Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~astro/School/Talks/hagen_backends.pdf Дата изменения: Tue Jul 12 04:32:06 2005 Дата индексирования: Sat Dec 22 15:10:29 2007 Кодировка: Поисковые слова: http www.astronomy.ru forum index.php topic 4644.0.html

BACK ENDS
BAN D PASS FILTER SQUARER Vout = Vin^2
Vin V out

RC L OWPASS FIL TER (AVERAGER)

1. TOTAL POWER 2. SPECTROMETRY

POLARIZATION "A"

C H AR T RECORDER

A-TO-D CONVERTER
Vin V out

POLARIZATION "B"

3. POLAR IMETRY
DIGITIZATION COUL D START HERE

COMPUTER

FRONT END + BACK END

FILTER BANK SPECTROMETER
POL B CHANNELS

RC L O WPASS FIL TER (AVERAG ER)

SQ UARER Vout = Vin^2 NARRO W BAND PASS F ILT ER BAND PASS F ILT ER NARRO W BAND PASS F ILT ER NARRO W BAND PASS F ILT ER
Vin Vout

BAND PASS F ILT ER

A-T O -D CO NVERT ER

POL "A"

PO LARIZ AT IO N "A"

90
COMPUTER
A-T O -D CO NVERT ER
PO LARIZ AT IO N "B"

NARRO W BAND PASS F ILT ER

COMPUTER
NARRO W BAND PASS F ILT ER

SINGLE C HANNEL POL AR IMETER

SPECTROMETER/POLARIMETER
N A R R OW BAN D PASS F IL T ER BAN D PASS F IL T ER N A R R OW BAN D PASS F IL T ER N A R R OW BAN D PASS F IL T ER

HETERODYNE SPECTROMETER USES SYNCHRONOUS DETECTION
LOWPASS FILTER BANDWIDTH B/2
SQUARER Vout = Vi n^2

RC LOWPASS FILTER (AVERAGER)

P OL "A "

L O W PASS F IL T ER B/2

V in

V out

90
90

L O W PASS F IL T ER B/2

V in

V out

COMPUTER

LO1

N A R R OW BAN D PASS F IL T ER N A R R OW BAN D PASS F IL T ER

L O W PASS F IL T ER B/2

V in

V out

A - TO - D CONVERTER

90
LO2

L O W PASS F IL T ER B/2

V in

V out

FROM CORRESPONDING POL "B" FILTER

MULTIPLEXER

TO O TH ER FILTER C H AN N ELS

1


FOURIER TRANSFORM SPECTROMETER
LOWPASS FILTER B/2
V in V out

AUTOCORRELATION SPECTROMETRY
LAG UNIT
DELAYED DATA IN (DELAYED IF SIG NAL)
D EL AY EL EM EN T
DQ

90
L O1
L O C AL O SC .

A V E RA GE R

LOWPASS FILTER B/2

V in

V out

S QU A R E R

N -1

A-TO -D
n=0

Vn x e

j 2 p i n m / (N-1 )

2

C LOC K

D E LA Y E D D A T A O U T

X

+
C LOC K

D

TO OTHER FILTER CHANNELS

MULTIPLEXER

R EGISTER

N-1

PRO MPT DATA IN (IF SIGNAL)

PRO MPT DATA O UT

Vn x e
n= 0

j2pi nm/(N-1)

S(f)= fR() exp(i 2pi f ) d

R(tau) OUT

AUTOCORRELATOR
L A G UNIT 0
DE LA Y E LE ME NT
DQ DQ DQ

L A G UNIT 1

L A G UNIT 2
DE LA Y E D DA TA TO NE X T LA G UNIT

CLO CK CLO CK A -TO -D CO NV E RTE R

X

+
CLO CK

D

D

D

RE G IS TE R

P RO MP T DA TA TO NE X T LA G UNIT

INP UT 1

INP UT 2

INP UT 3

D IGITAL MU L TIPL EXER

O UTP UT DA TA TO CO MP UTE R

2