Books related to Digital signal processing:
- Digital Signal Processing - JohnG. Proakis
- Digital Signal Processing - Computer based Approach - Mcgraw Hill
- Discrete-time signal processing - Oppenheim
- FPGA-based Implementation of Signal Processing Systems
Resources related to Lock-in amplifiers:
- Wikipedia article
- About LIA
- Lock-in amplifiers: Principles and applications M.L. Meade
- Lock-in amplifier tutorial - Bentham Instruments LTD