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Facebook Achieves 20Gbps Data Rate Over MMW Radio Spectrum ( 61

An anonymous reader writes: Facebook's Connectivity Lab has announced that it has achieved data transmission rates of 20Gbps over the millimetre-wave (MMW) section of the radio spectrum; however, the transceiving stations need to be incredibly tightly calibrated to each other, with the team describing the margin for error as equivalent to 'a baseball pitcher aiming for a strike zone the size of a quarter'.
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Facebook Achieves 20Gbps Data Rate Over MMW Radio Spectrum

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  • Fantastic. (Score:5, Funny)

    by Oswald McWeany ( 2428506 ) on Thursday November 10, 2016 @01:32PM (#53258635)

    That's fantastic they can violate your privacy even faster now.

  • by Anonymous Coward

    The article does not spell this out, but I lived in Woodland Hills so I know from looking at the map that the path between the receiver and transmitter is not even remotely line-of-sight. That's up over a very tall ridge and then back down onto the floor of the san fernando valley.

    • As I said up-thread, the part of the article that talked about a large parabolic reflector aimed within 0.07 degrees implies a very precise line-of-sight alignment. If it were possible to bounce this signal off an atmospheric layer or rely on backscatter, they wouldn't need that kind of accuracy. From looking at the terrain on Google, I don't think towers would do the trick -- I'll bet that they had the transmitter and receiver set up on peaks near Malibu and Woodland Hills, high enough to see each other.


  • margin for error as equivalent to 'a baseball pitcher aiming for a strike zone the size of a quarter'.

    For fixed-point unobstructed line-of-sight this isn't so difficult, especially if you use lasers to do your initial calibration.

    The problems happen if you have obstructions (trees, rain) or movement (buildings move in the wind, so top-of-skyscraper to top-of-skyscraper would be hard to maintain). But for indoor use or near-ground-level use for tens or hundreds of meters, this might work. If you have a way of keeping calibration despite movement, these limits may be relaxed.

    I can see this as a possible way

    • It would be easier and less trouble to just run a fiber that short distance and ta-da... trouble free communication without interference and easier to reach higher speeds without worry of eavesdropping..

  • Of course (Score:4, Funny)

    by 93 Escort Wagon ( 326346 ) on Thursday November 10, 2016 @01:58PM (#53258891)

    It's well understood that compression efficiency is inversely correlated with the amount of information contained in the data string. Since we're talking about Facebook, the information content is basically nil.

  • by poofmeisterp ( 650750 ) on Thursday November 10, 2016 @02:46PM (#53259355) Journal

    Conveniently, they left out the effective radiated power (ERP) needed to get microwave radiation in the 30-300GHz range to a receiving point at the distance mentioned in the article of 13km.

  • You don't have to worry about the wind drift. The Pringles can is able to squeeze the signal real tight.

  • Ford claims making breakthrough in petroleum refining processes
  • 'a baseball pitcher aiming for a strike zone the size of a quarter'

    These comparison are really useful when have never seen a baseball field and only have an extremely vague idea of how far a pitcher is standing from the strike zone.

    To be honest, I don't actually know how big an olympic-sized swimming pool is either

  • 1/32" radio or some other absurd imperial unit?

  • heck it's easy if the "pitcher" is a computer controlled servo system that keeps the beam on point.

  • by Anonymous Coward

    as equivalent to 'a baseball pitcher aiming for a strike zone the size of a quarter'.

    I don't think that's American enough. Can we get it in terms of Statue of Liberties per acre of Freedom?

"The eleventh commandment was `Thou Shalt Compute' or `Thou Shalt Not Compute' -- I forget which." -- Epigrams in Programming, ACM SIGPLAN Sept. 1982