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C.2 sdm-650b fairchild-compatible modem, C.3 sdm-650b aydin data rate modem, C.4 sdm-650b comstream modem – Comtech EF Data SDM-650B User Manual

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Field Compatibility

SDM-650B Satellite Modem

C–2

Rev.

6

C.2 SDM-650B Fairchild-Compatible Modem

To change the standard modem to a Fairchild-compatible modem, the following changes
must be made:

M&C Software

U9 FW/0714-6X

Modulator Card

AS/0773-3 (Resistor Pack Changes)

Demodulator Daughter Card

AS/0929-3 — Variable Rate
AS/0698-X FDC COMP — Fixed Rate

Decoder Software U8

FW/0562-2

C.3 SDM-650B Aydin Data Rate Modem

To change the Fairchild-compatible modem to an Aydin compatible data rate, additional
changes must be made to the Fairchild-compatible configuration:

Modulator Card AS/0773

12 (Aydin Data Rate, crystal = 4.117333 MHz)

Decoder Card

AS/0365

4 (Aydin Data Rate, crystal = 4.117333 MHz)

C.4 SDM-650B Comstream Modem

To change the modem to a Comstream-compatible modem, the following changes must
be made:

M&C Software

U9 FW/0714-9X

Decoder Card Software

U8 FW/0562-3X

Interface Board

AS/0627-2
V.35 Interface with Engineering Waiver #212 Modifies
Carrier ON/OFF Control Using RTS (RS)