High resolution images underwater

I'm assuming you're referring to high bandwidth. With low bandwidth, you can still transmit high resolution if you are patient, just as they do for space probes.

Possibly this..https://www.mit.edu/~millitsa/resources/pdfs/oc05.pdf

No,I am talking about real time data.Maybe it has been removed by government agencies because of it's value to the military.

The article I read showed real time full color images transmitted to a submarine under water,but I can not find it now,but nothing ever really dies on the internet,so it is out there somewhere in the Netland Universe.

I think that what Rixter is getting at is:

Is this a technology specific to imaging, or, just any high bandwidth data?

Well, it depends on how far you want to communicate. With a good blue laser, you can get 10-100 Mb/s at 100 meters or maybe a GigaBit/sec close in, depending on how clear the water is.

https://www.researchgate.net/publication/233669755_High-Bandwidth_Underwater_Communications

I suspect you remembered the hopes and not the results of old research. If high-speed data could be transmitted through mirky(?) waters then underwater robotics would only need power tethers.

There was a facility in Australia, owned by the USA military to transmit to their submarines when submerged at a place called Pine Gap and the supposed transmission range was global.

If I recall correctly, that was an ELF (Extremely Low Frequency) system. Obviously (for those who know something about communications theory), the bandwidth limits it to text messaging for anything sent in a useful time frame.

I do remember some details about the method,and it depended on temperature and salinity of the water as well as depth and pressure.There was a lot of buffering of the signal at the receiver,and the data was digital.If a scene did not change,the image was not refreshed.. a form of compression at the source..in other words,a stationary back ground was not repeated,only the active parts of the video,and the range was definitely limited .The digital format served also to filter out background noise and reflections.

That is about all I recall about the technology at the time.This has been many years ago,and I am sure the methods have improved.

Some amazing technologies have occurred over the years,such as supercavitating torpedoes,that travel faster than the speed of sound underwater,and supercavitating projectiles for destroying underwater mines from above.

Sending just changes is pretty standard for image compression. Dependence on temperature, salinity, depth, and pressure sounds like the transmission was very likely acoustical. I suspect they were using a number of signal processing "tricks", knowing the characteristics of the signal being received, to tease the signal out of the ambient noise.

Maybe something like this.

I figure they were sending info in packets,with preamble and eop for each packet,containing the number of bits,spaces,and data length,etc.

And I am sure there are many other very sophisticated error detection/correction methods being used also.

CAILabs claim to have an adaptive optics underwater laser communications solution. There's no mention of using cavitation (which would be dangerously noisy for submarines to use, unless somehow disguised as cavitation from pistol shrimp).

TILBA improves the reliability of underwater laser communication by compensating for turbulence.

There are several other companies with similar technology.

Crystal oscillators aren't limited by being underwater so long as they stay nice and dry inside a waterproof housing along with the rest of the electronics. The problem is that the radio frequencies at which they oscillate are not readily transmitted in water. Thus, electromagnetic communication is pretty much limited to ELF or blue-green light, or (maybe) near-surface operation to pick up above-water radio, typically with an antenna protruding from the water. Blue-green light is still relatively short range - probably not much more than 200 meters in ocean water.

I accept this can provide communication for a short range of fewer than 300 meters but particulate scattering by everything from plankton, algae, bubbles, fish schools, etc. will attenuate the carrier signal. Increasing the source's luminous intensity to reach 300 meters will mean detectable light will get to the surface and remove the stealth nature of submarines.

Thanks,SE.You are the master of the internet searches!