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Time-delay regulating method for analog amplitude modulation broad casting transmitter changing to digital broadcasting transmitter

A technology of digital broadcasting and AM broadcasting, applied in transmitter monitoring, AM carrier system, transmission monitoring, etc., can solve problems such as difficult objective quantitative analysis, judgment, cumbersome search, etc., and achieve delay adjustment method and equipment simplification and guarantee The effect of precision

Inactive Publication Date: 2005-09-28
BEIJING BEIGUANGKE DIGITAL BROADCASTING TELEVISION TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The problem with this method is that it is very cumbersome to search at the stage of capturing poor signals
Since the general delay can reach 1-3ms, if the step is 50us, it will take dozens of attempts to find a suitable delay and enter the fine-tuning stage; on the other hand, the shape of the signal spectrum needs to be observed manually, which is difficult to be objective Quantitative Analysis, Judgment

Method used

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  • Time-delay regulating method for analog amplitude modulation broad casting transmitter changing to digital broadcasting transmitter
  • Time-delay regulating method for analog amplitude modulation broad casting transmitter changing to digital broadcasting transmitter
  • Time-delay regulating method for analog amplitude modulation broad casting transmitter changing to digital broadcasting transmitter

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Embodiment Construction

[0039] a) Connect the dual-trace oscilloscope 9 between the audio terminal 4, the high-frequency terminal 5 and the mixer tube 6, such as figure 2 shown;

[0040] b) Input the special test signal 8 into the module 2 of "modulus seeking" and the module 3 of "radio frequency phase modulation", see figure 2 . The characteristics of this dedicated test signal 8 are: the same direction signal I t equal to the quadrature signal Q t , and is equal to the cosine of the product of frequency Ω and time t, namely: I t =Q t =cos(Ωt), wherein the frequency Ω can be adjusted continuously within a certain range;

[0041] c) Set the frequency Ω of the special test signal 8 to 125Hz, observe the double-trace oscilloscope 9, and look for the phase jump point, Figure 5 Measure the delay difference at the position of the dotted line in the middle, and make rough adjustments to adjust the delay difference to within 200us;

[0042] d) increase the frequency Ω of the special test signal 8,...

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Abstract

The present invention relates to a regulation method of time domain time-delay in the course of remaking analog amplitude-modulated broadcast transmitter into digital broadcast (DRM) transmitter. It is a method which can be utilize dual-trace oscilloscope or other twin-channel signal acquisition equipment to test specific test signal, find out the time error between the audio-frequency envelope signal and high-frequency phase-modulated signal which are reached to mixer tube, make regulation and finally eliminate time error.

Description

technical field [0001] The invention relates to a method for adjusting the signal delay of an audio envelope branch and a phase branch when an analog AM broadcast transmitter is transformed into a digital broadcast (DRM) transmitter, and particularly relates to a dual-trace oscilloscope test method based on a special test signal And two-way synchronous acquisition card automatic test method. Background technique [0002] Digital broadcasting (DRM) utilizes analog AM broadcast transmitter to realize double sideband AM modulation function, which can be expressed mathematically as follows: [0003] When our audio input signal is: I Ω cos Ωt [0004] Then the output signal we get is: i(t)=(I T +I Ω cosΩt)cos(ωt+) {1} [0005] where I T Is the carrier signal amplitude, ω is the carrier frequency. [0006] The signal processing process of the analog AM transmitter is generally divided into audio signal processing, DC component superposition, audio + DC signal amplification...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/04H04B17/10H04L27/04
Inventor 吕锐杨占昕徐伟掌侯亚辉卢起斌邓纶晖曾志斌周剑
Owner BEIJING BEIGUANGKE DIGITAL BROADCASTING TELEVISION TECH