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Questions tagged [modulation]

Generic term for coding information onto another carrier signal

36
votes
9answers
57k views

What is the basic difference between AM and FM radio?

I want to know the basic/fundamental difference between AM and FM radio. Why nowadays FM radio has replaced AM and has become more popular?
15
votes
3answers
36k views

What is Overmodulation?

The Wikipedia article is very short and doesn't explain the concept very well, and there aren't any other sites that I can find that give a simple explanation. What does it mean by 100% modulation? I ...
2
votes
4answers
797 views

What solutions, if any, are there for visible light transmission (VLC)?

I want to know what ways are there to transmit data using LED's that are available to us today. I currently can find only one reasonable resource for this topic, which is this: http://www.siemens.com/...
0
votes
2answers
69 views

frequency modulation and incoming signal selection

I have some understanding of what frequency modulation entails - it entails "adding" a new frequency to the frequency spectrum of a signal. But how, exactly, is a modulated signal selected in the ...
4
votes
3answers
2k views

FM transmitter design?

I stumbled across a relatively simple FM radio transmitter online. Credit: makezine.com I wanted to understand how it works (it is called "super simple" on the website), but several hours I have ...
3
votes
5answers
2k views

Transmission of a digital signal over a medium

A digital signal is said to have a infinite bandwidth. If a transmission medium cannot have infinite bandwidth then how can a digital signal be transmitted over such mediums? Please correct me if I ...
1
vote
2answers
6k views

Current modulator for laser driver?

For a project, I like to feed a sine wave to laser, this sine wave must have a DC value of 2V and it should oscillate between 2.5 and 1.5V at 100KHz. The current required is <50mA. What is the ...
1
vote
6answers
2k views

Why does more bandwidth guarantee high bit rate?

The definition of bandwidth is frequency range and it seems to be correct to say that higher bandwidth guarantees higher data rate. However, i do not understand why it does. Data rate depends on ...
0
votes
3answers
4k views

Operation of LC circuit in Frequency Modulation with simulation and linking it to the basic principle of frequency modulation [duplicate]

Can somebody help how message signal (words spoken near microphone) is modulated using LC circuit and how lc circuit oscillates at particular frequency by applying dc voltage. In the below circuit l1 ...
5
votes
1answer
2k views

Questions about heterodyne receivers

All radio receivers seem to use the heterodyne principle. I can see that it will be easier to work with a fixed frequency than demodulating from a wide range. Questions: what's the difference ...
3
votes
2answers
5k views

QAM modulation - how data in different frequencies are laid out?

I know that QAM modulation uses a change in phase and amplitude to send data. But We use a series of frequency spaces as bandwidth to send data. However, we know that different frequencies oscillate ...
5
votes
1answer
4k views

FM Transmitter Modulation

I am designing an FM transmitter as a learning experience and for fun, but I am having some difficulty with FM modulation. I am using a VCO with a Colpitts topology and common emitter configuration. ...
2
votes
2answers
2k views

How to get BPSK data from I/Q signal

I am using AD8347(0.8 GHz to 2.7 GHz Direct Conversion Quadrature Demodulator) to demodulate a BPSK modulated carrier wave. There is no intermediate frequency used. By feeding the signal into this ...
1
vote
1answer
3k views

Analysis of Class C AM modulator

The following schematic is a class C AM modulator without use of any transformers I've just changed the parameters in spice to get a correct modulation. however I want to find the theoretical value ...
1
vote
2answers
1k views

How is it decided what modulation is used during an 802.11 communication?

I understand, that 802.11x protocolls can use different type of modulations. BPSK, QPSK, 16-QAM, 64-QAM... I also understand that the used modulation depends on the quality of the channel, I guess on ...
1
vote
0answers
181 views

Why more bandwidth means more bit rate per second? [duplicate]

According to this link ( and some other sources I have found ) more bandwidth on a wire means more bit rates per second... Can someone try to explain why this is so as simple as possible? This is ...
0
votes
1answer
354 views

FM Transmitter Circuit (range 3 km) on Multisim

I am new to the telecom simulations system specially multisim, which I am having a project that I want to simulate. My project in (Analog Communications) is consisting to have FM Transmitter (...
0
votes
1answer
1k views

How is FM modulation is achieved using a single BJT

I want to understand how this circuit achieve frequency modulation. The BJT is a 2N3904. I found that millers effect comes into play and varies the frequency of the tank circuit about a center ...
0
votes
1answer
235 views

How to modulate Transceiver module for use with ATmega164PA

I am using a transceiver TFDU4101-TR3 to communicate with another device which has exactly the same transceiver. I bought this thinking I can communicate with the transceiver using my microcontroller ...