stereo signals L, R to the power amplifiers 34L, 34R. That is, the electronic volume circuit 33 alternately switches from the output of the first receiver TUN1 to the output of the second receiver TUN2 or vice versa, with a fade-in and fadeout action performed at time of switching.

The left and right stereo signals L, R from the electronic volume circuit 33 are amplified by the power amplifiers 34L, 34R and then reproduced by the speakers 35L, 35R.

The intermediate frequency amplifiers 27, 28 send a signal representing the level of the intermediate frequency signal, i.e. a signal representing the reception field intensity, to a central processing unit 36 consisting of a microprocessor.

The central processing unit 36 is connected with a keyboard 37 from which to enter a desired reception frequency and with a display 38 that shows the reception frequency.

The central processing unit 36 is also connected with PLL circuits 39, 40 that control the oscillated frequencies of the local signal oscillators 25, 26, so as to give a factor N to a programmable divider (not shown) of the PLL circuits 39, 40. Hence, the oscillated frequencies of the local signal oscillators 25, 26 are changed according to the value of N, changing the reception frequencies of the first receiver TUN1 and the second receiver TUN2.

In the above configuration, we will explain the sequence of operation when the BSM function is activated, by referring to the flowchart of Figure 2.

In Figure 2, when the first receiver TUN1 is tuned in to a station A and the demodulated voice output is being reproduced (step S1), it is checked whether any input is entered from the keyboard 37 (step S2).

When there is an input from the keyboard 37, it is then checked whether the input is a request for the BSM function (step S3). If the input is determined to be the BSM function request, a key acceptance sound is generated to indicate that the BSM function request is accepted (step S4).

Then the central processing unit 36 sends a signal to the PLL circuit 40 of the second receiver TUN2 that is not selected by the electronic volume circuit 33, which is an output selection circuit. The second receiver TUN2 scans the reception band and each time a specified output level is obtained from the intermediate frequency amplifier 28, the central processing unit 36 stores the corresponding reception frequency in memory (steD S5).

The scanning is performed from the low end to the upper end of the reception band (step S6).

When the scanning is completed (step S7), a plurality of reception frequencies stored in memory of the central processing unit 36 are sorted in the order of output level taken from the intermediate frequency amplifier 28 (step S8).

Then, the central processing unit 36 sends a signal to the PLL circuit 40 to tune in to a frequency with the highest output level. The second receiver TUN2 thus tunes in to a station B (step S9). Thenr a BSM operation completion sound is generated to indicate that the BSM function has been executed and completed (step S10).

With the above steps completed, the central processing unit 36 sends a control signal CTL to the electronic volume circuit 33, which is controlled to fade out the reproduced output from the first receiver TUN1 and fade in the reproduced output from the second receiver TUN2 (step S11).

As a result, a broadcasting signal from the station B which has the highest reception field intensity in the region is reproduced, and the program returns to the first step (S1).

When the BSM function is activated again thereafter, the similar process occurs with the first and second receivers TJUN1, TUN2 this time performing the roles of one another.

While in the above embodiment a sound is generated at step S4 and step S10 to annunciate the start and end of the BSM function, it is possible to flash a letter "BSW on the display at step S4 and turn it off at step S10.

In the above example, the electronic volume circuit is used as an output selection circuit to fade in and fade out the reproduced outputs. This circuit may be replaced with one which instantly switches the reproduced outputs.

While the above description takes as an example a radio receiver with a BSM function, this invention can also be used in applications for activating reset recall, reset scan or seek tuning functions.

As mentioned in the foregoing, the radio receiver of this invention incorporates at least first and second receivers. When a BSM function is activated, this function is carried out by one of the receivers which is not selected by the output selection circuit. When the BSM function has been executed and completed, the output selection circuit switches to the demodulated output of the receiver that has executed the BSM function. This eliminates the problem of a muted waiting time experienced with the conventional receivers during the BSM operation in which the demodulated voice output is interrupted.

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Claims

CLAIMS:

1. A radio receiver comprising: a first receiver for receiving an RF signal and producing a demodulated voice signal; a second receiver for receiving an RF signal and producing a demodulated voice signal; an output selection circuit for selecting the demodulated voice signal from one of the first receiver and the second receiver; and a control circuit for issuing a first command signal to the first receiver that is not selected by the output selection circuit to cause the first receiver to start a tuning operation, said control circuit also issuing a second command signal, after the first signal, to the output selection circuit to switch from the demodulated voice signal of the second receiver that is selected by the output selection circuit to that of the first receiver.

2. A radio receiver as claimed in claim 1, wherein said tuning operation includes a Best Station Circuit (BSM) function.

3. A radio receiver as claimed in claim 1, wherein said output selection circuit includes an electronic volume circuit to fade in and fade out reproduced outputs from speakers.

4. A radio receiver as claimed in claim 1, 2 or 3, wherein said radio receiver is used for automobiles.

Published 1991 at The Patent Office. Concept House. Cardiff Road. Newport. Gwent NP9 I RH. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwmfelinfach. Cross Keys. Newport, NP1 7HZ. Printed by Multiplex techniques ltd. St Mary Cray. Kent.