New answers tagged

3 votes

Basics of interpolation: is filter or upsample first?

To add to Gillespie's correct answer, it's worth knowing that in the literature of DSP the terminology used to describe "sample rate change" is often confusing. Here's some of the ...
user avatar
2 votes

Spreading sequence in DSSS

the spreading sequence is known only to the receiver and the transmitter. is only necessarily known to the receiver and the transmitter. There's nothing that says it needs to be a secret. In fact, it'...
user avatar
3 votes

Basics of interpolation: is filter or upsample first?

You wrote: Which one is correct? Filter + upsample or upsample + filter? The answer is actually neither. Lowpass filtering is part of upsampling, not an extra step. ...
user avatar
  • 598
0 votes

Power of noise signal through a matched filter (Digital Receiver)

Can anyone explain why that is? Which is the starting thought, or formula that yields to different times $t_1$ and $t_2$? The noise power $P_N(t)$ at any given time $t$ at the output of any filter (...
user avatar
1 vote

Order statistics: always applicable tool in wireless communication?

Ok, first, we'll need to acknowledge that the channels you're looking at are very specifically about such a channel. It's no coincidence! In all these papers it's about considering the order ...
user avatar
2 votes
Accepted

Understanding Pathloss and latency

There are many possible ways to model path loss to include both attenuation and delay (latency). For example, this page from Molisch gives a way to include both: the Power Delay Profile approach.
user avatar
  • 22.5k
0 votes
Accepted

convert from binary to hexadecimal according to the algorithm "keeloq"

As per @tonys in the comments. \begin{matrix} 1101 \ 1111 \ 1101 \ 1101 & \rightarrow& \mbox{inverted, bit reversed} & \rightarrow& \tt 0x04 \ 0x44\\ 0001 \ 0111 \ 0001 \ 0111 & \...
user avatar
  • 22.5k
2 votes

Why should costas loop be done after clock recovery, as opposed to before?

The job of the costas loop is to "derotate" the constellation points. But for that you first need to look at the constellation points at the symbol instants. If you look at the signal ...
user avatar
1 vote

High error when adding small value of SFO into the OFDM signal

The sampling frequency offset will induce a time offset on every symbol that is increasing from symbol to symbol. This results in the rotation as observed. Frequency is the derivative of phase with ...
user avatar
  • 37.1k
1 vote
Accepted

Sampling frequency offset vs carrier frequency offset effects

If $x[n]$ is your OFDM signal in the time domain, and you compute $x[n] e^{j 2\pi \frac{\Delta f_s}{f_s} n}$ then you are simulating a carrier frequency offset of magnitude $\Delta f_s$ given a ...
user avatar
  • 1,372
0 votes

Designing a PI filter for a Costas Loop

The low pass filters used must have cutoff frequencies at least 10x higher than the PLL loop bandwidth and of minimum delay so as to not affect loop stability. I recommend using minimum phase filters ...
user avatar
  • 37.1k
3 votes
Accepted

How to choose correctly oversampling ratio?

The referenced post does not imply that 8 samples per symbol are required, that is only what was used in order to show the extended spectrum as copied below: What I have also included in this copy of ...
user avatar
  • 37.1k
1 vote

Question on Signal to noise ratio (SNR)

Assuming the path losses are all equal and direct with no subsequent reflections (an unlikely but simplifying assumption), the signals if correlated (phase aligned, which beam-steering would provide) ...
user avatar
  • 37.1k

Top 50 recent answers are included