New answers tagged modulation
2
votes
Help me understand the concept of IQ signals
It might be best to compare an IQ signal with complex numbers, or circle on an XY plane, or phasors.
As the IQ signal is a sum of sine wave with some amplitude and cosine wave with some amplitude, the ...
- 2,248
4
votes
Help me understand the concept of IQ signals
The important takeaway is: using a radio, you can transmit two signals "at the same time" (technically: over the same bandwidth). One of the signals is known as I (in-phase), the other as Q (...
- 14.9k
1
vote
Help me understand the concept of IQ signals
In SDRs, multiplying a real-valued bandpass signal by a cosine wave, and simultaneously multiplying that real-valued bandpass signal by a sine wave, generates a complex-valued signal that has been ...
- 5,577
0
votes
What is the relationship between Symbol Duration and Sampling Frequency in a 256 MPSK radio link
There is a difference between the information bits that you are sending and the bits that represent the samples that you obtain at the receiver. Each sample should be represented by high enough number ...
- 1
2
votes
Accepted
How is the normalized power required for unipolar NRZ twice that of polar NRZ?
If the levels of the polar signal were $\pm V$ you would be right, but then it wouldn't be a fair comparison with the unipolar signal with levels $+V$ and zero. A fair comparison would be to have the ...
- 88.8k
1
vote
Pulse amplitude modulation
For getting started with digital communications, I think Sklar ("Digital Communications: Fundamentals and Applications") and Haykin ("An Introduction to Analog and Digital ...
- 14.9k
3
votes
Accepted
Is BPSK relevant, or does it even exist, in wireless data transmission?
You are mostly correct. The main problem is that the introductory textbook definition of BPSK as a train of square pulses multiplied by a carrier is so simplistic that it hides what is really going on....
- 14.9k
1
vote
How does PAM-4 encoding of a digital signal relate to theoretical *pulse* amplitude modulation?
There are two different concepts at play here sharing the name PAM, and the Wikipedia article is not helpful at all to disentangle them.
The first meaning of PAM is related to the problem of ...
- 14.9k
Top 50 recent answers are included