about FSK data question....

super

Dear all :
              In fsk close loop direct Frequency modulation ,
          1.  data rate is higher than loop BW  or lower than loop BW ?
          2.  And what's the relation between data rate and Loop BW ?
! b" R; n0 |$ `! N
7 j7 s( Z. D9 @           Because modulation from VCO , it's a high pass function for VCO vs PLL.
! I0 J# X6 ^; f# H           If modulation frequency > BW , it will be supress by VCO vs PLL transfer function.
* q! W0 {* |( @* C/ n6 ?           It will be trace and fix it.  So modulation function is fail.
" k8 e* V$ ~# ^% z# B' H! m- e             Is this concept is right ?
                  
                    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
& H5 O/ `+ n" L; B
' v. L9 k' p# W9 q; Y3 V  s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