Digital modem development
Northwest DSP designs the physical layer of digital links: modulation, synchronization, acquisition and the analysis that shows the link will close. Designs are carried from model to fixed-point and RTL when hardware is the goal.
Common problems
Representative situations this work addresses. They describe the kind of work, not completed client projects.
Acquisition fails near the sensitivity limit
Detection and synchronization that hold up at low SNR.
Carrier sync breaks under Doppler or frequency offset
Acquisition and tracking loops designed for the real frequency uncertainty.
Fixed-point quantization costs performance
Word-length studies that trade resources against measured degradation.
The implementation loss is unknown
BER curves compared against theory to show where the decibels go.
Capabilities
Modem architecture
Waveforms and receivers sized to the link and the hardware.
- Digital modem architecture
- BPSK, QPSK, OQPSK, FSK and CPM
- Direct-sequence spread spectrum
- Equalization and channel coding
Synchronization and acquisition
Getting and keeping lock when signal-to-noise is low and frequency is uncertain.
- Carrier-frequency estimation
- Carrier and timing synchronization
- Preamble acquisition and frame sync
- Doppler compensation
Analysis and validation
Knowing how the receiver performs before and after it is built.
- Receiver sensitivity and link-budget analysis
- Fixed-point quantization studies
- BER versus Eb/N0 simulation and test
- Robustness to RF impairments
Typical deliverables
Scoped in each statement of work. You keep everything listed for your project.
- Floating-point reference model
- Fixed-point model
- Performance curves and analysis
- RTL for the receiver datapath
- Test vectors
- Technical report
Ways to start
Algorithm feasibility study
Simulation that shows whether an approach can meet the requirement, and roughly what it will cost in hardware.
Receiver performance investigation
Finding where a receiver loses performance by comparing the model, the RTL and measured data.
Prototype development
A working prototype of a waveform, modem or SDR function, carried from model to hardware within an agreed scope.
Each engagement is scoped and quoted in writing. See all ways to start.
Have a project in mind?
Describe what you are building and where you are stuck. You will hear back from Mike directly.
