SU1603541A1

SU1603541A1 - Digital fm signal demodulator

Info

Publication number: SU1603541A1
Application number: SU884407889A
Authority: SU
Inventors: Олег Викторович Гофайзен; Сергей Адольфович Горьев; Татьяна Дмитриевна Крюкова
Original assignee: Одесский Электротехнический Институт Связи Им.А.С.Попова
Priority date: 1988-02-15
Filing date: 1988-02-15
Publication date: 1990-10-30

Abstract

Изобретение относитс к телевидению. Цель изобретени - повышение точности демодул ции. Устройство содержит первый, второй, третий и четвертый блоки 1 - 4 умножени , первый, второй и третий фильтры низких частот (ФНЧ) 5 - 7, цифровой частотно-модулированный генератор (ЦЧМГ) 8, первый и второй блоки 9 и 10 дифференцировани , первый и второй квадраторы 11 и 12, первый и второй блоки 13 и 14 суммировани , блок 15 делени , генератор 16 управл ющих сигналов, регистр 17 пам ти и электронный коммутатор 18. Выходной демодулированный цифровой сигнал с выхода блока 15 поступает на вход электронного коммутатора 18, управл емого генератором 16. Код сигнала ошибки с выхода электронного коммутатора 18 фильтруетс в третьем ФНЧ 7 и записываетс в регистр 17, с выхода которого подаетс на первый управл ющий вход ЦЧМГ 8, при этом в нем осуществл етс компенсаци ухода частоты ЦЧМГ 8 по отношению к частоте поко входного сигнала. 1 ил.The invention relates to television. The purpose of the invention is to improve the accuracy of demodulation. The device contains the first, second, third and fourth blocks 1 - 4 multiplication, the first, second and third low-pass filters (LPF) 5 - 7, the digital frequency-modulated oscillator (CHCMG) 8, the first and second blocks 9 and 10 differentiation, the first and the second quadrants 11 and 12, the first and second summation blocks 13 and 14, dividing unit 15, control signal generator 16, memory register 17 and electronic switch 18. The output demodulated digital signal from the output of block 15 is fed to the input of electronic switch 18, controlled by a generator 16. Signal code osh bki with electronic switch output 18 is filtered in the third low-pass filter 7 and is written in the register 17, the output of which is fed to the first control input TSCHMG 8, wherein it is carried out frequency offset compensation TSCHMG 8 with respect to the rest frequency of the input signal. 1 il.

Description

Изобретение относитс к телевидению (ТВ) и может быть использовано дл демодул ции цветового сигнала системы СЕКАМ, представленного в виде цифрового кода.The invention relates to television (TV) and can be used to demodulate the color signal of a SECAM system represented as a digital code.

Цель изобретени - повышение точности демодул ции.The purpose of the invention is to improve the accuracy of demodulation.

На чертеже представлена структурна электрическа схема демодул тора.The drawing shows a structural electrical circuit of the demodulator.

Устройство содержит первый 1, второй 2, третий 3 и четвертый 4 блоки умножени , первый 5, второй 6 и третий 7 фильтры низких частот (ФНЧ)„The device contains the first 1, second 2, third 3 and fourth 4 multiplication blocks, the first 5, second 6 and third 7 low-pass filters (LPF) „

цифровой частотно-модулированный ге- 5 лустрочной частоты), поступающий на нератор (ЦЧМГ) 8, первый 9 и второйвторой управл ющий вход ЦЧМГ 8, уп10 блоки дифференцировани , первый 11равл ет выбором опорной частоты вdigital frequency-modulated helix-frequency frequency), fed to the non-generator (CECMG) 8, the first 9 and the second control input of the CECMG 8, 10 differential blocks, the first 11 selects the reference frequency in

и второй 12 квадраторы, первый 13 и второй 14 блоки суммировани , блокиand second 12 quadrants, first 13 and second 14 summation blocks, blocks

15 делени , генератор 16 управл ющих 20 сигналов, регистр 17 пам ти и комму- мутатор 18.15 divisions, a generator 16 of control signals 20, a memory register 17 and a switch 18.

Устройство работает следующим образом .The device works as follows.

В блоках 1 и 3 входной цифровой 25 ЧМ-сигнал S(пТ) умножаетс на косинусоидальную и синусоидальную составл ющую комплексного сигнала несущей, которые формируютс ЦЧИГ 8. После.In blocks 1 and 3, the input 25 digital FM signal S (pT) is multiplied by the cosine and sine wave components of the complex carrier signal, which are generated by JCG 8. After.

соответствии с последовательностью сигнала цветности в полном ТВ-сигналеmatch the chrominance sequence in a full tv signal

Claims

Invention Formula

A demodulator of a digital frequency-modulated signal containing a serially connected first multiplication unit, a first low-pass filter (LPF), a second multiplication unit, a first summation unit, and a division unit whose output is output (| output on the outputs of the first 5 and 0 device) and also a sequence of the second 6 LPF, the third block of the P (pT) and imaginary Q (nT) parts of the combo, the second LPF and the fourth multiplication block, the output of which is connected to the second input of the first block of the sumplex envelope, are actually connected her input signal. After differentiation in blocks 9

the second, the second low pass filter and the fourth multiplication block, the output of which is connected to the second input of the first sum block

and 10 and the corresponding multiplication, world, with the first inputs in blocks 2 and 4, at the output of block 13 a signal is formed

p (nT) .Q (nT) - F (nT) .Q (iiT),

the first and third blocks are multiplied combined and are the input of the device, the first and second outputs of the digital frequency-modulated gene

proportional to the input frequency

signal.

In this case, at the output of block 14, after squaring in blocks 11 and 12, a signal is generated

P (pT) + Q (nT),

proportional to the input module.

From the output of block 15, the frequency-demodulated signal is removed.

“. p (nT) -Q (nT) - P (tiT). dChPT) F (nr) P (pT) + dg (pT)

50 whose input is combined with the input of the first quadrant and connected to the output of the first low-pass filter, the second input of the second multiplication unit is connected to the output of the second differentiation unit, the input

In this case, the error due to parasitic

amplitude modulation fully combined - which is combined with the input of the second

penny .quadrator and is connected to the output of the VT signal from the output of the block 15 of the input-rogram of the low-pass filter, which differs

em in the feedback circuit, formed by the fact that, in order to increase the accuracy

electronic switch 18, demodulation, the last 603541 is entered into it

the third low pass filter 7 and the register 17. The electronic switch 18 is triggered at the time of arrival of the horizontal damping pulse from the generator 16. The error signal code from the output of the electronic switch 18 is filtered in the third low pass filter 7 and is written to the register 17, which is fed to the first JO control The main component of the TsChMG 8, while it compensates for the drift of the frequency of the TsChMG 8 relative to the frequency of the rest of the input signal.

Color burst signal (according to the chrominance signal sequence in the full TV signal.

Invention Formula

A demodulator of a digital frequency modulated signal comprising a serially connected first multiplication unit, a first low frequency filter (LPF), a second multiplication unit, a first summation unit, and a division unit whose output is a device output, as well as serially connected third unit -

home device, as well as sequentially connected third block intelligently

the second LPF and the fourth multiplication block, the output of which is connected to the second input of the first summation block, with the first inputs

world, with the first entrances

of the first and third multipliers are combined and are the input of the device, the first and second outputs of the digital frequency-modulated generator are connected to the second inputs of the first and third multiplicators, respectively, the second input of the division unit is connected to the output of the second summation unit, the first and second

the inputs of which are connected to the outputs of the first and second quadrants, respectively, the second input of the fourth multiplication unit is connected to the output of the first differentiation unit,

the input of which is combined with the input of the first quadrant and connected to the output of the first low-pass filter, the second input of the second multiplication unit is connected to the output of the second differentiation unit, the input

16035416

LNG KOMNVTarop, third-control first, pi "digital input 1" ™ frequency-modulated control signal generator, switch, the second control input of which and the second output of which is connected to the third output of the general with control inputs corresponding control signals, while

of the electronic switch and the comm-information input of the comm; memory co-ogger, the output of which is connected to the output of the dividing unit.