Radio Definition and 691 Threads

Homework Statement Describe how the concept of wave superimposition is used to create AM radio waves. Homework Equations The Attempt at a Solution O.K, I am not sure that I understand how this works. In the picture attached it shows the carrier frequency inside of the audio...

Hi All, I wonder if the modulation of RF waves (Amplitude Modulation, Frequency Modulation, and Phase Modulation) can be explained in terms of photons. Thanks, Srini

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...

I am merely getting curious in thinking about building a radio-wave laser. I'm not seriously pursuing this, but I think it would be cool to build a laser that is ~10km in length. Is anyone aware of any research into this type of monstrosity? Any thoughts about the feasibility or the potential...

Two radio antennas A and B radiate in phase. Antenna B is a distance of 130 m to the right of antenna A. Consider point Q along the extension of the line connecting the antennas, a horizontal distance of 50.0 m to the right of antenna B. The frequency, and hence the wavelength, of the emitted...

hello i have been given six weeks to design a low-power FM radio transmitter for my project however there are no lectures for this course so i have to do the research on my own. so far from researching on the web. i have found that a simple radio transmitter may consist of a number of stages...

This might be a stupid question, but here goes. I'm trying to build my first radio and I want to know if LCR meters are capable of measuring current and voltage or if I have to purchase a separate multimeter to perform those measurements. Any help would be appreciated.

As I understand Interferometry, a baseline does not refer to the distance between two RA scopes. It's the distance between two line of sites for each scope. They are parallel, when directed at the same object. Suppose we have two scopes at two stations that are some distance apart, say...

I understand that the simplest tuner you can have is a capacitor and inductor connected in series, and i understand that radio waves use AC current to send signals, and that capacitors block DC current. I think i also understand that an inductor even without an iron core experiences an opposing...

I am modelling a radio wave propagation simulator for a Wifi at 2.4 Ghz. I know that the refracted index of glass for light is around 1.5, how do I translate this to a 2.4 Ghz radio wave. And what about other materials, such as concrete, brick wall etc. Thanks.

Hi guys, We all know that a shadow could be generated by radiating light waves to an object. Would it be possible to design a system with radio waves, an object made by a special material and a sensor plane in order to create a shadow of the object on the plane? Cheers!

Homework Statement A radio station transmits 680kHz at a power of 50000W from a transmitter. Estimate the strength of the signal as it was received by the antenna 35 km away. Homework Equations I don't know any equation for this that's the problem! The Attempt at a Solution I can't...

Hi! I need to carry out radio frequency heating (heating by radio waves) for a reaction. Can anyone please help me design a circuit for that?

Can anyone help me/suggest some links to make a radio frequency heating apparatus? I need to carry out radio frequency heating (heating by radio waves) of some reactant samples. Please help..

Can anyone explain why cranes in construction sometimes experience induced currents from antennas radiating from distances of up to several Kilometers. I have looked into the phenomenon several times, and have not been able to find a study or baselines to follow. I have a basic understanding...

Hey everyone, Ive been learning RLC circuits recently and all is ok now in the understanding side of things. We have also been learning about AM transmition and LCAM. Also how LCAM uses just a diode, capacitor and resistor to demodulate as that circuit will trace the peaks and recreate the...

Here's a bit of a weird one. My grandmother (93 years old but "still with it" mostly) had a natural gas heater installed last year. It's one of those wall mounted heaters with a flue. Anyway, several weeks ago she told my parents she could hear the radio through it at night. I was quick to...

Good day, I have been given the task to create an inventory database for the books at the library at my school using the RFID to monitor the books. However the books have specific codes based on their type and location in the library. I was wondering if someone could give me some information as...

Regarding the concept of radio frequency interference, electromagnetic waves, as broadcast, never actually interfere with each other. The interference exists as interference to the induction measured at the receiving antenna. So my question is, has anyone ever tried to produce an intelligent...

Homework Statement A radio receiver is set up on a mast in the middle of a calm lake to track the radio signal from a satellite orbiting the Earth. As the satellite rises above the horizon, the intensity of the signal varies periodically. The intensity is at a maximum when the satellite is 1...

Hello everyone! I was just thinking about whether it will be possible to utilise the energy transmitted through the radio waves to produce back electricity for a household. Most of the houses in the world are blanketed by radio waves from all directions. Will it be possible to use an antenna...

http://news.yahoo.com/s/dailybeast/20110513/ts_dailybeast/14060_rushlimbaughandrightwingtalkradioflameoutaslistenerstunetoindependents_1 Imo, right-wing radio and TV has gone a long way towards destroying the social fabric of this country. I see it as being more damaging to our way of life...

Ok I've done my research and so long as the transmitter isn't outputting at a high level of power, you'll be fine. Why I ask is because I'm looking into getting a job with a small company, where they install network elements such as optical and radio transmissoin (and multiplexers). Now I...

If I know the: Frequency Effective Radiated Power Height Above Average Terrain Radiation Center Above Mean Sea Level Radiation Center Above Ground Level of a radio signal / tower, is there a way to determine the rough range of the radio signal?

Ok I've done my research and so long as the transmitter isn't outputting at a high level of power, you'll be fine. Why I ask is because I'm looking into getting a job with a small company, where they install network elements such as optical and radio transmissoin (and multiplexers). Now I...

Hello all I have been trying for sometime now to find the effects that magnetic field has on radio waves (such as cell phone signals and wireless broadband signals). If anyone of you could guide me towards right direction, would be very much appreciated! Thanks Ashutosh

Homework Statement For radio transmission in free space, signal power is reduced in proportion to the square of the distance from the source, whereas in wire transmission, the attenuation is a fixed number of dB per kilometer. The Attempt at a Solution this is not the whole problem...

http://www.thisamericanlife.org/radio-archives/episode/293/a-little-bit-of-knowledge (The story about the crackpot starts at at the 30:40 mark.) Act 3 of this episode of This American Life is a story about an actual crackpot, with a crackpot theory, told from the point of view of a friend of...

Homework Statement Roger in ship offshore listening to baseball game on his radio. He notices there is destructive interference when seaplanes from nearby Coast Guard station fly directly overhead at elevations of 777 m, 970 m, and 1163 m. The broadcast station is 98 km away. Assume there is...

hello i am new, i thinking to make a fm radio receiver but i don't know what i need (capacitor, oscillator etc) can someone help me with more knowledge than me ? if you have link or something else that maybe help me is welcome. i search the internet but i don't can find anything that suit in my...

Homework Statement My solution isn't working out for this question. Radio waves of wavelength 125 m from a galaxy reach a radio telescope by two separate paths. One is a direct path to the receiver, which is situated on the edge of a tall cliff by the ocean, and the second is by...

I am working on an independent project at A level and have chosen to look at scavanging energy from radio waves. i have built a rectifier circuit and tested various types of dipole to induce a dc current. so far so good, got some very good results. however, there is very little...

I find EM waves very intriguing. But i get more confused and new questions pop up in my head every time i read something about it. I have a few basic questions. 1. Wavelength: As wavelength is distance between two peaks, how can we measure this distance in cm, meter etc. as physically there...

If a particular radio telescope is 100ft in diameter and has a cross section modeled by the equation x^2=167y, how deep is the parabolic dish? What is the location of the focus? can someone show me some steps to solving this? I have (167/4,0) as the focus for the second part but I am not...

Homework Statement If we placed a radio receiver inside a cage made of 100mm grid wire mesh, would the radio reception be better for low (eg 1 MHz) or high (eg cellphone) radio frequencies. Explain Homework Equations The Attempt at a Solution I think the reception would be better...

Hi, I'm reading about the discovery of the cosmic microwave background radiation and don't understand this part ... What power does a source called with liquid helium produce and how is it related to the amplifier circuits ? I don't get what they did and why ? Thanks !

hi guys , I d like to ask you some comments and recommendations, I am an undergrad working ,trying to, on a project. I was thinking that if I could connect an antenna to a prism and then create light of different wavelength which could be used for ...I don t know photoelectric effect and...

Just a thought. We have the capability to use viral transfection to stimulate brain cells into producing channelrhodopsin proteins which cause the brain cell to fire in response to a light impulse of a specific frequency. If neuroscientists were able to synthesize a protein with similar...

Hi, I want to ask how can i refract or reflect radio wave. I know it can go trough my wall or glass in window(like wi-fi). But why does that happen? According to what we learned on physics lectures electromagnetic wave must refract or reflect when it goes from one optical medium to another...

I have a challenging question about electromagnetics. I presume if two antennas were designed to broadcast the same signal, but were designed somehow be exactly phase shifted by 180 degrees. And the antennas were stationed very close together. So that no electromagentic noise would be detected...

Homework Statement A radio (power = 150 W) and a water heater (resistance = 40 Q) are connected in parallel. The current, needed for them is fused at 10 A maximum. Homework Equations Does the fuse stand the simultaneous use of the radio and the heater? The voItage is 240 V. The...

Hi all, I can't figure this one out, but I'm sure I'm probably missing something simple. Here's the problem I'm having: From what I've been told in my SCUBA class (as well as from online article's and forums) light is attenuated in water in the order red->violet (red being attenuated first)...

Homework Statement The capacitance of the variable capacitor of a radio can be changed from 100 to 350 pF by turning the dial from 0° to 180°. With the dial set at 180°, the capacitor is connected to a 130 V battery. After charging, the capacitor is disconnected from the battery and the dial...

Homework Statement ...Consider a diffuse gas cloud that contains carbon monoxide (CO) molecules... What are the radio wavelengths (in cm) and frequencies (in GHz = gigahertz = 109 Hz) corresponding to transitions between the ground state, the first excited state, and the second excited...

A person runs a 9.0 V, 12.0 W radio for 1.33 hours. How many coulombs of charge pass through the wires in the radio during this time? I used Power= pot difference/Resistance = 9v/120w=7.5e-2 I=current Then I used I²=P/R= 120v/7.5e-2 = 1.6e3 I=40A 1.33h*60mins*60secs = 4.788e3...

Homework Statement i was wondering why would high-voltage transmission cables disturb a car's radio reception with static?Homework Equations The Attempt at a Solution Could it be because of the frequency of the voltage? Or something in terms of frequency? Thanks :smile:

Homework Statement So I have to make a snapshot & history graph of a wave. I chose to do a radio wave. However, I just want to know what the measurements for amplitude and wavelength. Also, there's no specific way to draw a snapshot of a radio wave is there? I can just draw the wave...

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...

Can anyone give me a good, concise explanation of how radio waves are generated and used? I've searched a lot around the net for a good explanation, but all I can find is info about how antennas are oscillated at specific frequencies to produce radiation at the same frequencies...I want to know...

Homework Statement A car’s radio antenna is located at a distance of 56.983 m from a brick wall, which is assumed to act like a dense barrier. The car is attempting to listen to an FM radio station with a frequency of 89.5 MHz. These waves travel at the speed of light, 3.00 × 108 m/s. The...