Encyclopedia of radio electronics and electrical engineering / Civil radio communications
Comments on the article
Non-standard use of microcircuits can sometimes lead to unexpected effects. This. for example, they showed attempts to deal with a well-known fact - the noise levels for different copies of the Ural-R radio station are different. In particular, some of them make almost no noise, but they have reduced sensitivity. Many radio amateurs think that this is determined by the noise characteristics of the UHF input stage transistor, and begin to experiment in this direction. In most cases, these experiments do not give noticeable results.
The thing is. that the main reason for the different "noisiness" of radio stations is the penetration of the signal of the second local oscillator (174 MHz) into the IF path of the K10,235URZ microcircuit. This chip is designed to operate at a frequency of 10,7 MHz. and in the Ural-R radio station it is used at a frequency of 465 kHz. The signal of the second local oscillator falls into the operating frequency band of the microcircuit and is amplified by it. The measurements showed that at the input of the piezofilter of the second IF (465 kHz), the voltage of the second local oscillator in the radio station "Ural-R" can reach 50 ... 100 mV. The piezo filter suppresses this signal by 55...60 dB. therefore, at the input of the microcircuit, the local oscillator voltage can be 50 ... 200 μV, which exceeds the level corresponding to the limit threshold.
In other words, two signals are received at the input of the microcircuit: useful (with a frequency of 465 kHz and accompanying noise) and heterodyne. And the sensitivity of the radio station depends on which one is more powerful. If the noise "wins", then the sensitivity will be maximum (it is determined by the first UHF stage). If the local oscillator signal is more powerful, then in the amplifier-limiter of the microcircuit it will suppress as noise. as well as a useful signal. The way out in this situation will be additional shielding of the corresponding nodes of the radio station.
Author: I.Nechaev (UA3WIA)
See other articles Section Civil radio communications.
Read and write useful comments on this article.
<< Back
<< Back
Latest news of science and technology, new electronics:
A New Way to Control and Manipulate Optical Signals
05.05.2024
The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>
Primium Seneca keyboard
05.05.2024
Keyboards are an integral part of our daily computer work. However, one of the main problems that users face is noise, especially in the case of premium models. But with the new Seneca keyboard from Norbauer & Co, that may change. Seneca is not just a keyboard, it is the result of five years of development work to create the ideal device. Every aspect of this keyboard, from acoustic properties to mechanical characteristics, has been carefully considered and balanced. One of the key features of Seneca is its silent stabilizers, which solve the noise problem common to many keyboards. In addition, the keyboard supports various key widths, making it convenient for any user. Although Seneca is not yet available for purchase, it is scheduled for release in late summer. Norbauer & Co's Seneca represents new standards in keyboard design. Her ... >>
The world's tallest astronomical observatory opened
04.05.2024
Exploring space and its mysteries is a task that attracts the attention of astronomers from all over the world. In the fresh air of the high mountains, far from city light pollution, the stars and planets reveal their secrets with greater clarity. A new page is opening in the history of astronomy with the opening of the world's highest astronomical observatory - the Atacama Observatory of the University of Tokyo. The Atacama Observatory, located at an altitude of 5640 meters above sea level, opens up new opportunities for astronomers in the study of space. This site has become the highest location for a ground-based telescope, providing researchers with a unique tool for studying infrared waves in the Universe. Although the high altitude location provides clearer skies and less interference from the atmosphere, building an observatory on a high mountain poses enormous difficulties and challenges. However, despite the difficulties, the new observatory opens up broad research prospects for astronomers. ... >>
| Random news from the Archive Mixed reality for cars
23.11.2020
Volvo announced the use of gaming technology in the development of vehicles.
The Swedish automaker's engineers have begun using mixed reality technologies to develop new models and test technologies in the areas of safe driving and autopilot. This is helped by a new simulator, which includes a movable driver's seat, a steering wheel with tactile feedback and virtual reality glasses.
The simulator allows you to simulate driving a car on various roads right within the walls of the laboratory. To do this, we used the Unity real-time 3D modeling platform, realistic high-definition XNUMXD graphics, augmented reality glasses and a Teslasuit full body suit that provides tactile feedback from the virtual world and tracking body reactions, as well as the experience of Finnish experts in the field of virtual reality. and mixed reality Varjo.
As the authors of the project note, testing active safety systems and unmanned driving technologies on a simulator makes it possible to achieve absolute safety of all tests while simultaneously realizing all work in various traffic scenarios on a real test track with a real car. Mixed reality also allows you to speed up research work without wasting time building prototypes and recreating the necessary conditions for tests.
|
Other interesting news:
▪ Subminiature unwound inductors
▪ Nokia camcorder for capturing panoramic video
▪ Hypersonic passenger aircraft
▪ Intel to build chip factory in Ohio
▪ USB blood test device
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ section of the site Experiments in chemistry. Article selection
▪ article Case tobacco. Popular expression
▪ article What is gold for fools? Detailed answer
▪ article How water was forced to flow upward. Children's Science Lab
▪ article Remote temperature control in a country house. Encyclopedia of radio electronics and electrical engineering
▪ article Miniature directional antenna for the range of 144-146 MHz. Encyclopedia of radio electronics and electrical engineering
Leave your comment on this article:
All languages of this page
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua
2000-2024
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese