Ryszard Golański

Study on the dynamic range of delta modulations with time-varying sampling periods

The theory of 1-bit adaptive delta modulations (ADM) systems with uniform sampling rate is well known. Analytical study on the influence of sampling rate adaptation on companding capabilities of delta modulations have been carried out in the present paper. The described ADM systems encode the input signal by changing the sampling intervals and/or step size according to its time-varying slope characteristics. Based on quantitative analysis, a rule that the total companding gain of the doubly adaptive DM system can be expressed, in decibels, as a sum of the companding gain from sampling frequency and step size, has been proved. This rule indicates on possibility obtaining of large dynamic ranges, without considerable variation of both companded parameters. In practice, it is reflected by the increase of not only compression ratio but also the SNR peak value. The dependences of ADM systems companding gain from range changes of both the sampling frequency and the step size, have been found. The relation between the range of sampling frequency changes and companding gain of the variable-rate sampling ADM systems have been described by the LambertW function. The analytical results presented in this study are useful for design the dynamic range of NS-DM and ANS-DM modulations.

Antialiasing filter for NSDM codec

A consideration for an analog antialiasing filter performance, addressed to a nonuniform sampling coding technique was described. The filer prototype design and its implementations are presented. The Sallen-Key architecture based on CMOS inverters and the solution of achieving resistor formed by transmission gates with long MOSFETs are presented. Finally the simulation results are discussed.

Proposition of the full synchronization method for transmission systems with variable duration of bits

The paper reports the problem of synchronizing clocks in the delta codecs systems with variable length of bits. The original synchronization method, valuable in systems dedicated to transmission the bits with variable time duration was projected and experimentally verified. Performed measures and observations have shown elimination of the synchronization lose phenomenon. Stand on the Spartan 3E evaluation modules, a flexible platform for the implementation the transmission system with non-uniform sampling delta codecs was developed.

Recovery synchronization in ANS-DM demodulator

Adaptive Non-uniform Sampling Delta Modulation (ANS-DM) is one of the waveform coding techniques, where a sampling instant and a quantization step size are adopted. The ANS-DM modulator produces an output binary stream, that caries information about signal and includes necessary information of coder parameters (sampling instant and quantization step). In demodulator this values have to be recovered for proper signal reconstruction. To date, no systematic investigation that considered signal decoding of the delta systems with sampling instant and step size adaptation were extensively analyzed. In the paper the analytical analysis of a parasitic signal oscillations in the reconstructed signal, as a consequence of the recovery synchronization process in ANS-DM demodulator, have been discussed. Drowned conclusions allow improving the quality of received signal transmitted over ANS-DM system in presence of noises in transmission channels.

Transmission system with variable duration of bits — Proposal of synchronization

Based on the Spartan 3E evaluation module, a flexible platform for the implementation of different algorithms for A/D conversion was created. The aim of presented work was to develop the concept of the sampling rate adaptation to the input signal rate of change in terms of practical issues including synchronization of delta codecs. The new, original synchronization method, useful in systems dedicated for transmission of variable duration of bits was proposed and experimentally verified. Performed measures and observations have shown elimination of the synchronization lose phenomenon.