JP3063570B2 - Radio receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiver capable of switching between a first reception mode capable of demodulating only voice information and a second reception mode capable of demodulating both voice information and character information. It is.

[0002]

2. Description of the Related Art Generally, a radio receiver of an electronic tuning system having two receiving modes having different receiving systems, such as AM broadcasting and FM broadcasting, having different modulation systems on the transmitting side and different demodulating systems on the receiving side, generally has one mode. When one mode is operating, the other mode is not operating.

[0003] This is because the PLL circuit for tuning the receiver has only one system per receiver from the viewpoint of cost and practicality. That is, one circuit for supplying a varactor voltage for tuning according to the reception frequency is provided in the receiver and shared. In general, on the side using a receiver, when the required information is only audio output, the above-mentioned conventional method has no problem and is practical. That is, for example, when the receiver user tries to receive the AM broadcast, the audio output of the AM broadcast is required as information,
No broadcast audio output is required.

[0004]

However, when both audio information and text information are transmitted as information as in the case of FM multiplex broadcasting today, one receives the audio information of the AM broadcast and the other receives the audio information of the AM broadcast. There has been a demand for receiving text information of FM broadcasts, and conventional radio receivers could not cope with this.

[0005] Such a problem can be realized by providing two PLL circuits for tuning. However, there are problems such as a complicated circuit and a significant increase in the cost of the receiver.

An object of the present invention is to solve such a conventional problem and to provide an inexpensive and excellent radio receiver which can simultaneously obtain both voice information and text information in different reception modes. It is assumed that.

[0007]

According to the present invention, in order to achieve the above object, a varactor voltage for tuning is held on a second receiving mode side capable of obtaining both audio information and text information by multiplex broadcasting. A circuit is provided which is operated when audio information in the first reception mode is being obtained, so that character information in the second reception mode is also obtained at the same time.

[0008]

In the present invention, the character information in the second reception mode is simultaneously obtained when the audio information is obtained in the first reception mode, so that only one system is required for the tuning PLL circuit. An inexpensive radio receiver can be realized with the function.

[0009]

FIG. 1 shows the configuration of an embodiment of a radio receiver according to the present invention. In FIG. 1, reference numeral 1 denotes an AM tuner for the first reception mode, and 2 denotes an F tuner for the second reception mode.
M tuner section, 3 is an audio switching circuit, 4 is an audio output,
5 is PLL circuit, 6 is AM-OSC output, 7 is FM-O
SC output, 8 is a varactor voltage, 9 is a reception mode switching circuit, 10 is an FM multiplex decoder, 11 is a display, 12
Is a varactor voltage holding circuit.

Next, the operation of the above embodiment will be described.
The AM tuner unit 1 and the FM tuner unit 2 operate independently, and receive in synchronization with a desired broadcast signal. An audio signal is output from each of the tuners 1 and 2, and is output as an audio output 4 from a speaker or an earphone via an audio switching circuit 3. The PLL circuit 5 tunes to a desired signal in each reception mode so that each of the tuners 1 and 2 outputs A
A loop is formed in which the M-OSC output 6 and the FM-OSC output 7 are obtained, and the varactor voltage 8 is output so as to be tuned to a desired signal.

The reception mode switching circuit 9 switches the audio switching circuit 3 and the PLL circuit 5 for switching the reception mode according to a desired reception mode. That is, the audio switching circuit 3 does not transmit the audio output of the mode not desired to the subsequent stage. Also, the PLL circuit 5 does not accept the OSC output of the mode not desired, and
The LL circuit 5 is one system.

The FM multiplex decoder unit 10 obtains a composite signal from the FM tuner unit 2, demodulates the upper part of characters of the FM multiplex broadcast, and outputs character information to the display unit 11.

Next, the varactor voltage holding circuit 12 inserted between the PLL circuit 5 and the FM tuner unit 2 will be described. The varactor voltage holding circuit 12 is connected to the reception mode switching circuit 9 and performs the following operation according to the reception mode. That is, when receiving the FM mode, the operation becomes a through state and does not operate. When the AM mode is received, the operation is performed and a certain DC voltage output is transmitted to the FM tuner unit 2. In the FM tuner unit 2, the tuning D
Since the C voltage can be obtained, the FM multiplex decoder unit 1
0 demodulates the character information of the FM multiplex broadcast by obtaining a composite signal and outputs the character information to the display unit 11.

The varactor voltage holding circuit 12 is effective when it is desired to simultaneously obtain AM broadcast audio information from a state in which FM multiplex broadcast is being received. That is, in the initial state, tuning to the FM multiplex broadcast station A is performed, and the PLL circuit 5
When the varactor voltage 8 is obtained from the user, the user can simultaneously obtain the voice information and the text information of the FM broadcast. When receiving the AM broadcast station B from this state, the PLL circuit 5 sets the P to tune to an arbitrary AM broadcast station B.
The LL circuit 5 is operated to output the tuning varactor voltage 8 to the AM tuner unit 1 for tuning, and output the audio output of the AM broadcast.

Generally, the varactor voltage values of the broadcasting stations A and B are different, but the varactor voltage holding circuit 12 holds the varactor voltage value C in the initial state, and supplies this to the FM tuner unit 2. , FM tuner 2
Can output the composite signal to the FM multiplex decoder unit 10, demodulate the character information of the FM multiplex broadcast, and display the character information on the display unit 11, Can be output.

[0016]

According to the present invention, as is apparent from the above embodiment, a circuit capable of holding a tuning varactor voltage on the second receiving mode side capable of obtaining both audio information and text information by multiplex broadcasting. Since this circuit is operated when the voice information of the first reception mode is obtained, the character information of the second reception mode can be obtained at the same time.
Since voice information and character information in different reception modes can be obtained at the same time, and the receiver requires only one PLL circuit, a multifunctional and inexpensive radio receiver can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a radio receiver according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 AM tuner section 2 FM tuner section 3 Audio switching circuit 4 Audio output 5 PLL circuit 6 AM-OSC output 7 FM-OSC output 8 Varactor voltage 9 Reception mode switching circuit 10 FM multiplex decoder section 11 Display section 12 Varactor voltage holding circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/06-1/16

Claims (2)

(57) [Claims] 1. A first reception mode tuner section capable of demodulating only audio information, a second reception mode tuner section capable of demodulating both audio information and character information, and a desired signal in each of the reception modes. One PLL circuit for outputting a varactor voltage for tuning to each tuner unit, a varactor voltage holding circuit connected between the second receiving mode tuner unit and the PLL circuit, and a varactor voltage holding circuit A radio receiver comprising: a reception mode switching circuit that operates a circuit while obtaining audio information in the first reception mode to obtain character information in a second reception mode. 2. The radio receiver according to claim 1, wherein the first reception mode is an AM broadcast, and the second reception mode is an FM broadcast.