I’m the administrator of kbin.life, a general purpose/tech orientated kbin instance.

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Cake day: 2023年6月29日

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  • To the best of my knowledge the ads-b transponders operate with the same interface as previous transponders. That is they can be active, stand by or off. Commercial airliners should never turn them off in the air, but they do have the ability to.

    For military aircraft this requirement is almost certainly only going to apply when in “friendly airspace” and at altitudes with commercial traffic. Especially when not on an operational mission.

    For truly secretive missions they will likely get blanket clearances in friendly airspace to travel at specific altitudes so they can travel transponder off while avoiding the commercial traffic.

    But I’m not an expert by any means.









  • I think my question on all this would be whether this would ultimately cause problems in terms of data integrity.

    Currently most amplifiers for digital information are going to capture the information in the light, probably strip off any modulation to get to the raw data. Then re-modulate that using a new emitter.

    The advantages of doing this over just amplifying the original light signal are the same reason switches/routers are store and forward (or at least decode to binary and re-modulate). When you decode the data from the modulated signal and then reproduce it, you are removing any noise that was present and reproducing a clean signal again.

    If you just amplify light (or electrical) signals “as-is”, then you generally add noise every time you do this reducing the SNR a small amount. After enough times the signal will become non-recoverable.

    So I guess my question is, does the process also have the same issue of an ultimate limit in how often you can re-transmit the signal without degradation.


  • Pretty sure this was made clear in the article but… I’ll outline the little I know on the subject as a complete layman.

    Currently we have been able to use quantum effects to create single runs of fibre that cannot be intercepted. That is, if the data is intercepted by any known means the receiver will be able to detect this.

    The shortcoming of this method, is that of course when you need to amplify the signal, that’s generally a “store and forward” operation and thus would also break this system’s detection. You could I guess perform the same operation wherever it is amplified, but it’s then another point in which monitoring could happen. If you want 1 trusted sender, 1 trusted receiver and nothing in between, this is a problem.

    What this article is saying, is they have found a way to amplify the information without ever “reading” it. Therefore keeping the data integrity showing as “unseen” (for want of a better word). As such this will allow “secure” (I guess?) fibre runs of greater distances in the future.

    Now the article does go into some detail about how this works and why. But, for the basic aspect of why this is a good and useful thing. This is pretty much what you need to know.