CN2762154Y - High frequency ground rada digital coherent receiver - Google Patents

High frequency ground rada digital coherent receiver Download PDF

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Publication number
CN2762154Y
CN2762154Y CN 200420057632 CN200420057632U CN2762154Y CN 2762154 Y CN2762154 Y CN 2762154Y CN 200420057632 CN200420057632 CN 200420057632 CN 200420057632 U CN200420057632 U CN 200420057632U CN 2762154 Y CN2762154 Y CN 2762154Y
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frequency
front
end
analog
circuit
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CN 200420057632
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Chinese (zh)
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文必洋
白立云
吴世才
张国军
严颂华
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武汉大学
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Abstract

The utility model relates to a high-frequency ground wave radar digital coherent receiver which comprises a radio frequency analog front end, an A/D sampling circuit, a frequency synthesizer, a synchronous control circuit and a digital signal processing chip, wherein the radio frequency analog front end, the A/D sampling circuit and the digital signal processing chip are orderly and electrically connected; the frequency synthesizer and the radio frequency analog front end are connected; the synchronous control circuit is connected with the frequency synthesizer and the radio frequency analog front end. The utility model is characterized in that the intermediate frequency is the nominal intermediate frequency 21.4MHz. The utility model has the advantages of stable performance, simplified structure, easily obtained parts, high system linearity degree and high dynamic range.

Description

高频地波雷达数字相干接收机 HFSWR digital coherent receiver

技术领域 FIELD

本实用新型涉及一种高频地波雷达接收机,具体地说,涉及一种基于线性调频体制的相干高频地波雷达数字接收机。 The present invention relates to a ground wave radar receiver, in particular, to a digital receiver coherently HFSWR system based chirp.

背景技术 Background technique

高频接收机工作于3~30MHz的短波波段。 HF receivers operating in the short wave band 3 ~ 30MHz. 在该频段内,外部干扰严重,为了满足灵敏度指标要求,并有效抑制镜向干扰,通常采用三次变频结构的超外差接收机。 In this band, external interference is serious, in order to meet the sensitivity of the indicator, and to effectively suppress interference mirror, usually three conversion superheterodyne receiver configuration. 对海探测的高频地波雷达接收机工作于短波波段,其结构也采用了与普通高频接收机类似的结构。 Sea detected HFSWR receiver operating in the short wave band, which uses a structure with a structure similar to the ordinary high-frequency receiver. 通信系统大都以单通道方式工作,一般不存在通道一致性等问题。 Most communication systems operating in single-channel mode, channel there is generally no consistency problems. 高频地波雷达的接收机通常以多通道方式工作,对于多通道接收机而言,复杂的多次变频结构给接收机的稳定性、通道一致性要求带来许多麻烦。 HFSWR receivers typically operate in a multi-channel mode, for a multi-channel receiver, the complex structure of a multiple frequency stability of the receiver, the channel coherence requires much trouble.

为简化雷达结构、提高接收机的稳定性,出现了基于软件无线电思想的一次混频的高频接收机(高频数字化接收机前端电路的设计,《电子工程师》2001年02期),这类接收机采用中频为40MHz以上高中频结构,工作于短波全频段。 To simplify the structure of the radar, to improve the stability of the receiver, there is a mixing of Software Radio frequency based receiver (high-frequency digital receiver front end circuit design, "Electronic Engineer" 2001 02), such using the receiver IF of 40MHz or more high-frequency structure, operating in a short full band.

对海探测的高频地波超视距雷达,其工作频率通常低于14MHz,针对高频地波超视距雷达的特点,可以适当降低中频,进一步简化雷达结构。 Sea ground wave detected HF OTH radar, which is usually lower than the operating frequency of 14MHz, the characteristics of high frequency ground wave OTH radar IF can be suitably reduced, to further simplify the structure of a radar.

高频地波雷达接收机均为相干接收机。 HFSWR receiver are coherent receiver. 相干接收机的本振信号、发射信号均由一个时钟源通过分频、倍频、混频等技术得到,其频率合成器十分复杂。 Coherent receiver local oscillator signal, by transmitting a clock signal by dividing the source, frequency, and mixing techniques, to give a frequency synthesizer is very complex.

发明内容 SUMMARY

本实用新型的目的是针对高频地波雷达实际使用的频段,选用较低中频,采用不同于一般高频接收机的模拟前端结构,采用全DDS(Digital Direct Synthesis)技术实现频率综合器,提供一种稳定可靠,具有较高性价比的高频地波雷达数字相干接收机。 The object of the present invention for the HFSWR frequency band actually used, the use of lower frequency, analog front end structure is different from the high-frequency receiver, all-DDS (Digital Direct Synthesis) frequency synthesizer technology, to provide a stable and reliable, has high cost HFSWR digital coherent receiver.

本实用新型的技术方案是:高频地波雷达数字相干接收机,它包括射频模拟前端、A/D采样电路、频率合成器、同步控制电路及数字信号处理芯片组成,射频模拟前端、A/D采样电路、数字信号处理芯片依次电连接,频率合成器与射频模拟前端相连接,同步控制电路与频率合成器及射频模拟前端相连接,其特征在于中频频率为标称中频21.4MHz。 Aspect of the present invention are: HFSWR digital coherent receiver, which comprises a radio frequency front end an analog, A / D sampling circuit, a frequency synthesizer, the synchronous control circuit and a digital signal processing chips, RF analog front end, A / D sampling circuit, a digital signal processing chip are electrically connected sequentially, the frequency synthesizer is connected to the RF analog front-end, the synchronization control circuit and a frequency synthesizer and an analog front end is connected to a radio frequency, characterized in that the nominal IF frequency of the IF 21.4MHz.

如上所述的高频地波雷达数字相干接收机,其特征在于所述射频模拟前端由天线开关,带通滤波器,混频器,低噪声放大器,晶体滤波器,放大器,晶体滤波器依次电连接组成。 HFSWR digital coherent receiver as described above, wherein the RF analog front end by the antenna switch, a band pass filter, a mixer, a low noise amplifier, crystal filters, amplifiers, sequentially electrically crystal filter connected components.

如上所述的高频地波雷达数字相干接收机,其特征在于所述频率合成器由两块完全相同型号的DDS芯片组成,输出二路斜率完全相同、起始频率相差21.4MHz的线性调频信号。 HFSWR digital coherent receiver as described above, wherein the frequency synthesizer by two identical models DDS chips, output Road identical slope, the initial frequency chirp signal phase difference of 21.4MHz .

如上所述的高频地波雷达数字相干接收机,其特征在于所述频率合成器输出的线性调频信号,发射与本振线性调频信号的重复周期相同,在每一周期的起始时刻,发射信号与本振信号的初始相位归零。 HFSWR digital coherent receiver as described above, wherein the frequency of the chirp signal output from the synthesizer, local oscillator emits repetition period of the same chirp signal, the starting time of each cycle, emission signal with initial phase of the local signal to zero.

如上所述的高频地波雷达数字相干接收机,其特征在于所述A/D采样电路的采样率为160KHz。 HFSWR digital coherent receiver as described above, wherein the sampling rate of A / D sampling circuit 160KHz.

具体地说,本实用新型一是将雷达的中频设定为标称中频21.4MHz,该中频下可使用价格低廉,性能优良的成品晶体滤波器;二是设计了不同于一般通信接收机的模拟前端结构,使其更适合高频段外部噪声较高、高频地波雷达收发共站的特点;三是设计严格控制初始相位的DDS频率合成技术,发射与本振信号均由DDS器件直接输出,大大简化了频率合成器;四是采用较低的采样率,使用一块数字信号处理芯片DSP即可完成数字下变频、FFT(快速傅立叶变换)及其它信号处理工作。 Specifically, the present invention is one radar IF is set to 21.4 MHz nominal intermediate frequency, the intermediate frequency can be used at low cost and excellent performance finished crystal filter; the second is different from the general design of an analog communication receiver front end structure, to make it more suitable for high external high frequency noise, co HFSWR transceiver station characteristics; three is designed to strictly control the initial phase DDS frequency synthesis technique, and transmitting the local oscillation signal output by the DDS devices directly, It simplifies the frequency synthesizer; Fourth lower sampling rate, using a digital signal processing chip DSP to handle digital down converter, an FFT (fast Fourier transform) processing, and other signals. 这些措施都有利于提高雷达接收机性能指标并降低成本。 These measures are conducive to improving the radar receiver performance and reduce costs.

为了实现上述目的,本实用新型采用了如下技术措施:1)采用一次混频,中频直接带通采样的结构;2)中频频率选用标称中频21.4MHz,中频滤波器选用中心频率标称值为21.4MHz的晶体滤波器;3)采用无高放的结构,带通滤波器与混频器直接连接,其间没有传统的高频放大器;4)使用100MHz以上时钟作为DDS的系统时钟,直接产生发射信号与本振信号。 To achieve the above object, the present invention adopts the following technical measures: 1) a configuration using a mixer, an intermediate frequency bandpass sampling directly; 2) selected nominal intermediate frequency 21.4 MHz IF, IF filter center frequency nominally selected 21.4MHz crystal filter; 3) a high discharge-free configuration, a bandpass filter and a mixer connected directly, without a conventional high frequency amplifier therebetween; 4) use DDS 100MHz more clock as a system clock, produced directly emitted signal and the local oscillator signal. 二路信号线性调频斜率相同,起始频率相差21.4MHz。 Road same chirp slope signal, a start frequency difference of 21.4MHz. 每一线性调频周期的起始时刻,发射信号与本振信号的初始相位相同;5)采用14位ADC器件对每一模拟通道的中频信号进行带通采样,采样率在60~160KHz之间,采样信号送至DSP;7)DSP芯片完成滤波、数字下变频及FFT算法,数据经USB或其它总线传输给外部计算机作后处理。 Each chirp starting time period, the same initial phase of the transmitted signal and the local signal; 5) 14-bit ADC device IF signal for each channel an analog bandpass sampling, the sampling rate is between 60 ~ 160KHz, sampled signal to DSP; 7) DSP filter chips is completed, the digital conversion and FFT algorithm, or other data via the USB bus to the external computer for processing.

本实用新型具有以下优点:①使用标称中频21.4MHz作为中频频率,一是可以从市场直接采购性能优良的中频滤波器,无需专门定制;二是在较低中频条件下,可采用较低采样率,降低了数字下变频的负担,直接由DSP即可完成数字下变频工作,不需要额外的硬件数字下变频电路;②这种接收机只有一次混频,模拟器件少,非线性产物相应减少,系统线性度得到提高;③混频器前无高放,提高了接收机的动态范围;④采用100MHz~160MHz的时钟信号作为DDS器件的系统时钟,DDS器件可直接输出满足要求的本振频率,即频率合成器不需其它变频电路;⑤利用数字滤波器保证滤波器带宽与有用信号带宽的一致性,实现最佳滤波。 The present invention has the following advantages: ① as the nominal IF 21.4MHz intermediate frequency, one can purchase a high performance IF filter directly from the market, without customized; two conditions at lower intermediate frequency, a lower sampling may be employed rate, reduces the burden of DDC, the direct conversion by the DSP to complete digital work, without requiring additional hardware digital conversion circuit; ② only once such a receiver mixer, less analog components, a corresponding reduction product linear , the linearity of the system is improved; ③ no mixer before high level, improve the dynamic range of the receiver; ④ 100MHz ~ 160MHz using clock signals as the system clock of the DDS device, DDS devices can be directly output to meet the requirements of the local oscillation frequency , i.e. without further conversion frequency synthesizer circuit; ⑤ using a digital filter with the filter bandwidth to ensure consistency of useful signal bandwidth, optimum filtered.

附图说明 BRIEF DESCRIPTION

下面结合附图和系统工作过程对本实用新型进一步说明。 In conjunction with the following drawings further illustrate the present invention and the system works right.

图1-本实用新型系统结构图;图1中,细实线表示的框图是接收机的硬件部分,粗实线是接收机的软件部分,其中:A1-接收天线;A2-是发射天线;1-天线开关,在雷达发射机与接收机共站时,防止发射信号直接进入接收机;2-带通滤波器,带宽与雷达工作频率相适应;3-混频器;4-低噪声放大器;5-晶体滤波器,标称中心频率21.4MHz;6-放大器;7-晶体滤波器,标称中心频率21.4MHz;8-A/D转换器;9-I/Q信号分离算法;10-数字下变频;11-第-次FFT;12-第二次FFT;21-系统时钟;22-同步控制器;23-DDS器件,用于产生线性调频的本振信号;24-DDS器件,用于产生线性调频的发射信号;25-功率放大器。 Figure 1 - a system configuration diagram of the present invention; FIG. 1, a block diagram of a thin solid line shows the hardware parts of the receiver, the thick solid line is the software portion of the receiver, wherein: A1- receiving antenna; A2- is the transmitting antenna; 1- antenna switch, when the radar transmitter and the receiver station common to prevent the transmission signal directly to the receiver; 2- bandpass filter bandwidth adapted to the operating frequency of the radar; 3- mixer; 4- low noise amplifier ; 5- crystal filter, the nominal center frequency of 21.4MHz; 6- amplifier; 7- crystal filter, the nominal center frequency of 21.4MHz; 8-A / D converter; 9-I / Q signal separation algorithm; 10- digital downconversion; 11- - of times FFT; 12- second FFT; 21- a system clock; 22- synchronous controller; 23-DDS devices, a local oscillation signal generated chirp; 24-DDS device, with to generate a chirped transmission signal; a power amplifier 25.

图2是图1中模拟前端的电路图。 FIG 2 is a circuit diagram of an analog front end of FIG.

具体实施方式 detailed description

参见图1,本实用新型的具体实施例中,高频地波雷达数字相干接收机它包括:由1-7组成的射频模拟前端,A/D采样电路8,由23与24组成的频率合成器,同步控制器22及数字信号处理芯片DSP(9-12在其中进行),射频模拟前端、A/D采样电路8、数字信号处理芯片DSP(进行9-12的工作的器件)依次电连接,频率合成器与射频模拟前端相连接,同步控制电路与频率合成器及射频模拟前端相连接其特征在于中频频率为标称中频21.4MHz。 Referring to Figure 1, the present invention embodiments, HFSWR digital coherent receiver comprising: 8, 23 and 24 by a frequency synthesis RF analog front-end component, A / D sampling circuit 1-7 composed of , a synchronous controller 22 and a digital signal processing chip DSP (9-12 therein), an analog front end RF, a / D sampling circuit 8, a digital signal processing chip DSP (9-12 working device) is electrically connected sequentially , the frequency synthesizer is connected to the RF analog front-end, the synchronization control circuit and a frequency synthesizer and RF analog front end is connected wherein the nominal IF frequency of the IF 21.4MHz.

图1对应的系统工作过程描述。 1 corresponds to the system working process described in FIG.

21是系统时钟,频率在100MHz~300MHz之间。 21 is the system clock frequency between 100MHz ~ 300MHz. 23、24是完全相同的DDS芯片。 23 and 24 are identical DDS chip. 24输出发射信号。 24 outputs the transmission signal. 23输出本振信号。 23 outputs the local oscillator signal. 本振信号与发射信号的线性调频斜率完全相同,但频率相差21.4MHz。 Chirped local oscillator signal and the slope of the transmitted signal are identical, but the frequency difference of 21.4MHz. 24产生的发射信号经25放大至需要的强度,由发射天线A2向空中发射。 Transmission signal 24 generated by 25 is amplified to a required strength, emitted into the air by the transmitting antenna A2. 所发射的电磁波与目标作用后,将产生反射或散射。 After the action of the electromagnetic waves emitted by the target, the reflection or scattering.

目标回波进入接收天线A1后,首先经过天线开关1。 After entering the target echo receiving antenna A1, a first switch through the antenna. 天线开关的作用是防止发射天线所发射的直达波进入接收机而堵塞接收机。 Antenna switch action is to prevent the transmitting antenna into the receiver of the direct wave emitted clogging receiver. 因此发射机工作时,天线开关1应处于断开状态。 Therefore, when the transmitter is operating, the antenna switch should be in an OFF state. 天线开关1输出的信号中含有回波信号及外部干扰,通过带通滤波器2滤掉部分工作频带以往的干扰,以提高信号质量。 Antenna switch signal output from the echo signals and contains external interference, the interference portion 2 of the conventional filtered through a bandpass filter operating frequency band, to improve signal quality.

目标回波随之与本振信号(由23输出)分别同时作用于混频器3,两信号经混频后形成两个信号分量。 Target echo along with a local oscillator signal (output of 23) are simultaneously applied to the mixer 3, after two mixed signal components of two signals are formed. 频率较低的信号分量是以21.4MHz为载波、消除了调频斜率的信号,是我们所需要的信号。 Lower frequency signal components is 21.4MHz for the carrier, eliminating the slope of the FM signal is a signal that we need. 另一个频率较高,将被后续滤波器滤除。 Another higher frequency, are filtered out subsequent filter.

混频器3输出的信号较弱,经低噪声放大器4放大后,经过第一个晶体滤波器5滤波,形成基带信号。 Signal output from the mixer 3 is weak, amplified by the low noise amplifier 4, a crystal filter 5 through the first filter, a baseband signal is formed. 该基带信号经放大器6进一步放大,送至第二个晶体滤波器7滤波。 The baseband signal is further amplified by the amplifier 6, a crystal filter to the second filter 7. 晶体滤波器7输出的基带信号被A/D转换器8带通采样,生成数字信号送至DSP处理。 The baseband signal output from the crystal filter 7 is supplied to the DSP processing A / D converter 8 bandpass sampling generates a digital signal.

本实用新型所采用的前端结构显著不同于传统短波接收机的地方是,本实用新型把传统接收机中混频器前的低噪声放大器置于混频器之后。 A front end structure of the present invention used significantly different from conventional shortwave receiver where the present invention prior to the conventional receiver low noise amplifier mixer was placed after the mixer. 好处是可以较大范围地提高系统的线性度,增加接收机的动态范围,代价是灵敏度指标略有下降。 Benefits can be improved to a large range of linearity of the system, increase the dynamic range of the receiver, the price sensitivity index is slightly decreased. 接收机对灵敏度指标的要求是,灵敏度应小于外部噪声。 Receiver sensitivity requirements index is less than the sensitivity to external noise. 对于微波雷达而言,外部噪声电平很低,灵敏度指标要求相应就高。 For microwave radar, the external noise level is low, the indicator corresponding to high sensitivity. 对高频地波雷达而言,外部噪声远高于机内噪声,过高的接收机灵敏度指标没有意义。 For HFSWR, the external noise is much higher than the machine noise, high receiver sensitivity index meaningless. 本实用新型中,低噪声放大器后置虽然影响了接收机的灵敏度,但最后的灵敏度指标仍然比外部噪声低,不会影响接收机的总体性能指标。 The utility model in the low-noise amplifier set although the impact of the sensitivity of the receiver, but the final sensitivity index is still lower than the external noise, does not affect the overall performance of the receiver.

本实用新型的频率合成器主要由二块DDS器件构成,二路信号线性调频斜率相同,起始频率相差21.4MHz。 The present invention is a frequency synthesizer DDS is mainly composed of two components, the slope of the linear FM signal is identical Road, starting frequency difference of 21.4MHz. 每一线性调频周期的起始时刻,发射信号(由24输出)与本振信号(由23输出)的初始相位相同。 Each chirp starting time period, the transmitted signal (from the output 24) with the same local oscillator signal (output of 23) of the initial phase. 这一技术使得频率合成器一步到位,结构十分简单,同时又能保证信号的相干性。 This technology allows the frequency synthesizer in one step, the structure is very simple, while ensuring coherence signal.

本方案的数字接收机没有采用硬件数字下变频电路,直接由DSP完成数字下变频工作。 The digital receiver of the program does not use the hardware digital conversion circuitry, digital direct frequency conversion work completed by the DSP. A/D转换器的采样率按照带通采样的要求设计。 Sampling rate of A / D converter according to claim bandpass sampling design. 高频地波雷达属于相干接收机,需要获取回波的相位信息,即采样信号须变为相互正交的基带I路和Q路信号。 HFSWR belonging coherent receiver needs to obtain the phase information of the echo, the sampling signal has to be perpendicular to each other becomes the base band I and Q signals. 由DSP对采样信号通过数字处理(例如多相滤波)的部分实现基带I路和Q路信号的分离。 By the DSP sampling signal by digital processing (e.g. polyphase filtering) the separation portion of the baseband I and Q-signals.

本实例中所用基准时钟源是120MHz有源晶体振荡器,经过时钟驱动电路后,作为DDS器件AD9854的系统时钟。 As used in the present example the reference clock source is a crystal oscillator 120MHz active, after the clock driving circuit, the system clock as the AD9854 DDS device. 在120MHz系统时钟条件下,AD9854输出信号最高频率可达48MHz。 Under conditions of the system clock 120MHz, AD9854 output signal of maximum frequency of 48MHz. 一路AD9854输出射频信号至发射机,另一路AD9854输出本振信号。 All the way to the transmitter radio frequency signal output AD9854, AD9854 another output channel local oscillator signal. 在线性调频工作方式下,除起始频率控制字不同(本振信号与发射信号的起始频率相差21.4MHz)外,这两路DDS器件所有其它控制字应完全相同,以保证雷达相干性,以及中频输出信号的纯净度。 In linear FM mode of operation, the different control words in addition to the start frequency (starting frequency of the LO signal and the transmission signal phase difference 21.4 MHz), the two way all other DDS device control words should be identical, to ensure coherence radar, IF output signal and purity. 在线性调频信号的起始期,通过强制复位,保证二路DDS器件输出的线性调频信号的初始相位均为0。 Start Time of the linear FM signal, by forced reset, to ensure the initial phase of the chirp signal output from DDS devices are Road 0.

图2是一个中心工作频率11~15MHz的高频地波雷达接收机的模拟前端的一个电路图实例。 FIG 2 is a circuit diagram of an example of an analog front end center operating frequency of the HF radar receiver of 11 ~ 15MHz. 图中虚线框左上角的数字对应图1中模块的数字。 FIG digital numbers correspond to the top left of the dashed box in FIG. 1 module.

图2中收发开关选用SA630D,收发隔离度>70dB;带通滤波器为SBP-13,作用是抑制镜频和中频干扰。 FIG 2 is a transceiver switch selection SA630D, transceiver isolation> 70dB; band pass filter SBP-13, and the role is to inhibit the IF image frequency interference. SBP-13的3dB带宽为4MHz,抑制40dB频率为10.5MHz和17.5MHz。 SBP-13 3dB bandwidth is 4MHz, suppressing 40dB and frequency of 10.5MHz 17.5MHz. 对中频21.4MHz的抑制大于45dB,对镜频55.8MHz的抑制大于62dB,可满足抑制上述干扰的需要。 Inhibition of 21.4MHz intermediate frequency is greater than 45dB, 55.8MHz image frequency suppression is greater than 62dB, to meet the need to suppress such interference. 为了提高动态范围,在本实例中,采用了高本振的混频器HAS-3H,本振工作电平为17dBm。 In order to improve the dynamic range, in the present example, using a high local oscillator mixer HAS-3H, LO operating level is 17dBm. 由DDS输出的本振信号强度不足以直接驱动混频器HAS-3H,故在DDS输出的本振信号之后加入一个本振放大器RF2137。 Local signal intensity of the DDS output is insufficient to directly drive the mixer HAS-3H, it is after the local oscillation signal output from the addition of a DDS LO amplifier RF2137.

为了保证一定的系统灵敏度,在混频器之后立即连接一个低噪声放大器GALI-5。 In order to ensure a certain degree of sensitivity of the system after the mixer is connected a low-noise amplifier GALI-5 immediately. 为了保持通道稳定,一般不将多个放大器相连,否则会因增益太高,导致不稳定性。 To maintain a stable channel, not normally connected to a plurality of amplifiers, otherwise they will gain is too high, leading to instability. 因此在第一个GALI-5之后接入中心频率为21.4M的晶体滤波器21.4MB4F。 Therefore, after the first access to a GALI-5 center frequency of the crystal filter 21.4MB4F 21.4M. 随后,信号AD603和GALI-5进一步放大,使其满足后续A/D采样的要求。 Then, the signal AD603 GALI-5, and further amplified to satisfy requirements of the subsequent A / D sampling. 另外放大器不是理想的线性器件,会产生谐波和交调干扰,在最后一级放大器之后放置一个滤波器,能够有效抑制放大器产生的谐波和交调干扰。 Further amplifiers are not linear over the device, will produce harmonics and intermodulation interference, a filter is placed after the last stage amplifier, the harmonics can be effectively suppressed, and crosstalk produced by the amplifier. 使A/D采样的信号更加纯净。 The A / D sampling a signal more pure.

需要特别说明的是,晶体滤波器21.4MB4F和21.4C3的输入输出阻抗为1.5KΩ/2pF,与50Ω相差很远,AD603的输出阻抗只有2Ω。 Of particular note, the crystal filter 21.4MB4F 21.4C3 and input and output impedance 1.5KΩ / 2pF, and very far 50Ω output impedance is only AD603 2Ω. 晶体滤波器输入输出阻抗只有在匹配条件下才有最优的性能,因此,各级器件之间应仔细设计匹配电路。 Crystal filter input and output impedance matching condition have only under optimum performance, therefore, should be carefully design the matching circuit between the device levels. 本实例中,我们采用结构简单的L网络阻抗变换来实现晶体滤波器的匹配。 In this example, we use a simple structure to implement an impedance transformation network L matched crystal filter.

据带通采样理论,在21.4MHz中频下,可采用160KHz的采样率进行A/D转换。 According bandpass sampling theory, at 21.4MHz intermediate frequency, may be employed 160KHz sampling rate A / D conversion. 利用多相滤波的办法,形成二路完整的I/Q信号,每路信号的数据率为80kHz。 Polyphase filtering approach, a complete two-way I / Q signal, the data rate of each signal 80kHz. 对每一路信号进行滤波和抽取,总的抽取率为256,使数据率降至312Hz。 Each channel signal is filtered and the extraction, the extraction rate of the total 256, so that the data rate to 312Hz. 对每一线性调频期间的I路信号作为实部,Q路信号作为虚部,进行傅立叶变换,得到不同线性调频周期期间的距离回波信号,对特定距离元上的回波信号按先后顺序排列,作为傅立叶变换的输入信号,作傅立叶变换处理,即可得到该距离上回波信号的多普勒谱。 For the I signal during each chirp as a real part, Q-channel signal as an imaginary part, Fourier transform, obtained from the echo signals during different periods chirp, echo signals are arranged on a certain distance element according to the order as an input signal of the Fourier transform, the Fourier transform processing, can be obtained from the Doppler spectrum of the echo signal.

Claims (5)

  1. 1.高频地波雷达数字相干接收机,它包括射频模拟前端、A/D采样电路、频率合成器、同步控制电路及数字信号处理芯片组成,射频模拟前端、A/D采样电路、数字信号处理芯片依次电连接,频率合成器与射频模拟前端相连接,同步控制电路与频率合成器及射频模拟前端相连接,其特征在于中频频率为标称中频21.4MHz。 1. HFSWR digital coherent receiver, which comprises a radio frequency front end an analog, A / D sampling circuit, a frequency synthesizer, the synchronous control circuit and a digital signal processing chips, RF analog front end, A / D sampling circuit, a digital signal sequentially processing chip electrically connected to the RF frequency synthesizer is connected to the analog front end, the synchronization control circuit and a frequency synthesizer and an analog front end is connected to a radio frequency, characterized in that the nominal IF frequency of the IF 21.4MHz.
  2. 2.如权利要求1所述的高频地波雷达数字相干接收机,其特征在于所述射频模拟前端由天线开关,带通滤波器,混频器,低噪声放大器,晶体滤波器,放大器,晶体滤波器依次电连接组成。 2. HFSWR the digital coherent receiver of claim 1, wherein said RF analog front end by the antenna switch, a band pass filter, a mixer, a low noise amplifier, a crystal filter, an amplifier, crystal filters are sequentially electrically connected components.
  3. 3.如权利要求1或2所述的高频地波雷达数字相干接收机,其特征在于所述频率合成器由两块完全相同型号的DDS芯片组成,输出二路斜率完全相同、起始频率相差21.4MHz的线性调频信号。 HFSWR as claimed in claim 1 or 2 or a digital start frequency requirement coherent receiver, characterized in that the frequency synthesizer by two identical models DDS chips, the same as the slope of the output Road, chirp signal of 21.4MHz phase difference.
  4. 4.如权利要求3所述的高频地波雷达数字相干接收机,其特征在于所述频率合成器输出的线性调频信号,发射与本振线性调频信号的重复周期相同,在每一周期的起始时刻,发射信号与本振信号的初始相位归零。 4. HFSWR the digital coherent receiver of claim 3, wherein the frequency of the chirp signal output from the synthesizer, the transmit local oscillation repetition period identical chirp signals in each cycle starting time, and the initial phase of the transmission signal of the local oscillator signal to zero.
  5. 5.如权利要求1或2或4所述的高频地波雷达数字相干接收机,其特征在于所述A/D采样电路的采样率为160KHz。 5. HFSWR number 1 or 2 or as claimed in claim 4, wherein the coherent receiver, characterized in that the sampling rate of the A / D sampling circuit 160KHz.
CN 200420057632 2004-12-13 2004-12-13 High frequency ground rada digital coherent receiver CN2762154Y (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101833083A (en) * 2010-04-16 2010-09-15 武汉大学 Radio-frequency front-end circuit of L-band radar receiver
CN102608421A (en) * 2012-03-07 2012-07-25 北京无线电计量测试研究所 Frequency range extender for Fourier analysis for phase noise
CN101484827B (en) 2006-07-13 2012-08-15 艾利森电话股份有限公司 A method and radar system for coherent detection of moving objects
CN102841336A (en) * 2012-09-04 2012-12-26 中船重工鹏力(南京)大气海洋信息系统有限公司 High-frequency ground wave radar multi-frequency signal coherent receiver
CN103630894A (en) * 2013-06-04 2014-03-12 中国科学院电子学研究所 Broadband multichannel coherent radar imaging system and control method thereof
WO2015176250A1 (en) * 2014-05-21 2015-11-26 武汉德威斯电子技术有限公司 Portable high-frequency ground wave radar for surveying ocean dynamics parameters
CN105824020A (en) * 2016-03-12 2016-08-03 浙江大学 Subcarrier-modulation-based continuous wave Doppler radar sensor and motion demodulation method

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101484827B (en) 2006-07-13 2012-08-15 艾利森电话股份有限公司 A method and radar system for coherent detection of moving objects
CN101833083A (en) * 2010-04-16 2010-09-15 武汉大学 Radio-frequency front-end circuit of L-band radar receiver
CN102608421A (en) * 2012-03-07 2012-07-25 北京无线电计量测试研究所 Frequency range extender for Fourier analysis for phase noise
CN102841336A (en) * 2012-09-04 2012-12-26 中船重工鹏力(南京)大气海洋信息系统有限公司 High-frequency ground wave radar multi-frequency signal coherent receiver
CN103630894A (en) * 2013-06-04 2014-03-12 中国科学院电子学研究所 Broadband multichannel coherent radar imaging system and control method thereof
CN103630894B (en) * 2013-06-04 2016-08-24 中国科学院电子学研究所 Broadband multi-channel coherent radar control method of the imaging system
WO2015176250A1 (en) * 2014-05-21 2015-11-26 武汉德威斯电子技术有限公司 Portable high-frequency ground wave radar for surveying ocean dynamics parameters
CN105824020A (en) * 2016-03-12 2016-08-03 浙江大学 Subcarrier-modulation-based continuous wave Doppler radar sensor and motion demodulation method
CN105824020B (en) * 2016-03-12 2018-06-12 浙江大学 Continuous wave doppler radar motion sensor and demodulation of the subcarrier modulation method

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