Radio Definition and 671 Threads

Hello. I'm trying to understand electromagnetic radiation. Any help would be appreciated. From my understanding a photon is a basic "unit" of electromagnetic radiation with an energy corresponding to hv. Additionally radios transmit electromagnetic waves by sending an AC through an...

Hello, I've got a question about distance measuring via radio. I would like to measure the distance between two devices, relatively small ones, using radio and my question is how fine that measurement can be? The devices would be a maximum of say 15 metres apart and a preciseness of about a...

How "bright" are radio and other EM signals? Greetings, I am wondering how "bright" man made EM signals such as radio are. That is, if they were in the visible range, how would they compare to visible light sources? Would they be barely visible? Would they be daytime sky bright in every...

Good day everyone. I'm starting to become interested in listening to radio waves. I'm very new, just reading generally on what types of radios waves exist and what they are used for. However, mostly my interest is in the area is of the sounds of these waves. I'm wondering if there are any...

Hi Experts :!), I tried to use a 5v dc voltage source to power a normal handheld 3v radio using a resistor to regulate the voltage. The voltage drop across the resistor seems to fluctuate constantly by about +/- 0.8 volts. So, the voltage drop across the resistor fluctuates between 1.5v...

Siting listening to the radio i hear a quit loud (pop) ,enough to make me wonder what the heck, looking around i could'nt think of what could caused it, it was only after hearing this (pop) several tlimes over the weeks that i found the cause, it was a coke bottle POPING back to its normal...

Is there a way to monitor and block intrusive radio waves?

How do you connect a variable capacitor to an inductor to make a series radio tuner? And where do you tap the resonant frequency to send to the RF amplifier?

I think NPR radio is the most unbiased media. What do you think? You don't need to reply if you think Fox is unbiased :)

I found the following extremely interesting article about the jamming of pro-Western broadcasts in Estonia during the Soviet period: http://www.okupatsioon.ee/english/mailbox/radio/radio.html" One part of the author's description I'm puzzled about: "Although all LW, MW, and SW broadcasts...

Hi Just have a quick question, for audio input (AUX) into speakers would it be possible to make a powerless radio receiver plug in, or would it require power? Thanks

Homework Statement Three radio-equipped plumbing vans are broadcasting on the same frequency f_0. Van 1 is moving north of van2 with a speed of v, van 2 is fixed, and van 3 is moving west of van 2 with a speed of v. What change in frequency (f-f_0) does van 3 hear from van 1? Homework...

Like the title says, I'm wondering what exactly is the definition for radio luminosity. A search on Google doesn't turn up with anything. I think it means the intensity of radio waves emitted, but I'm not sure. I'd rather you explain the term without using the word luminous or any variation of...

I have a minor bit of circuit experience. As a fun project id like to build a shortwave radio. Does anybody have any tips on where to start.

While their electronics stock has been slowly diminishing for years, until recently it was still possible to make a quick run to Radio Shack for an emergency 7805 or 741, but it seems that day is over. I stopped by the local store yesterday and found only two drawers of stock with only the most...

For an exam I am studying for, I have to understand the effect of measurement tolerance, calibration accuracy and time-related drift on frequency measurements. Im aware that the time-related drift is due to the oscillator frequency becoming less accurate (due to continuous crystal vibration)...

Homework Statement An AM Radio station broadcasts isotropically(equally in all directions) with an average power of 4.00kW. A dipole receiving antenna 65.0cm long is at a location 4.00 mi from the transmitter. Compute the amplitude of the emf that is induced by this signal between the ends of...

Does anyone know what the typical bandwidth of the RTTY, PSK31 and FSK amateur radio transmission schemes are ?

Hi, I am completing the study of telecommunications. As I've lost some lecture notes and I like to keep references on my bookshelf I am looking for a good book about Electromagnetism, electromagnetic radiation and radio communications. From the comprehensive online offer it is not easy to...

I searched around this forum and google but couldn't come up with anything definitive. Now, I know that the radio in your car needs an external antenna because your car acts as a Faraday cage, and most radio waves don't make it through. But I'm having some reception issues. I own a 1986...

hi, i wanted a simple explanation of a series rlc circuit in a radio as i know the rlc circuit consists of resistor,inductor,capacitor i know the function of each of them but what i don't understand is how by combinig them we can make a radio tuner!? i searched many websites but i can't find a...

This is probably an easy solution, but I can't figure it out for the life of me. I have a bunch of radio buttons with corresponding text right next to it. What I want to happen is that when the mouse is moved over the radio button, I want the text background to get highlighted. As you can see...

Right this is a question about some radio noise that I picked up from my speakers last night. My speakers were plugged into my tv with the volume off, this tv was plugged into a Freeview box which had an aerial cable plugged into that connects to the aerial in the loft. Just after I...

Dynamic Soaring takes advantage of differeing wind flows separated by a thin wind shear boundary. Recently the record for radio control glider reached 392 mph (peak speed is over 400mph, but the convention is to measure the uphill return speed: http://www.youtube.com/watch?v=WaQB16ZaNI4&fmt=18

I'm not knowledgeable about these things, with all the free energy nonsense I frequently see. So what do you think? http://tech.yahoo.com/blogs/null/143945 Does this sound right? If so, it looks like exciting news. Even for stand-by charging, that's still a good thing.

Homework Statement Two coherent sources of radio waves, A and B, are 5.00 meters apart. Each source emits waves with wavelength 6.00 meters. Consider points along the line connecting the two sources. At what distance from source A is there constructive interference between points A and B...

Homework Statement What is the percentage amplitude reduction of 10MHz radio waves that travel through 250 meters of water? Construct a plot of the average energy per unit volume stored in these radio waves as a function of depth from 0 to 250 meters in terms of the initial electric field at...

Homework Statement 'Briefly explain the importance of skin depth in the context of radio communications.' Homework Equations The Attempt at a Solution A guess would be that, the frequencies of the radio transmissions should be kept small so that the signal has a large skin depth...

Hello, I noticed that with my radio sometimes when I am getting static if I bring my hand close to the antenna, the radio suddenly becomes clear and I can hear the station very clearly.I can either touch the antenna with some metal, or more dramatically, I just bring my hand close to the...

I was wondering what kind of things you would need to transmit to a satellite or something on Mars and get video and whatever other signals back from there. Like transmit controls there for a rover to take and possibly to bring it back. So for the journey there and back.

I know that light (such as that emitted by a fluorescent bulb) is generated by electrons falling into lower energy states and releasing an amount of energy as a photon. But radio is transmitted by producing an alternating current in a conductor, and (I assume) it's the acceleration and...

Hi, I travel by train nearly every day, and I am using a crappy portable radio connected to my phone (it's just a very small radio receiver built into the earphones) to listen to the radio during the journey. I can't help but noticing two effects, one that can probably be explained pretty...

I'm putting together the Itty Bitty Radio Telescope. In the instructions (see: http://www.aoc.nrao.edu/epo/teachers/ittybitty/procedure.html), it says to use a .1Mhz RF Choke. I have been unable to locate this particular frequency, as the only one I have been able to locate has been a 1kHz RF...

I've learned the basics of waves but now I have a burning question. No amount of googling appears to help. I was wondering how radio station broadcasts don't interfere with one another causing loss of information on the signals. After all they are waves and interference occurs when waves...

Hey all! Now I'm working on wireless communication, not a physician. In many courses in ECE, we learn about principle of superposition of radio waves. But I have a stupid question which has been considered no wonder so far. There are two radio senders(S1,S2) and one receiver(R). Let's...

Minimum Resolution Angle Problem Homework Statement The radio telescope at Arecibo, Puerto Rico, has a reflecting spherical bowl of 295 m diameter. Radio signals can be received and emitted at various frequencies with appropriate antennae at the focal point of the reflecting bowl. At a...

Homework Statement If you are located 100 [km] from a transmitting radio tower, how long would it take the signal to reach you? Homework Equations Have no clue how to start.

I accidently got into AM radio mode in my car for the last two days, and I can't figure out how to take it back into FM because there isn't a stupid AM/FM button. I had to have hit some funky combination of buttons to go into AM and now I am stuck. ANYWAYS, I've been stuck with this AM radio for...

My Sony 400-CD carousel died last week, and I have been waiting all that time for a replacement to arrive. My collection (about 75% of it fits in that player) is a mix of blues, rock, country, country/rock (think Poco, Buffalo Springfield, etc), bluegrass, R&B, etc. I unloaded all my CDs from...

Why does my body act as a radio Receiver.Last year i accidently grabed the socket to my computer speakers while they were turned on at the power outlet.The computer speakers were not connected to the computer and we do not have a radio receiver at all in our home.I only held the plug for one...

can someone tell me how to make a radio that would tune between about 1000 and 10000 Hz please. ? Or at least where to begin.

Homework Statement Two coherent sources of radio waves, A and B, are 5.00 m apart. Each source emits waves with wavelength 6.00 m. Consider points only along the line connecting the two sources. (a) At what distance from source A is there constructive interference between points A and B...

Homework Statement Seeking a method of calculating the number of photons instantaneously present within a given volume surrounding a radio transmitter at given power and frequency. Homework Equations E=hv, and other equations involving power and wavelength. The Attempt at a...

Homework Statement FM station KCOM ("All commercials, all the time") transmit simultaneously, at a frequency of 97.1 MHz, from two broadcast towers placed precisely 32.44 m apart along a north-south line. (a) What is the wavelength of KCOM's transmissions? Homework Equations...

Homework Statement Your favorite radio FM radio station broadcasts at a carrier frequency of 94.7 Megahertz. What is the wavelength of the carrier frequency radio signal? Homework Equations velocity=wavelength(frequency) The Attempt at a Solution 94.7x10^-6(w)= 3x10^8 w= 3.2...

So I did a little search and I can't seem to find any threads regarding amateur radio. Is anyone a ham out there and what frequencies do you lurk at and where? I'm a new ham, don't know why I decided to get into it but timing seems to be about right with new radios like Yaesu VX-8R and many...

Homework Statement Radio 4 transmits on FM at a frequency of 92.5 MHz Calculate the wavelength and use it to explain why listeners in deep valleys cannot pick up radio 4 FM. Homework Equations The Attempt at a Solution

Hi. I am designing an experiment focused on radio waves for my experiment and this is the basis of it: Three antenna's will be tested for point to point transmission (VHF): [ 144 MHz ] >>3/4 Wave antenna >>1/4 Wave antenna >>5/8 Antenna (Best Angle of Radiation Usually) These...

Hi. I have been assigned the task of designing an interesting experiment involving waves of any kind for physics class. I have chosen to focus on radio waves for my experiment and this is the basis of it: Three antenna's will be tested for point to point transmission (VHF): [ 144 MHz ]...

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