metrologia_enotita 7
DESCRIPTION
μετρολογια μετρολογια μετρολογια μετρολογια μετρολογια μετρολογια μετρολογια μετρολογια μετρολογια μετρολογιαTRANSCRIPT
-
19
20
u U
13
14
15
16
17
18
u
(
m
/
s
)
0.27 0.28 0.29 0.30 0.319
10
11
12
time series (sec)0.4
x/c=0.3 x/c=1 x/c=4x/c=7
0.1
0.2
0.3
x/c 7
2009 2010 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 140.0
Velocity fluctuations (m/s)
-
7
, ,
-
, .
.. S1(t)=5t, S2(t)=20t2, S3(x,y)=3x+2xy+10y2
.. ( )N
1( )sin[2 ( ) ( )]
N
i i ii
A t F t t
( (.., )
, ,
-
( ) ( ...)
,
, ,
-
Acos
p=1/F A
t0
x(n) x(t)x(n)=x(nt)
Discretetimesignal
t0 1 2 3 4 5 6 7 8 9
tT 2T 5T 9T t=nT
x(n)
D i i i
Digitalsignal
, ,
Deterministic: Random: ( , ) n0 1 2 3 4 5 6 7 8 9-1
-
radians/secp=1/FA
Acos( ) cos( ),
12 F=
X t A r t
F
t0
Acos
2 , Fp
FT
/sec
( ) ( ), 1/p pX t T X t T F
, ,
-
radians/( ) cos( )x n A n
( ) cos( ), x n A n n
( ) ( )=/6f=1/12 A
2 f n0
(f=k/N N:) x(n+N)=x(n)
/-A
(f=k/N, N:). x(n+N)=x(n)cos[2f0(N+n)+]=cos(2f0n+)
2 2 kf N k f N
31 3060 2f N f N
0 02 2f N k f N
, , 21=2k
1 1 2 2 60, 260 60f N f N
-
( Shannon) , .
fm , m fm .
(Shannon) f fm , . fs >=2 fm
fs Nyquist.
f f
, ,
fs < fm ( Aliasing)
-
, , , , , . (Digital Signal Processing, DSP), (real time) :
Inputfilter
ADCwith sample
and hold
Digital Processor DAC
Outputfilter
x(t) y(t)x(n) y(n)
x(t) , (aliasing) .
and hold
(ADC Analog to Digital Converter), . (sample and hold). ( ) x(n)
. (DSP Digital Signal Processor) (IC). y(n) , DAC (Digital to Analog Converter) y(t).
, ,
( g g ) y( ) (DSP) ADC DAC.
-
, , , . :1. ,
.2. 2 , ,
bits .3. .
x(t)01011x(n) xq(n)
A/D Converter
Sampler( ) ( )
CoderQuantizer
, ,
(Sampling) (Quantization) (Coding)
-
x(n)( )
1.0 x(n)x(t)
1.0
x(t)
0 4
0.6
0.8
0.6
0.8
q
0 1 2 3 4 5 6 7 8 9
0.2
0.4
0 1 2 3 4 5 6 7 8 9
0.2
0.4
n0 1 2 3 4 5 6 7 8 9
T =1 secT
n0 1 2 3 4 5 6 7 8 9
:2 1 2
fs fsB B
V Vq : 12 2
fsB
Vq V : ADCVfs: ADCB: bits ADC
*
, ,
* *
-
ADC 12 bits ( 5 5) V ADC 12 bits (5 5) V . , x500 Seebeck 50 V/oC [1600]
: 1210 2.44
2 2fsB
Vq mV
[1600].
V 10 V lt 122 2B
: 1.22 2q mV
Vfs=10 VoltsB=12
2
E=a, : , = Seebeck, T=
x500 ~ Vfs=10/500=0.02 Volts q=0.02/212=4.910-6 V
E1600=4 910-6 *1600=7 810-3 V E=a => =E/ a =156 oC
, ,
E 4.9 10 1600 7.8 10 V E a > E/ a 156 C