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80 - 99 of 201

Martin Ryba
Last activity am 12 Dez. 2023

AWGN SNR calibration for band limited signals

Seeing a colleague make this mistake (one I've had to fix multiple times in other's work too) makes me want to ask the community: would you like the awgn() function/blocks to give the option for creating a SNR at the bandwidth of the signal? Your typical flow is something like this:

Create a signal, usually at some nominal upsampling factor (e.g., 4) such that it's now nicely over sampled, especially if you're using a RRC or similar pulse shaping filter.
Potentially add a frequency offset (which might make the sample frequency even higher)
Add AWGN channel model for a desired SNR
Put this into your detector/receiver model

The problem is, when someone says, "I'm detecting XYZ at foo SNR," it should not magically improve as a function of the oversample. The problem isn't that awgn() generates white noise, that's what it's supposed to do and the typical receiver has noise across the entire band. The problem is that SNR is most properly defined as the signal power over the noise power spectral density times the signal's noise equivalent bandwidth. Now I looked and there's no handy function for computing NEBW for an input signal (there's just a function for assessing analysis windows). In practice it can get a bit tricky. The occupied bandwidth or HPBW are often close enough to the NEBW, we're usually not haggling over hundredths of a dB. So, in my not so humble opinion, the "measured" flag for awgn() should give an option for bandwidth matching or at least document the behavior better in the help page. All too often I'm seeing 3-6 (or worse) dB errors because people aren't taking the signal's bandwidth into account.

Contests

David
Last activity am 1 Dez. 2023

Anyone using Generative AI for their contest entries this year?

Unlike last year's contest, there are some new technologies this year that might offer some advantages. Namely generative AI's like ChatGPT, Bard, etc. Not to be excluded, MathWorks just launched the AI Chat Playground :)

https://www.mathworks.com/matlabcentral/discussions/ai/831462-the-matlab-ai-chat-playground-has-launched

Here's a link to this years animation contest.

playground

Contests

Hans Scharler
Last activity am 16 Feb. 2024

Oh, my! The flipbook gallery is awesome!

https://www.mathworks.com/matlabcentral/communitycontests/contests/6/entries/

Contests

Chen Lin
Last activity am 10 Nov. 2023

MATLAB Flipbook Mini Hack Starts Today! Have Fun and Win Prizes!

The 2023 community contest - MATLAB Flipbook Mini Hack - starts today on Nov. 6th!

Participants across all skill levels are welcome to join! You can participate by creating a new animation or remixing an existing one with up to 2,000 characters of MATLAB code.

Contest Tips:

Before you start, we highly recommend you check out the two examples - Bouncing and Spinning - to understand how the contest works.
Share your thoughts, ask questions, or connect with others in our contest discussion channel.

Note that the first week (Nov. 6th, 2023, ~ Nov. 12th, 2023) is for creating entries only. Voting does not begin until the second week.

We look forward to seeing your creative work. Let the contest begin!

2023contestannouncements

Fun

Image Analyst
Last activity am 31 Okt. 2023

BATLAB

Just in time for Halloween.

meme

Fun

Chen Lin
Last activity am 12 Mär. 2024

What costume are you going to wear for Halloween?

Share your fun photos in the comments!

halloween

Ideas

Julian
Last activity am 5 Feb. 2024

Naming x-values in bar(x,y)

I know the latest version of MATLAB R2023b has this feature already, put it should be added to R2023a as well because of its simplicity and convenience.

Basically, I want to make a bar graph that lets me name each column in a basic bar graph:

y=[100 99 100 200 200 300 500 800 1000];

x=["0-4" "5-17" "18-29" "30-39" "40-49" "50-64" "65-74" "75-84" "85+"];

bar(x,y)

However, in R2023a, this isn't a feature. I think it should be added because it helps to present data and ideas more clearly and professionally, which is the purpose of a graph to begin with.

Ideas

Matt J
Last activity am 1 Mär. 2024

Implicit expansion for CAT()

Would it be a good thing to have implicit expansion enabled for cat(), horzcat(), vertcat()? There are often situations where I would like to be able to do things like this:

 x=[10;20;30;40];
 y=[11;12;13;14];
 z=cat(3, 0,1,2);
 
 C=[x,y,z]
 

with the result,