Questions tagged [dsp]

DSP stands for Digital Signal Processing or Digital Signal Processor.

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84
votes
6answers
47k views

What is the difference between a DSP and a standard microcontroller?

I understand that a DSP is optimized for digital signal processing, but I'm not sure how that impacts to the task of choosing an IC. Almost everything I do with a microcontroller involves the ...
66
votes
6answers
179k views

What is the relation between FFT length and frequency resolution?

If I have sampled a signal using proper sampling methods (Nyquist, filtering, etc) how do I relate the length of my FFT to the resulting frequency resolution I can obtain? Like if I have a 2,000 Hz ...
40
votes
18answers
13k views

What are good microcontrollers available today? [closed]

I have experience with assembly and C programming for microcontrollers, but I'm not familiar with the various MCU and DSP families offered by today's companies. (eg: Texas Instruments, Atmel, Renesas) ...
28
votes
10answers
21k views

When can FPGA's be used and Microcontrollers/DSPs not?

I have to choose between a course on advanced microcontrollers and a course on advanced FPGA's. I have had introductory courses in both subjects, and what troubles me now is that I am already pretty ...
18
votes
8answers
6k views

Writing DSP algorithms directly in C or assembly? [closed]

I m working on a DSP project(IIR filtering) on an Analog Devices digital signal processor(BF706) with the compiler suite coming with it, CrossCore Studio. It has some examples for simple DSP stuff ...
18
votes
9answers
6k views

DSP recommendation for beginners [closed]

I am considering a project involving a fair share of digital signal processing. As far as I know, the best type of IC suited for this are the Digital Signal Processors. I have never worked with them ...
13
votes
2answers
3k views

What's the sharpest frequency response for a non-causal low-pass filter whose step response doesn't overshoot?

Butterworth, Bessel, Chebychev, and sinc low-pass filters are used in various cases where there are different tradeoffs between having a uniformly-decreasing frequency response, a uniform phase ...
12
votes
3answers
2k views

What is the “Nyquist” rate for sampling the derivative of a signal?

Background: I'm sampling the current through a capacitor. The signal of interest is the voltage across the capacitor. I will digitally integrate the current measurement to obtain the voltage. ...
12
votes
3answers
14k views

What actually is a shadow register?

I noticed the term Shadow Register while going through a datasheet of a TMS320F28335 DSP. What does it actually mean? Does it have a physical location in the CPU as ...
11
votes
6answers
46k views

Code example for FIR/IIR filters in VHDL?

I'm trying to get started with DSP in my Spartan-3 board. I made a AC97 board with a chip from an old motherboard, and so far I got it to do ADC, multiply the samples for a number <1 (decrease ...
10
votes
5answers
6k views

VHDL: Using '*' operator when implementing multipliers in design

Present day FPGAs have built in DSP blocks, the latest FPGAs even have built in IEEE-754 compliant floating point units. It is possible to create DSP entity/module using a GUI after selecting the ...
10
votes
3answers
431 views

Which freeware analysis software most closely resembles the functionality of Matlab DSP toolbox

I'm looking for some freeware that will do (as much as possible) of what Matlab does DSP-wise... Filtering tools Modulation File I/O (as I need these to compare vhdl simulation results to software ...
9
votes
3answers
2k views

what really are: Microcontroller (uC), System on Chip (SoC), and Digital Signal Processor (DSP)?

The actual question is at the end. But reading that alone might not show you why am I confused. I wrote this post starting with some definitions, assumptions, and speculations and then asking the ...
9
votes
2answers
1k views

All Digital Phase Lock Loop

I'm looking to implement a phase lock in an FPGA without using any external components (other than the ADC). For simplicity locking to a simple binary pulse is adequate. The frequency of the signals ...
9
votes
2answers
7k views

How to select frequency resolution and window size in FFT?

I am doing spectrum analysis of a time varying signal with frequency changing from 200Hz to 10kHz. I am using the FFT for analyzing the frequency component in the signal. My questions are: How to ...
9
votes
2answers
2k views

Is it possible to create an IIR filter in an FPGA that's clocked at the sample frequency?

This question is about implementing a IIR filter in a FPGA with DSP slices, with very specific criteria. Lets say you're making a filter with no forward taps and only 1 reverse tap, with this ...
8
votes
5answers
2k views

Does anyone know of a microcontroller/DSP with no clock speeds or any oscillators in excess of 1.705 MHz?

I am planning on making a simple electronic device which I might eventually try to market if it works out O.K. Before taking the plunge and trying to mass produce it, I would first try to sell a few ...
8
votes
3answers
7k views

What can the dsPIC do which the humble PIC microcontroller cannot do?

I have not used a DSP chip as of yet. All I know is that their architecture is such that they can carry out calculations quite fast, usually within a clock cycle, they have multiply-accumulate ...
8
votes
3answers
6k views

What's so great about PPC? There's gotta be something

With this question in mind (the first one that stackexchange is offering me right now among the "Questions with similar titles"), I'd like to steal the idea of the question and ask it about PPC. What'...
7
votes
2answers
8k views

Why does rectification of a digital signal double the frequency content?

I'm performing envelope detection in the digital domain. This consists of rectifying the signal (i.e. taking the absolute value) and low pass filtering it to extract the slower varying envelope signal....
7
votes
5answers
447 views

Removing digital noise in software

I have a design which expects a TTL level square wave from a radio reciever which is fed into a microcontroller. There is some TTL level noise as no encoding is done on the transmit end. I was ...
7
votes
3answers
4k views

Why does radar processing always require FIR filters?

Digital signal processing in radar applications is usually done using finite impulse response filters. Why is that the case? Wouldn't the use of an infinite impulse response filtering be much faster ...
7
votes
2answers
26k views

How do I calculate needed pixel clock frequency?

If I want to have a resolution of X * Y pixels, updating in frequency f. How do I calculate the pixel clock speed? Example: 1280 x 1024 @ 85Hz usually have a pixel clock of 157.5 MHz, but how do I ...
7
votes
1answer
893 views

TMS320 Floating Point (Texas Instruments DSP from '98)

Background Is there anybody here who is an EE with programming experience who has worked with the Texas Instruments TMS320 C3X-series DSP? I am currently doing some work with the C3X for a project. ...
6
votes
3answers
1k views

Were mask ROMs with stock contents ever sold? or why not?

To clarify: did any of the mask ROM or discrete IC vendors make and sell ROMS (or effective ROMs optimized by giant Karnaugh map) with fixed non-proprietary contents that could be used in building a ...
6
votes
4answers
3k views

High Quality Audio ADC and DAC with Embedded

I am starting work on a project where I want to do some DSP using an embedded solution ideally with very low latency as it will be in a real time environment. In addition I want high quality, ...
6
votes
3answers
8k views

What are the the advantages of a switched capacitor filter over a digital filter?

The main advantage that switched capacitor filters seem to have over digital filters is the potential to achieve a high dynamic range, since the signal does not have to be quantized. As discrete time ...
6
votes
2answers
2k views

Meaning of phase in Fourier Transform of audio signal

I'm looking at the Fourier Transform (really, at a sliding DFT) to analyze (visually and intuitively) the frequency components of a sound over time. But the DFT produces complex numbers, and I'm not ...
6
votes
4answers
331 views

Tiny 8MSPS DSPs?

I have a problem: I've got five tiny CMOS image sensors (2mm x 2mm), each in a small space (about 10mm x 15mm). They take a clock signal in, and output an analog signal, requiring an 8MSPS ADC each. ...
6
votes
2answers
474 views

Resource recommendations for DSP beginners

I was searching around and I have had some trouble finding some decent resources for an engineer first entering the world of DSP. What resources (books, tutorials, DVDs, online courses, etc) do you ...
6
votes
3answers
377 views

Digital signal controller with GNU toolchain?

Does any manufacturer offer a digital signal controller (which basically means a microcontroller with some DSP functionality like a MAC instruction and other stuff) to which I could compile software ...
5
votes
2answers
329 views

Selecting a platform for DSP

I have experience with selecting low end PICs, but haven't had to select a controller for DSP before. Initially I thought about the dsPIC line, but the only reason for this because I am comfortable ...
5
votes
6answers
2k views

Preventing audio signal saturation

I am trying to implement an algorithm on audio signals. The algo operates on the signal on a frame-by-frame basis. One of the intermediate stages requires addition of the signal to the previous frames....
5
votes
4answers
10k views

Avoiding echo/feedback on speaker-phones, how?

Even a $20 mobile phone with a speakerphone has no problems of feedback. While I understand that companies like Mediatek have use crazy volumes to bring down mobile chipset prices so low, but reading ...
5
votes
3answers
2k views

What are the origins of the window functions in DSP? Why not just use a rectangular window?

As far as I know, in DSP we wish to remove or reduce the effect of some undesired signals by separating its frequency spectrum from the spectrum of the whole signal (our main signal and the noise). ...
5
votes
2answers
2k views

How do I go about intentionally aliasing a signal, and upsampling work with audio file in MATLAB

My objective is to show the results of: How do I go about intentionally aliasing a signal? undersampling Nyquist rate sampling and oversampling I'm first going to get the MATLAB code ...
5
votes
1answer
3k views

FFT Beat Detection Circuit

I have for over a year now tried to figure out both the electronic aspect and the software aspect of my project. I have somewhat successfully managed to make the overall idea to work, the bumps I ...
5
votes
2answers
2k views

Low-end DSP vs High-end MCU

I'm currently working on a Guitar DSP project, based on STM32F407VGT6 but as I progress I come to conclusion that I'm gonna need a bigger unit (with SDRAM). The question that is ringing in my head is ...
5
votes
1answer
356 views

Jumping from microcontroller to DSPs

I have been using microcontroller like ARM Cortex M4 32bit based microcontrollers. Now I am thinking to move towards DSPs, but I really don't know how things work in Processors and DSPs, I mean in ...
4
votes
5answers
4k views

Serial to USB converter

I have a DSP kit with a serial connection. Since, I am operating on my laptop, I do not have access to a serial port. So, I would require a Serial to USB converter How do I create a Serial to USB ...
4
votes
2answers
6k views

How much current can a microcontroller/DSP pin sink/source?

I'm using a TMS320F2812 and want to drive LEDs of some of the pins. I couldn't figure out what the safe levels of current were which could go in or come out of the IO pins from the datasheet. What is ...
4
votes
6answers
6k views

Why do we need transforms (Fourier, Laplace, Z and wavelet etc.) for a signal to analyse?

Why do we need transforms (Fourier, Laplace, Z and wavelet etc.) for a signal to analyse? Is it necessary for practical calculations and analysis?
4
votes
1answer
926 views

How to use an audio codec as an ADC?

I would like to add ADC functionality to a TI C6748 dev board. I need 16bit precision, but relatively low sample rate(~5K). Not finding any suitable daughter ADC card, I am considering the ...
4
votes
2answers
744 views

What is the meaning of my fourier transform results?

I've been experimenting with Fourier transforms, and I'd like to understand some of the results I'm seeing. I've written a simulator which generates a data stream of length 1/120 seconds, sampled at ...
4
votes
1answer
1k views

How can I high pass (DSP) filter a low frequency signal without introducing lag?

I need to high pass filter a signal, and my design just isn't cutting it. The part that's making it tricky is that I can't tolerate lag. I am sampling at 20Hz, the signal I care about is 1/12 to 1/...
4
votes
1answer
325 views

256-point FFT, but only need 5-6 frequencies, is there a better way?

Due to the constraints of my system, I have a 256pt FFT. However, I only care about the energy at 5 or 6 of the 256 bins. 256pt FFT is still faster than 5 or 6 specific DFTs, but it seems wasteful ...
4
votes
3answers
492 views

Reduce and clip voltage of a 5Mhz ultrasonic signal from +-50V to 0-3.3 V

I know there are a lot of posts similar to this one but some differences make it worth posting it. I’m working on a project where I have a 5MHz AC signal with the largest amplitude of +-50V. It’s an ...
4
votes
1answer
325 views

Can Blackfin DSPs boot from 'any type' of SPI external flash?

So I'm working on a project that contains a Blackfin processor, specifically the BF592 datasheet One thing that confuses me is how exactly the boot up process will work. During development, I plan on ...
4
votes
2answers
200 views

Capturing a 16.368MHz data stream with a MCU running at 32MHz

I have a 32MHz MCU (Atmel XMEGA A4) and I need to recover a digital signal coming from a GPS front end chip which is outputting SIGN and MAGNITUDE data at 16.368MHz. Clearly this is a hell of a task ...
4
votes
2answers
751 views

Development Board / Micro-controller with an onboard camera or external addon

I wanted to use a micro-controller with a camera module to be able to do some processing on the captured images. The Arduino was my choice, but since it has only 256K of Flash memory, it clearly is ...