上海事大学 音乐均衡器/调音器 O图形均衡器(G) 】图形巧需器G 置 ++t 信号与系统
X 音乐均衡器/调音器 信号与系统
上海事大学 按键式电话机 A DTMF signal consists of the sum of two sinusoids-or tones -with 1209Hz1336Hz1477Hz frequencies taken from two mutually exclusive groups DEF 697Hz Each pair of tones contains one frequency of the low group (697 Hz, 770 Hz, 852 Hz, 941 Hz) and one 770Hz frequency of the high group(1209 Hz, 1336 Hz, 1477Hz) and represents a 852Hz unique symbol The frequencies allocated to the push 941H buttons of the telephone pad are shown below: 信号与系统
X 按键式电话机 ◼ A DTMF signal consists of the sum of two sinusoids - or tones - with frequencies taken from two mutually exclusive groups. ◼ Each pair of tones contains one frequency of the low group (697 Hz, 770 Hz, 852 Hz, 941 Hz) and one frequency of the high group (1209 Hz, 1336 Hz, 1477Hz) and represents a unique symbol. ◼ The frequencies allocated to the push - buttons of the telephone pad are shown below: 信号与系统
上海事大学 各按键的时域波形 Time response of each tone of the telephone pad Symbol"1:697.1209 mb3:697.1471 20 Symbo"5"70.1336 symb6[770.147 yml"7:8521209 Symbo"8"-18521336 Symbol 9: [852, 1477 Symbal"019411336 信号与系统
X 各按键的时域波形 信号与系统
上海事大学 各按键频谱 Estimation of the frequencies contained in each tone of the telephone pad using goertzel symb"1":[697.1209] SyInbui.1697,1336 Yinbai"3-.697,1477 200 100 100 70z78085993 21013271483 121013271483 121013271483 Symbol4"[70.1209 Symbol"5":【70.1336 Symbol"6°:70.1477 70280859937 121013271483 702780859937 121013271483 Symbol"7"[8521209 Symbo"":8521336 Symbol"9:1852,1477] 100 50 0280859937 013271483 Symbol:[941.1209 Symbol"0:[941.1336 Symbo"#:[941,147 Z80859937 12101327148 信号与系统
X 各按键频谱 信号与系统
上海事大学 §3-1非周期信号的频域分析-傅里叶变换 ■1.非周期信号的傅里叶变换 任何满足狄里克雷( Dirichlet)条件的非 周期连续信号都可表示为无限多个幅度无 穷小、频率连续变化的复正弦信号的叠加, 即 f()=nJmF(0)-ao(傅里叶逆变换 (10)=」f()emt(傅里叶变换 信号与系统
X §3-1非周期信号的频域分析-傅里叶变换 ◼ 1.非周期信号的傅里叶变换 任何满足狄里克雷(Dirichlet)条件的非 周期连续信号都可表示为无限多个幅度无 穷小、频率连续变化的复正弦信号的叠加， 即： ( ) ( ) ( ) ( ) 1 2 j t j t f t F j e d F j f t e dt + − + − − = = （傅里叶逆变换） （傅里叶变换） 信号与系统