# Tag Info

### do digital equalizers use Fourier transforms?

Fourier transform technology Well, Fourier theory is behind every kind of equalizer. We wouldn't know what "equal" means without; the Fourier transform is how we know how to describe a ...
• 31.3k
Accepted

### OFDM time vs. frequency domain channel estimation/equalization

Traditionally, OFDM became popular in WiFi and LTE because the channel model consisted of multi-path. That is, the radio signal transmitted in 1-6GHz frequencies bounced from various obstacles (walls, ...
• 2,263
Accepted

### Group delay compensation for non coincident drivers

For the first question, given the linear process, what you do to the sum with regards to filtering is equivalent to what you do to each and then sum. For the second question, the dip is in the ...
• 52.4k

### Why do inverted impulse responses sound awful when applied to an audio system?

For simplicity we assume that the room and the source are fixed. A room's impulse response depends on a LOT of different factors which include the exact position, directivity and orientation of the ...
• 45.7k

### Least Squares Solution Using the DFT vs Wiener-Hopf Equations

Following Royi's derivation, we want to show that, \begin{align} \hat{h} = \arg \min_h||Xh - y||^2 = (X^T X)^{-1} X^H y = IDFT(Y \oslash X) \end{align} where $X$ is a circular convolution matrix ...
• 587
Accepted

### What is the difference between an equalizer and a channel estimator?

In communication systems, transmitted signals are distorted by the physical medium (the channel) charactheristics. The channel estimator tries to identify the transmission channel characteristics, by ...
• 28.3k

### Group delay compensation for non coincident drivers

I'm not sure whether this is a purely academic exercise or supposed to do something useful in the real world. Assuming it's the later, there are a few additional points to consider Typically when ...
• 45.7k
Accepted

### Histogram Equalization

Assuming that in your question $T(r)$ denotes a map $:\mathbb{R}\to[0,1]$ and assuming that it is continuous and strictly increasing, then it is obviously an isomorphism among $r\in[0,1]$ onto its ...
• 768

### Remove a frequency and all its multiple (harmonics)

The choice of algorithm depends on your application scenario - i.e. there is no best solution per se. If your focus is on minimum computational requirements, a comb filter will probably be optimum. If ...
• 647

### CMA Equaliser and FSK

The confusion comes from the fact that what is tagged as "transmitted" isn't the real transmitted waveform but its baseband representation, which are $\left\{+1,-1\right\}$ symbols in 1 dimension. For ...
• 1,792

### Why do the OFDM training (and payload) symbols have silent sub-carriers (aka virtual carriers)?

From the first to the sixth OFDM-Symbol you have spread virtual carriers equally across [0,..,51] with a distance of 3. With this way you have spread your 'energy' loss over a wide spectrum. In ...
Accepted

### What is the difference between pulse shaping and equalizers when used to cancel Inter-symbol Interference (ISI)?

1. This is a question investigated by many researchers decades ago. They discovered that the bandwidth limitation of R/2 Hz is not a fundamental limit set by nature. It is just a criterion if we don't ...
• 784
Accepted

• 4,295

### What Is the Difference between RLS, LMS and Wiener Filter? When Is One Preferred Over Another?

All three are Estimators / Predictors. All of them try to estimate the coefficients of Linear Filter which minimizes an MMSE Cost Function. The Wiener filter assumes all data is given and sets the ...
• 19.9k
Accepted

### Constant modulus algorithm - performance poor?

The constant modulus algorithm does not work for QAM because the amplitude of QAM at the symbol decisions is not constant (therefore not a constant modulus signal), such as BPSK and QPSK. SIR is the &...
• 52.4k

### Magnetometer coil equalization

I would equalize both channels. The most robust method is to cut both back to a lower bandwidth. Then you only need to equalize the gains. Assuming that your scanning by hand a 1-2 second sweep rate ...
• 425
Accepted

### Determining pulse shape for Viterbi Equalization

I'll answer my own question with what I've learned in the past 28 days. Hopefully I've got it right! Viterbi equalization is just one way to equalize the channel, as an alternative to some other ...
• 417