A New Sampling Algorithm Could Eliminate Sensor Saturation (scitechdaily.com)

Baron_Yam shared an article from Science Daily: Researchers from MIT and the Technical University of Munich have developed a new technique that could lead to cameras that can handle light of any intensity, and audio that doesn't skip or pop. Virtually any modern information-capture device -- such as a camera, audio recorder, or telephone -- has an analog-to-digital converter in it, a circuit that converts the fluctuating voltages of analog signals into strings of ones and zeroes. Almost all commercial analog-to-digital converters (ADCs), however, have voltage limits. If an incoming signal exceeds that limit, the ADC either cuts it off or flatlines at the maximum voltage. This phenomenon is familiar as the pops and skips of a "clipped" audio signal or as "saturation" in digital images -- when, for instance, a sky that looks blue to the naked eye shows up on-camera as a sheet of white.

Last week, at the International Conference on Sampling Theory and Applications, researchers from MIT and the Technical University of Munich presented a technique that they call unlimited sampling, which can accurately digitize signals whose voltage peaks are far beyond an ADC's voltage limit. The consequence could be cameras that capture all the gradations of color visible to the human eye, audio that doesn't skip, and medical and environmental sensors that can handle both long periods of low activity and the sudden signal spikes that are often the events of interest.
One of the paper's author's explains that "The idea is very simple. If you have a number that is too big to store in your computer memory, you can take the modulo of the number."

Comments

already had circuit elements that could do this

[iggymanz]

pure analong systems have been doing this for decades, let's bring back the vacuum tube

Re:What genius!!

[Anonymous Coward]

No, it's not normalization. From a preliminary reading, they're just doing rudimentary frequency analysis to provide qualifications under which modular representations can be inversely mapped to a real world Voltage reading, i.e. a low-enough-energy high frequency component such that an extremely high to extremely low (or vice-versa) transition can be interpreted unambiguously as bounds clipping rather than a transition within the typical dynamic range of the device. That's why they're taking the sampling theory approach.

Nothing mind-blowing, I agree, and the headline is definitely hyperbolic, but if you're gonna talk shit you should get your shit straight first.

It's not an algorithm

[johannesg]

It's a different type of ADC, one that resets when it reaches saturation. So you can forget about using this 'new algorithm' in your existing equipment.

Re:No, this does not solve the problem.

[Zorpheus]

So you pretty much want to read out the sensor at a higher framerate, and combine multiple images to one. This means that the sensor must be capable of a much higher framerate. And the image quality might get worse due to the readout noise, but I don't know if this is relevant in normal, uncooled cameras.

Re:No, this does not solve the problem.

[Arkh89]

And every time you read out a sub-frame you are penalized by the read noise... after accumulation of the variances, you end-up with an extremely noisy image. If you want to do that you don't just need a very good quantum efficiency (the probability of a incident photon to be absorbed and to release an electron) you need an almost perfect read-out circuitry (if you want to operate without cooling). Eric Fossum has proposed a "Quanta" binary sensor which would do this with a ~0.15e- RMS read-out noise which has to be compared with the 1.5+e- of the best sensors used in consumer applications today.

Fake Paper or just Naive?

[labnet]

I've skip read the Paper and /. comments, and this reads like mathematical wank by guys that have never touched an oscilloscope.

First, they are waving their hands in the are about a magic 'resetting ADC'... seriously...
Do they even know what reset means? It has to be performed at the hardware level, It has to performed with DC offsetting (from a D/A converter), it has to be performed to 1 least significant bit of accuracy, and the input signal has to be rate limited. No way this will happen for any practical systems without adding artefacts when the offsetting circuitry tries to slew the input within one sample period.

The only real world way I can think of, that still retains DC accuracy, is servoing the input.
This is where a 'counteracting' force is used to subtract from the input... but servoing has hairs all over it, as it has to be super accurate in terms of amplitude and frequency response.

They should have talked to an electrical engineer before spouting off this rubbish.

Re:What genius!!

[green is the enemy]

I'm an EE. This concept is interesting to me, but then I'm left wondering how they really tackle the problem of signal limits. It's not just that ADC that limits the signal. The amplifiers in the chain also do it. Maybe I should just read about it. The whole self-resetting ADC concept just strikes me as odd. I have a feeling it was invented to improve the dynamic range or sampling rate or reduce the power usage of ADCs, but not to magically sample arbitrarily large signals.

Re:Digital != silicon

[Khyber]

"So what you are claiming is that you had pure analogue, analogue to digital converters?"
"Replacing silicon transistors with valves does not change the fact that the circuit is still digital."

All circuits are analog. Period. That's the physics of it. 'Digital' is just a sampled section of the signal measured against a reference voltage. Those are still both analog waveforms or sections thereof.

It's like people suddenly forgot the bare fucking basics and physics of basic electronics when the world went digital. You dipshits fell hook line and sinker for the digital marketing hype.