Trajetória da extremidade de um fasor de uma modulação AM para um único tom:

Dr. H.M. de Oliveira, CENTRO DE TECNOLOGIA E GEOCIENCIAS CTG-UFPE  (UFPE)

parâmetros de controle são {m, fm/fc }, respectivamente, o índice de modulação AM e a relação frequência do tom para frequência da portadora.

m=0,2

m_0v2_fmDIVfc_0v1.PNGm_0v2_fmDIVfc_0v3.PNGm_0v2_fmDIVfc_0v7.PNG

fm/fc=                   0,1                                                                        0,3                                                                                        0,5                                                                        0,7 

m=0,5

m_0v5_fmDIVfc_0v1.PNGm_0v5_fmDIVfc_0v3.PNGm_0v5_fmDIVfc_0v5.PNGm_0v5_fmDIVfc_0v7.PNG

fm/fc=                   0,1                                                                        0,3                                                                                        0,5                                                                        0,7 

 

m=0,8

m_0v8_fmDIVfc_0v1.PNG m_0v8_fmDIVfc_0v3.PNG m_0v8_fmDIVfc_0v5.PNG m_0v8_fmDIVfc_0v7.PNG

fm/fc=                   0,1                                                                        0,3                                                                                        0,5                                                                        0,7 

 

m=1,0

m_1_fmDIVfc_0v1.PNGm_1_fmDIVfc_0v3.PNGm_1_fmDIVfc_0v5.PNGm_1_fmDIVfc_0v7.PNG

fm/fc=                   0,1                                                                        0,3                                                                                        0,5                                                                        0,7 

 

CASOS em que a portadora é mais lenta que o sinal (não usual em modulação AM para transmissão).

m=0,2

m_0v2_fmDIVfc_2.PNGm_0v2_fmDIVfc_3.PNGm_0v2_fmDIVfc_5.PNG

fm/fc=                                   2                                                                                            3                                                                              5

m_0v2_fmDIVfc_7.PNGm_0v2_fmDIVfc_10.PNGm_0v2_fmDIVfc_25.PNG

fm/fc=                                   7                                                                                            10                                                                            25

m=0,5

m_0v5_fmDIVfc_2.PNGm_0v5_fmDIVfc_3.PNGm_0v5_fmDIVfc_5.PNG

fm/fc=                                   2                                                                                                           3                                                                                               5

   m_0v5_fmDIVfc_7.PNGm_0v5_fmDIVfc_10.PNGm_0v5_fmDIVfc_25.PNG

fm/fc=                                   7                                                                                            10                                                                                           25

m=0,8

m_0v8_fmDIVfc_2.PNGm_0v8_fmDIVfc_3.PNGm_0v8_fmDIVfc_5.PNG

fm/fc=                                                   2                                                                                            3                                                                                              5

m_0v8_fmDIVfc_7.PNGm_0v8_fmDIVfc_10.PNGm_0v8_fmDIVfc_25.PNG

fm/fc=                                      7                                                                                           10                                                                                                       25

m=1,0  CASOS LIMITES SEM SOBREMODULAÇÃO—sinal modulador mais rápido que portadora

m_1_fmDIVfc_2.PNGm_1_fmDIVfc_3.PNGm_1_fmDIVfc_5.PNG

fm/fc=                                                   2                                                                                            3                                                                                              5

m_1_fmDIVfc_7.PNGm_1_fmDIVfc_10.PNGm_1_fmDIVfc_25.PNG

fm/fc=                                      7                                                                                            10                                                                                                       25

CASO BITONAL (exemplo)   fm1/fc=5  fm2/fc=0,1

m1_0v3_m2_0v1fmDIVfc_5_0v1.PNGm1_0v3_m2_0v3fmDIVfc_5_0v1.PNGm1_0v3_m2_0v5fmDIVfc_5_0v1.PNGm1_0v3_m2_0v8fmDIVfc_5_0v1.PNG

m1=0,3 m2=0,1                                                 m1=0,3 m2=0,3                                                 m1=0,3 m2=0,5                                                m1=0,3 m2=0,8

 

CASO BITONAL (exemplo)   m1=0,5  m2=0,2

fm2_fm0v1.GIFfm3_fm0v1.GIFfm5_fm0v1.GIFfm7_fm0v1.GIF

 

fm1 & fm2=                 2 & 0,1                                                             3 &0,1                                                                    5 & 0,1                                                              7 & 0,1

 

Relações apresentam algumas similaridades com

DIAGRAMAS DE OLHO, e com alguns DIAGRAMAS DE NYQUIST, figuras geométricas (folio, lemniscatas, cardioides...), FIGURAS DE LISSAJOURS...

 

Algumas animações mostrando a evolução das figuras ao aumentar gradativamente a profundidade de modulação m são mostradas:

 

Transition0v3.gif 

 

Transition3.gifTransition5.gif