Figure 3-23. Rf Loopback; Figure 3-24. If Loopback - Comtech EF Data SDM-300A Installation And Operation Manual

Operation
C USTO M ER
D ATA
R E M O T E S E R IA L
IN T E R FA C E
FA U LT IN D IC ATO R S
S AT E LLITE M O D E M
Note: When RF loopback is turned on, the demodulator receive frequency is programmed to be the same frequency as the modulator transmit
frequency. This test mode will verify the satellite link without changing the programmed frequency of the demodulator. When RF loopback is
turned off, the demodulator is programmed back to the previous frequency.
CUSTOM ER
IBS, IDR or 308-2
DATA
R E M O T E S E R IA L
IN T E R FA C E
FA U LT IN D IC ATO R S
S ATE LLITE M O D E M
Note: When IF loopback is turned on, the demodulator is looped back to the modulator inside the modem and the demodulator is programmed to
the same frequency as the modulator. This test mode will verify the operation of the modem. When IF loopback is turned off, the demodulator is
programmed back to the previous frequency and is reconnected to the IF input.
3–72
DATA
IBS o r IDR EN C O DER /
IN TERFAC E M ODU LATOR
M IC R O-
CO M P UT ER
DE M O DU LATO R /
D EC O DER

Figure 3-23. RF Loopback

E NCOD ER/
INTER FACE M O DULATOR
MICR O-
C OM PUTER
DEM OD ULATOR/
DECO DE R

Figure 3-24. IF Loopback

T X = 7 0 M H z
PO W E R SUP P LY
R X = 7 3 M H z
R F L B K = 7 0 M H z
L O O P B A C K C H A N G E S D E M O D
R E C E IV E FR E Q U E N C Y TO
7 0 M H z W IT H O U T LO S IN G
O R IG IN A L P R O G R A M M IN G
IN FO R M ATIO N .
PO W ER SUP PLY
SDM-300A Satellite Modem
TR AN SM IT R F
EQU IPM E NT
AN TE NN A
A C P O W E R
RE C EIVE RF
E QUIPM E NT
TRANSM IT RF
EQUIPMENT
A NTENNA
A C P O W E R
R ECEIVE R F
EQ UIPM ENT
Rev. 4