JPH0750853B2 - Receiver - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving device used in radios, televisions and the like.

2. Description of the Related Art In recent years, tracking adjustment in receiving devices has been moving toward automation using semiconductor technology.

An example of a conventional receiving device will be described below with reference to the drawings.

FIG. 2 is a block diagram of a conventional receiving device. In FIG. 2, 1 is an RF amplifier, 2 is a mixer, 3 is a digital control local oscillator, and 4 is a channel selector.

The tracking adjustment operation of the receiving apparatus configured as described above will be described below.

First, the oscillation output signal of the digital control local oscillator 3 is supplied to the mixer 2, while the analog control voltage is fed to the RF amplifier 1
Is supplied as a tuning control signal. Here, the tracking adjustment in the RF amplifier 1 is performed so as to obtain the maximum sensitivity by adjusting the coil or trimmer capacitor (both not shown) of the tuning circuit inside the RF amplifier 1.

Problems to be Solved by the Invention However, in the above-mentioned configuration, since the coil or the trimmer capacitor is a mechanical adjustment component, there is a problem that it cannot be automatically adjusted.

In view of the above problems, the present invention provides a receiving device that eliminates mechanical adjustment by a coil or a trimmer capacitor and can perform tracking adjustment utilizing semiconductor technology.

Means for Solving the Problems In order to solve the above problems, a receiver of the present invention is a frequency counter that counts the oscillation frequency of a local oscillator, an offset memory that uses the count output as addressing data, and its memory output. It is equipped with a D / A converter that converts data to analog voltage, and acts so that the memory output data of the offset memory is automatically selected according to the local oscillation frequency and the tuning frequency in the RF amplifier is set. It will be.

Action The present invention has the above-described configuration, the oscillation output frequency of the local oscillator is counted by the frequency counter, the offset information signal of the offset memory having the count output signal as the address signal is read, and this is converted into an analog voltage by the D / A converter. Converted and added with the control voltage of the local oscillator, and used as the tuning control voltage of the voltage controlled tuner installed in the RF amplifier, the RF tuning control is performed corresponding to the oscillation frequency of the local oscillator, thereby Optimal tracking adjustment is possible.

Embodiment A receiver according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a receiving apparatus according to an embodiment of the present invention. In FIG. 1, 5 is an RF amplifier,
6 is a mixer, 7 is a local oscillator, 8 is a frequency counter, 9
Is a digital signal converter, 10 is an offset memory, 11 is
D / A converter, 12 is an adder.

The operation of the receiving apparatus configured as above will be described.

In FIG. 1, the offset memory 10 stores tracking adjustment data in advance, and normally, all the tracking adjustment data corresponding to the reception channels are input. Then, in order to select the necessary one corresponding to the reception channel from the respective tracking adjustment data, the oscillation output signal of the local oscillator 7 is counted by the frequency counter 8, and the count output signal is designated in the offset memory 10. Used as data. Here, a digital signal converter 9 is installed to arbitrarily convert this addressing data.
Its installation is optional. On the other hand, the memory read output data of the offset memory 10 is input to the D / A converter 11 and converted into an analog voltage. Then, the analog voltage is superimposed on the control voltage of the local oscillator 7 by the adder 12 and supplied to a variable capacitance diode (not shown) in the tuning circuit of the RF amplifier 5. Here, the output voltage of the D / A converter 11 may be directly supplied to the RF amplifier 5, and the addition of the adder 12 is optional.

As described above, according to the present embodiment, in order to select the tracking adjustment data from the offset memory 10, the frequency counter 8 that counts the local oscillation frequency is provided, and the count output is used as the memory address data. Tracking adjustment setting can be performed without using a coil or a trimmer capacitor having a mechanically movable adjusting portion that has been used conventionally.

Needless to say, the local oscillator 7 used here may be a manual tuning type, a PLL synthesizer tuning type, or an open synthesizer tuning type.

As described above, according to the present invention, the frequency counter 8 that counts the local oscillation frequency, the offset memory 10 that stores the tracking adjustment data, the D / A converter 11, the digital signal converter 9, and the adder 12 are RF. Amplifier 5 and mixer 6
By providing a receiving circuit composed of the local oscillator 7 and the local oscillator 7, the tracking adjustment can be performed electronically. As a result, a stable tracking adjustment state can be maintained for a long time, and a high-performance receiving device can be realized. Furthermore, the same high-performance receiver can be realized for all circuit systems without depending on the circuit system of the local oscillator 7.

Since the local oscillation control voltage signal is used as a part of the tuning control voltage signal for the RF amplifier, it is possible to maintain tracking stability performance with respect to changes in ambient temperature with high accuracy. That is, when the PLL synthesizer system is used as the local oscillator, the oscillation control voltage signal is variably controlled to compensate for the temperature dependence of the oscillation frequency.
It also functions in the same direction as temperature compensation for the tuning frequency of the amplifier. As a result, it becomes possible to compensate the temperature dependence of the tracking performance.

Further, in terms of the number of tuning variable elements in the RF tuner, it is possible to share the main tuning variable element and the tracking correction variable element, so use only one tuning variable element per tuning circuit. Can be configured with. This makes it possible to reduce the size and cost of the receiver.

[Brief description of drawings]

FIG. 1 is a block diagram of a receiver according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional receiver. 5 ... RF amplifier, 6 ... Mixer, 7 ... Local oscillator, 8
...... Frequency counter, 9 ...... Digital signal converter, 10
...... Offset memory, 11 …… D / A converter, 12 ……
Adder.

Claims (1)

[Claims] 1. A local oscillator, an offset memory for storing an offset signal corresponding to a tracking error correction value, a D / A converter for converting a memory output of the offset memory into an analog voltage, and an oscillation control voltage for the local oscillator. And an analog voltage adder that adds the analog output voltage of the D / A converter, an RF amplifier that is tuned and controlled by the added output voltage of the analog voltage adder, an oscillation output signal of the local oscillator, and an amplification of the RF amplifier. A mixer for mixing the output signals, a frequency count for counting the frequency of the oscillation signal of the local oscillator, and a digital signal converter installed between the frequency count output section and the address input of the offset memory, Converting frequency count output to memory addressing signal in converter Therefore, a receiving device characterized by minimizing a tracking error.