Hybrid solutions

Modems designed to support single or multiple E1/T1, E3, n x STM-1, STM-4 streams for TDM and Ethernet for IP traffic with capacity varying from few Mbps to 820 Mbps. From end of Q2 2011, dual polarized mode will be added to base configuration of the modem extending data capacities to 1+ Gbps.

E1/T1 carry 2.048/1.554 Mbps respectively, and n x E1/T1 can be multiplexed in order to have required number of voice and data channels. STM-1 data circuit carries fixed 155.52 Mbps and two and more STM-1 can be multiplexed for supporting larger number of synchronous data channels. For wayside channel, 10/100/1000 BASE-T Ethernet is used.

For instance, 8 E1 will reserve 16.384 Mbps and 680 Mbps will be transported via Ethernet interface. Alternatively, STM-1 and Ethernet can be used, where voice communication is transmitted over STM-1 and data over Ethernet. In that case, 1 STM-1 channel is allocated for voice traffic with 155.52 Mbps and 541 Mbps for Ethernet. The Ethernet subsystem in Modesat QAM modem can be enhanced with QoS filters and queue management as well as with data compression for throughput improvement.

The configuration of typical hybrid TDM and Ethernet radio is described below.

• Modulation: QPSK to 1024QAM
• I/Q baseband, complex IF or real IF interface
• Input and output carrier frequencies are freely software configurable
• Transport stream is a multiplex of n x E1/T1, STM-1 or STM-4, and Ethernet data sources
• Adaptive Coding and Modulation
• Quality of Service support
• Roll-Off factor: software configurable 16-25%
• Bandwidth: software configurable 5 to 112MHz*
• Symbol rate: software configurable 4.5-104 MSym/s
• Includes PilotSync™ technology
• FEC Reed-Solomon encoder/decoder, LDPC optionally for Altera hardcopy
• Interleaver/Deinterleaver depth: I = 1/2/3/4/6/12/17
• XPIC with dual polarized modem in single low cost FPGA**
• Configuration via 8bit parallel host interface or RS 232
• Single external analogue loop for AGC 18 bits
• Input from ADC: 11-12 bits (1 or 2 (I/Q) channels)
• Output to DAC: 10-16 bits (1 or 2 (I/Q) channels)
• Decision Feed-Forward Equalizer in the receiver channel
• Modem master clock / sampling rate: single, fixed 200 or 210MHz XO clock source
• Shape Filter: Root-Raised-Cosine
• Internal PRBS generator and internal BER tester

* 5-56 MHz channel spacing for 1024QAM supported
** will be available in Q2 2011