This work presents algorithmic methods of errors reduction and 2-D signals compression in a combined PCM-DM formats. Also methods of defining Delta Modulation (DM) sampling rate and maximum and minimum DM step size in real time, basing on maximum derivative apriori estimate, are presented. This estimate is proposed to be defined by a spectrum of the previous signal realization, which is known. Further data compression in real time is achieved with help of Extremal Analysis (EA)' . EA of pictures is based on the 2-D differences -in rows (columns) or in diagonals2. This type of data compression is based only on the definition the extreme signal, and distance between these extremes. The algorithm ofrigorous, unrigorous, and unclear extreme defining is universal, and independently from any method of digitalization of pixels is presented. Also methods of errors analysis and their decrease are described. After compression with EA, the image is reconstructed in real time.

In this paper the use of signal representation in signum delta modulation format (SignDM) has been proposed in order to increase the efficiency of the correlation analysis (CA) in real time of short highly noised time series and 2-D data. The SigUDM codes are specified by comparing the values of differences between signal samples in PCM formats with a differential zone which is defined apriori. These codes belong to the set {-1 , 0, 1 } . In this paper mathematical operations on such codes have been studied. SignDM's sampling rate equals Nyquist's frequencyThe following approaches are suggested to be applied when conducting determination with the help of CA: 1) the frequency of short highly disturbed periodic signals will be specified on the basis of a maximum of the proper power spectrum from their autoconelation function in the format of SignDM ; 2) time shifts between two short and highly noised signals of the same frequency will be defined by the cross-correlation function in SignDM format. Using Wiener & Flinczyn's transform of autocorrelation function increases the effectiveness of the correlation analysis for measuring and processing highly noised periodic signals. In this paper there have been presented the algorithms for the operation of specialized processors used for the correlation analysis of signals in SignDM format, as well as the results of computer simulation for time series N 30, and SNR up to -14dB at the chosen differential zone. These algorithms are regular and economical and especially applicable in on-board data processing for space experiments.

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