67 votes
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Why is TV static noise always black and white?

The color burst is also an indicator that there is a color signal. This is for compatibility with black and white signals. No color burst means B&W signal, so only decode the luminance signal (no ...
Juancho's user avatar
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29 votes
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What sampling frequency should I use if Nyquist is not available?

HINT When you sample at below the Nyquist rate, aliasing happens. That means frequencies higher than half the sampling rate get folded back down to below half the sampling rate. Have a read about ...
Peter K.'s user avatar
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27 votes

Why is TV static noise always black and white?

In the absence of a valid color burst signal, the "color killer" circuit disables the color difference signals, otherwise you would indeed see colored noise. This is mainly intended for displaying ...
StessenJ's user avatar
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21 votes

What sampling frequency should I use if Nyquist is not available?

As correctly stated in Peter K.'s answer, this question is about aliasing. Since you can't sample at a rate that is sufficiently high to avoid aliasing - i.e., $f_s>50\textrm{ kHz}$ - you have to ...
Matt L.'s user avatar
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9 votes
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What is the difference between continuous, discrete, analog and digital signal?

A signal is indeed a function. Given a signal $f(x)$, according to whether continuous or discrete for both the variable $x$ and the function $f(x)$, there are four types of combinations: (1) $\mathbf{...
lxg's user avatar
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8 votes
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Scipy filter analog vs. digital

The function butter() doesn't do any signal processing. It is a routine to design a filter, either digital or analog. I.e., it computes the filter coefficients. I ...
Matt L.'s user avatar
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7 votes

Linearizing digital-analog converters

well i'm assuming you mean "conventional" DACs and not $\Sigma \Delta$ DACs. in a conventional DAC (like an R-2R ladder or something), there are the micro errors that occur between neighboring DAC ...
robert bristow-johnson's user avatar
7 votes

Amplifier Placement in a Wireless Receiver

Placing the amplifier first will result in a lower noise figure for the receiver and hence more sensitivity but the amplifier will be exposed to all of the ingested signals, including undesired ...
GrapefruitIsAwesome's user avatar
5 votes

Compensating the Group Delay of an Analog Filter using DSP

It's often easier to design FIR filters for compensating group delay. At the same time they could also compensate the magnitude if necessary. The easiest method is to use a complex least squares ...
Matt L.'s user avatar
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5 votes
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Are there analog re-configurable filters?

can we have re-configurable analog filters? Yes. The knob you turn on your grandma's kitchen or living room radio changes the tuning of an oscillator by changing the capacitance of a component. Any ...
Marcus Müller's user avatar
5 votes
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DSP alternatives

That's a very broad question and hence difficult to answer. The best choice of hardware is typically determined by a complicated trade off determined by the specific application and/or product ...
Hilmar's user avatar
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4 votes

Going from digital to analog filters

The main trick is knowing how typical lumped circuit element impedances are represented in the $s$-domain. Recall the current-voltage relationship for a capacitor: $$ i(t) = C \frac{dv(t)}{dt} $$ ...
Jason R's user avatar
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4 votes

Signal and Space/Time

You probably have a small misunderstanding here. In the definition it is not said "time" and "space" but "time" or "space". Some signals vary with time, as your ...
MimSaad's user avatar
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4 votes

FIR analog low-pass filter?

You have to clearly define what you mean by an "analog FIR filter". "No poles" is not correct because (discrete-time) FIR filters do have poles; they are just all at the origin of the $z$-plane (for ...
Matt L.'s user avatar
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4 votes

Why is TV static noise always black and white?

In PAL, the colour information (chrominance or chroma) is modulated onto the black and white (luminance or luma) baseband signal. The chroma is at ~4.4MHz offset from DC and is about 1.3 MHz wide. ...
Roger Lucas's user avatar
4 votes

Analog vs digital

Try digitizing a 17GHz signal.. You will quickly find it difficult to procure a fast enough adc that does not cost a fortune and you will also need memory bandwidth of tens of Gb/s (depending on adc ...
Martin's user avatar
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4 votes

How to simulate analog VU meter response to audio?

if you have input signal as vector of floating point numbers, try following code. It won't behave as real VU meter, but by modifying two constants you should get something very similar. Visualize the ...
gabonator's user avatar
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4 votes

How Can Telecommunication System Know Which Part Is Signal and Which Is Noise?

To elaborate on MM's answer just a little bit. Unless the receiver has some sort of expectation of the nature of the signal there is no way to tell. With an expectation (for instance a pure tone), ...
Cedron Dawg's user avatar
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4 votes
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Analog Square Root Raised Cosine Filter

Here's Octave code for a (digital) RRC filter: ...
Andy Walls's user avatar
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4 votes
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Amplifier Placement in a Wireless Receiver

GrapefruitIsAwesome's answer is right in mentioning that Friis noise formula says to put the most amplification possible as far up front as possible to minimize overall noise figure, but I'd like to ...
Marcus Müller's user avatar
3 votes

How increasing the Signal to Quantization noise increases the resolution of ADC

Here is a very simple example demonstrating how we can get increased precision by taking more samples and then filtering (averaging): Consider "truth" to be a constant 8.2, we quantize by rounding to ...
Dan Boschen's user avatar
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3 votes

Linearizing digital-analog converters

Another typical approach, that independently of my other answer works, is predistortion, for example with the look-up table mentioned by robert, or with a correction polynomial. If you can really ...
Marcus Müller's user avatar
3 votes
Accepted

DAC to Analog Filter to ADC

You wouldn't normally do that because it isn't worth the cost (hardware.) FIR filters get computationally very expensive if you need sharp cutoffs. Digital IIR filters that provide the same cutoff ...
JRE's user avatar
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3 votes

Proof-of-concept for active noise cancellation to block consistent low-frequency HVAC noise transmission

I went ahead with the proof of concept. $60 is a minimal investment to make and implementing high-school-level science experiments at home is never a bad idea. What I discovered is that yes, low ...
rjacobs's user avatar
  • 211
3 votes

Why is a bandpass filtered analog PM signal still PM and not AM

Conventional AM and narrowband PM signals look quite similar: $$x_{AM}(t) = A \cos(\omega_c t) + m(t) \cos(\omega_c t) $$ $$x_{NBPM}(t) = A \cos(\omega_c t) - A k_p m(t) \sin(\omega_c t) $$ And based ...
Fat32's user avatar
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3 votes
Accepted

How basses are reconstructed on small speakers

The acoustic efficiency of a small speaker drops drastically with frequency. The standard way of dealing with this is to simply boost the bass through a linear EQ. However that's limited by the ...
Hilmar's user avatar
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3 votes

Emulating an analog Oscillator in DSP

That's a fairly broad question. I'm eager to understand how one might emulate an analog oscillator digitally. If you really want to model an analog circuit this is typically done by using ...
Hilmar's user avatar
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2 votes
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Can we determine if a filter is butterworth or chebyshev from its physical topology?

As pointed out in a comment by Jason R, you can obviously come up with some random coefficients for the numerator and denominator polynomials of the filter's transfer function, and you'll end up with ...
Matt L.'s user avatar
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2 votes

FIR analog low-pass filter?

You can use a bucket-brigade device to introduce a delay, or a piezoelectric or other type of delay line.
Arnfinn's user avatar
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2 votes

Linearizing digital-analog converters

So, the intuitive reaction to this situation is oversampling. Basically, if you use twice the sampling rate, you can always average to samples to get one "output sample value" (thanks, Nyquist!). ...
Marcus Müller's user avatar

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