Radio Definition and 691 Threads

What is modulation in radio communication?

I'm curious why can AM radio waves be heard on the other side of a mountain from where they are propogated and FM not? Thanks

http://news.bbc.co.uk/2/hi/technology/4059011.stm

Hello, I was just wondering if anyone around here is a Ham/ interested in amateur radio at all. I got my ticket two years ago when I was sixteen but don't operate much lately due to college and the horrible reception you get in the average dorm. KB3HTS

Ok, so we all know that the shorter the wavelength, the higher the frequency, and the higher the photon energy for EM radiation. How does this relationship explain why X rays are highly dangerous to living things, and radio waves are not? Thanks in advance.

Hey i was wondering if anyone had any sites on how to build a Spark Gap Radio Transmitter, i need to do this for history to show how marconi invented the radio. Thanks- Andrew

Please help with problems please! All questions need to be solved using vectors. See enclosure for questions :biggrin: Thank you! Or go to: http://img128.exs.cx/img128/9089/questions2.jpg

Hi, I'm trying to design a low-cost digital radio interface to communicate with a robot. I'm not interested in exchanging a lot of data, or doing it at high speeds. This design will work well if I can get even 300 baud out of it since I never exchange more than about 1K bytes during a...

if a car with a radio is moving at some speed and it receives radio waves shouldn't these waves get Doppler shifted and the radio signal be disrupted?

There is an archived program of an interview I conducted with Dr. Kaku about a year or so ago. We discussed worm holes, alien life, god, dimensions and more.. Check it out, on the front page here: http://www.infidelguy.com

I just read of an idea to send a craft outside our solar system using the various stellar bodies to sling shot it and also create a way for it to continually accelerate. In which case it would eventually near the speed of light. So in fifty years it could send us pictures and what not of faraway...

I have come to understand the meaning of the terms "am" and "fm" as different kinds of radio emissions. Sadly, I have not understood the meaning of the numbers used to identify certain radio stations. If someone could tell me, it would be fantastic. :smile: I've been dying to know. :-p

Could a crystal radio use a lead sulfide or lead selenide antenna an pick up in the infrared?

Can a crystal types radio be made to work in infrared? With an antenna of lead sulfide or lead selenide perhaps?

How would u make a radio that's tuned into 120.55 Mhz? or any frequency? I thought you would fallow this formula... (120.55 * 10^6 Hz) = 1/(2 pi sqrt(LC)), where L is the inductence, and C the capacitor. well i figured a 1 micro (10^-6) Henry inductor and a 1.743 pF (10^-12) would create...

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...

Ok, I saw this guy trying to unlock his car with his radio controlled keyring with no luck, he put the device next to his head and it worked. The keyring was the same distance to the car in both cases give or take 1/4 meter. Would the same happen if you put the keyring next to a conductive metal...

Through my school, I'll be working with a radio telescope. I was wondering if you guys had any ideas or suggestions of cool things that I could research or observe with the radio telescope. Thanks!

has anyone here ever built a crystal radio? what parts would i need and where can i get them? in the physics forum they said one could be constructed to run off the radio waves themselves, which is the kind i would like to build. thanks

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 :)

Im not talking about TVs, but radio astronomy. We receive signals from say a distant star and turn it into a picture, but how?

A friend and I are trying to build a radio controlled airplane, but an LCR circuit tuner would be too heavy. Does anybody know of a way to make a tuner without an inductor coil? Any help would be appreciated.

A radio inductor. Please help! Hello. I am seeking immediate help with a problem I have. Here is the problem: A Radio Inductor. You want the current amplitude through a inductor with an inductance of 4.60 mH (part of the circuitry for a radio receiver) to be 2.20 mA when a sinusoidal...

Hello everyone I was curious if anyone was a user of satelite radio? If so, may you comment on it? I am curious what are the advantages of XM Radio vs Sirrus?

http://news.bbc.co.uk/2/hi/science/nature/3567729.stm

http://www.arrl.org/tis/info/HTML/plc/

sorry for my bad english, but this problem is translated from french. In this problem, i have to make a low-pass AM radio filter using the following information: frequency: 130 kHz Condensor Capacity: 12 nF This filter must be installed in parallel with the synthesisor. It says to use...

I'm in IB math methods, working on a project and I can't seem to figure out what to do with this problem. A radio transmitter sends signals to a railway which run along a straight track. When a set of coodinate axes is used to represent this system, the transmitter is at R(1,0), and the track...

Hi, i was interested in a detector that could measure the intensity of a radio wave of a particular frequency, at a point. Either by using a capacitor or a radio diode (or any other way). If such a devise exists please tell me where I can find one, if not any advise on how I might be able to...

I doubt that my physics teacher (who is coincidentally Mark2711 on this forum) has found out the answer for this question that he was wondering about , so i have decided to take the initative and ask. We know that photons are the quantas of energy in the electromagnet spectrum. Well we know...

If you have a radio and it is tuned to a specific freq, is it possible to find out what that freq is without touching the radio? I have this radio that has a button that tunes to an unknown freq when press. I can't seem to tune to the unknow freq. with other radio. is it special or something...

SO I am doing a Powerpoint for my Science class. Well anyways maybe you guys could help me out a bit. Which kind of bondings to Radio Active Elemenets (actinide and Lanthonide) use, and why? And what is so unique about Radio Active Element. If anyone could respond to this tonight I...

hi all, Can anyone tell me a easy way to create radio waves,micro waves reciver and emiter? I hope someone will help me. -benzun all for God.

i was reading an article about the new RFID tags that could replace ATM cards. these tags respond to query via a radio tranmission. the tag then uses the power that was in the initial radio transmission to reply back to the system. how are the tags using the power from the transmission? can...

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?

hey guys, can you find any links on the web that discusses how a analog radio tuner works... i'm talking about in the level of an electronics and communications engineer...an in-depth study and discussiion would be highly appreciated... is this related to an RL circuit?

http://www.wired.com/news/privacy/0,1848,60408,00.html

What is particle "spin", and does it have anything to do with radio activity? I keep hearing about the "spin" of sub-atomic particles like such-and-such particle has a spin of 1/2 or 1. I heard even some have a spin of 2. And it also seems that I have heard that some radioactive particles have...

Libby's observation that all the carbon in the world's living cycle is kept uniformly radioactive through the production of C-14 by cosmic radiation led to his development of the radioactive carbon dating method. Samples of carbon in the life cycle have been found to have a disintegration rate...

Im not sure of this, but visible light is an EM wave just like radio waves are, right? If I am right, does that mean mirrors reflect all ranges of EM waves, radio included? Also what is it about a mirror that reflects photons?

I'm not sure where to post this. On my FM radio (yes, I am pretty old fashioned), if you tune it to be slightly out of a station or if there is a weak signal or something, you can distinctly here a strange pattern of interference in the background. This consists of a rapid pulsing of white...