The decibel tag has no wiki summary.
1
vote
4answers
154 views
Headphones impedance and the SPL
The headphones A has an impedance of 32 Ohms.
The headphones B has an impedance of 250 Ohms.
Both of the headphones are similar by size.
Is it right that the headphones B will play quieter by ...
6
votes
5answers
369 views
What does it mean for a signal to have an amplitude below 0 dB?
I am a software developer (using high level languages like .NET,C,C++ etc) trying to understand how computers work at a lower level.
I understand that amplitude is always positive because it is ...
1
vote
1answer
59 views
Power and decibels
In one of the examples in a engineering textbook, I noticed that the decibel value for the Power of a transmitter (also known as modulator) was 20DB and this was said to be equivalent to 100W.
...
5
votes
4answers
570 views
Why do we use dB to represent the difference between two voltages?
For example, the passband of a LC resonant circuit is the differences of frequency at +3db and -3db.
Why do we prefer dB?
6
votes
2answers
1k views
What is the significance of -3dB?
My oscilloscope has 100 MHz -3dB bandwidth. -3dB is 0.707 units (sqrt(2) / 2). What does this mean, why 70.7% attenuation? Is there any particular reason for this attenuation level?
17
votes
5answers
2k views
What does dBm mean?
When working with radios, I've seen the term "dBm". What does this mean?
The wikipedia page gives a table showing the equivalent power in Watts. Is the dBm output just the power level of a ...
