JP4793274B2 - Image removal type receiver - Google Patents

Description

  The present invention relates to an image removal receiving apparatus that removes an image component superimposed on a baseband signal subjected to quadrature detection when receiving and demodulating a radio communication wave.

  Conventionally, a superheterodyne method with high frequency selectivity has been adopted as a receiving device for receiving radio communication waves, but with the miniaturization of the device, many image removing method receiving devices using a mixer have been developed. Has been done. For example, Patent Document 1 describes a conventional receiving apparatus that employs an image removal method. According to this Patent Document 1, the conventional receiver generates frequency-converted received signals to generate orthogonal I channel signals and Q channel signals, further frequency converts these signals, and converts the orthogonal components into I channel signals and Image components are removed by removing from the Q channel signal. Further, as shown in FIG. 3 or FIG. 6 of Patent Document 1, the conventional receiving apparatus detects and divides the average power of each signal in order to suppress the amplitude difference between the I channel signal and the Q channel signal. Thus, it has the function of obtaining the amplitude difference and correcting the signal.

JP 2004-128694 A

  The conventional image removal type receiving apparatus has a function of correcting the amplitude difference between the I channel and the Q channel as described above. However, in order to stabilize the signal level at the time of demodulation of the received signal in the receiving apparatus. However, in the conventional image removal type receiving apparatus, the gain adjusting means has not been studied, and if the gain adjusting means is separately provided in the receiving apparatus, the scale of the apparatus increases. There was a problem of doing. In addition, the receiving apparatus that performs such gain adjustment and amplitude difference correction has a problem in that the image removal effect is deteriorated due to the influence of radio waves from adjacent communication channels.

  The present invention has been made to solve the above-described problems, and can perform gain adjustment and amplitude correction on an intermediate frequency signal, and can suppress deterioration in image removal effect due to an adjacent channel signal. An object of the present invention is to obtain an image removing type receiving apparatus capable of

An image removal type receiving apparatus according to the invention of claim 1 is a frequency converting means for frequency-converting a received signal to output orthogonal intermediate frequency I channel signals and Q channel signals;
Gain adjusting means for adjusting the gain of the intermediate frequency I channel signal and Q channel signal;
Image removing means for removing an image by frequency-converting and synthesizing the gain-adjusted I channel signal and Q channel signal with a phase difference of π / 2,
The gain adjusting means receives the intermediate frequency I channel signal and the Q channel signal, and outputs a control signal so that the level addition value of the intermediate frequency I channel signal and the Q channel signal becomes a predetermined value. circuit,
An amplitude difference detector that receives the intermediate frequency I-channel signal and Q-channel signal and detects and outputs an amplitude difference between the intermediate-frequency I-channel signal and Q-channel signal;
Based on the signal input by adding the output signal from the amplitude difference detector and the control signal, the gain of the I-channel signal of the intermediate frequency is adjusted, and the AGC circuit, the amplitude difference detector, and the image are adjusted. A first variable gain device that outputs to the removing means;
A second variable gain unit that adjusts the gain of the Q channel signal of the intermediate frequency based on the control signal and outputs the adjusted gain to the AGC circuit, the amplitude difference detector, and the image removing unit;
Gain adjustment of the intermediate frequency I-channel signal and Q-channel signal input to the image removing means is performed.

An image removal type receiving apparatus according to a second aspect of the present invention is a frequency converting means for frequency-converting a received signal to output orthogonal I-channel signals and Q-channel signals,
Gain adjusting means for adjusting the gain of the intermediate frequency I channel signal and Q channel signal;
The frequency-adjusted gain-adjusted I channel signal and Q channel signal are generated by a local oscillation signal to generate a baseband I channel signal and Q channel signal, and a baseband I channel orthogonal component and Q channel orthogonal component, Image removing means for image-removing the baseband I-channel signal with the Q-channel quadrature component, image-removing the baseband Q-channel signal with the I-channel quadrature component, and outputting the image;
The gain adjusting means receives the intermediate frequency I channel signal and the Q channel signal, and outputs a control signal so that the level addition value of the intermediate frequency I channel signal and the Q channel signal becomes a predetermined value. circuit,
An amplitude difference detector that receives the intermediate frequency I-channel signal and Q-channel signal and detects and outputs an amplitude difference between the intermediate-frequency I-channel signal and Q-channel signal;
Based on the signal input by adding the output signal from the amplitude difference detector and the control signal, the gain of the I-channel signal of the intermediate frequency is adjusted, and the AGC circuit, the amplitude difference detector, and the image are adjusted. A first variable gain device that outputs to the removing means;
A second variable gain unit that adjusts the gain of the Q channel signal of the intermediate frequency based on the control signal and outputs the adjusted gain to the AGC circuit, the amplitude difference detector, and the image removing unit;
Gain adjustment of the intermediate frequency I-channel signal and Q-channel signal input to the image removing means is performed.

An image removal type receiving apparatus according to a third aspect of the present invention is a frequency conversion means for frequency-converting a received signal to output orthogonal I-channel signals and Q-channel signals,
Gain adjusting means for adjusting the gain of the intermediate frequency I channel signal and Q channel signal;
The frequency-adjusted gain-adjusted I channel signal and Q channel signal are generated by a local oscillation signal to generate a baseband I channel signal and Q channel signal, and a baseband I channel orthogonal component and Q channel orthogonal component, Image removing means for image-removing the baseband I-channel signal with the Q-channel quadrature component, image-removing the baseband Q-channel signal with the I-channel quadrature component, and outputting the image;
The gain adjusting means receives a baseband I-channel signal and a Q-channel signal, and outputs a level calculator that outputs a square sum of the baseband I-channel signal and the Q-channel signal as a level addition value;
An AGC circuit that receives a level addition value from the level calculator and outputs a control signal so that the level addition value becomes a predetermined value;
An amplitude difference detector that receives the intermediate frequency I-channel signal and Q-channel signal and detects and outputs an amplitude difference between the intermediate-frequency I-channel signal and Q-channel signal;
Based on the signal input by adding the output signal from the amplitude difference detector and the control signal, the gain of the I-channel signal of the intermediate frequency is adjusted, and the AGC circuit, the amplitude difference detector, and the image are adjusted. A first variable gain device that outputs to the removing means;
A second variable gain unit that adjusts the gain of the Q channel signal of the intermediate frequency based on the control signal and outputs the adjusted gain to the AGC circuit, the amplitude difference detector, and the image removing unit;
Gain adjustment of the intermediate frequency I-channel signal and Q-channel signal input to the image removing means is performed.

  According to a fourth aspect of the present invention, there is provided an image removal type receiving apparatus according to any one of the first to third aspects, wherein the gain adjusting means is an I channel signal having the intermediate frequency. And the amplitude difference between the Q channel signals is detected by the signal level of the pilot signal included in the received signal.

  An image removal type receiving apparatus according to a fifth aspect of the present invention is the image removal type receiving apparatus according to any one of the first to third aspects of the present invention, wherein an I channel signal and a Q are transmitted in a specific channel of the received signal. It detects the amplitude difference between channel signals.

  An image removal type receiving apparatus according to a sixth aspect of the present invention is the image removal type receiving apparatus according to any one of the first to third aspects of the present invention, wherein the gain adjusting means controls the I channel signal and the Q channel signal. When the amplitude difference is detected, the received signal does not include an adjacent communication channel signal.

  According to a seventh aspect of the present invention, there is provided an image removal type receiving apparatus according to any one of the first to third aspects of the present invention, wherein the gain adjusting means is configured to specify a specific pattern in the received signal. When receiving, an amplitude difference between the I channel signal and the Q channel signal is detected.

  An image removal type receiving apparatus according to an eighth aspect of the present invention is the image removal type receiving apparatus according to any one of the first to third aspects, wherein the frequency converting means is a communication channel included in the received signal. The frequency conversion is performed so that the signal frequency after frequency conversion of the signal and the signal frequency after frequency conversion of the adjacent communication channel signal included in the received signal have a frequency difference.

  An image removal type reception apparatus according to a ninth aspect of the invention is the image removal type reception apparatus according to any one of the first to third aspects, wherein the communication channel signal and the adjacent channel signal are included in the reception signal. Is modulated by a spread code or a scramble code, and suppresses the correlation component of the communication channel signal and the adjacent channel signal in the signal after frequency conversion by the frequency conversion means.

  According to the invention of any one of claims 1 to 3, the gain adjustment means adjusts the gain of the intermediate frequency I-channel signal and Q-channel signal based on the gain amount and the amplitude difference. The increase can be suppressed, and the deterioration of the image removal effect can be reduced by correcting the amplitude difference.

  According to the fourth aspect of the present invention, since the amplitude difference between the I channel signal and the Q channel signal of the intermediate frequency is detected by the pilot signal, the detection error can be reduced. According to the fifth aspect of the present invention, since the amplitude difference between the I channel signal and the Q channel signal of the intermediate frequency is detected in the specific channel, the signal coverage of the adjacent communication channel is reduced. The error can be reduced. According to the sixth aspect of the present invention, when detecting the amplitude difference between the I-channel signal and the Q-channel signal of the intermediate frequency, the reception signal does not include the adjacent communication channel signal, so that the detection error is reduced. can do. According to the seventh aspect of the present invention, the amplitude difference between the intermediate frequency I channel signal and the Q channel signal is detected when the specific pattern in the received signal is received, so that the detection error can be reduced. it can.

  According to the eighth aspect of the present invention, since the communication channel signal at the intermediate frequency and the adjacent communication channel signal have a frequency difference, the overlapping of the correlation components of these signals is reduced, and the I-channel signal and Q at the intermediate frequency are reduced. The detection error of the amplitude difference of the channel signal can be reduced. According to the ninth aspect of the present invention, since the communication channel signal and the adjacent channel signal are modulated by the spreading code or the scramble code, the correlation component of the communication channel signal and the adjacent communication channel signal is superimposed at the intermediate frequency. This can reduce the detection error of the amplitude difference between the I-channel signal and the Q-channel signal of the intermediate frequency.

Embodiment 1

  An image removal type receiving apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of an image removal type receiving apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is a distributor that distributes a received signal in the RF band, 2 and 3 are mixers that generate I-channel signals and Q-channel signals of orthogonal intermediate frequencies by frequency conversion, and 4 is a mixer to mixers 2 and 3 An oscillator 5 that oscillates and outputs a local oscillation signal and 5 is a phase shifter that shifts the local oscillation signal to the Q channel side by π / 2. Reference numeral 6 denotes a gain adjusting unit for adjusting the amplitudes of the intermediate frequency I-channel signal and the Q-channel signal. In the gain adjusting unit 6, 7 and 8 are variable gain units for adjusting the gain of the intermediate frequency I channel signal and the Q channel signal, respectively, and 9 is a level addition value obtained by adding the signal levels of the I channel signal and the Q channel signal. AGC (automatic gain controller) that outputs a gain so that this level addition value matches the command value from the control signal input terminal 10, and 11 is a signal level difference (amplitude difference) between the I channel signal and the Q channel signal. And 12 is an adder for adding the gain amount output from the AGC 9 and the amplitude difference output from the amplitude difference detector 11. Reference numerals 13 and 14 denote mixers for converting the intermediate frequency I-channel signal and Q-channel signal to low frequency. The local oscillation signal from the oscillator 15 is phase-shifted by π / 2 by the phase shifter 16 and input to the mixer 14. Reference numeral 17 denotes a synthesizer that synthesizes the I-channel signal and the Q-channel signal that have been low-frequency converted by the mixers 13 and 14. Note that the I-channel signal line and the Q-channel signal line after the mixer 2 and the mixer 3 up to the preceding stage of the mixer 13 and the mixer 14 are low-pass components that remove high-frequency components included in each signal after mixing. Although a filter may be provided, this low-pass filter is not shown.

  The operation of the image removal type receiving apparatus shown in FIG. 1 will be described. The received signals are converted to a low frequency by the mixers 2 and 3 and converted to orthogonal I channel signals and Q channel signals of intermediate frequencies. An image component generated by mixing with the local signal is superimposed on the I channel signal and the Q channel signal. The variable gain units 7 and 8 adjust the gain of the I channel signal and the Q channel signal, respectively. The gain control amounts of the variable gain devices 7 and 8 are determined by calculation by the AGC 9, the amplitude difference detector 11, and the adder 12. The AGC 9 obtains the level addition value of the I channel signal and the Q channel signal. This level addition value is calculated, for example, by the square sum of the signal level of the I channel and the signal level of the Q channel or the square root thereof. The AGC 9 sets and outputs the gain amount so that the level addition value matches the command value from the control signal input terminal 10. The command value from the control signal input terminal 10 is set so that the baseband signal level is sufficiently ensured in the detection of the phase at the time of demodulation in the subsequent stage. The command value is a command value based on an upper limit value and a lower limit value, and the gain amount in the AGC 9 may be set so that the level addition value falls within the range defined by the upper limit value and the lower limit value. The same applies to the embodiments. The amplitude difference detector 11 detects the respective levels of the I channel signal and the Q channel signal, for example, based on the average power, and detects the amplitude difference based on the difference between these signal levels. A gain control amount obtained by adding the amplitude difference to the gain amount output from the AGC 9 is input to the variable gain device 7. By adjusting the gain in the gain adjusting unit 6, it is possible to adjust the gain amount in the present apparatus and correct the amplitude difference between the I / Q channels. The I-channel signal and the Q-channel signal are respectively converted into low frequencies by the mixers 13 and 14 and synthesized by the synthesizer 17, thereby removing the image components generated in the mixer 2 and the mixer 3. The gain adjustment unit 6 corrects the amplitude difference between the I channel signal and the Q channel signal, and can suppress degradation of the image removal effect caused by the amplitude difference.

  FIG. 2 is a block diagram showing another example of the configuration of the image removal type receiving apparatus according to Embodiment 1 of the present invention. In FIG. 2, reference numeral 18 denotes an image removal circuit unit that outputs a baseband I-channel signal and a Q-channel signal by converting an intermediate-frequency I-channel signal and a Q-channel signal to a low frequency and removing the image. In the image removal circuit unit 18, 19 is an oscillator that oscillates and outputs a local oscillation signal, 20 is a mixer that mixes the I channel signal and the local oscillation signal from the oscillator 19 and converts them to a low frequency baseband, and 21 is a Q channel. This is a mixer that mixes the signal and the local oscillation signal from the oscillator 19 and converts the signal to a baseband at a low frequency. 22 is a π / 2 phase shifter, 23 is a mixer that mixes the I channel signal and the local oscillation signal from the π / 2 phase-shifted oscillator 19 and outputs a baseband I channel quadrature component, 24 It is a mixer that mixes the Q channel signal and the local oscillation signal from the oscillator 19 phase-shifted by π / 2 and outputs a baseband Q channel quadrature component. Reference numeral 25 denotes an adder that adds (minus addition) the Q-channel quadrature component output from the mixer 24 to the baseband I-channel signal output from the mixer 20, and reference numeral 26 denotes a low-pass signal that removes high-frequency components from the output of the adder 25. It is a filter. An adder 27 adds the I-channel quadrature component output from the mixer 23 to the baseband Q channel signal output from the mixer 21, and 28 is a low-pass filter that removes high-frequency components from the output from the adder 27. 2, circuits denoted by the same reference numerals as those in FIG. 1 indicate the same or corresponding circuits as those in FIG.

  Next, the operation of the image removal type receiving apparatus shown in FIG. 2 will be described. The operations of the mixers 2 and 3 and the gain adjusting unit 6 are the same as those of the image removal type receiving apparatus shown in FIG. In the image removal circuit unit 18, the intermediate frequency I channel signal is converted into a baseband I channel signal by the mixer 20, and is added (minus addition) to the baseband Q channel orthogonal component output from the mixer 24. Remove image components occurring in the channel. Also, the intermediate frequency Q channel signal is converted to a baseband Q channel signal by the mixer 21 and added to the baseband I channel quadrature component output by the mixer 23 to remove the image component generated in the Q channel. To do. Similar to the image removal type receiver shown in FIG. 1, the gain adjustment unit 6 corrects the amplitude difference between the I channel signal and the Q channel signal, thereby suppressing deterioration of the image removal effect caused by the amplitude difference. it can.

Embodiment 2

  An image removal type receiving apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing the configuration of an image removal type receiving apparatus according to Embodiment 2 of the present invention. In FIG. 3, 29 is an AGC that outputs a gain value so that the level addition value matches the command value from the control signal input terminal 10 except for the level addition operation function of the I channel signal and the Q channel signal, and 30. It is a level calculator that calculates a level addition value of a baseband I channel signal and a Q channel signal. The level calculator 30 may be considered as a part of the gain adjusting unit 6. 3, circuits denoted by the same reference numerals as those in FIG. 2 indicate the same or corresponding circuits as those in FIG.

  The image removal type receiving apparatus according to the second embodiment calculates the level addition value of the I channel signal and the Q channel signal in the baseband. In the image removal type receiving apparatus according to the first embodiment, the level value is calculated from the I-channel signal and the Q-channel signal of the intermediate frequency. In this case, the receiving apparatus is adjacent to the communication channel to be received. The degree of coverage that the adjacent communication channel signal is included in the I-channel signal and Q-channel signal of the intermediate frequency is low after the mixer 2 and the mixer 3 and on the circuit before the image removal circuit unit 18. Depends on the performance of the pass filter. In general, a low-pass filter at an intermediate frequency is composed of an analog circuit. If the filter performance is improved, the circuit scale increases and the cost becomes high. On the other hand, the low-pass filters 26 and 28 shown in FIG. 3 are in the baseband region, and the filter can be constituted by a digital circuit (or software), so that it is blocked by a small circuit such as a roll-off filter. A low-pass filter having steep filter characteristics in frequency can be configured, and the coverage of adjacent communication channel signals can be reduced. Therefore, according to the image elimination type receiver shown in FIG. 3, the level computing unit 30 reduces the coverage of adjacent communication channel signals, and the level addition value of the I channel signal and Q channel signal of the communication channel to be received is obtained. It can be calculated with high accuracy.

Embodiment 3

  An image removal type receiving apparatus according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing the configuration of the gain adjusting unit 6 in the image removal type receiving apparatus according to Embodiment 3 of the present invention. In FIG. 4, reference numeral 31 denotes a bandpass filter for detecting a pilot signal included in the intermediate frequency I channel signal, and reference numeral 32 denotes a bandpass filter for detecting the pilot signal included in the intermediate frequency Q channel signal. 4, circuits denoted by the same reference numerals as those in FIGS. 1 and 2 indicate the same or corresponding circuits as those in FIGS. The gain adjusting unit 6 shown in FIG. 4 is replaced with the gain adjusting unit 6 shown in FIGS. 1 and 2 to obtain an image removal type receiving apparatus.

  The gain adjusting unit 6 shown in FIG. 4 detects the pilot signal (signal having a frequency different from that of the communication channel to be received) included in the received signal by the bandpass filters 31 and 32. The pilot signal I channel signal detected by the bandpass filter 31 and the pilot signal Q channel signal detected by the bandpass filter 32 are input to the amplitude difference detector 11 to detect the average power of each signal, By calculating the difference, it is possible to detect an amplitude difference generated between the I channel side and the Q channel side. In general, an unmodulated wave or a simple modulated wave can be used for the pilot signal, so that the signal is more stable than a modulated wave such as a communication channel signal, and each average power of the I channel signal and the Q channel signal is detected. Errors can be suppressed, and each average power can be detected in a short time. Therefore, errors occurring in the amplitude difference detected by the amplitude difference detector 11 can be suppressed, and the amplitude difference can be detected in a short time.

Embodiment 4

  As described in the second embodiment, when the signal of the adjacent communication channel is included in the I channel signal and the Q channel signal of the intermediate frequency, the level addition value detected by the AGC 9 and the amplitude difference detected by the amplitude difference detector 11 are changed. The adjacent communication channel signal enters and these values cannot be detected with high accuracy. Therefore, in the fourth embodiment, a receiving apparatus that is not easily affected by an adjacent communication channel will be described with reference to FIGS. Hereinafter, detection of the level addition value in the AGC 9 and the amplitude difference in the amplitude difference detector 11 is collectively referred to as level detection.

  FIG. 5 is a schematic diagram showing frequency allocation of communication waves received by an image removal type receiving apparatus according to Embodiment 4 of the present invention. FIG. 5 (a) is a view in which a plurality of communication channels and vacant channels are alternately arranged and assigned to the system frequency band, and is the idea of reducing the influence of adjacent channels at the time of reception most simply. In that respect, improvement is required. In FIG. 5B, a level detection channel (specific channel) is provided apart from a plurality of communication channels, and an empty channel or a wide guard band is formed adjacent to the level detection channel. . In this case, it is sufficient to create a free area only in the adjacent part of the level detection channel in the frequency band in the communication system, and the frequency can be effectively used. When the received signal has a communication wave having a channel configuration as shown in FIG. 5 (b), the level elimination type receiving apparatus according to the present invention switches and receives the reception channel when detecting the level, and receives the I channel signal and the Q channel signal. The amplitude difference and the level addition value are detected.

  FIG. 6 is a schematic diagram for explaining level detection at the time of reception on the control channel and the communication channel, considering level detection on a control channel (also considered as a specific channel) provided separately from the communication channel. Is. For example, in a communication system such as a mobile phone system, a control channel is provided in a predetermined frequency band in addition to a communication channel, and the control channel is received during a standby period or at the start of communication. As shown in FIG. 6, the communication channel is received during the communication period, but the channel is switched so that the control channel is received before and after this communication to detect the level. In this case, the level addition value of the I channel signal and the Q channel signal is detected throughout the reception period, and the amplitude difference detection is performed during reception of the control channel. If the adjacent frequency region of this control channel is set to an empty channel or a wide guard band, it is difficult to be affected by the adjacent channel. Also, since control channel reception is discrete, it is possible to detect an average amplitude difference over a long period of time by averaging the control channel signals received in a discrete manner when detecting the amplitude difference. It is.

  FIG. 7 is a schematic diagram showing received signals in the communication channel and the adjacent communication channel. In order to suppress the influence of the adjacent channel signal, the communication signal in the adjacent channel is dropped during level detection. Many communication systems use a method of synchronous reception that is received in synchronization with a predetermined communication frame. When assigning a communication signal to a communication frame on the system side, during a level detection period in one communication channel, By deleting the communication signal on the frame of the adjacent channel, the influence of the adjacent channel in level detection in one communication channel can be removed. The missing communication signal in the adjacent channel may be performed on the communication channel adjacent to both sides of one communication channel or may be performed on one side (especially the adjacent channel having a higher frequency).

  In order to reduce the detection error in the level detection of the I channel signal and the Q channel signal, it is also effective to perform the level detection while receiving a specific pattern signal. In general, the fixed pattern such as continuous wave (CW) has a frequency characteristic closer to a line spectrum, so that the level detection error is reduced and the level can be detected in a short time. Such a specific pattern may be provided exclusively for level detection, but it also serves as a specific pattern for carrier wave reproduction, symbol rate reproduction, voice activation, etc., thereby suppressing a decrease in the communication information amount of the communication frame format. be able to.

Embodiment 5

In Embodiment 5, when there is a correlation between a signal to be image-removed and a received signal, an image-removing type receiving apparatus that reduces this correlation will be described with reference to FIGS. Let n (t) be a received signal, and r (t) be a signal whose image is to be removed, such as an adjacent channel signal. At this time, the signal S _I and the signal power P _I included in the I-channel signal can be expressed by the following equation.

The signal power PI includes a correlation component of n (t) × r (t) and n ^* (t) × r ^* (t), and becomes an error factor when detecting the level of the I channel signal. The same applies to the Q channel signal. FIG. 8 is a schematic diagram for explaining the principle of reducing the correlation between adjacent channel signals and the like in the image removal type receiving apparatus according to the fifth embodiment of the present invention. In FIG. 8, 33 is a communication channel signal having a center frequency ω ₀ + Δω, and 34 is an adjacent channel signal having a center frequency ω ₀ −Δω. By performing a low frequency conversion to an intermediate frequency with the local signal frequency being ω ₀ -ΔΩ, the communication channel signal 33 becomes a signal 35 with a center frequency of Δω + ΔΩ, and the adjacent channel signal 34 has a center frequency of Δ The signal 36 becomes ω−ΔΩ, and these signals can be shifted in the frequency domain. As a result, the correlation between n (t) and r (t) is reduced, and the correlation component is reduced, so that the detection error at the time of level detection of the I channel signal (also in the case of the Q channel signal) is reduced. can do. Further, after the image removal, the level of the signal 38 to be removed by the adjacent channel or the like can be suppressed with respect to the signal level of the communication channel signal 37 in the baseband.

FIG. 9 is a schematic diagram for explaining the principle of another technique for reducing the correlation between adjacent channel signals and the like in the image removal type receiving apparatus according to the fifth embodiment of the present invention. In FIG. 9, it is assumed that the communication channel signal 33 and the adjacent channel signal 34 are modulated by different spreading codes and scramble codes. By performing the low frequency conversion to the intermediate frequency with the frequency of the local oscillation signal being set to ω ₀ , the communication channel signal 35 and the adjacent channel signal 36 at the intermediate frequency become signals having a center frequency of Δω, but orthogonal spreading Since the correlation component of these signals is reduced by the code or the like, the detection error at the time of detecting the level of the I channel signal and the Q channel signal can be reduced. Further, after the image removal, the level of the signal 38 to be removed by the adjacent channel or the like can be suppressed with respect to the signal level of the communication channel signal 37 in the baseband.

It is a block diagram showing the structure of the image removal type | mold receiving apparatus which concerns on Embodiment 1 of this invention. It is a block diagram showing another example of the image removal type | mold receiving apparatus structure which concerns on Embodiment 1 of this invention. It is a block diagram showing the structure of the image removal type | mold receiving apparatus which concerns on Embodiment 2 of this invention. It is a block diagram showing the structure of the gain adjustment part in the image removal type | mold receiving apparatus which concerns on Embodiment 3 of this invention. It is a schematic diagram showing the frequency allocation of the communication wave which the image removal type | mold receiving apparatus concerning Embodiment 4 of this invention receives. It is a schematic diagram explaining the level detection at the time of reception by a control channel and a communication channel. It is a schematic diagram showing the received signal in a communication channel and an adjacent communication channel. It is a schematic diagram explaining the principle which reduces the correlation of an adjacent channel signal etc. in the image removal type | mold receiving apparatus in Embodiment 5 of this invention. In the image removal type | mold receiving apparatus in Embodiment 5 of this invention, it is a schematic diagram explaining the principle of another method of reducing the correlation of an adjacent channel signal etc. FIG.

Explanation of symbols

2, 3 Mixer 6 Gain adjuster 9, 29 AGC
DESCRIPTION OF SYMBOLS 11 Amplitude difference detector 7, 8 Variable gain device 13, 14 Mixer 17 Synthesizer 18 Image removal circuit part 30 Level calculator 31, 32 Band pass filter

Claims (9)

A frequency converting means for frequency-converting a received signal and outputting an orthogonal intermediate frequency I channel signal and Q channel signal;
Gain adjusting means for adjusting the gain of the intermediate frequency I channel signal and Q channel signal;
Image removing means for removing an image by frequency-converting and synthesizing the gain-adjusted I channel signal and Q channel signal with a phase difference of π / 2,
The gain adjusting means receives the intermediate frequency I channel signal and the Q channel signal, and outputs a control signal so that the level addition value of the intermediate frequency I channel signal and the Q channel signal becomes a predetermined value. circuit,
An amplitude difference detector that receives the intermediate frequency I-channel signal and Q-channel signal and detects and outputs an amplitude difference between the intermediate-frequency I-channel signal and Q-channel signal;
Based on the signal input by adding the output signal from the amplitude difference detector and the control signal, the gain of the I-channel signal of the intermediate frequency is adjusted, and the AGC circuit, the amplitude difference detector, and the image are adjusted. A first variable gain device that outputs to the removing means;
A second variable gain unit that adjusts the gain of the Q channel signal of the intermediate frequency based on the control signal and outputs the adjusted gain to the AGC circuit, the amplitude difference detector, and the image removing unit;
An image-removing type receiving apparatus, wherein gain adjustment of the intermediate frequency I-channel signal and Q-channel signal input to the image removing means is performed . A frequency converting means for frequency-converting a received signal and outputting an orthogonal intermediate frequency I channel signal and Q channel signal;
Gain adjusting means for adjusting the gain of the intermediate frequency I channel signal and Q channel signal;
The frequency-adjusted gain-adjusted I channel signal and Q channel signal are generated by a local oscillation signal to generate a baseband I channel signal and Q channel signal, and a baseband I channel orthogonal component and Q channel orthogonal component, Image removing means for image-removing the baseband I-channel signal with the Q-channel quadrature component, image-removing the baseband Q-channel signal with the I-channel quadrature component, and outputting the image;
The gain adjusting means receives the intermediate frequency I channel signal and the Q channel signal, and outputs a control signal so that the level addition value of the intermediate frequency I channel signal and the Q channel signal becomes a predetermined value. circuit,
An amplitude difference detector that receives the intermediate frequency I-channel signal and Q-channel signal and detects and outputs an amplitude difference between the intermediate-frequency I-channel signal and Q-channel signal;
Based on the signal input by adding the output signal from the amplitude difference detector and the control signal, the gain of the I-channel signal of the intermediate frequency is adjusted, and the AGC circuit, the amplitude difference detector, and the image are adjusted. A first variable gain device that outputs to the removing means;
A second variable gain unit that adjusts the gain of the Q channel signal of the intermediate frequency based on the control signal and outputs the adjusted gain to the AGC circuit, the amplitude difference detector, and the image removing unit;
An image-removing type receiving apparatus, wherein gain adjustment of the intermediate frequency I-channel signal and Q-channel signal input to the image removing means is performed . A frequency converting means for frequency-converting a received signal and outputting an orthogonal intermediate frequency I channel signal and Q channel signal;
Gain adjusting means for adjusting the gain of the intermediate frequency I channel signal and Q channel signal;
The frequency-adjusted gain-adjusted I channel signal and Q channel signal are generated by a local oscillation signal to generate a baseband I channel signal and Q channel signal, and a baseband I channel orthogonal component and Q channel orthogonal component, Image removing means for image-removing the baseband I-channel signal with the Q-channel quadrature component, image-removing the baseband Q-channel signal with the I-channel quadrature component, and outputting the image;
The gain adjusting means receives a baseband I-channel signal and a Q-channel signal, and outputs a level calculator that outputs a square sum of the baseband I-channel signal and the Q-channel signal as a level addition value;
An AGC circuit that receives a level addition value from the level calculator and outputs a control signal so that the level addition value becomes a predetermined value;
An amplitude difference detector that receives the intermediate frequency I-channel signal and Q-channel signal and detects and outputs an amplitude difference between the intermediate-frequency I-channel signal and Q-channel signal;
Based on the signal input by adding the output signal from the amplitude difference detector and the control signal, the gain of the I-channel signal of the intermediate frequency is adjusted, and the AGC circuit, the amplitude difference detector, and the image are adjusted. A first variable gain device that outputs to the removing means;
A second variable gain unit that adjusts the gain of the Q channel signal of the intermediate frequency based on the control signal and outputs the adjusted gain to the AGC circuit, the amplitude difference detector, and the image removing unit;
An image-removing type receiving apparatus, wherein gain adjustment of the intermediate frequency I-channel signal and Q-channel signal input to the image removing means is performed . The gain adjustment means detects an amplitude difference between the I-channel signal and the Q-channel signal of the intermediate frequency based on a signal level of a pilot signal included in the received signal. The image removal type receiving apparatus according to the item. The image removal type according to any one of claims 1 to 3, wherein the gain adjusting means detects an amplitude difference between an I channel signal and a Q channel signal in a specific channel in the received signal. Receiver device. 4. An adjacent communication channel signal is not included in the received signal when detecting the amplitude difference between the I channel signal and the Q channel signal by the gain adjusting means. The image removal type | mold receiving apparatus of Claim 1. The gain adjusting means detects an amplitude difference between the I channel signal and the Q channel signal when receiving a specific pattern in the received signal. The image removal type receiving apparatus described in 1. The frequency converting means is configured such that the signal frequency after frequency conversion of the communication channel signal included in the received signal and the signal frequency after frequency conversion of the adjacent communication channel signal included in the received signal have a frequency difference. The image removal type receiving apparatus according to any one of claims 1 to 3, wherein frequency conversion is performed. The communication channel signal and the adjacent channel signal included in the received signal are modulated by a spreading code or a scramble code, and the correlation component of the communication channel signal and the adjacent channel signal is suppressed in the signal after frequency conversion by the frequency conversion means. The image removal type receiving apparatus according to any one of claims 1 to 3.

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