標題: about FSK data question.... [打印本頁] 作者: super 時間: 2007-11-8 06:41 PM 標題: about FSK data question.... Dear all :# j1 N9 @$ _" Z* W/ t1 l h2 U& a
In fsk close loop direct Frequency modulation , , j* s' x# c8 l4 j) y/ j 1. data rate is higher than loop BW or lower than loop BW ? 7 L" x, e" e( z, t5 g- N, X5 Q; H- D 2. And what's the relation between data rate and Loop BW ?" S6 x- B( n% O2 Z2 J
0 f4 v5 X+ v1 } n5 B$ _0 k8 V8 ] Because modulation from VCO , it's a high pass function for VCO vs PLL.1 W- ]: _/ g; b& w. o6 g
If modulation frequency > BW , it will be supress by VCO vs PLL transfer function. 0 j- s# Z; H9 W! v: v3 d It will be trace and fix it. So modulation function is fail. % O9 C+ y9 W0 y! H/ X' _- x Is this concept is right ?$ F8 C: @9 W* K
) p* V6 [: c0 v Thanks .作者: simenkid 時間: 2007-11-10 02:34 AM
1.data rate可以高於loop bandwidth, 也不可以.端看用什麼architecture9 C" u" ]* ?7 o7 r+ V1 |. u6 S
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" O% T8 E9 a, O" \: {9 J% A' V