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47 votes
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Difference between bit rate and baud rate and its origins?

Baud rate is the rate of individual bit times or slots for symbols. Not all slots necessarily carry data bits, and in some protocols, a slot can carry multiple bits. Imagine, for example, four ...
Olin Lathrop's user avatar
34 votes
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Frequencies are inherently positive physical quantity.... what does it mean?

Frequency is how many times something happens every second. So it can't be "minus 5 times a second". However when you do actual signal processing, you'll see negative frequency on the graph ...
TQQQ's user avatar
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30 votes

Difference between bit rate and baud rate and its origins?

The line bit rate is the number of bits per second being moved. The data bit rate is the number of information bits being moved per second. The baud rate is the number of symbols per second (Baud is ...
Peter Smith's user avatar
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25 votes
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Can I use the FFT to recognize musical notes on a piano?

The concept is good, but you will find it is not so simple in practice. Pitch is not simply the predominant tone, so there's problem number 1. The FFT frequency bins can't hit all (or even multiple)...
JRE's user avatar
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25 votes

How is it that two electric currents can travel in opposite directions on the same wire, at the same time, without interfering with each other?

in the sense that two telegraph signals (in other words, two electric currents) can travel in opposite directions on the same wire, at the same time, without interfering with each other This is the ...
DK2AX's user avatar
  • 901
25 votes
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Why would you put your input amplifier in front of your filtering for an ECG signal?

Am I missing some important reason why you would do the signal conditioning in this order? Yes you are... The front-end differential amplifier will be chosen such that it has a common-mode ...
Andy aka's user avatar
  • 465k
23 votes

Writing DSP algorithms directly in C or assembly?

If the compiler writers put some effort into optimizing it for that target, it will at least make some use of the special DSP instructions / architecture. But for ultimate performance it will never ...
pericynthion's user avatar
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23 votes
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Can sampling rate be a floating point number?

Forget sampling rate for a few seconds... Think about sampling period for a second, which is the time interval between two consecutive samples. This time can be an integer or any real number (as long ...
joribama's user avatar
  • 2,237
23 votes

Ethernet port as a signal generator

Is it technically possible? No. Highly specialized hardware, relatively specific coupling, and a very limited set of amplitudes actually imposable on the line make that infeasible. Don't get me wrong:...
Marcus Müller's user avatar
22 votes

Detection of signals buried in noise

The only way that a signal that is "buried in the noise" can be detected is if you can run the signal + noise through some filter that attenuates the noise more than it attenuates the signal. At ...
TimWescott's user avatar
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22 votes

How much data could be stored on a standard compact cassette using modern encoding?

Have there been any projects trying to explore that? Ben North attempted to play video from a standard audio cassette tape using QAM modulation. First he tested the signal through a loopback cable. ...
Bruce Abbott's user avatar
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21 votes

Writing DSP algorithms directly in C or assembly?

Premature optimization is the root of all evil. - Donald Knuth When you find that you don't get enough performance from your code, profile your program first, find the bottlenecks, analyze your ...
Nick Alexeev's user avatar
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21 votes
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Writing DSP algorithms directly in C or assembly?

It's always better to have your algorithm implemented in a higher-level language (which C is compared to assembly), even if you plan to implement everything in assembly in the end. chances are, you ...
Dmitry Grigoryev's user avatar
21 votes
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Does "a signal is buried in noise" mean that the noise amplitude is still smaller than the signal amplitude? (Special case: Lock-in amplification)

What you're missing is the bandwidth, both of signal and noise. If you look at, let's say, a 1 V rms sinewave signal, together with 10 V rms noise on an oscilloscope, you'll see only noise. However, ...
Neil_UK's user avatar
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21 votes
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How do receivers decode multiple GPS signals on the same carrier frequency?

The system takes advantage of a couple of mathematical properties of the PRNs: First, the cross-correlation of a PRN with itself (i.e. the auto-correlation) looks somewhat like a single impulse with ...
nanofarad's user avatar
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21 votes
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DFT of a pure sine wave not showing ideal sine wave

You say you have an ideal sinewave. But do you? You probably only have a good approximation to one. Depending on whether it's in 32 bit or 64 bit reals, you will, at best, have quantisation noise in ...
Neil_UK's user avatar
  • 169k
19 votes
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Lossless compression technique for digital signals in an embedded system

Compression is all about finding the redundancies in the data and removing them. Since you don't seem to be able to tell us much about your actual data sets, this answer will have to be very generic. ...
Dave Tweed's user avatar
  • 175k
18 votes

Writing DSP algorithms directly in C or assembly?

Your DSP will be advertised with a maximum sustained MACs, assuming all the pipes are filled. That is obviously an upper limit to what can be achieved. You know how many MACs your filters and other ...
Neil_UK's user avatar
  • 169k
17 votes

Is the so called kTC noise, that is inherent in an RC filter, dependent on bandwidth?

The KTC noise is actually the total RMS noise power at the output of the low pass RC filter. The noise power is the product of the noise power spectral density (PSD) and the bandwidth (more accurately ...
sarthak's user avatar
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17 votes
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Why can the effective number of bits be a non-integer? What does this physically represent?

It is a result of calculating the number of bits after the imperfections such as noise and distortion are taken into account. An ENOB of 6.8 basically tells you that for example an 8-bit ADC has real ...
Justme's user avatar
  • 158k
16 votes
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Sampled 100 Hz sinusoidal signal from Hall sensor shows 10 Hz sidelobes when sampled at 500 Hz

If the sensor is set to 500 Hz sampling, and you have a MCU timer also set to 500 Hz to read the results, this is never going to work, because nothing is ever exact, especially devices with internal ...
Justme's user avatar
  • 158k
15 votes
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How does a car with keyless entry know where the key is?

They either use multiple antennas for each exterior zone of the car and/or use RF in combination with other sensors, for instance detecting that the user has touched the front driver's side door ...
ajb's user avatar
  • 3,434
14 votes

Performing FFT at low frequencies but high resolution?

I assume for "high speed" you mean a small delay from data collection to the resultant FFT. With a low sample rate, your computational ability isn't the limiting factor, given modern computers. The ...
user2943160's user avatar
  • 2,908
14 votes

What does "shift keying" mean in the context of digital modulation?

It's not (phase) (shift keying), for example. It's (phase shift) (keying). Another answer has explained why the word keying is used --- it dates to the days when modulation was controlled by a human ...
The Photon's user avatar
  • 131k
14 votes

Can sampling rate be a floating point number?

Yes, the sampling rate can be any number you want. But you obviously would not get partial samples in the end, you just have to round down. In your example the first sample is taken at \$ \frac{1}{15....
jusaca's user avatar
  • 9,619
14 votes

Why is a signal that is finite in time domain, infinite in its frequency domain?

Many texts prove that a signal cannot be both time limited and bandlimited. It is quite a deep result and depends on complex analysis, but the shortest proof I know starts with a bandlimited signal \$...
Tesla23's user avatar
  • 3,366
14 votes
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Does the DC component of any signal also carry information?

A fixed DC signal has information - the DC offset - that would be lost if it were blocked (that is, reset to 0V potential.) The bandwidth of that information is nevertheless 0Hz. This idea comes up in ...
hacktastical's user avatar
13 votes
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How is it that two electric currents can travel in opposite directions on the same wire, at the same time, without interfering with each other?

The physics explanation is that waveguides (including the free space) have orthogonal modes for the two propagation directions. This means that the two signals traveling in opposite directions will ...
Andreas H.'s user avatar
13 votes

Can sampling rate be a floating point number?

Some things are always an integer. Samples are always integer. You can take 108 or 109 samples. Sample rate can be a floating point number, or more generally a rational, or even a real. You ...
Neil_UK's user avatar
  • 169k

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