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【判断题】
因压缩比越高,功率越大,故压缩比越高越好。
A.
正确
B.
错误
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举一反三
【简答题】普通调幅信号的()与调制信号的()
【单选题】are you a male
A.
yes
B.
no
C.
i don't know
D.
nothing
【单选题】In drawing up the plan, they went to the library to _____ many books. [     ]
A.
bring up
B.
referr to
C.
look for
D.
try on
【简答题】A.packing up to go abroad. B.Brushing up on her English. C.Drawing up a plan for her English course. D.Applying for a visa to the United States.
【简答题】A.Packing up to go abroad. B.Brushing up on her English. C.Drawing up a plan for her English course. D.Applying for a visa to the United States.
【简答题】用低频信号去改变高频信号______的过程,称为调幅。普通调幅信号的特点是:已调信号的包络变化与______信号变化规律相同,内含______分量,______分量和______分量。
【单选题】普通调幅信号电流的频谱和LC并联谐振回路阻抗的幅频特性和相频特性如图所示,则产生的普通调幅信号为( )。【图片】
A.
u AM = R e I sm [1 + m a cos( W t - p / 4)]cos w c t
B.
u AM = R e I sm (1 + m a cos W t )cos w c t
C.
u AM = R e I sm [1 + 0.707 m a cos( W t - p / 4)]cos w c t
D.
u AM = R e I sm (1 + 0.707 m a cos W t )cos w c t
【判断题】普通调幅信号的包络与调制信号的幅度变化规律相同。
A.
正确
B.
错误
【简答题】You might just as well tell the manufacturer that male customers ________ not like the design of the furniture. A.must B.shall C.may D.need
【单选题】解调哪种信号需要载波插入_____。
A.
普通调幅信号
B.
调频信号
C.
单边带抑制载波信号
D.
单边带全载波信号
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