What is Radio signals: Definition and 22 Discussions

A time signal is a visible, audible, mechanical, or electronic signal used as a reference to determine the time of day.
Church bells or voices announcing hours of prayer gave way to automatically operated chimes on public clocks; however, audible signals (even signal guns) have limited range. Busy seaports used a visual signal, the dropping of a ball, to allow mariners to check the chronometers used for navigation. The advent of electrical telegraphs allowed widespread and precise distribution of time signals from central observatories. Railways were among the first customers for time signals, which allowed synchronization of their operations over wide geographic areas. Dedicated radio time signal stations transmit a signal that allows automatic synchronization of clocks, and commercial broadcasters still include time signals in their programming.
Today, global navigation satellite systems (GNSS) radio signals are used to precisely distribute time signals over much of the world. There are many commercially available radio controlled clocks available to accurately indicate the local time, both for business and residential use. Computers often set their time from an Internet atomic clock source. Where this is not available, a locally connected GNSS receiver can precisely set the time using one of several software applications.

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  1. A

    A Exploring Time Travel Teleportation: Computer Bytes & Radio Signals

    Time travel teleportation can be achieved in small scale experiment in millisecond. Using a computer byte in radio signals. I look forward for comments.
  2. A

    These Are The Most Promising SETI Radio Signals

    Hi! Just in case someone is interested in SETI, I made a video about the most promising radio signals detected so far. Here it is: https://www.youtube...h?v=4MxNEfIfQjI Hope you enjoy it! What is the most promising SETI radio signal for you guys? Do you think we will discover an intelligent...
  3. P

    SR - Time dilation, space-time diagram, and radio signals

    Homework Statement P.S.: I'm not sure if it is allowed to ask multi-part questions. Two equally old sisters Alice and Barbara leave Earth simultaneously in opposite directions. The following velocities and distances have been measured in the Earth system. Alice travels with a speed of ##v_A =...
  4. C

    Creating a Multi-Radio Wave Demonstration: How to Find the Right Machine

    Is there a machine that can emit multiple radio waves simultaneously? I am trying to create a demonstration, but it requires multiple radio waves at once and cannot find any machines that can do so.
  5. C

    Interference of radio signals

    Homework Statement July 22,2017. Homework Statement Television and radio waves can reflect from nearby mountains or from airplanes. Such relfections can interfere with the direct signal from the station. a. Determine what kind of interference will occur when 75-MHz television signals arrive at...
  6. physicsEnthu_123

    Can Antenna reduce the radio signal strength when it receive

    When antenna receive the radio signal does it reduce the actual radio signal strength or strength indeed depends on the dispersion loss and other dielectric absorption? If antenna doesn’t reduce the radio signal strength(power), how it generates the current in the receiving antenna circuit? How...
  7. J

    Transferring a handheld radio into a antique style radio box

    I'm pretty darn new to engineering, so I'm just diving in and hoping all goes well. I've got roughly 6 months to finish this project as it's a Christmas gift in the making. My current plan is to carve a large spruce log into the shape of an old cathedral style antique radio, make a cabinet...
  8. king yasin ally

    Deep Space antenna (dish)

    I am trying to build my own communication / listening dish, multi frequency antenna, basically my own deep space antenna network. how to get the needed supply for such endeavour? help with any info on this, a new field for me. thanks!
  9. U

    Questioning RF Frequency & Filters: A Guide

    My question is about RF frequency... The RFs are electromegnetics waves...That means they are one type of Light waves... right?? The other question is about perticular frequency of RF signals...When we want to transmit or receive some perticular frequency... we tune our radio at that perticular...
  10. Chronos

    Exploring Transient Radio Signals: Could They Be ET?

    This paper 'Provocative radio transients and base rate bias: a Bayesian argument for conservatism', http://arxiv.org/abs/1211.7338, discusses transient radio signals as possible signs of extraterrestrial intelligence. I knew of the 'WOW' signal, but, was unaware of other similar detection events.
  11. J

    So if FM radio signals modulate the frequency of the EM wave

    then how can you tune into, say, 101.1 when its not at 101.1 MHz all the time given the frequency change?
  12. W

    How antennas receive AM radio signals

    The greater the amplitude of a given frequency of light hitting an antenna the greater the induced speed of electricity in the antenna? Reply in simple english please.
  13. L

    Could a coaxial cable be used for electric current instead of radio signals?

    http://en.wikipedia.org/wiki/Coaxial_cable http://en.wikipedia.org/wiki/Poynting_vector Could a coaxial cable be used for electric current instead of radio signals? 'For example, the Poynting vector within the dielectric insulator of a coaxial cable is nearly parallel to the wire axis...
  14. N

    Some questions about Radio signals.

    Hi All, Always wondered a few things about radio transmission, hoping to get some questions answered. 1. Is there a reason why certain frequencies are free to use by everyone and certain ones are reserved? Is it something to do with the fact that the cost (or means) to send signals on...
  15. M

    [Mystery Solved] What household objects can pick up radio signals?

    I have just had a very strange experience, and would like to know if there is an explanation for it. There was a small tin of black olives on my kitchen work surface. I put a teaspoon into the tin, to get an olive. The moment I did this, I heard what sounded like a radio broadcast of a...
  16. R

    Spurious radio signals - dBc

    Just some background - I am trying to measure spurious radio signals around a carrier in dBc units. It seems easy until you consider the resoultion bandwidth you are going to set your specan up with. If you start with a large bandwidth the spurious signals can get mixed up with the carrier and...
  17. S

    Shouldn't we have heard alien radio signals by now? Why not?

    I figure that intelligent life couldn't have formed until, at the very least, the second generation stars that started birthing forth carbon (maybe 3 billion years after the Big Bang?). On Earth, it took something like 2.5 billion years until multicellular life formed, and so maybe we can...
  18. J

    Unlocking the Power of Radio Signals: Regulatory Compliance

    Homework Statement Regulations require that licensed radio stations have limits on their broadcast power so as to avoid interference with signals from distant stations. You are in charge of checking compliance with the law. At a distance of 25 km from a radio station that broadcasts from a...
  19. S

    Unlocking the Mystery of Radio Signals

    I've been puzzling how it is that you can tune into a signal on a particular frequency. How can it be possible to get rid of all the other signals that are added together? I don't know how much of this makes any sense, but I have tried to specify the problem mathematically. Suppose R_1(t)...
  20. Z

    Receiving AM Radio Signals from Philadelphia

    AM radio -- please help! Hello, Here is some background info. I don't know if it is all necessary to find a solution but here it is anyway: I am currently living in State College, PA. I would like to be able to listen to an AM radio station broadcasting from Philadelphia, PA...
  21. K

    Question about radio signals

    can AM radio waves pass through glass been than FM radio waves? please explain why/how and how this can be shown in an experiment thx :)
  22. wolram

    Exploring the Limits of Radio Signals

    it has always seemed incredible to me how little power it takes to transmit radio signals over vast distances,i have read about how these signals are self sustaining, i was wondering how long a signal could retain its information, could it go clear across the galaxy?