about FSK data question....

super

Dear all :
              In fsk close loop direct Frequency modulation ,
, ^3 P+ R8 {" r0 ^8 y          1.  data rate is higher than loop BW  or lower than loop BW ?
3 \5 q' Y  S6 L5 ^  p          2.  And what's the relation between data rate and Loop BW ?

           Because modulation from VCO , it's a high pass function for VCO vs PLL.
           If modulation frequency > BW , it will be supress by VCO vs PLL transfer function.
; b& A1 M6 o9 }/ h+ T           It will be trace and fix it.  So modulation function is fail.
3 g$ N+ A( h3 z5 r0 N8 g5 v             Is this concept is right ?
                  
: \: d, B$ E/ A  r6 v. V, U                    Thanks .

simenkid

1.data rate可以高於loop bandwidth, 也不可以.端看用什麼architecture
2.假使單純在multi-modulus或是由reference端做調制, data-rate高於loop bandwidth則勢必產生失真
: N, l# l3 Y( B  p4 y) S/ Z( h; e
$ \" V/ {. Y- x5 c. Y2 |2 Y0 U直接由PLL Synthesizer調制提升FSK, FM, GMSK等固定波包調制之data rate
可選擇如pre-emphasis或two-point modulation(同時兼顧inband與outband,理論上無頻寬限制)的方式