# Questions tagged [digital-communications]

Digital Communication is the physical transfer of data (a digital bit stream) over a point-to-point or point-to-multipoint communication channel.

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### Help on understanding Gardner's original paper for QPSK symbol timing recovery?

I am fairly new to DSP and RF receivers in general, and I was recommended to read Gardner's original paper for symbol timing error recovery for QPSK signals. I have a question regarding an equation ...
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### Bandwidth and BER of FM0 encoding

What is the bandwidth (i.e., the lowest possible bandwidth) and BER for FM0 encoding? To be precise, this is my example of an FM0 encoded waveform: There is always a transition between each bit. For ...
38 views

### Approximate IIR filter with FIR filter with energy restrictions

Hi I was presented with this problem I would like some guidance to solve: I am given the following DT channel model: $$C(z) = 1-0.3z^{-1}$$ I am first asked to design an IIR linear zero forcing ...
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### How can we generate an orthogonal sinusodial signal to any other signal?

I have three signals which are \begin{align} A&=\cos\left(2\pi ft + \frac \pi2\right)\\ B&=\cos\left(2\pi ft\right)\\ C&=\cos\left(2\pi ft + \frac {5\pi}4\right) \end{align} What i need ...
41 views

### pulse shaping concept

I'm a little confused about pulse shaping I know that pulse shaping is a filter used to convert a signal that needs to be transmitted from a rectangular pulse signal into a signal that similar to Sinc....
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### The use of LS estimation with Vector OFDM

I work in Vector OFDM, but I had an issue in channel estimation in that scheme. For example, I try to use LS channel estimation but I can't get the performance back. However, in conventional OFDM, I ...
43 views

### How can I shape my time channel response, in order to have Gaussian shaped Doppler Spread?

I know how to generate a Rayleigh fading channel but I have no clue how I can shape the Doppler spectrum to be Gaussian. Any help will be really appreciated. ps: I am coding on matlab
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61 views

### processing gain in the receiver

I am always confused about the processing gain in the receiver. assume my receiver had LNA-> mixer->filter->ADC. does the filter in the analog section has any role to play with the processing gain? ...
49 views

### MIMO multipath delay [duplicate]

How is multi-path delay dealt with in MIMO systems? Most of the theory I have read on MIMO doesn't address multipath delay and assumes the multipath interference is limited to secondary antenna ...