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Articles related to "signal"


Signal app downloads spike as US protesters seek message encryption

  • Looking at Big Tech as the next Big Oil. In the past week, US protesters have staged large-scale demonstrations against racism and police brutality across all 50 states.
  • The spike in downloads coincides with calls from Twitter users and privacy-focused organizations like the Electronic Frontier Foundation, urging American protesters to communicate with each other with encrypted apps like Signal.
  • In recent years, protest organizers have turned to encrypted messaging to evade censorship and surveillance while sharing information about the times and locations of demonstrations.
  • Signal’s rank among overall iOS App Store downloads jumped from 936 to 126 in the past week.
  • Signal provides a greater degree of anonymity than some other popular messaging apps, because in addition to encrypting the content of messages, it doesn’t store metadata about who sent and received a message, when it was sent, and the location of the participants.

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Signal now has built-in face blurring for photos

  • Apps like Signal are proving invaluable in these days of unrest, and anything we can do to simplify and secure the way we share sensitive information is welcome.
  • To that end Signal has added the ability to blur faces in photos sent via the app, making it easy to protect someone’s identity without leaving any trace on other, less secure apps.
  • Put them together and boom, a new feature that lets you blur all the faces in a photo with a single tap.
  • This is helpful for the many users of Signal who use it to send sensitive information, including photos where someone might rather not be identifiable.
  • Normally one would blur the face in another photo editor app, which is simple enough but not necessarily secure.

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Analyzing seasonality with Fourier transforms using Python & SciPy

  • We can use the Fourier transform, commonly used by engineers, to accomplish exactly that—separate signal from noise.
  • The Fourier transform allows you to transform a function of time and signal into a function of frequency and power.
  • Real data often contains noise and the Fourier transform lets us see through the noise, and see which frequencies actually matter.
  • The frequencies with the highest amplitude are indicative of seasonal patterns.
  • If we look at those frequencies with the highest amplitudes and convert them into hours and days, we see that the top seasonal pattern has a daily frequency (the period is ~1 day).
  • Here’s what that looks like if we chart the filtered signal over the original signal for the first 5 days of data.
  • This will help us figure out when seasonality spikes by trying different inputs inspired by our Fourier results.

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Analyzing seasonality with Fourier transforms using Python & SciPy

  • We can use the Fourier transform, commonly used by engineers, to accomplish exactly that—separate signal from noise.
  • The Fourier transform allows you to transform a function of time and signal into a function of frequency and power.
  • Real data often contains noise and the Fourier transform lets us see through the noise, and see which frequencies actually matter.
  • The frequencies with the highest amplitude are indicative of seasonal patterns.
  • If we look at those frequencies with the highest amplitudes and convert them into hours and days, we see that the top seasonal pattern has a daily frequency (the period is ~1 day).
  • Here’s what that looks like if we chart the filtered signal over the original signal for the first 5 days of data.
  • This will help us figure out when seasonality spikes by trying different inputs inspired by our Fourier results.

save | comments | report | share on


Analyzing seasonality with Fourier transforms using Python & SciPy

  • We can use the Fourier transform, commonly used by engineers, to accomplish exactly that—separate signal from noise.
  • The Fourier transform allows you to transform a function of time and signal into a function of frequency and power.
  • Real data often contains noise and the Fourier transform lets us see through the noise, and see which frequencies actually matter.
  • The frequencies with the highest amplitude are indicative of seasonal patterns.
  • If we look at those frequencies with the highest amplitudes and convert them into hours and days, we see that the top seasonal pattern has a daily frequency (the period is ~1 day).
  • Here’s what that looks like if we chart the filtered signal over the original signal for the first 5 days of data.
  • This will help us figure out when seasonality spikes by trying different inputs inspired by our Fourier results.

save | comments | report | share on


Analyzing seasonality with Fourier transforms using Python & SciPy

  • We can use the Fourier transform, commonly used by engineers, to accomplish exactly that—separate signal from noise.
  • The Fourier transform allows you to transform a function of time and signal into a function of frequency and power.
  • Real data often contains noise and the Fourier transform lets us see through the noise, and see which frequencies actually matter.
  • The frequencies with the highest amplitude are indicative of seasonal patterns.
  • If we look at those frequencies with the highest amplitudes and convert them into hours and days, we see that the top seasonal pattern has a daily frequency (the period is ~1 day).
  • Here’s what that looks like if we chart the filtered signal over the original signal for the first 5 days of data.
  • This will help us figure out when seasonality spikes by trying different inputs inspired by our Fourier results.

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From Citizen to Signal, the most popular apps reflect America’s protests

  • They’ve also rushed to download Signal, a secure messaging app, and Citizen, a community safety app that sends out police alerts.
  • People have long used police scanner hardware to follow crime, but this new generation of apps brings that technology to more lay users.
  • The first iteration of the app launched in 2016 with the mission to “open up the 911 system” so that “everyone can do their part.” Many, including the New York Police Department, argued at the time that the app encouraged vigilante justice — it was literally called Vigilante — and it relaunched in 2017 as Citizen.
  • The vast majority of updates on Citizen come from employees who monitor various publicly available police and fire department transmissions and then post select incidents on the app and notify nearby users.

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Anti-Ghosting

  • Ghosting Ghosting occurs when an unintended signal/character is sent due to the maximum number of simultaneous key presses being reached.
  • Some keyboard keys don't work when multiple keys are pressed simultaneously.
  • On most keyboards, even some that are explicitly marketed as "Anti-Ghosting," this happens with many three key combinations.
  • Typically, ghosting is the result of one or more of following three limitations: the hardware can't read the given key combination, the software on the computer doesn't support multiple simultaneous keys, or the communication protocol between the hardware and software limits the maximum number of simultaneous keys reported.
  • Even if only one column with closed contacts is activated, the two rows allow for a clear distinction to be made.
  • For example, if W, S, and D are struck simultaneously, E appears as a ghost because the keyboard cannot distinguish between the four individual buttons.

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Writing to the Framebuffer

  • The image displayed on the monitor is stored in your computer’s video RAM on the graphics card in a structure called a framebuffer.
  • The video RAM is continuously read out by a specialized DMA component on the video card and sent to the monitor.
  • Now, you probably realize that for a 1920x1080 display with 4 bytes per pixel, you only need about 8 MB to store the image, but the video RAM in your computer is probably many times that size.
  • I’ve been running this from the linux console (rather than x server or another display server), which I believe is just rendering text and basic colors to the framebuffer.
  • We’ve already got a smooth color gradient and an image is just a file format we have to read pixel data to and encode/dump to the framebuffer.

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Reliving the Dial-Up Experience in 2020

  • Many things could be downloaded directly through the browser, but download managers were much more advisable, since lines could disconnect at any time (especially with call waiting signals or the unintentional picking up of the phone) and losing your progress really sucked.
  • Hearing a second set of ranging signals afterward would indicate a failure to negotiate V.90, thus a V.34 connection would be made instead, meaning a slower internet connection (~60% of the speed) and a frustrating experience.
  • Most “unlimited” ISPs had session time limits which would forcibly disconnect users that hit five or six hours of continuous connection time to give a chance to users which may have encountered busy signals during peak periods, but often the longer a connection went, the slower the connection would become as line interruptions and impairments often pushed the speeds down as the modems retrained.

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