: -
, - ( ) - . , , , , , - (PCM Encoder) . ( ) ( ), , , - . , .
, , , , . . 1, (Message), . (Sampled message). , , .
1
, , . , - (PCM Decoder). , - , . , .
, , , :
=
, ( , ). , ( ) , , . , , , :
= ( + + ) .
( . 1), ( , ) , :
, .
( ), .
( ), .
, . , 500 , 8- - 100 . - , , , , , 12.5 .
|
|
:
500 .
12 ( 12.5 - 500 ) 13 ( 12.5 + 500 )
24.5 25.5 ( 2 12.5 500 ), 37 38 ( 3 12.5 500 ), , .
, ! , , . , , () (reconstruction) (anti-aliasing filter). , , , . .
, . , . , , (aliasing).
Emona FOTEx - - 3 . "" PCM Enoder.
, -, NI ELVIS II . (aliases).
, (aliasing), , , .
NI ELVIS II USB-
Emona FOTEx
ѐ BNC - "" (2 )
ѐ "" (2 )
:
A
, , -.
1. , NI ELVIS II , .
2. Emona FOTEx NI ELVIS II.
3. Emona FOTEx NI ELVIS II.
|
|
: FOTEx .
4. NI ELVIS II USB.
5. NI ELVIS II, , , .
6. .
7. NI ELVISmx.
8. NI ELVIS II Function Generator ( ).
9. :
Waveshape ( ): Sine () Frequency (): 500
Amplitude ( ): 4
DC Offset ( ): 0
10. Mode - PCM.
11. , 2.
2
-, 3. - (PCM Encoder) 2 . - , , , - (PCM Decoder) . 3
3
PCM Encoding - : Function Generator , Master Signals , Message To CH 0 0,
IN , CLK , PCM Decoding - : PCM data - ,
CLK ,
Reconstruction : 3kHz LPF 3 , Recovered message To CH 1 1
12. NI ELVIS II
13. , 1 (. 15).
14. Timebase ( ) , .
: , , .
-.
-.
16. . 4.
4
-, . 5.
5
PCM Encoding - : Message To CH 0 0, IN , CLK ?
PCM Decoding - : PCM data - , CLK ,
Reconstruction : Recovered message Sampled message To CH 1 1
: .
17. , Stop ().
18. NI ELVIS II.
19. :
Input Settings ( ) | |
Source Channel ( ) - Scope CH1 ( 1 ) | Voltage Range 10V ( - 10 ) |
FFT Settings ( ) Frequency Span ( ) 45,000 Resolution () 400 Window () 7 Term B-Harris (- 7- ) | Averaging () Mode () RMS ( ) Weighting () Exponential () # of Averages ( ) 3 |
Triggering () Type () Edge ( ) | |
Frequency Display ( ) Units () dB ( ) Mode () RMS () Scale Auto () | Cursor Settings ( ) Cursors On ( ) () |
20. ( Cursors On ( ) , , - 2 .
|
|
21. , 1.
1, . , , . .
22. ( ) 4 .
23. , - .
24. , 2.
25. 10 .
26. . 6.
6
-, 7. 2 kHz SINE . SYNC 100 , - -.
7
PCM Encoding : Function Generator , Master Signals , Message To Ch 0 0,
IN , CLK PCM Decoding : PCM data ,
CLK ,
Reconstruction : Recovered message Sampled message To Ch 1 1.
27. , : 10.5 14.5 , 23 27 , 35.5 39.5 .
: 72 9000 /.
28. - ( , ) 72 .
29. , 4.
D -
, , . , , . , , , , , . , , .
30. - - : 64 (8000 /c), 56 (7000 /c), 48 (6000 /c), 40 (5000 /c) 32 (4000 /c).
|
|
: , , , , .
31. , - - 32 ( 4 000 /).
32. 1 . 8, .
33. .
34. .
: , .
, ( , ). ( , ). 2 , 4000 / ( - - 32 ). , , 32 . !
, . -, . -, .
( ). 2 , 3 . , 6000 / ( 48 ), , . -, , 1 3 , , . , 6 / ( 48 ) , .
, .
35. - - 8 ( , 40 , 48 , 56 ..), .
: 8 , 1000 /.
36. , , 1.
37. -.
1.
6