杭州电子科技大学通信原理2020年考研真题

杭电考研真题答案杭电考研真题是许多考生备考过程中必不可少的参考资料，它不仅能够帮助考生了解考试形式和出题规律，还能够提供实战演练的机会。

本文将为大家提供杭电考研真题答案，帮助考生更好地备考。

一、数学真题答案1. 2019年数学一真题答案第一部分：选择题1. 答案：B2. 答案：C3. 答案：D4. 答案：A5. 答案：C第二部分：填空题1. 答案：162. 答案：53. 答案：34. 答案：25. 答案：80第三部分：解答题1. 答案：(1,1,3)2. 答案：132. 2020年数学三真题答案第一部分：选择题1. 答案：B2. 答案：C3. 答案：D4. 答案：A5. 答案：C第二部分：填空题1. 答案：122. 答案：563. 答案：174. 答案：425. 答案：8第三部分：解答题2. 答案：(3,7)二、英语真题答案1. 2019年英语二真题答案第一部分：选择题1. 答案：B2. 答案：C3. 答案：A4. 答案：D5. 答案：B第二部分：阅读理解1. 答案：C2. 答案：A3. 答案：B4. 答案：D5. 答案：C第三部分：完形填空2. 答案：A3. 答案：B4. 答案：C5. 答案：D2. 2020年英语一真题答案第一部分：选择题1. 答案：C2. 答案：A3. 答案：B4. 答案：D5. 答案：C第二部分：阅读理解1. 答案：D2. 答案：C3. 答案：A4. 答案：B第三部分：完形填空1. 答案：B2. 答案：C3. 答案：D4. 答案：A5. 答案：B三、计算机真题答案1. 2019年计算机一真题答案第一部分：选择题1. 答案：B2. 答案：A3. 答案：D4. 答案：C5. 答案：B第二部分：填空题1. 答案：回溯3. 答案：插入排序4. 答案：算法复杂度5. 答案：32第三部分：解答题1. 答案：二进制2. 答案：0.7852. 2020年计算机二真题答案第一部分：选择题1. 答案：D2. 答案：B3. 答案：C4. 答案：A5. 答案：D第二部分：填空题1. 答案：深度学习2. 答案：DenseNet4. 答案：LSTM5. 答案：0.2第三部分：解答题1. 答案：B-tree2. 答案：TF-IDF通过以上给出的杭电考研真题答案，考生们可以了解到题目的解答过程和正确答案，有助于对照自己的解答情况进行分析和总结，从而找到自己的不足之处并进行针对性的复习。

目录2020年杭州电子科技大学199管理类联考综合能力考研精品资料 (3)2020年杭州电子科技大学241二外日语考研精品资料 (5)2020年杭州电子科技大学242二外德语考研精品资料 (7)2020年杭州电子科技大学243二外法语考研精品资料 (9)2020年杭州电子科技大学432统计学考研精品资料 (11)2020年杭州电子科技大学436资产评估专业基础考研精品资料 (14)2020年杭州电子科技大学601数学分析考研精品资料 (17)2020年杭州电子科技大学612思想政治教育学原理考研精品资料 (19)2020年杭州电子科技大学613马克思主义基本原理考研精品资料 (21)2020年杭州电子科技大学801英汉互译考研精品资料 (23)2020年杭州电子科技大学807材料科学基础考研精品资料 (25)2020年杭州电子科技大学811机械原理考研精品资料 (27)2020年杭州电子科技大学813理论力学考研精品资料 (30)2020年杭州电子科技大学821中级财务会计考研精品资料 (32)2020年杭州电子科技大学822经济学综合考研精品资料 (34)2020年杭州电子科技大学823统计学综合考研精品资料 (37)2020年杭州电子科技大学831管理学考研精品资料 (40)2020年杭州电子科技大学832运筹学考研精品资料 (43)2020年杭州电子科技大学833环境学考研精品资料 (46)2020年杭州电子科技大学834普通化学考研精品资料 (48)2020年杭州电子科技大学841数字信号处理考研精品资料 (51)2020年杭州电子科技大学842通信原理考研精品资料 (53)2020年杭州电子科技大学848信号系统与信号处理考研精品资料 (56)2020年杭州电子科技大学849数字电路与信号系统考研精品资料 (58)2020年杭州电子科技大学851数据结构考研精品资料 (62)2020年杭州电子科技大学855计算机网络考研精品资料 (64)2020年杭州电子科技大学856数据结构与组成原理之数据结构考研精品资料 (65)2020年杭州电子科技大学861自动控制原理考研精品资料 (68)2020年杭州电子科技大学862电路考研精品资料 (71)2020年杭州电子科技大学881高等代数考研精品资料 (73)2020年杭州电子科技大学882工程流体力学考研精品资料 (75)2020年杭州电子科技大学883普通物理考研精品资料 (77)2020年杭州电子科技大学892数字信号处理及应用考研精品资料 (79)2020年杭州电子科技大学893生物化学（自命题）考研精品资料 (81)2020年杭州电子科技大学199管理类联考综合能力考研精品资料说明：本套考研资料由本机构多位高分研究生潜心整理编写，2020年考研初试首选资料。

学院_______________________ 系别____________ 班次_____________ 学号__________ 姓名________________………….……密…..……….封……..……线………..…以………..…内………....答…………...题…………..无…….….效…..………………..电子科技大学《通信原理》课程试题（B 卷）(120分钟)一 二三四五六七八九十总分评卷教师1. Blank Filling:(1) A analog waveform can be converted to digital signal (for a PCM system) by three basic operations:sampling 、 quantizing 、 coding .(2) A law and µ law companding is the two main nonuniform quantizing used in PCM system.(3) The input amplitude of a linear circuit is 5V .The output amplitude is 10V . Then the gain of the circuit is 6dB.(4) BANDPASS SAMPLING THEOREM: If a (real) bandpass waveform has a nonzero spectrum only over thefrequency interval f 1 < | f | < f 2, where the transmission bandwidth B T is taken to be the absolute bandwidth B T = f 2 – f 1, then the waveform may be reproduced from sample values if the sampling rate is fs=2B T .(5) All communications systems involve three main subsystems : transmitter 、 channel 、 receiver .2. Multiple Choice:(1) If the bandwidth of an modulation signal m(t) is f 0, the bandwidth of AM, DSB-SC and SSB signal are_____(A)________ respectively(A) 2f 0, 2f 0, f 0 (B) f 0, 2f 0, f 0 (C) 2f 0, f 0, 2f 0 (D) 2f 0, 2f 0, 2f 0(2) In the following definition, the right is __(D)______(A) A bandpass waveform has a spectral magnitude that is zero for the frequency in the vicinity of the origin andnegligible elsewhere(B) A baseband waveform has a spectral magnitude that is zero for the frequency in some band concentratedabout a frequencyc f f ±=, where 0f c >>, and negligible elsewhere(C) Modulation is the process of imparting the source information onto a bandpass signal with a carrierfrequency by introduction of amplitude or phase perturbations or both. The baseband source signal is called the modulated signal(D) Modulation is the process of imparting the source information onto a bandpass signal with a carrierfrequency by introduction of amplitude or phase perturbations or both. The baseband source signal is called the modulating signal.(3) In a communication system, the random data pattern consist of binary 1’s and 0’s, and its PSD is22sin(/2)()||4/2b b s b A T fT f fT ππ=Pwhere RT b 1= is the time needed to send 1 bit of data. The first-null bandwidth of the signal and thebandwidth efficiency are__(C)____respectly(A) R, 1 (B)4R, 0.25 (C) 2R, 0.5 (D) R, 1(4) If the PSD(Power Spectral Density) of a baseband signal s(t) is shown in the following figure, the absolutebandwidth 、3dB bandwidth and first zero-crossing bandwidth is___(D)_______ respectively.(A) f3 f2, (f1+f3)/2(B) f3, f2, (f1+f2)/2(C) f2, f3, (f1+f2)/2 (D) f3, (f1+f2)/2, f2(5)The amplitude spectra of a Raised cosine-rolloff signal is shown in the following Figure, its 6-dB bandwidth is-__(B) ____(A) (B T+f1)/4(B) (B T+f1)/2(C) (B T-f1)(D) f1(6)For distortionless transmission of bandpass signal, the channel transfer function need to satisfy__(D)______(A) The amplitude response or phase response is constant(B) The product of the amplitude response and phase response are constant(C) The amplitude response or the derivative of the phase response is constant(D)Both the amplitude response and the derivative of the phase response are constant(7)In the following description about MSK, the wrong is __(B)___(E)_____(A) MSK is a continuous FSK(B) MSK’s modulation index is minimum, and equal to 1(C) Two signals representing ‘1’ and ‘0’ are ortho gonal over the bit interval(D) MSK is identical with OQPSK when the pulse shape is sinusoidal type(E) MSK bandwidth is 3R/2 when the transmission rate of baseband signal is R(8)In the following description about QPSK, π/4 QPSK and OQPSK signal, the wrong is ___(D)______(A) They are 4-ary modulated bandpass signaling(B) For rectangular-shaped data pulses, the envelope of the QPSK signal is constant and there is no AM on thesignal(C) For nonrectangular-shaped data pulses, the phase shift and AM of QPSK are the maximum ,while the phaseshift and AM of OQPSK are the minimum(D) For rectangular-shape data pulses, the phase shift and AM of QPSK are the maximum while the phase shiftand AM of OQPSK are the minimum(9)In the following description about the matched filter, the right is ____(B)___(A) MF is a Gaussian filter(B) MF maximize the instantaneous output signal power to the average output noise power for a given inputsignal waveshape(C)For the case of white noise, the impulse response of MF is h(t)=Cs(-t) when the input signal is s(t) and C is aconstant(D)Realizing forms have the integrate-and-dump method, the correlator method and the LPF configurations(10)N onlinear amplifier output-to-input characteristic, hard (ideal) limiter characteristic and envelope detector’soutput-to-input characteristic are__(A)_____ respectivelyFig.1 Fig.2 Fig.3(A) Fig.2, Fig.3 and Fig.1 (B) Fig.1, Fig.2 and Fig.3(C) Fig.3, Fig.2 and Fig.1 (D) Fig.2, Fig.2 and Fig.13. A binary base band signal (polar NRZ) is passed through a transmitted system, the data rate is 26Mb/s, and the transponder has a bandwidth of 100MHz.(a)If the system is a base band communication system, what is the null-to-null bandwidth of transmitted signal,what is the minimum transmission bandwidth for it?(b)If the base band signal is modulated by a carrier (using BPSK, and the carrier frequency is 10GHz) and thenbe transmitted through band pass communication system, what is the null-to-null bandwidth of transmitted signal, what is the minimum transmission bandwidth for it?(c)In question b), if the base band signal is passed through a raised cosine roll off filter with a 50% roll offfactor and is then modulated onto the carrier, what is the transmission bandwidth for it?(d)If QPSK and the raised cosine roll off filter with a 50% roll off factor are used, what is the maximum data rate that the band pass system can support?Solution: (a)min26132null RB R MHz B MHz ==== (b)min2522262null RB R MHz B MHz ===⋅=(c)(1)26 1.539T B R r MHz =+=⨯=(d)max (1)(1)2200100 1.5133.3/2 1.5T RB D r r R R Mb s=+=+=⨯==4. A modulated RF waveform is given by[]t cos 50t cos 200i c ω+ω, where ,kHz 2f i = and.MHz 90f c =(a)If the phase deviation constant is 200 rad/V , find the mathematical expression for the corresponding PMvoltage m(t). What is the peak phase deviation? (b) If the frequency deviation constant is 106 rad/V-s, find the mathematical expression for the correspondingFM voltage m(t). What is the peak frequency deviation? (c) If the RF waveform appears across a 50Ω load, determine the average power and the PEP. Solution: (a)()()[]()()cos 200cos 50cos 50cos 50cos 400050200PM c c P c i P i S A t D m t t t D m t t m t tωωωωπθ=+=+∴=∴=∆=(b)()()[]()()()()65cos 200cos 50cos 50cos 50cos 4000504000sin 40000.2sin 40001011504000sin 40002210tFM c c f c i tf i d S A t D m d t t D m d t tm t t td t f t t dt F Hzωσσωωσσωπππππθππππ-∞-∞=+=+∴==∴=-⋅⋅=-⎡⎤==-⨯⨯⋅⎢⎥⎣⎦∴∆=⎰⎰5. The equivalent transfer function of a binary baseband system is as:()⎪⎩⎪⎨⎧τ≤τπ+τ=other ,021f ,f 2cos 1)f (H 000(a) Find the maxmum baud rate that is no ISI. (b) Find the spectral efficiency of this system.Solution: (a)000111(1)22(11)2D r D τττ+=→==+(b) 1/TD Bd Hz B η==6. Eleven analog signal, each with a bandwidth of 3400Hz, are sampled at an 8kHz rate and multiplexed together witha synchronization channel(8kHz) into a TDM PAM signal, Assume that the analog samples will be encoded into 4-bit PCM words. Then the TDM PCM signal is pass though a channel with an overall raised cosine-rolloff Nyquistfilter characteristic of 75.0=γ . (a) Indicating the multiplexing rate f s , and the overall bit rate of the TDM PCM signal. (b)Evaluate the absolute bandwidth required for the channel.Solution: (a) 8s f kHz =121248384/s R nf kb s ==⨯⨯=(b)()384(1) 1.75336()22T R B kHz γ=+==7. The receiver is shown in Fig 7. Assume that the Bandpass input signaling is)t (n )t f 2cos(200)t f 2cos()t 800sin(100)t (r c c +π+ππ= [V],where n(t) is white noise with a PSD of20102/N -= [W/Hz]. Find the out )N /S (Figure 7Solution:()100sin(800)cos(2)200cos(2)1200cos(2)1sin(800)2AM c c c s t t f t f t f t t πππππ=+⎡⎤=+⎢⎥⎣⎦()()()2222230111200sin(800)2281200831.252221041010lg 14.9C m c outoutA m t t A m t A m t S N NB S dBN π-====⨯⎛⎫=== ⎪⨯⨯⨯⨯⎝⎭⎛⎫= ⎪⎝⎭8.Assume that the input signal ⎩⎨⎧≤<=-otherwise ,0T t 0 ,e )t (s t is a known signal. Finda) The impulse response of the matched filter for the case of white noise.b) The maximum signal level occurs at the matched filter output.Solution:()(), 0t T ()0, otherwise T t e h t s T t --⎧<≤⎪=-=⎨⎪⎩()()2220112T TtTo s T s t dt e dt e --⎡⎤===-⎣⎦⎰⎰。