Fri, 09 Jun 23 11:32 am EST    Languages: Español  Français  Português
Extranet Login | Site Map | Contact Us

Our Coordinates: Lat 42.75 N, Long 71.85 W  

SDSL Modems


Sdsl.gif (8597 bytes)

Model 1257 SDSL 768Kbps Modem transfers symmetric data over a single twisted pair copper wire, driving data at distances up to 13,000 ft.  The DSL advanced electronics combined with complex 2B1Q technology provides Model 1257 with high performance fiber quality data transfers.  

The modems operate in pairs with a Central unit and a Remote unit.  The Model 1257 modems automatically configure and synchronize when powered allowing quick, easy, plug 'n play connections.

From the front panel, select from the push button controls to run common testing features.  The front panel LED indicators display testing and maintenance functions.  More comprehensive system monitoring and diagnostics can be performed by using the maintenance port via the RS-232 (DB-9) on the front panel.

The units accommodate a 110/220 VAC power source using plug-in power module or can receive a direct connection of 48 VDC source.  The Remote unit can be powered by the Central Unit through the SDSL line.. 


Model 1257 offers V.35 or RS-530 interfaces to connect customer equipment to meet various interface applications.  The rear panel accommodates a copper line connection of RJ-45 or 2-wire screw down.

V.35 Interface - The V.35 provides a M-34 female connector that maximizes the use of network equipment with superior performance.  The V.35Interface is a common connection between routers, terminals, bridges and controllers, where V.35 standards are required. 

RS-530 Interface - The RS-530 provides a DB female connector.  This interface is ideal for multiplexors, and video where RS-530 standards are required. 

Features and Benefits

  • The Model 1257 transmits 768Kbps data rates across single pair copper wire up to 2.5 miles (13,000 ft).      
  • Model 1257 offers front panel LED status, RS-232 maintenance port, diagnostic loop backs and self tests to support quick and easy diagnostics.     
  • SDSL employs 2B1Q technology with echo cancellation, and does not require removal of bridge taps that may exist in leased or private analog lines.      
  • SDSL utilizes existing copper infrastructure allowing quick installations without the need for costly fiber optic cabling.     
  • Install SDSL between your campus area networks for LAN/WAN connections, Video Conferencing, Distance Learning, Internet Access, PBX Network and Voice Traffic Distribution. 


Start Up TimeLess than 28 Seconds Maximum Per Attempt


LineSingle Line Twisted Pair, 120 Ohm characteristic impedance
Signal FormatFull Duplex 784Kbps Per Pair, SDSL-2B1Q Code
Drive Distance2.5 Miles (4km) on 24 AWG, 2.3 Miles (3.7km) on 26 AWG
Transmit Signal Power13.4dBm (min), 14.0dBm (max)
Transmission DelayOne Way <200uSec
Return Loss18dB 10kHz @ 125 Ohms
Loop Provisioning Loss30dB @ 500kHz
Line Termination Connector2 Position Screw Terminal & 8 Position Modular Jack (RJ-45) 
Data Rate768Kbps


DiagnosticsLocal Loop, Remote Loop, Self Test
Maintenance PortSDSL Line Status, Interface Line Status, System Status, 24hr-@ 15 minute intervals and 100 day Performance
Front PanelLED monitoring indicators, Push button reset, Loop Back, Testing
Rear PanelRJ-45 Line Terminator, 2-wire Screwdown Line Terminator, Power Connector, DTE Interface Connector
Power and Dimensions
Power Requirements100-250 VAC, 50-60 Hz or local 48 VDC
Power ConsumptionCentral and Remote units locally powered, 5 watts each.  Central unit supplying line power to Remote unit, 17 watts.
Dimensions1.52"H x 5.57"W x 9.75"D
Weight2.2 lbs.
Operating Temperature0-50 degree C
Humidity90%, non-condensing

DTE Interface

ConnectorV.35 is a M-34 Female, RS-530 is a DB-25 Female
Clock SelectionFront Panel Selectable Internal, External, Recovered