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dippy [2019/11/04 16:43]
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dippy [2019/12/02 10:01] (current)
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 A cheap eBay laser pen claims to have a 10 mile range, that's 53 μs, about the same time delay as the PAL line.  I can't imagine getting 16 of these working with line of sight or mirrors parallel enough to get multiple reflections,​ but someone else may know how to ([[wp>​Free-space_optical_communication]]). ​ It seems that 24 core optic fibre comes in at about [[https://​www.alibaba.com/​product-detail/​Factory-Produce-24-Core-Single-Mode_62081957225.html|$240 per km]], so if the rest was built in TTL it may work (much faster than acoustic). A cheap eBay laser pen claims to have a 10 mile range, that's 53 μs, about the same time delay as the PAL line.  I can't imagine getting 16 of these working with line of sight or mirrors parallel enough to get multiple reflections,​ but someone else may know how to ([[wp>​Free-space_optical_communication]]). ​ It seems that 24 core optic fibre comes in at about [[https://​www.alibaba.com/​product-detail/​Factory-Produce-24-Core-Single-Mode_62081957225.html|$240 per km]], so if the rest was built in TTL it may work (much faster than acoustic).
  
-The start of the [[wp>​ionosphere]] is 75km up, if the bounce was clean (which it won't be) the [[wp>​Shortwave_radio]] would give a 0.5ms delay. ​ It would have to be quite broadband, but [[wp>​Spread_spectrum]] >50MHz is [[https://​www.ofcom.org.uk/​spectrum/​radio-spectrum-and-the-law/​licence-exempt-radio-use/​licence-exempt-devices|licence free]]. ​ The real problem is the bounce has no chance of being clean. ​  We can detect lasers on the moon...+The start of the [[wp>​ionosphere]] is 75km up, if the bounce was clean (which it won't be) the [[wp>​Shortwave_radio]] would give a 0.5ms delay. ​ It would have to be quite broadband, but [[wp>​Spread_spectrum]] >50MHz is [[https://​www.ofcom.org.uk/​spectrum/​radio-spectrum-and-the-law/​licence-exempt-radio-use/​licence-exempt-devices|licence free]]. ​ The real problem is the bounce has no chance of being clean. ​  We can detect lasers on the moon and used to bounce communications off the moon before we had satellites The round trip is about 2.6s, so the clock speed would be low.  It also needs GHz or very high power, which runs into Radio spectrum licencing issues.
  
 Cassette tape:  It runs at 4.75 cm/s and can store at 300 or 1200 bps (BBC model B).  Say 64 registers at 64 bits each, so need 4096 bits on tape and instruction cycle is about 12s or 4s.  Really don't need much tape - only 60cm max.  Interesting. ​ Very very slow CPU - if design variable speed read/write then can speed up via driving motor. ​  Push to max speed, 2560 bps and 16 bits in 16 registers - then 10 Hz... Cassette tape:  It runs at 4.75 cm/s and can store at 300 or 1200 bps (BBC model B).  Say 64 registers at 64 bits each, so need 4096 bits on tape and instruction cycle is about 12s or 4s.  Really don't need much tape - only 60cm max.  Interesting. ​ Very very slow CPU - if design variable speed read/write then can speed up via driving motor. ​  Push to max speed, 2560 bps and 16 bits in 16 registers - then 10 Hz...
dippy.txt · Last modified: 2019/12/02 10:01 by admin