about FSK data question....

super

Dear all :
. n( D; t7 ^9 o4 W6 q              In fsk close loop direct Frequency modulation ,
- E" D+ g% D8 T          1.  data rate is higher than loop BW  or lower than loop BW ?
" o% W9 m1 {7 ]          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.
) v1 S& X, h- v. u, t# _$ \           If modulation frequency > BW , it will be supress by VCO vs PLL transfer function.
6 z  P! U' K& ^% i6 w4 J# Z           It will be trace and fix it.  So modulation function is fail.
2 i0 `' h% e1 ~; p& ?+ |+ n             Is this concept is right ?
# C9 m; r/ K. {- K8 F                  
                    Thanks .

simenkid

1.data rate可以高於loop bandwidth, 也不可以.端看用什麼architecture
) [; p8 j" i7 x2.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
/ X+ L( n5 v: u9 f9 Z- y
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