SU1626442A1 - Multi frequency receiver of adaptive delta modulated signals - Google Patents

Abstract

The invention relates to radio engineering. The circuit of the invention is increased noise immunity. The multi-frequency receiver contains a block 1 of level estimation, matched filters (SF) 2, multiplier 3, adders 4, sources 5 of the correction signal and threshold blocks (PG) 6 o The input signal, which is an adaptive delta modulation signal, goes to the SF 2, which distinguish its harmonic components, as well as through block 1 and multiplier 3 to adders 4. Decisions on the presence of certain harmonic components are made further by means of CB 6 on the basis of a comparison of the output signals of the SF 2 with the corresponding thresholds New adders 4 and sources 5 "The increase in noise immunity from false alarms in the i-th frequency channel is achieved by the fact that two additional variable components participate in the formation of threshold values, depending on whether or not PB 6 has worked in the adjacent frequency channels fi 1) and (i-tl). 4 il. (L

Description

The invention relates to radio engineering and can be used in electrical and radio communications to detect harmonic components of delta-modulated signals.

The purpose of the invention is to improve the noise immunity.

FIG. 1 depicts a structural multi-channel receiver circuit; in fig. 2 - scheme of the matched filter; in fig. 3 - diagram of the source of the correction signal; in fig. 4 is a diagram of a level evaluation unit.

The multichannel receiver contains a level evaluation unit 1, matched filters 2, multiplier 3, adders 4, correction signal sources 5, threshold blocks 6. Matched filter 2 contains reversible counters 7 and 8, controlled inverters 9 and 10, adder 11, adders 12 and 13 modulo two. Source 5 corrective signal contains the switches 14 and 15 and the adder 16. Block 1 contains the register 17 shift, the elements EXCLUSIVE OR 18, the element OR NOT 19, the counter 20.

Multichannel receiver works as follows

The input signal, which is an adaptive delta modulation signal, is fed to the N matched filters 2 and the level evaluation unit 1. In block 1 of the level estimator, bursts of four symbols of the same name are detected in a delta-modulated sequence (0000 or 1111) using the shift register 17 of the EXCLUSIVE OR 18 elements and the OR-NO element 19, the output of which appears 1 in those cases when all the outputs of the shift register 17 simultaneously contain all ones or all zeros. In such cases, logical 1, which enters the counting input of the counter 20 from the element OR NOT 19, allows the calculation of the next clock pulse. The considered variant corresponds to adaptive (with inertial compounding) of delta modulation, in which the control of the quantization step size in the delta coder is carried out on the basis of the analysis of the frequency of the tracking of quad packets of the same-name sim- nolosis. Selection of harmonic components of the input signal

produced by N matched filters 2, each of which implements a transfer function of the form

.-W; nTAz n o)

H-1 H; (Z) -XX

0

five

0

five

0

five

0

five

where i is the number of the matched filter (the number of the frequency component to be detected);

f is the frequency of the i-th harmonic component;

Ti is the sampling period;

N is the number of characters of the delta-modulated signal X (pTd) located on one processing cycle.

The implementation of the specified transfer

function reduces to calculating two M-

А 2EL x (nTA) sin (ПТА) and М-1 АА values

In x (nT.) Cos (2ef pT.) Representing the actual and imaginary

the component of the complex spectral reference at the frequency fj, followed by the calculation of the modulus F; conducted approximately by the formula F- (A) + (B). In matched filters 2, one-bit weights were used, which in the above expressions for A, B corresponds to the use of the functions sign (sin (2 if, pTd)) and sign (cos (2 / iTf; pTd), due to which the multiplication under the sign sums in A, B can be implemented on adders 12 and 13 (modulo 2 adders with inversion), while the negative values of the functions are represented by a logical zero.

The values A, B are formed using reversible counters 7 and 8, the most significant bits of which, determining the sign of the number, control the controlled inverters 9 and 10, at the outputs of which by the end of the processing cycle the values (A) and (B) are formed . The result of filtering in the form of the value (A) + (B) is formed at the output of the adder 11. Decisions about the presence of certain harmonic components are made by threshold blocks 6 based on a comparison of the output signals F; matched filters 2 with the corresponding thresholds PJ, formed with the help of adders 4 and the sources 5

tiruyuschego signal according to the following rule:

PJ p; + oiU3 +, and, -., + Aft2u

where P;

a constant value determining the detection threshold of the i-th harmonic component of the signal x (pTd) (generally different for different i);

$ U is the variable component of the threshold P j, which is formed from the output signal U of the level estimation unit 1, due to which the values of all thresholds increase with increasing signal level.

In contrast to the known receiver, the threshold values P | generated in the proposed receiver, two additional variable components are involved, depending on whether or not threshold blocks 6 in the adjacent frequency channels (i-1) and (i + 1) have been triggered. For the triggered threshold unit 6, its output signal U, (or U) is equal to one — that is, the value of which is P, is paid; .-) the value of U ft m (D (; 2), than POVP ,, interference immunity from sawdust the i-th frequency band, which were possible and-hr for the south, chcho (1-1) - and (1 + 1) - partial components partially penetrate into the viho,., matched filter 2 of the i-in frequency channel J commutations

(, D P ig at the output of the 1st frequency source 5 is corrected. The ro signal is produced with the help of

14 and 15 (each of which is a plot to be executed, for example, on a set of keys with combined control inputs) and an emultiplier 16, which are part of the sources 5 corrective signals.

ten

15

20

25

40

45

The choice of the values of D. ft, 2 can be made on the basis of the measured value of the signal at the output of the 1st matched filter when applying delta modulated harmonic components to the adjacent frequency channels (i-1) -and (i + 1) -i.

Claims (1)

Invention Formula An adaptive delta modulation multi-channel receiver of signals containing N matched filters, clock, information.: The initial installation inputs of which are connected to the corresponding inputs of the level estimator and are clock, information and initial settings of the multi-frequency receiver, the additional inputs of which are weight coefficients N matched filters, the output of the level estimator is connected via a serially connected multiplier and adder connected to the first input of the threshold threshold the second block, the second input of which is connected to the output of the first matched filter, the codes of the remaining N-I voices of the filter OF — jeiniJO “f siopj” vsdami cr from qty i op, i, j-1 ri — poi oi; -., 1-cove,. ihsd- ;; THRESHOLD iriCKOx YAG..I HAVE BI-HHS. iMii МНО1 О lar -Ol НГГ-i npHt-М ШЧ, Pi 1 h a id n h,; ; ION, honor, with i: cibt J h Gg., Front,, days 1: g i. IHJTT, JB Correspondent SIG) .1., I Jr -1 DULLS I cUbHMX. Tgfo, j-seals whose inputs are from .cn- i and n from hhp, ohm succator, and c. NHO.1Y svoy nn-1 additional with mpayura with outputs I use the signal, exit the (X-1) -th signal gspnngi cvy-mat oor; v ie: ibf with the second inputs N -1 threshold; Cove, and Phol ,. 1 st IS. EARLIC CORR; GuYu1Ds: GS. i.i gchla goodylnechi. Ryizami (1-1) -th and (i + 1 -th rmporoi brv; block. Fig.Z