sigma=<0..∞> | factor for the parametric windows:
|
|||||||||||||||||||||
nT=<-1,0..∞> |
|
|||||||||||||||||||||
Win=<1:29> | windowing functions. The marked* ones are parametric and make use of sigma , while the double-marked** ones are a function of As :
a[0:4] , are hidden)
1+20 terms, five decimals (not digits) accurate for As=120dB )
.sub file for ".subckt FIR_FS ", then locate the fspl(x) function and then add the frequency domain response for the interval <0..π> .
|
|||||||||||||||||||||
Choice=<0:6> | the possible additional functions/combinations with Win :
3 = raised cosine 4 = (square) root-raised cosine
nT , while SPS (oversampling) and beta (rolloff) are calculated from BWp and BWs :SPS=round[f0/(BWs+BWp)] beta=(BWs-BWp)/(BWs+BWp)Notes:
6 = Hilbert transformer This allows for windowing with functions from Choice=<2:6> . (FIR, FIRx, FIR2)For FIR_FS, Choice is only used to determine the type in the table below.
|
|||||||||||||||||||||
sim | s | total .TRAN simulation time, needs test=1 . E.g.: if the command is .TRAN 25m , then sim=25m . (optional) |
||||||||||||||||||||
test=<0,1> | 0 disables, 1 enables pins 0.2 and 0.3 . (optional) |
|||||||||||||||||||||
SH=<0,1> | disables/enables (forces) a real sample&hold behaviour. There are two scenarios:
|
|||||||||||||||||||||
Fact=<-k:k> | for k=<1:32> :
|
|||||||||||||||||||||
f0 | Hz | the sampling frequency. For interpolation/decimation, f0 is set to match the input's frequency and BWp, BWs are calculated according to the specified f0 .E.g. for input of f0=1kHz and Fact=4 ⇒ f0=1k and BWp, BWs are calculated for 1kHz sampling frequency.For external synchronization set SH=1 , f0=−f0 while the external clock must have the output's sampling rate, CLK=f0*|Fact|sgn(Fact) .Examples:
|
||||||||||||||||||||
fc | Hz | the center frequency. (also see the description for f0). | ||||||||||||||||||||
BWp | Hz | the pass-band bandwidth. (also see the description for f0). | ||||||||||||||||||||
BWs | Hz | the stop-band bandwidth. (also see the description for f0). | ||||||||||||||||||||
See the graphs on how to get the desired function with fc , BWp and BWs . |
||||||||||||||||||||||
G=<-∞..∞> | gain, linear. | |||||||||||||||||||||
As | dB | stop-band attenuation, positive value. | ||||||||||||||||||||
N=<0:257> N=<0:1025> (FIRx, only) |
Choice and N :
|
|||||||||||||||||||||
Hidden: | ||||||||||||||||||||||
a0 a1 a2 a3 a4 | the five terms for the general cosine window. | |||||||||||||||||||||
td, tr | s | delay and rise times of the clock, effective if SH=1 ; default values are tr=f0/1000 and td=0 . |