KR100374488B1 - Apparatus for preventing image interference in a receiver - Google Patents

Abstract

The present invention provides a radio frequency reception apparatus, in which an input frequency is completely different, but when an image frequency is introduced during a conversion of a frequency converter, another interference frequency in the required band of an intermediate frequency is eliminated. It relates to a possible receiving device.

In a conventional receiver, when an image frequency is introduced together with an input frequency, two intermediate frequencies having different components may be generated, thereby generating image interference in which two different signals may be detected and mixed.

In the present invention, by generating an auxiliary local oscillation frequency, by setting and supplying each local oscillation frequency for each intermediate frequency conversion using the original local oscillation frequency and the auxiliary local oscillation frequency, image interference before converting to an intermediate frequency By converting to any intermediate frequency to be removed and converting from such intermediate frequency to the final intermediate frequency, image interference can be eliminated.

Description

Apparatus for preventing image interference in a receiver}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio frequency receiver, and more particularly, to an image interference cancellation receiver.

In the receiving device, interference can be classified into two types. Firstly, when another communication or radio frequency interferes in a required band of an input frequency being received, another signal of an interference wave is different in detecting an original information signal. It can be seen that the incoming and altering the original signal is a whole body.

The second is image interference, where the input frequency is completely different, but when the image frequency is introduced during the conversion of the frequency converter, another intermediate frequency interferes in the required band of the intermediate frequency.

The present invention relates to a receiving device capable of removing such image interference.

1 is a block diagram showing the configuration of an embodiment of a conventional radio frequency receiver according to the related art.

Looking at the configuration, an input band filter 1 for a high frequency input, a high frequency amplifier 2 for amplifying a predetermined band frequency passed through the input band filter 1, and an oscillation for intermediate frequency conversion. A local oscillator 3 for outputting a frequency, a frequency converter 4 for converting the local oscillation frequency and the high frequency amplified frequency signal of the local oscillator 3 into an intermediate frequency conversion, and an intermediate frequency converted through the frequency converter 4. The intermediate frequency band filter (5), the intermediate frequency amplifier (6) for amplifying the intermediate frequency passing through the intermediate frequency band filter (5), and the amplified intermediate frequency to detect and output a predetermined target signal. It consists of a detector (7).

Prior to describing the operation of the conventional receiving apparatus having such a configuration, the following definitions for the following frequencies are made as follows.

Intermediate Frequency = Local Oscillation Frequency-Input Frequency

; Intermediate Frequency: 10.7MHz, Local Oscillation Frequency: 167MHz, Input Frequency: 156.3MHz

Image Frequency = Local Oscillation Frequency + Intermediate Frequency

; If local oscillation frequency> input frequency,

Image Frequency = Input Frequency + (2 × Middle Frequency)

; If local oscillation frequency> input frequency,

Image Frequency = Local Oscillation Frequency-Intermediate Frequency

; If local oscillation frequency <input frequency,

Image Frequency = Input Frequency-(2 × Middle Frequency)

; If local oscillation frequency <input frequency,

As such, the intermediate frequency may be represented by Equation 1, and the image frequency may be represented by Equations 2 to 5 according to the relationship between the local oscillation frequency and the input frequency.

According to this, when the intermediate frequency is 10.7MHz and the local oscillation frequency is larger than the input frequency as 167-156.3, and applied to Equation 2 or 3,

The image interference frequency can be obtained as 167 + 10.7 = 177.7 MHz or 156.3 + (2 x 10.7) = 177.7 MHz.

In the case where an input frequency of 156.3 MHz and an image interference frequency of 177.7 MHz flow into a receiver in free space,

The input frequency is passed by the input band pass filter (1) without loss at a frequency of 156.3 MHz, and the image interference frequency is passed at a loss of about 60 decibels with an image frequency of 177.7 MHz. Even if the input band pass filter 1 is used because the force is very high at the frequency corresponding to channel 7, the force passed may be equal to the input frequency level.

At this time, when the input frequency 156.3 MHz and the image interference frequency 177.7 MHz are amplified together through the high frequency amplifier 2 and mixed with the local oscillation frequency 167 MHz through the frequency converter 4,

According to Equation 1, the original intermediate frequency by the input frequency of 156.3 MHz is

167 MHz-156.3 MHz = 10.7 MHz,

The intermediate frequency at image frequency 177.7 MHz is

177.7 MHz-167 MHz = 10.7 MHz.

In this way, when two intermediate frequencies having different components appearing at the same intermediate frequency are detected by the detector 7 through the intermediate frequency band filter 5 and the intermediate frequency amplifier 6, the two different signals are detected and mixed. This will occur.

This is called image interference.

As described above, in the conventional receiving apparatus, when the image frequency as in the condition definition equations 2 to 5 is introduced together with the input frequency, two intermediate frequencies having different components may be generated. Detection can result in image interference that can be blended.

In the present invention, in order to solve such a conventional problem, by generating an auxiliary local oscillation frequency, using the original local oscillation frequency and the auxiliary local oscillation frequency to set and supply each local oscillation frequency for each intermediate frequency conversion By converting to an intermediate frequency at which image interference is eliminated before converting to an intermediate frequency, and converting from such intermediate frequency to a final intermediate frequency, the object can be eliminated.

1 is a block diagram showing the configuration of a general radio frequency receiver.

Figure 2 is a block diagram showing an embodiment configuration of the image interference cancellation receiver of the present invention.

Figure 3 is a block diagram showing a configuration of another embodiment in the present invention.

According to the present invention having the above object, in a receiver for converting from an input frequency to a predetermined intermediate frequency to detect a desired signal, an intermediate frequency to be converted with a local oscillation frequency as shown in Equations 2 to 5 A local oscillation frequency (hereinafter referred to as a first local oscillation) for converting from an input frequency to a first intermediate frequency by setting it to an intermediate frequency (hereinafter referred to as a first intermediate frequency) in which image interference is removed in consideration of the image frequency in relation to Frequency) and an auxiliary local oscillator and frequency converting means for respectively setting local oscillation frequencies (hereinafter referred to as second local oscillation frequencies) for converting from the first intermediate frequency to the final intermediate frequency. In this thing,

The image interference cancellation reception apparatus of the present invention,

A radio frequency receiver for converting an intermediate frequency according to a local oscillation frequency supplied to a high frequency amplified input frequency and outputting a desired signal,

A first frequency converter converting the first intermediate frequency according to the first local oscillation frequency supplied to the high frequency amplified input frequency;

A band filter of the first intermediate frequency,

A first intermediate frequency amplifier for amplifying the first intermediate frequency input through the first intermediate frequency band filter;

A second frequency converter for converting the first intermediate frequency output from the first intermediate frequency amplifier into a second intermediate frequency according to the supplied second local oscillation frequency;

A band pass filter of a second intermediate frequency,

A second intermediate frequency amplifier for amplifying the second intermediate frequency input through the second intermediate frequency band filter;

A detector for detecting a second intermediate frequency amplified by a second intermediate frequency amplifier, a local oscillator for supplying a local oscillation frequency for intermediate frequency conversion,

A first local oscillation frequency and a second local part for converting a first intermediate frequency and a second intermediate frequency by using a predetermined set local oscillator and using a local oscillation frequency of the local oscillator and an auxiliary local oscillation frequency of the auxiliary local oscillator; It is configured to include a local oscillation frequency supply control unit for supplying an oscillation frequency,

In the local oscillation frequency supply control unit, the local oscillation frequency of the auxiliary local oscillator is a frequency value from which image interference is removed in consideration of a relationship between a local oscillation frequency for converting to an intermediate frequency and an intermediate frequency to be converted. It is characterized in that it is set in consideration of the local oscillation frequency of the local oscillator so as to detect the final second intermediate frequency value from the first intermediate frequency.

With reference to the accompanying drawings of the present invention having such a feature, the configuration and operation will be described as follows.

An input band filter 10 for a high frequency input, a high frequency amplifier 20 for amplifying a predetermined band frequency passed through the input band filter 10, and a high frequency amplifier 20 according to the supplied first local oscillation frequency A first frequency converter 30 for converting an input frequency amplified from the first frequency into a first intermediate frequency, a first intermediate frequency band filter 40 for the converted first intermediate frequency, and a first intermediate frequency band filter 40. A first intermediate frequency amplifier (50) for amplifying the first intermediate frequency passed through the second frequency converter (60) for performing a final second intermediate frequency conversion for signal detection according to the supplied second local oscillation frequency; And, a second intermediate frequency band filter 70 for the converted second intermediate frequency, a second intermediate frequency amplifier 80 for amplifying the second intermediate frequency passing through the second intermediate frequency band filter 70, Detects the amplified second intermediate frequency and A detector 90 for detecting and outputting an appropriate signal, a local oscillator 100 for providing a local oscillation frequency for intermediate frequency conversion, and a first intermediate frequency by frequency converting an oscillation frequency supplied from the local oscillator 100 The first local oscillation frequency is supplied to the first frequency converter 30 for conversion, and the second local oscillation frequency is supplied to the second frequency converter 60 to output the final second intermediate frequency from the first intermediate frequency. It consists of a local oscillation frequency supply control unit 110.

The local oscillation frequency supply control unit 110 outputs an oscillation frequency output from the auxiliary local oscillator 111 and the auxiliary local oscillator 111 to output a predetermined oscillation frequency, and the oscillation frequency converter 113 and the phase delay unit 116. The first local oscillation frequency for converting the first intermediate frequency by mixing the distributor 112 and the oscillation frequency output from the local oscillator 100 with the oscillation frequency output from the auxiliary local oscillator 111 Amplifying the local oscillation frequency signal passing through the oscillation frequency converter 113, the local oscillation filter 114 for the first local oscillation frequency converted by the oscillation frequency converter 113, and the local oscillation filter 114 A local delay amplifier 115 and a phase delay unit 116 for delaying the oscillation frequency input through the distributor 112 by a predetermined set phase angle and supplying it to the second frequency converter 60. do.

In the embodiment of the present invention having such a configuration,

When the predetermined local oscillation frequency (100 MHz) is output from the auxiliary local oscillator 111, such an auxiliary local oscillation frequency is applied to the oscillation frequency converter 113 through the divider 112.

In the oscillation frequency converter 113, the auxiliary local oscillation frequency input as described above is mixed with the oscillation frequency of the local oscillator 100 to output the first local oscillation frequency for the first intermediate frequency conversion.

The first local oscillation frequency output from the oscillation frequency converter 113 through the frequency conversion is passed only through the corresponding frequency band through the local oscillation filter 114, and the first local oscillation frequency of the local oscillation amplifier 115 Amplified output through

The first frequency converter 30 converts the input frequency amplified by the high frequency through the high frequency amplifier 20 into a first intermediate frequency according to the amplified first local oscillation frequency.

The first intermediate frequency output as described above passes the first intermediate frequency signal of the corresponding band through the first intermediate frequency band filter 40, and receives the final second intermediate frequency through the first intermediate frequency amplifier 50. Amplified output for detection.

The second frequency converter 60 converts the auxiliary local oscillation frequency output from the auxiliary local oscillation frequency 111 to the second intermediate oscillation frequency as a second local oscillation frequency and converts the first intermediate frequency output through the amplifier 50 to a second intermediate frequency. The frequency conversion is performed, and the second intermediate frequency is a mid-frequency amplified band only through the second intermediate frequency band filter 70 and the second intermediate frequency amplifier 80, and finally through the detector 90. Output the desired signal.

Then, the operation of the embodiment of the present invention for removing the image interference frequency in detail as follows.

When the oscillation frequency converter 113 adds or subtracts an oscillation frequency (100MHz) of the auxiliary local oscillator 111 inputted through the distributor 112 to the local oscillation frequency,

(a). 167 MHz + 100 MHz = 267 MHz

(b). 167 MHz-100 MHz = 67 MHz

This local oscillation frequency can be obtained.

Thereafter, the local oscillation filter 114 is configured to allow only one of the bands of the frequencies of (a) and (b) to pass, which means that the local oscillation filter ( In the case of the upper band, 267 MHz is used as the first local oscillation frequency, and in the case of the lower band, 67 MHz is used.

Here, a case where the upper band is used in the transmission apparatus will be described. For example, the local oscillation filter 114 is configured as a band pass filter that passes only a frequency in the 267 MHz band. Only MHz is passed.

The local oscillator amplifier 115 amplifies only the attenuation amount generated by the oscillation frequency converter 113 and the local oscillation filter 114 and outputs the first local oscillation frequency to the first frequency converter 30.

At this time, since the input frequency is 156.3 MHz, the first intermediate frequency is obtained as follows.

267 MHz-156.3 MHz = 110.7 MHz

Therefore, according to the conditional equations 2 and 3 defined above, the image interference frequency is,

267 MHz + 110.7 MHz = 377.7 MHz or 156.3 MHz + (2 × 110.7) MHz = 377.7 MHz

Will appear.

Such 377.7MHz is not only easy to filter in the input band filter 10, but also in the conventional 177.7MHz is a broadcast band, its power is very high, but 377.7MHz is low in power and fully filtered by the input band filter 10. As it becomes possible, interference can be eliminated.

In this case, since the frequency converter is additionally configured in comparison with the related art, the auxiliary local oscillator 111 may generate a slight noise and apply it to the main signal, so that the auxiliary local oscillation frequency is divided through the divider 112. To the 113 and the second frequency converter 60,

As it is supplied to the oscillation frequency converter 113 through the divider 112 and is supplied to the second frequency converter 60 as the first intermediate frequency through the first intermediate frequency amplifier 50, it passes through a number of stages, thus causing a time delay phenomenon. This will occur.

Accordingly, in the phase delay unit 116, the secondary local oscillation frequency is delayed by 180 ° so that the on-noise forces are canceled through the first intermediate frequency amplifier 50 so that the second local oscillation frequency is applied to the first frequency converter 60. In addition to preventing noise increase, image interference can be eliminated.

Here, the auxiliary local oscillation frequency of the auxiliary local oscillator 111 is very effective when set in consideration of the surrounding radio frequency and output.

The first intermediate frequency amplifier 50 may further amplify about 1 to 2 decibels to the loss of the first frequency converter 30 and the first intermediate frequency band filter 40.

Here, it is described in the case of the upper band, when using the lower band frequency, the first local oscillation frequency will be 67 MHz, and if the intermediate frequency conversion is performed in preparation for the input frequency (156.3 MHz), the first intermediate frequency Is represented by 89.3 MHz.

However, the second intermediate frequency originally intended to be obtained is as it is at 10.7 MHz.

3 is a diagram showing the configuration of another embodiment of the present invention, wherein the local oscillation frequency supply control unit when the oscillation frequency of the auxiliary local oscillator 111 is set to a frequency (267 MHz) after frequency conversion with the local oscillation frequency is shown. 110 is a different configuration.

Referring to the configuration of FIG. 3, the first local frequency converter 30 amplifies the oscillation frequency of the auxiliary local oscillator 111 'and the auxiliary local oscillator 111' for supplying the first local oscillation frequency for the first intermediate frequency conversion. The oscillation frequency of the local oscillator 115 and the local oscillator 100 of the local oscillator 100 and the oscillation frequency of the auxiliary local oscillator 111 'are mixed to output a second local oscillation frequency for the second intermediate frequency conversion. By delaying the phase of the oscillation frequency converter 113, the local oscillation filter 117 of the oscillation frequency output from the oscillation frequency converter 113, and the second local oscillation frequency inputted through the local oscillation filter 117, And a phase retarder 116 for supplying the two frequency converter 60.

3, the oscillation frequency of the auxiliary local oscillator 111 'is set to 267 MHz.

It is configured to use the oscillation frequency of the auxiliary local oscillator 111 'as the first local oscillation frequency as it is to obtain the first intermediate frequency (110.7MHz), and the second intermediate frequency (110.7MHz) from the first intermediate frequency (110.7MHz). 10.7MHz) to mix the oscillation frequency of the auxiliary local oscillator (111 ') and the oscillation frequency of the local oscillator (100) to supply to the second local oscillation frequency (100MHz),

Accordingly, the band pass filter of the local oscillation filter 117 is configured to be 100 MHz.

In the embodiment of the present invention as shown in FIG. 3, an oscillation frequency of 267 MHz using the upper band is configured, but the same second intermediate frequency (10.7 MHz) can be detected using the oscillation frequency of 67 MHz of the lower band. In this case, the first intermediate frequency becomes 89.3 MHz, and the second local oscillation frequency converted through the auxiliary frequency converter 113 becomes 100 MHz as it is.

As described above, the present invention sets the optimum first intermediate frequency in consideration of the image interference frequency before the intermediate frequency set to detect the desired signal from the input frequency, and the following equation is obtained from the first intermediate frequency. By using the relationship as shown in Fig. 6, the oscillation frequency of the auxiliary local oscillation frequency is configured.

First intermediate frequency = auxiliary local oscillation frequency ± intermediate frequency (second intermediate frequency)

Therefore, in order to obtain the first intermediate frequency and the second intermediate frequency according to the oscillation frequency of the auxiliary local oscillation frequency, various configurations are possible without the limitations of the configuration as shown in FIG.

As described above, in order to prevent an image interference frequency, a predetermined first intermediate frequency may be set in consideration of the corresponding frequency band, and the first intermediate frequency may be converted and the second intermediate frequency may be changed from the converted first intermediate frequency. By setting the auxiliary local oscillation frequency so as to detect the corresponding signal from the input frequency, it is possible to prevent the image interference caused by the inflow of the image frequency.

Claims (6)

delete In the radio frequency receiver for outputting a desired signal by converting the intermediate frequency according to the local oscillation frequency supplied to the high frequency amplified input frequency, A first frequency converter 30 for converting the first intermediate frequency according to the first local oscillation frequency supplied to the high frequency amplified input frequency; A band filter 40 of the converted first intermediate frequency, A first intermediate frequency amplifier 50 for amplifying the first intermediate frequency input through the first intermediate frequency band filter; A second frequency converter 60 for converting the first intermediate frequency output from the first intermediate frequency amplifier 50 into a second intermediate frequency according to the supplied second local oscillation frequency; A band filter 70 of a second intermediate frequency, A second intermediate frequency amplifier 80 for amplifying the second intermediate frequency input through the second intermediate frequency band filter 70; A detector 90 for detecting a second intermediate frequency amplified by the second intermediate frequency amplifier 80, Local oscillator 100 for supplying a local oscillation frequency for intermediate frequency conversion, An auxiliary local oscillator 111 for outputting a predetermined set oscillation frequency, a distributor 112 for supplying an oscillation frequency output from the auxiliary local oscillator 111 to an oscillation frequency converter 113 and a second frequency converter 60; An oscillation frequency converter 113 for mixing the oscillation frequency output from the local oscillator 100 with the oscillation frequency from the auxiliary local oscillator 111 and outputting a first local oscillation frequency for first intermediate frequency conversion; A local oscillation filter 114 for the first local oscillation frequency converted by the oscillation frequency converter 113, and a local oscillation amplifier 115 for amplifying the local oscillation frequency signal passing through the local oscillation filter 114; Local oscillation frequency including a supply control unit 110, In the local oscillation frequency supply control unit 110, the local oscillation frequency of the auxiliary local oscillator 111 is a frequency value from which image interference is removed in consideration of a relationship between a local oscillation frequency for converting to an intermediate frequency and an intermediate frequency to be converted. Has a first intermediate frequency and is set in consideration of a local oscillation frequency of the local oscillator (100) so as to detect a final second intermediate frequency value from the first intermediate frequency. 3. The local oscillation filter 114 according to claim 2, wherein the local oscillation filter 114 determines an upper band or a lower band of a use band of the oscillation frequency according to the input frequency characteristic of the transmitter, and accordingly the frequency of the auxiliary frequency converter 113 according to the determined use band. An image interference cancellation receiver, characterized in that configured to determine the passband of the oscillation frequency that can be converted. In the radio frequency receiver for outputting a desired signal by converting the intermediate frequency according to the local oscillation frequency supplied to the high frequency amplified input frequency, A first frequency converter 30 for converting the first intermediate frequency according to the first local oscillation frequency supplied to the high frequency amplified input frequency; A band filter 40 of the converted first intermediate frequency, A first intermediate frequency amplifier 50 for amplifying the first intermediate frequency input through the first intermediate frequency band filter; A second frequency converter 60 for converting the first intermediate frequency output from the first intermediate frequency amplifier 50 into a second intermediate frequency according to the supplied second local oscillation frequency; A band filter 70 of a second intermediate frequency, A second intermediate frequency amplifier 80 for amplifying the second intermediate frequency input through the second intermediate frequency band filter 70; A detector 90 for detecting a second intermediate frequency amplified by the second intermediate frequency amplifier 80, Local oscillator 100 for supplying a local oscillation frequency for intermediate frequency conversion, A local oscillator for amplifying the oscillation frequency of the auxiliary local oscillator 111 'and the auxiliary local oscillator 111' for supplying the first local oscillation frequency for the first intermediate frequency conversion to the first frequency converter 30; An oscillation frequency converter 113 for mixing a local oscillation frequency of the local oscillator 100 and an oscillation frequency of the auxiliary local oscillator 111 'and outputting a second local oscillation frequency for a second intermediate frequency conversion. And a local oscillation frequency supply control unit 110 including a local oscillation filter 117 for passing the oscillation frequency output from the oscillation frequency converter 113 and supplying it to the second frequency converter 60 as a second local oscillation frequency. It is configured to include, In the local oscillation frequency supply control unit 110, the local oscillation frequency of the auxiliary local oscillator 111 'is a frequency from which image interference is removed in consideration of the relationship between a local oscillation frequency for converting to an intermediate frequency and an intermediate frequency to be converted. The apparatus has a first intermediate frequency, and is configured in consideration of the local oscillation frequency of the local oscillator 100 so as to detect the final second intermediate frequency value from the first intermediate frequency. . 3. The phase delay unit 116 according to claim 2, further comprising a phase delay for supplying the second local oscillation frequency supplied to the second frequency converter 60 to the second frequency converter 60 by delaying the phase by a predetermined set phase angle. Image interference cancellation reception apparatus characterized in that it comprises a. 5. The phase delay unit 116 of claim 4, further comprising a phase delay for supplying the second local oscillation frequency supplied to the second frequency converter 60 to the second frequency converter 60 by delaying the phase by a predetermined set phase angle. Image interference cancellation reception apparatus characterized in that it comprises a.