All Questions

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0
votes
2answers
80 views

Why don't we use analog remote mics?

All remote microphones sends digital samples over the ether. Why no analog remote microphones? I know that digital signals are less sensitive to noises, but there are several advantages of analog ...
0
votes
0answers
51 views

iPhone headphone out as a signal source for AM modulation circuit

EDIT: I wonder what is the appropriate model for an iPhone/MP3 player audio out? I imagined it as a voltage source that would support whatever current the resistance it’s connected to necessitates. Is ...
10
votes
1answer
2k views

What could this signal at 119.9 MHz be?

I had some fun with an RTL-SDR dongle, and I noticed this weird signal with no noticeable pattern at 119.9 MHz. What's even weirder is that the signal is symmetrical. What might this be? Or is ...
1
vote
2answers
185 views

what is wideband phase shifter in modulator?

in these days I have been studying communication systems. and I want to know the role of wideband phase shifter in the picture above.
14
votes
1answer
871 views

Why FM stereo uses DSB-SC instead of VSB?

Using vestigial sideband instead of double sideband supressed carrier could make the baseband stereo signal more compact. Would there be any other benefits or downsides of employing VSB?
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 ...
16
votes
4answers
6k views

If an FM signal has different frequencies, how does the radio receive the signal in a fixed frequency?

If an FM signal has different frequencies according to the modulation, how does the radio receive the signal in a fixed frequency like 103.2 MHz?
0
votes
2answers
140 views

Which characteristics of a Radio signal are involved to be selected by radio receiver? [duplicate]

the radio antennas receives millions of signals. how our radio selects the appropriate signal as it's input? which characteristics of the signal are involved for this selection.
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?
3
votes
4answers
1k views

How Does FM Get Around the Gabor Limit?

The Gabor Limit states that it's impossible to simultaneously localize a signal in both frequency and time. FM communication modulates the instantaneous frequency of the carrier in step with changes ...
1
vote
1answer
134 views

What are the main power draws within a mobile phone radio?

It is often quoted that "3g uses more power than 2g on voice calls" or other similar things, but it seems from a theory perspective that transmitting low bandwidth voice data with a high bandwidth ...