• 2022-05-26
    设r为接收机输入端信噪比,则2ASK调制系统相干解调的误码率计算公式为 ( )
    A:
    B:
    C:
    D:
  • B

    举一反三

    内容

    • 0

      c(NaCl) = 0.1mol/L的NaCl水溶液的质子平衡式是( )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/9b7be57053c646c5aa738c0535f65770.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/b1382afa5c5d4951aef3b50dec2d582d.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/1887e7216893436fb1e402c407d2ffaa.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/c2d7158b33f44091a8b75598cbb3245d.png" />

    • 1

      依发电惯例,并励直流电动机的电压平衡方程可写成( )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/ba26910c3c8d43f3a8de1f46e82f946e.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/7609c39c539e4b11872334eef825e47e.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/a3c975313b99405da12dba5b1deba6eb.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/7e29646ee8764fc68d50ff9f89df6f6b.png" />

    • 2

      用莫尔法测定氯离子时,下列离子对测定结果没有干扰的是( )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/728e724646424bc29bfdde8843811830.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/2817f15029de441b8ade7fa47e0dbad4.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/8c7213f65d54485491577b8a9a8eadaa.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/a132f00401f8474eaf89e33d7d2113a6.png" />

    • 3

      偏心受压构件计算中,通过哪个因素来考虑二阶偏心矩的影响( )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/644d7258ea6b4667af5e583bc17ef89e.png" /> B: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/2a0b0bdd8f4641fc8e0e811f749223e2.png" /> C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/5faa01da09ba40ffbf09b6e3c8a587db.png" /> D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/be2081fe40ce490c975864d1cb9b2cb4.png" />

    • 4

      混凝土强度等级由立方体抗压试验后的( )。 A: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/bf4e3c08bb664f88a72fad7dbd80223b.png" />确定 B: 平均值μ确定 C: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/3b93a3139951423b9b3441c7f14a5c46.png" />确定 D: <img src="https://image.zhihuishu.com/zhs/doctrans/docx2html/202107/dfaa321c576b414e91a6e7fca8060fbf.png" />确定