66
votes
How can the GPS position update rate be 10 Hz?
50 bps is indeed the bitrate at which the almanacs and ephemerides are transmitted. Given the size of this data as well as framing and other overhead, it takes far more than 0.1 seconds (and more than ...
- 18.1k
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 ...
- 6,164
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 ...
- 37.8k
21
votes
Accepted
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 ...
- 25.7k
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 ...
- 159k
18
votes
Accepted
What is the "Nyquist" rate for sampling the derivative of a signal?
Taking a derivative (or an integral) is a linear operation — it doesn't create any frequencies that weren't in the original signal (or remove any), it just changes their relative levels.
So the ...
- 169k
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 \$...
- 3,083
11
votes
Accepted
what really are: Microcontroller (uC), System on Chip (SoC), and Digital Signal Processor (DSP)?
uC = a stand-alone processing chip: CPU, RAM, ROM, some peripherals.
DSP = processor chip (can be a separate CPU, nowadays mostly a uC) that is optimized for signal processing. Often has fast MAC (...
- 48.4k
11
votes
Were mask ROMs with stock contents ever sold? or why not?
Character generator ROMs with 5x7 ASCII codes were certainly sold.
One example was the Signetics 2513, a rather nasty and sluggish P-MOS chip requiring three supply rails.
OTP and UV-erasable ...
- 379k
10
votes
Accepted
Uniform Linear Array (ULA) beamwidth and angular resolution using FFT
Theoretical Derivation
The antenna electric field pattern of array antenna consists of isotropic radiator can be given by
where N is the number of antenna elements
d is the spacing between antenna ...
- 293
9
votes
Accepted
FSK demodulation using DSP
A very simple but elegant approach to demodulate FSK is a delay and multiply. (Followed by a simple low pass filter). This is a non-coherent FM detector using the principal that the output of a ...
- 488
8
votes
Accepted
Distinguishing between FIR and IIR filters from transform function
First, note that FIR/IIR is not the same as non-recurrent/recurrent (where recurrent means that the output depends on previous inputs and previous outputs).
You can have a non-recurrent filter with ...
- 917
8
votes
Is there an efficient way for synchronising audio events real-time with LEDs using an MCU?
I am not fond of encoding command data as an analog signal in a digital file.
I think I would try something like encoding the lighting commands as text blocks in the lyrics block of the ID3 ...
- 67.8k
8
votes
Accepted
Trying to implement a digital IIR filter why is this happening?
It looks you already found the first bug: https://arm-software.github.io/CMSIS_5/DSP/html/arm__biquad__cascade__df1__f32_8c.html the function needs float arrays not int arrays
By fixing this you just ...
- 2,015
8
votes
What's importance of finite state machines (FSM) with respect to embedded systems implementation?
A FSM is a structured method of constructing a sequential machine. The machine can only exist in a fixed number of discrete states - ie ‘finite state’.
FSMs can be formally proven for correctness.
...
- 5,950
7
votes
Writing DSP algorithms directly in C or assembly?
Even though I answered this question already, I will add another answer to illustrate a different viewpoint:
Write in C, read in assembly!
So, instead of writing in assembly, you will write the ...
- 1,563
6
votes
Accepted
On what condition does Harmonic components of power generated in 50/60 Hz Grid Generators depend on?
It could be the generator, but it's more likely to be the type of loads being driven.
A simple rectifier/capacitor DC supply draws current only around the peaks of the supply voltage waveform, ...
- 159k
6
votes
Very big matrix multiplication in FPGA
This looks like a case of premature optimization. Start by implementing your algorithm iteratively, and see how fast it performs. Then you'll know exactly how much faster you need to make it, and ...
- 25.7k
6
votes
Running DSPIC33FJ64GP802 at high temperature
Thanks for everyone's good suggestions. It turns out that there are two versions of silicon for this chip, and the earlier version is only rated to 140 Celsius. Sheesh. This is noted in the "errata ...
- 10.5k
6
votes
Accepted
Is there an efficient way for synchronising audio events real-time with LEDs using an MCU?
Using an auxiliary DSP for decompression may make this difficult unless you limit yourself to constant bitrate files - if you need high time accuracy of the light events you may need to account for ...
- 33.3k
6
votes
Is there an efficient way for synchronising audio events real-time with LEDs using an MCU?
I once developed an application in which arbitrary events could be triggered by audio watermarks embedded in the sound. You could play the sound through tinny unamplified computer speakers at one end ...
- 169k
6
votes
Guitar to MIDI conversion
There isn’t enough information in 10 mS of sampled audio to reliably tell the difference in frequency between a low E and a low F or D# notes.
10 mS is barely more than 1 full pitch cycle at those ...
- 4,731
6
votes
Accepted
Difference CPU, ASIP, DSP
"ASIP" is not a term the industry bothers to use. The similar-sounding "ASIC" (application specific integrated circuit) basically means any piece of specialized IC design that isn't a general purpose ...
- 46.6k
6
votes
Digital signal processing vs. analog signal processing for a 100kHz DAQ project
ADCs usually need an anti-aliasing filter, otherwise frequencies above Fs/2 will alias to frequencies below Fs/2. For example if your sampling frequency is 48kHz and there is no anti-alias filter, a ...
- 70.8k
6
votes
Noise power v.s noise amplitude
When adding uncorrelated signals, it is the average power rather than the average amplitude that adds up as a statistic measure, even though the momentary value at any point of time is added non-...
- 2,664
6
votes
Noise power v.s noise amplitude
Why is amplitude not important?
It is important but, when incoherent noise sources come together (i.e. add in the time domain), the only thing that can be said is that their individual powers add ...
- 436k
5
votes
What is the meaning of my fourier transform results?
The first entry [1] in the FFT is your fundamental, but the zeroth entry [0] is DC!
A standard FFT will have the same number of output samples as input samples, and they will all be complex.
The ...
- 159k
5
votes
Are TI TMS320C6x and TI TMS320C2x compatible?
There is a big difference between C6000 and C2000.
Mainly, C6000 is a DSP (very high speed, starting from 456 MHz) and, as it is a DSP, it's more focused on signal processing.
C2000 is more like a ...
- 664
5
votes
256-point FFT, but only need 5-6 frequencies, is there a better way?
If you wanted 1 or 2 frequencies, the Goertzel algorithm would be a clear winner.
If you wanted several dozen, then the FFT would be a clear winner, even after throwing away most of the resultant ...
- 159k
5
votes
When can FPGA's be used and Microcontrollers/DSPs not?
One answer that isn't here is Data Acquisition. If you would like to use a ADC to sample a signal (for example, a RF signal) at 200Mhz and process it, a microcontroller is simply not going to be able ...
- 5,352
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