Overview

The COM-1826SOFT is a digital modem compliant with the TDRSS spread-spectrum standard. The generic VHDL source code is portable to most FPGAs.
Separate licenses can be purchased for the transmitter and the receiver.

• Modulation
• Direct-Sequence Spread-Spectrum, BPSK, SQPN
• Programmable symbol rate (typically 1Kbits/s to 2*150Kbits/s)
• Continuous mode operation
• Error Correction / Formatting
• Convolutional FEC code, rate 1/2
• NRZ conversion
• Performance
• Implementation losses < 1.5 dB at Eb/No = 2 dB
• Center frequency acquisition range: +/- 5 KHz
• Dynamic frequency table to compensate for orbit-related Doppler
• Symbol rate acquisition and tracking: +/- 50 ppm
• 120-bin parallel code epoch search for fast code acquisition
• Ancillary components
• Frequency table to compensate for predictable orbit-related Doppler
• BER tester
• Support for various modulated waveform formats:
  • Baseband complex (I/Q) samples to DAC/from ADC
  • SDDS-formatted UDP stream on GbE LAN for IF sampled waveforms and timestamps
  • Waveform text file during simulation

Documentation

Transmitter specifications
Receiver specifications
Low-cost receiver development for TDRSS DAS sustainment and CubeSat applications
Complete VHDL/IP Core license agreement

Buy

$2600 COM-1826SOFT_TX TDRSS DSSS digital transmitter

$5200 COM-1826SOFT_RX TDRSS DSSS digital receiver