BGAN Modem Subsystem (BMS)

The BGAN Modem Subsystem (BMS) provides software PHY functionality for an Inmarsat BGAN terminal. The BMS in concert with a customer-furnished protocol stack implements the complete Access Stratum of the IAI-2 air interface (the BGAN waveform).

The BGAN Modem Subsystem is comprised of:

  • BGAN Decoding Subsystem (BDS) for baseline, BGAN-X and LDR/HDR bearers
  • BGAN Forward Demodulator Subsystem (BFDS) for baseline, BGAN-X and LDR/HDR bearers
  • BGAN Return Modulation Subsystem (BRMS) for baseline, BGAN-X and LDR/HDR bearers
  • BGAN software Turbo decoder or FPGA Turbo decoder interface
  • Real-time framework with OS abstraction layer
  • Modem application

The BPLT/UT Interface (BUI) functional block, which is required in order to interface to the BPLT when running the UT physical layer Mandatory Test Requirement scripts (UTMTRs), is also available.

The BFDS is operational in SwiftBroadband (SBB) UTs from several vendors. The BMS is undergoing final type approval testing in an SB-SAT UT, which will be deployed in-orbit on a range of satellite platforms. (More)


  • Features

    • Complete Inmarsat BGAN UT modem subsystem (except Turbo decoder, available separately)
    • Derived from SPCI’s “Gold Brick” BGAN Physical Layer Tester (BPLT)
    • Available with support for UT Classes 1, 2 & 3 (Land transportable), 8, 9 & 14 (Maritime), 10 & 11 (Land mobile) and 6, 7 & 15 (Aeronautical). 
    • Equalizer available for Aeronautical Classes
    • Meets all Inmarsat transmitter and receiver specifications
    • Easily integrated with BGAN protocol stack
    • C++ fixed-point software implementation
    • Configurable frequency acquisition range
    • Internal code rate AVP detection and handling
    • Demodulator statistics available to application

    Supported Platforms

    • TMS320C64x, C64x+, C6727
    • Readily customizable for other platforms

    Performance Highlights

    • Meets all Inmarsat PER specs, margin > 0.25 dB
    • Compliant acquisition and recovery from blockage
    • Fast global bearer acquisition (PER ? 1e-3 within 5 frames over ±2kHz)
    • Compliant code rate detection and misidentification performance
    • Compliant C/No estimation
    • Large dynamic range demodulator typically removes need for hardware receiver AGC

    DSP Requirements

    • Compatible with 330 MHz C64x+
    • 2 MB external RAM (alternatives available for reduced external RAM)
    • Internal RAM required is dependent on DSP cache but nominally 128 kB
  • BMS Product Brief

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