Modem
ccessories
SMS-301 Modem
Protection Switch
2114 West 7th Street, Tempe,Arizona 85281 USA Voice 1 480 333 2200 Fax 1 480 333 2540 Email sales@comtechefdata.com
Comtech EF Data reserves the right to change specifications of products described in this document at any time withoutnotice and withoutobligation to notify any person of such changes. Information in this
document may differ from that published in other Comtech EF Data documents. Referto the website or contact Customer Service for the latest releasedproduct information.
© 2007 Comtech EF Data Part Number ds-sms301.doc 3/21/2006
FEATURES
• Full feature monitor and control processor
• Remote input for configuration and status
• 1:1 configuration
• One rack unit (1RU) chassis
APPLICATIONS
The SMS-301 is a fully programmable 1:1 protection
switch providing complete redundancy for one prime and
one backup modem. The SMS-301 switch is designed to
operate with Comtech EF Data satellite modems and is
a direct replacement for the SMS-651B 70/140 MHz
Switch.
Programming the SMS-301 is accomplished through the
front panel keyboard or the remote interface. Complete
functionality control and monitoring of switch status and
faults are easily accessed through the remote port
connection.
The SMS-301 simultaneously switches data and IF
paths, either independently or dependently. The
switching type is selectable through the front panel or
remote port, eliminating the need for firmware changes
and allowing maximum in-use flexibility.
When a fault is detected in the online modulator or
demodulator, a switch to the offline modem occurs if the
backup is not in a faulted condition. The transmit data is
sent to the backup modem by the 1:1 switch to prevent
false indications of transmit faults. The actual switching
can be accomplished in under 20 milliseconds, with
programmable modulator and demodulator switching
delays in the range of 0 to 127 seconds.
The front panel LEDs indicate which modulator and
demodulator (prime or backup) are online. The LEDs
also indicate the following:
• Active faults in the modulator or demodulator
• Status of the SMS-301’s redundant power supplies
• Mode of the switch (automatic or manual)
OTHER FEATURES
• Uses standard Comtech EF Data modem as backup
or prime
• Dependent or independent modulator and
demodulator switching
• Local/remote, automatic/manual control
• Redundant power supplies and AC inputs
• Easy installation
SIGNALS MONITORED
• Operation mode: Automatic or manual
• Switching mode: Independent or dependent
mod/demod
• Modulator/Demodulator online delay
• Modem online: A or B (dependent mode)
• Modulator/Demodulator online: A or B (independent
mode)
• Remote configuration (local only): EIA-232 or EIA-
485, address, baud, parity, bits per word
• Remote mode (switch)
• Clear stored faults
• Current faults
• Stored faults
• Switch status
• Equipment type
• Store/recall multiple switch configurations
• Remote access to modulator/demodulator status
• Modem configuration copy to opposite modem
