JPH0685696A - Radio transmitter - Google Patents

Abstract

PURPOSE:To respond to respective working state by automatically changing a transmission level or transmission signal characteristic when a radio transmitter is used indoors or outdoors in the radio transmitter capable of using selectively a commercial AC power source or a DC power source. CONSTITUTION:It is detected whether a connected current is the one of the commercial power source or the DC power source by a detecting part 4, and it is judged that the transmitter is used indoors when it is the commercial power source, and that it is used outdoors when it is the DC power source. The level or frequency characteristic of a transmission signal is automatically switched by a transmission circuit control circuit 7 corresponding to detecting output, then, it is introduced to an antenna 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmitter which can be selectively used with a commercial power source and a battery as power sources, and more particularly, to automatically change the characteristics of radio output according to the selection of the power source. With the configuration, the video signal and the audio signal are wirelessly output so that the video and the audio can be viewed by using another wireless receiver on a portable television, a VTR integrated television and the like. It is effective when applied to those with functions.

[0002]

2. Description of the Related Art Conventionally, there are portable small televisions and the like which have a function of wirelessly outputting their audio signals, and when used in a vehicle, a radio receiver attached to the vehicle is used. By outputting the audio signal to a speaker of a car and using it indoors to output it to the speaker by using a radio receiver such as a stereo device, so that it can be enjoyed at a higher volume. Has become.

[0003]

In the above-mentioned conventional portable television, etc., if the transmission output is too large when used indoors, there is a risk of interfering with other radio equipment or causing reception interference. Moreover, it is necessary to limit the transmission power to a certain level or less. However, the transmission output suitable for indoor use may not be sufficient for reception by an antenna outside the vehicle when used in an automobile, and noise may increase and sensitivity may drop. Further, since the frequency characteristic of voice transmission is constant, there is a problem that diversity buzz is conspicuous when a diversity antenna is used.

The present invention solves the above-mentioned problems of the prior art, and when the battery or the like of a car while being carried is used as a power source, the transmission output is automatically increased or the frequency characteristic is changed so that it can be used in the car. This is to enable good reception.

[0005]

In order to solve the above-mentioned problems, a radio transmitting apparatus according to the present invention is a radio transmitting apparatus in which a commercial AC power source and a DC power source can be selectively used as power sources. And depending on the choice of DC power supply
It is characterized in that the wireless transmission output of the wireless transmission device is automatically increased when a DC power source is selected as compared with when a commercial power source is used.

[0006]

When used outdoors for portable use, even if the transmission output is increased to some extent, it has less influence on other wireless receiving devices than when used indoors. Therefore, in the above configuration, when the device is driven by a DC power source such as a car battery or battery, it is determined that the device is used outdoors for portable use, and transmission is automatically switched to a large transmission output. By doing so, the wireless receiver can receive with high sensitivity. When the power source is a commercial power source for home use, it is determined that the power source is used indoors, and transmission is performed at a low output with the transmission output attenuated below a certain standard.

[0007]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a block diagram showing the essential parts of a radio receiving apparatus according to the present invention, which is, for example, a VTR-integrated television capable of wirelessly outputting an audio signal. In the figure, reference numeral 1 denotes a household AC100V commercial power source out of two types of power sources that can be used by the wireless transmission device, and reference numeral 2 denotes a DC 12 (or 24) V DC power source such as a battery for an automobile. Reference numeral 3 denotes a power supply unit that supplies the two types of power supplies described above to the wireless transmission apparatus. Reference numeral 4 denotes a detector, which detects which input the power supply unit 3 is operating by, for example, determining whether the voltage inside the circuit passes through a rectifying circuit that performs conversion from AC to DC. .

Reference numeral 5 denotes a voice input to be wirelessly output, and reference numeral 6 denotes a transmitter that FM-modulates the voice input 5 and outputs it at a constant carrier level. A transmission output control circuit 7 controls the magnitude of the transmission output from the transmitter 6 to the antenna 8 according to the output of the detector 4.

The operation of the radio transmitting apparatus having the above-mentioned configuration when it is used for portable use and when it is not used will be described. First, when the AC 100V power supply 1 is supplied as the input power supply to the power supply unit 3, the power supply unit 3 supplies the AC 100V power supply 1 as a power supply voltage to the wireless device. The detector 4 detects this and determines that it is used indoors or the like, not as being portable. At this time, a control voltage is transmitted from the power supply unit 3 to the transmission output control circuit 7 through the detector 4, so that the output from the antenna 8 does not interfere with other wireless devices or give reception interference so that the transmitter 6 can be controlled. The transmission power of is attenuated to a low power type limited to a certain level or less.

Next, when there is no input of the AC100V power source 1 and the input to the power source section 3 is a DC voltage, the detector 4 detects it and it is used as a portable device in the interior of an automobile or the like. to decide. At this time, the control voltage is not transmitted from the detector 3 and is transmitted to the antenna 8 in a high output form which can be received by the wireless receiver provided in the automobile with sufficient sensitivity and is transmitted with a large output.

In the above embodiment, the transmission output control is described as an example. However, if the control target is the frequency characteristic of the audio signal, the sound quality when it is used as a portable device and when it is not used is changed, and it is used in the vehicle. It can sometimes be used as a method for reducing diversity buzz. In addition, if applied to a method of controlling the brightness of a video signal, the brightness of a TV screen when used as a portable device can be made higher than that indoors to obtain a bright and easy-to-view screen outdoors.

[0013]

As described above, according to the wireless transmission device of the present invention, the output of the characteristic in which the wireless output is based on the indoor use and the output of the characteristic in consideration of the outdoor use in the automobile or the like are provided. In addition, since it automatically switches according to the type of power supplied, it can reduce interference and reception interference when used indoors, and other wireless receivers have high sensitivity when used outdoors. As well as being able to receive
It can be applied to voices with little buzz and bright and easy-to-see screens.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a wireless transmission device according to an embodiment of the present invention.

[Explanation of symbols]

 1 AC100V power supply 2 DC12 / 24V power supply 3 Power supply section 4 Detection section 5 Voice input 6 Transmitter 7 Transmission output control circuit 8 Antenna

Claims (2)

[Claims] 1. A wireless transmitter that selectively uses a commercial AC power source and a DC power source as power sources, and a wireless transmission output of the wireless transmitter device is selected according to the selection of the commercial AC power source and the DC power source. The wireless transmission device is characterized in that it automatically increases when a DC power source is selected compared to when a commercial power source is used. 2. A wireless transmission device that selectively uses a commercial AC power supply and a DC power supply as power supplies, and the characteristics of the wireless transmission output of the wireless device according to the selection of the commercial AC power supply and the DC power supply. A wireless transmission device characterized by changing the.