CN101539624B - Method and device for extracting local oscillation from wideband carrier - Google Patents
Method and device for extracting local oscillation from wideband carrier Download PDFInfo
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- CN101539624B CN101539624B CN2008100254892A CN200810025489A CN101539624B CN 101539624 B CN101539624 B CN 101539624B CN 2008100254892 A CN2008100254892 A CN 2008100254892A CN 200810025489 A CN200810025489 A CN 200810025489A CN 101539624 B CN101539624 B CN 101539624B
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Abstract
The invention discloses a method for extracting local oscillation from a wideband carrier, which comprises the following steps that: a received carrier signal is subjected to limiting amplification to serve as a local oscillation signal of a quadrature modulator for input, and an intermediate frequency signal output by a local intermediate frequency source is decomposed into two paths of orthogonal baseband signals to serve as I and Q signals of the quadrature modulator for input; and the quadrature modulator utilizes the single-sideband modulation characteristic thereof to extract a local oscillation signal Fc-IF or Fc+IF modulated by a single sideband from a carrier. A device for extracting local oscillation from the wideband carrier comprises a local intermediate frequency (IF) source, a limiting amplification circuit, an intermediate frequency signal decomposition circuit and the quadrature modulator; a signal which is output after the carrier signal passes through the limiting amplification circuit is sent into a local oscillation signal input end of the quadrature modulator, the two paths of the orthogonal baseband signals which are acquired after the intermediate frequency signal produced by the intermediate frequency (IF) source passes through the intermediate frequency signal decomposition circuit are input into I and Q signal input ends of the quadrature modulator respectively, and the quadrature modulator outputs the needed local oscillation signal. The method and the device can effectively extract the local oscillation frequency without a bandpass filter within the frequency range of wideband radiofrequency carrier.
Description
Technical field
The present invention relates to the signal Processing field of the electronics and the communications field, is a kind of method and device that extracts local oscillator from radio-frequency carrier, is suitable for wide band radio-frequency carrier frequency range of application.
Background technology
In radio communication, have only the radar signal of following the tracks of and locking the other side, could the other side's radar signal effectively be received and signal parameter analysis.Modern radio signal receiver generally adopts the superhet form, superhet form receiver is radio signal and the local frequency mixing that will receive, convert the signal into fixed intermediate frequency, then intermediate frequency is carried out filtering, amplification and detection, have highly sensitive and the good advantage of selectivity.Fig. 1 is a superheterodyne reception frequency conversion block diagram.Local frequency will be followed frequency input signal and be changed, and when local frequency differed to IF-FRE with the Radio Signal Frequency that receives, if bandpas filter just had signal output.If do not know the other side's radio frequency in advance, then at first to carry out frequency measurement, set local frequency according to the result of frequency measurement, in order to improve sensitivity and selectivity, the bandwidth of intermediate-frequency filter is narrow more good more, like this, accuracy requirement to frequency measurement is very high, has increased the complexity and the frequency measurement time of equipment.In actual environment, a lot of radar signals all are high-speed pulse and frequency agility signal, therefore the most effective way of radar signal that will follow the tracks of and lock the other side is obtained carrier frequency Fc exactly from the other side's radar signal, with the IF mixing of local IF-FRE source, extract local frequency FLO, from carrier wave, extract the local oscillator obtain like this, differ all the time with the signal that receives and be IF-FRE.Yet, because IF-FRE is lower, output frequency product after carrier frequency and the source mixing of local IF-FRE, the local frequency Fc-IF (or Fc+IF) that obtains except hope, also has image frequency Fc+IF (or Fc-IF), carrier frequency is leaked and a lot of other high-order mixed products Fc ± n * IF, wherein the local frequency of carrier frequency leakage and image frequency and desired extraction is very near, only differ IF and 2 * IF, amplitude is also suitable, it is main interfering frequency product, though can desirable local frequency Fc-IF (or Fc+IF) be elected with bandpass filter, bandpass filter has limited the carrier frequency bandwidth that is suitable for.
Summary of the invention
The problem to be solved in the present invention is: adopt the method for carrier frequency and the source mixing of local IF-FRE to extract local frequency from carrier wave, need the local frequency of desired extraction be elected with bandpass filter, bandpass filter has limited the carrier frequency bandwidth that is suitable for, if do not use bandpass filter, other frequency products of mixing output, especially carrier frequency leakage and image frequency produce serious disturbance to the application of local frequency, so that can't normally use.
Technical scheme of the present invention is:
A kind of extracting local oscillation from wideband carrier method, earlier the carrier signal amplitude limit that receives is amplified as the local oscillation signal of quadrature modulator and import, the intermediate-freuqncy signal of local IF-FRE source output is resolved into I, the Q signal input of the baseband signal of two-way quadrature as quadrature modulator; Quadrature modulator utilizes its single-sideband modulation characteristic, extracts the local oscillation signal Fc-IF or the Fc+IF of single-sideband modulation from carrier wave.
Use 90 degree electric bridges the intermediate-freuqncy signal of local IF-FRE source output to be decomposed into I, the Q two paths of signals of quadrature.Described carrier signal can be broadband rf signal or the later broadband rf signal of process one or many mixing that is directly received by antenna.
A kind of device of realizing said method comprises local medium-frequency IF frequency source, amplitude limiting amplifier circuit, local intermediate-freuqncy signal decomposition circuit and quadrature modulator; Carrier signal is imported the local oscillation signal input end of quadrature modulator into through the signal of amplitude limiting amplifier circuit output, the baseband signal of the two-way quadrature that the local intermediate-freuqncy signal that local medium-frequency IF frequency source produces obtains through the intermediate-freuqncy signal decomposition circuit is imported I, the Q signal input end of quadrature modulator, the local oscillation signal that quadrature modulator output is required respectively.
Described intermediate-freuqncy signal decomposition circuit comprises amplifier, wave filter and 90 degree electric bridges, and the signal of intermediate-freuqncy signal after amplifier and wave filter amplification filtering spent I, the Q two paths of signals that electric bridges are decomposed into quadrature through 90 again.Described amplitude limiting amplifier circuit comprises limiting amplifier, and limiting amplifier is the connecting band bandpass filter also.Described amplitude limiting amplifier circuit comprises the one-level limiting amplifier at least, promptly also can connect one or more groups limiting amplifier and bandpass filter successively after described bandpass filter.The sum of series full gain of limiting amplifier mainly is to be provided with according to the dynamic range needs that system handles carrier signal.
Described quadrature modulator output terminal also connects Hi-pass filter and amplifier successively.
Compared with prior art, the present invention adopts quadrature modulation method to extract local oscillator from carrier wave, carrier signal is carried out amplitude limit amplify, as the local oscillator of quadrature modulator; Local intermediate-freuqncy signal IF is resolved into the two paths of signals of quadrature, as I, the Q input signal of quadrature modulator; Output by quadrature modulator obtains single sideband modulated signal Fc-IF (or Fc+IF), utilize the single-sideband modulation characteristic of quadrature modulator, carrier frequency Fc and image frequency (being another sideband signals) Fc+IF (or Fc-IF) as local oscillation signal have obtained effective inhibition, therefore bandpass filter can be do not needed to use here, just local frequency can be in the wide band radio-frequency reference carrier frequency, extracted effectively.
Description of drawings
Fig. 1 is a superheterodyne reception frequency conversion block diagram
Fig. 2 is the theory diagram of circuit of the present invention
Fig. 3 is the circuit block diagram of circuit embodiments of the present invention
Embodiment
The invention will be further described below in conjunction with accompanying drawing and embodiment.
A kind of extracting local oscillation from wideband carrier method, the local oscillation signal input of the carrier signal amplitude limit amplification that receives, use 90 degree electric bridges that local intermediate-freuqncy signal is resolved into I, the Q signal input of the baseband signal of two-way quadrature as quadrature modulator as quadrature modulator; Then, quadrature modulator utilizes its single-sideband modulation characteristic, extracts the local oscillation signal Fc-IF or the Fc+IF of single-sideband modulation from carrier wave.Described carrier signal can be broadband rf signal or the later broadband rf signal of process one or many mixing that is directly received by antenna.
The circuit theory that realizes the said method device as shown in Figure 2, this circuit comprises local medium-frequency IF frequency source, amplitude limiting amplifier circuit, intermediate-freuqncy signal decomposition circuit and quadrature modulator; Carrier signal is imported the local oscillation signal input end of quadrature modulator into through the signal of amplitude limiting amplifier circuit output, the baseband signal of the two-way quadrature that the intermediate-freuqncy signal that local medium-frequency IF frequency source produces obtains through the intermediate-freuqncy signal decomposition circuit is imported I, the Q signal input end of quadrature modulator, the local oscillation signal that quadrature modulator output is required respectively.
Described intermediate-freuqncy signal decomposition circuit comprises amplifier, wave filter and 90 degree electric bridges, and the signal of intermediate-freuqncy signal after amplifier and wave filter amplification filtering spent I, the Q two paths of signals that electric bridges are decomposed into quadrature through 90 again.Described amplitude limiting amplifier circuit comprises limiting amplifier, and limiting amplifier is the connecting band bandpass filter also.Amplitude limiting amplifier circuit is the two-stage limiting amplifier, promptly also connects limiting amplifier and connecting band bandpass filter behind described wave filter successively.
Owing in the quadrature modulator output signal, can include intermediate frequency I, Q signal leakage, also connect Hi-pass filter and amplifier successively through the described quadrature modulator output terminal of receiver system.
Fig. 3 is a specific embodiment, and the input radio frequency signal frequency range is 1～2GHz, and IF-FRE is 135MHz, wishes that the local frequency of extracting is Lo=Fc-IF, so wish that the local frequency scope of extracting is 865～1865MHz.Limiting amplifier, bandpass filter adopt the product of permanent electric Electronics Co., Ltd., and model is respectively HDLP0102N3407, HDBPF0102P10.Local IF-FRE source adopts the 135MHz phase-locked oscilaltor through amplifying and the 135MHz band-pass filter, obtains the 135MHz intermediate-freuqncy signal.Crystal oscillator or other forms of frequency source circuit also can be adopted in the IF-FRE source, if amplitude is enough and frequency spectrum is pure, intermediate frequency amplifier and if bandpas filter also can.The 135MHz intermediate-freuqncy signal adopts 90 degree electric bridges to be decomposed into the two-way intermediate-freuqncy signal of quadrature, 90 degree electric bridges are selected rich prestige integrated circuit company limited product for use, model is PD2-135, two-way quadrature intermediate-freuqncy signal after the decomposition, the requirement amplitude equates, quadrature in phase, otherwise will influence carrier suppressed and sideband rejection after the orthogonal modulation, thus influence the sensitivity index of receiver.Quadrature modulator should be selected the wideband orthogonal modulator for use, select U.S. HITTIE company integrated circuit (IC) products in this example for use, model is HMC495LP3, the frequency of operation of this quadrature modulator covers 250～3800MHz, in this routine applying frequency scope, the carrier suppressed index reaches 38dBc, and sideband suppresses index and reaches 31dBc.Through quadrature modulator output, obtain the Fc-IF frequency signal, in broad frequency range, carrier suppressed and sideband suppress to reach 25dBc.In modern receiving system, the frequency mixer that frequency conversion is adopted all is the balanced type frequency mixer, have very high local oscillator noise and suppress ability, therefore the carrier wave, the sideband that comprise of the local oscillation signal that extracts by quadrature modulation method leaks and can be received that the balanced type frequency mixer effectively suppresses in the system, to systemic-function and not influence of performance.
Claims (7)
1. extracting local oscillation from wideband carrier method, it is characterized in that earlier the carrier signal amplitude limit that receives being amplified as the local oscillation signal of quadrature modulator importing, simultaneously the intermediate-freuqncy signal of local IF-FRE source output is resolved into I, the Q signal input of the baseband signal of two-way quadrature as quadrature modulator; Utilize its single-sideband modulation characteristic again by quadrature modulator, from carrier wave, extract the local oscillation signal Fc-IF or the Fc+IF of single-sideband modulation.
2. extracting local oscillation from wideband carrier method according to claim 1 is characterized in that using 90 degree electric bridges local IF-FRE source output intermediate-freuqncy signal to be decomposed into I, the Q two paths of signals of quadrature.
3. extracting local oscillation from wideband carrier method according to claim 1 and 2 is characterized in that described carrier signal can be broadband rf signal or the later broadband rf signal of process one or many mixing that is directly received by antenna.
4. a device for extracting is characterized in that comprising local medium-frequency IF frequency source, amplitude limiting amplifier circuit, intermediate-freuqncy signal decomposition circuit and quadrature modulator; Carrier signal is imported the local oscillation signal input end of quadrature modulator into through the signal of amplitude limiting amplifier circuit output, the baseband signal of the two-way quadrature that the intermediate-freuqncy signal that the medium-frequency IF frequency source produces obtains through the intermediate-freuqncy signal decomposition circuit is imported I, the Q signal input end of quadrature modulator, the local oscillation signal that quadrature modulator output is required respectively;
The extracting local oscillation from wideband carrier method that this device is realized is, earlier the carrier signal amplitude limit that receives is amplified as the local oscillation signal of quadrature modulator and import, simultaneously the intermediate-freuqncy signal of local IF-FRE source output is resolved into I, the Q signal input of the baseband signal of two-way quadrature as quadrature modulator; Utilize its single-sideband modulation characteristic again by quadrature modulator, from carrier wave, extract the local oscillation signal Fc-IF or the Fc+IF of single-sideband modulation.
5. device for extracting according to claim 4 is characterized in that described amplitude limiting amplifier circuit comprises limiting amplifier, and limiting amplifier is the connecting band bandpass filter also.
6. device for extracting according to claim 5 is characterized in that described amplitude limiting amplifier circuit comprises the one-level limiting amplifier at least, promptly also connects one or more groups limiting amplifier and bandpass filter after described bandpass filter successively.
7. according to claim 4 or 5 or 6 described device for extracting, it is characterized in that described quadrature modulator output terminal also connects Hi-pass filter and amplifier successively.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2008100254892A CN101539624B (en) | 2008-05-06 | 2008-05-06 | Method and device for extracting local oscillation from wideband carrier |
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| CN2008100254892A CN101539624B (en) | 2008-05-06 | 2008-05-06 | Method and device for extracting local oscillation from wideband carrier |
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| CN101539624A CN101539624A (en) | 2009-09-23 |
| CN101539624B true CN101539624B (en) | 2011-07-27 |
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| CN103004112B (en) * | 2012-09-11 | 2016-05-25 | 华为技术有限公司 | A kind of control method of signal frequency and device |
| CN108183720A (en) * | 2017-12-21 | 2018-06-19 | 北京遥感设备研究所 | A kind of ultra wideband receiver of self-mixing structure |
| CN113992488B (en) * | 2021-11-02 | 2023-12-19 | 北京润科通用技术有限公司 | Radio frequency single sideband modulation method and radio frequency single sideband modulator |
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| CN1346986A (en) * | 2000-10-08 | 2002-05-01 | 中国科学院电子学研究所 | System and method for correcting quadrature demodulation error of radar |
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| CN1346986A (en) * | 2000-10-08 | 2002-05-01 | 中国科学院电子学研究所 | System and method for correcting quadrature demodulation error of radar |
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