> Here, we demonstrate a covert communications method in which photon emission is rapidly electrically modulated both above and below the level of a passive blackbody at the emitter temperature. The time-averaged emission can be designed to be identical to the thermal background, realizing communications with zero optical signature for detectors with bandwidth lower than the modulation frequency
It sounds like maybe they're modulating the emissivity of a diode up and down so that over time, its IR spectrum looks like black body radiation. Only someone looking at the intensity of the thermal radiation coming from the diode at really fast timescales (kilohertz or megahertz) would notice that there was a signal being transmitted.
This looks great! I've been using ThumbsUp[1] for a similar purpose (creating a gallery of photos I can push S3), but adding album and photo captions required some un-ergonomical tricks. I'll try this out!
I appreciated the Pluto.jl mention! Going from Pluto notebooks that understand data flow to Jupyter notebooks where you have to tell the computer which order to run the cells in is always baffling to me. Why doesn't Jupyter know the run order and dependencies already? The way Pluto handles dependencies between code cells is really just so nice.
Yup, slight mix-up. Gravity waves are waves in the ocean and atmosphere (or other fluid bodies) where Earth's gravity is the restoring forces that causes wave propagation. Gravitational waves are the waves in spacetime caused by powerful astronomical events like black hole mergers.
Sure, all the water in the ocean is affected by gravity.
However, there are many different types of waves in physics, usually described by some form of wave equation[1]. And for some of those, body forces[2] like gravity doesn't play a direct role.
A relevant example is acoustic waves[3], which are the propagation of changes in pressure. In that case, the only thing gravity is doing is confining the water to a single body through which the acoustic wave can propagate, it doesn't affect the propagation otherwise as such.
Cool! It looks like the Wansview Q5 has a similar SoC/camera/wireless setup as the Wansview W7, which as an installer guide on the Thingino wiki [1]. I wonder if that same installation process (but with the q5 firmware) would work. For $16 I'm inclined to try it out.
> The analog ones are easy to play with. You just need a DAC to drive their VCO and then can sample the I/Q pins with an ADC
Do you have any reference or notes on how to access the IQ pins on one of these devices (ideally one of the FMCW ones)? I've been wanting to play around with one of these 24 GHz or 60 GHz units for coherent radar but it seems like most of the boards only report on distances over serial links. If there's an easy way to tap into the analog IF signal after down conversion I'd love to see how to do that!
Cool! Do you like that approach? I've thought about setting up that exact thing but I wasn't sure how well it would work in practice. Are there any pitfalls you ran into early on? I might give it a shot after your "very easy to set up and operate" review!
Honestly it was very easy. Their documentation is decent, and the defaults are good.
Setting up Pangolin on the VPS, and Newt on your lan, connecting them and adding e.g. a small demo website as a resource on Pagolin will take you about half an hour (unless your domain propagation is slow, so always start by defining the name in DNS and point it to your VPS IP to start with. You can use a wildcard if you do not want to manually make a new DNS entry each time)
From the abstract:
> Here, we demonstrate a covert communications method in which photon emission is rapidly electrically modulated both above and below the level of a passive blackbody at the emitter temperature. The time-averaged emission can be designed to be identical to the thermal background, realizing communications with zero optical signature for detectors with bandwidth lower than the modulation frequency
It sounds like maybe they're modulating the emissivity of a diode up and down so that over time, its IR spectrum looks like black body radiation. Only someone looking at the intensity of the thermal radiation coming from the diode at really fast timescales (kilohertz or megahertz) would notice that there was a signal being transmitted.
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