In radio reception, radio noise is unwanted random radio frequency electrical signals, fluctuating voltages, always present in a radio receiver in addition to the desired radio signal. Radio noise near in frequency to the radio signal being received (in the receiver's passband) interferes with it in the receiver's circuits. Radio noise is a combination of natural electromagnetic atmospheric noise ("spherics", static) created by electrical processes in the atmosphere like lightning, manmade radio frequency interference (RFI) from other electrical devices picked up by the receiver's antenna, and thermal noise present in the receiver input circuits, caused by the random thermal motion of molecules. The level of noise determines the maximum sensitivity and reception range of a radio receiver; if no noise were picked up with radio signals, even weak transmissions could be received at virtually any distance by making a radio receiver that was sensitive enough. With noise present, if a radio source is so weak and far away that the radio signal in the receiver has a lower amplitude than the average noise, the noise will drown out the signal. The level of noise in a communications circuit is measured by the signal-to-noise ratio (S/N), the ratio of the average amplitude of the signal voltage to the average amplitude of the noise voltage. When this ratio is below one (0 dB) the noise is greater than the signal, requiring special processing to recover the information. The limiting noise source in a receiver depends on the frequency range in use. At frequencies below about 40 MHz, particularly in the mediumwave and longwave bands and below, atmospheric noise and nearby radio frequency interference from electrical switches, motors, vehicle ignition circuits, computers, and other man-made sources tends to be above the thermal noise floor in the receiver's circuits. These noises are often referred to as static. Conversely, at very high frequency and ultra high frequency and above, these sources are often lower, and thermal noise is usually the limiting factor. In the most sensitive receivers at these frequencies, radio telescopes and satellite communication antennas, thermal noise is reduced by cooling the RF front end of the receiver to cryogenic temperatures. Cosmic background noise is experienced at frequencies above about 15 MHz when highly directional antennas are pointed toward the sun or to certain other regions of the sky such as the center of the Milky Way Galaxy. Electromagnetic noise can interfere with electronic equipment in general, causing malfunction, and in recent years standards have been laid down for the levels of electromagnetic radiation that electronic equipment is permitted to radiate. These standards are aimed at ensuring what is referred to as electromagnetic compatibility (EMC). (Wikipedia).
In this video i demonstrate sound waves interference and standing waves from loudspeaker used sound sensor. The frequency on loudspeaker is about 5500Hz. Enjoy!!!
From playlist WAVES
What is Sound? - Quickly Discover What Sound Really Is
What is Sound? This simple demonstration visually shows how sound waves are produced from a vibrating surface. A frequency generator is hooked up to a power amplifier, and the resultant signal is used to drive a loudspeaker. The signal is also sent to an oscilloscope. After listen
From playlist Physics Demonstrations
Sound vs. Noise: What’s the Actual Difference? (Part 1 of 3)
Noise and sound are not the same thing… really, they aren’t! What exactly is noise? Part 2 of 3 - https://youtu.be/XhFhK97hrdY Part 3 of 3 - https://youtu.be/yTyYZFcxGGQ Read More: Signal-to-Noise Ratio and Why It Matters https://www.lifewire.com/signal-to-noise-ratio-3134701 “You
From playlist Seeker Plus
Waves 4_2 Sources of Musical Sounds
Problems dealing with musical sounds.
From playlist Physics - Waves
Show Me Some Science! Speed Of Sound
Sound is a wave which travels through the air at about 330 m/s. The Little Shop of Physics Crew dances to the music together. When spread out along the track, it takes about a third of a second for the sound to travel from the first person to the last. The crew is blindfolded, so there are
From playlist Show Me Some Science!
Jonathan defines what white noise actually is and how it's used to mask other annoying sounds. Learn more at HowStuffWorks.com: http://science.howstuffworks.com/question47.htm Share on Facebook: http://goo.gl/n7YNrZ Share on Twitter: http://goo.gl/Fq9InS Subscribe: http://goo.gl/ZYI7Gt V
From playlist Episodes hosted by Jonathan
One of the loudest underwater sounds is made by an animal you wouldn’t expect
Here’s a hint: It has something to do with mating Keep reading: http://scim.ag/2CE1DuQ
From playlist Animals
The Concept Of Sound Waves And Frequency Explained In ONE Minute!! #Physics #Theory #Mechanics #Science #NicholasGKK #Shorts
From playlist Waves And Theories
GRCon19 - Spectrum Monitoring Network: Tradeoffs, Results, and Future Directions by Peter Mathys
Spectrum Monitoring Network: Tradeoffs, Results, and Future Directions by Peter Mathys, Todd Schumann, Jeff Wepman, Mike Cotton Due to its high inherent cost, there is limited use of professional grade test equipment in the field to monitor, or even identify, spectrum usage. Therefore, to
From playlist GRCon 2019
The ABC of Smart Machines - with Danielle George
Join radio frequency engineer and former Christmas Lecturer Danielle George as she will discuss both the ALMA and SKA telescopes and how these pioneering machines will generate huge amounts of data about our universe. Subscribe for regular science videos: http://bit.ly/RiSubscRibe Watch t
From playlist Computing/Tech/Engineering
GRCon20 - Software defined radio based Synthetic Aperture noise and OFDM (WiFi) RADAR mapping
Presented by Jean-Michel Friedt, and Weike Feng at GNU Radio Conference 2020 https://gnuradio.org/grcon20 Software defined radio based Synthetic Aperture noise and OFDM (WiFi) RADAR mapping (Main Track) [application] Session Chair: Jean-Michel Friedt, FEMTO-ST/Time & Frequency We demonst
From playlist GRCon 2020
Police Scanner: Equipment Autopsy #68
http://thegeekgroup.org/ - We explore the worlds of analog and digital radio as Chris opens up two different types of scanners. First is an old police scanner, which it tuned up by use of quartz crystal. It's followed by a more modern hand radio, which has made the switch to a completely d
From playlist Equipment Autopsies
YouTube Couldn't Exist Without Communications & Signal Processing: Crash Course Engineering #42
Engineering helped make this video possible. This week we’ll look at how it’s possible for you to watch this video with the fundamentals of signal processing. We’ll explore things from Morse Code, to problems like bandwidth capacity and noise, to how we arrived at the digital age. Crash C
From playlist Engineering
Seeing and Hearing the Cataclysmic Universe - Caltech Special Seminar - 10/16/2017
More Info: http://www.caltech.edu/news/caltech-led-teams-strike-cosmic-gold-80074 On August 17, 2017 scientists for the first time detected both the ripples in space and time known as gravitational waves as well as light produced and emitted during the same cosmic event: the spectacular
From playlist Our Research
GRCon21 - gr-genalyzer, a new OOT module to characterize data converter performance
Presented by Srikanth Pagadarai at GNU Radio Conference 2021 Emerging advancements in DAC/ADC technology in terms of enabling multi-channel, multi-mode, multi-band operation and supporting multi GSPS sample rates place stringent requirements on accurately characterizing the performance o
From playlist GRCon 2021
How are we searching for Extra Terrestrial messages ?
Go to http://www.squarespace.com/curiousdroid to get a free trial and 10% off your first purchase of a website or domain. We been searching for intelligent life outside out planet for over 100 years and yet we still haven't found anything that provides solid proof that is out there. So in
From playlist Space
Get Your Science On: You are the Antenna
Welcome to our newest podcast series, "Get Your Science On"! In this episode, Brian demonstrates how to build a cool science experiment out of an FM radio and a trash bin.
From playlist Get Your Science On
What is signal and what is noise?
This lecture discusses the distinction between "signal" and "noise" -- and important definition when working with large or complex datasets. This video is part of an online course called "Simulate, understand, & visualize data like a data scientist." The course includes 3+ hours of video
From playlist Simulate, understand, and visualize data