|View static image|
|Number of cells||52319|
|Bounding box||9108 × 3469|
|Discovered by||Jason Summers|
|Year of discovery||2003|
Telegraph (a.k.a. lightspeed crawler) is a pattern constructed by Jason Summers in February 2003. It uses complex glider construction recipes to send information at lightspeed along a chain of beehives at a rate of one bit per 1440 ticks. A single reburnable reaction is fairly small, and it produces the same chain of beehives as output that it consumes as input. However, it requires a series of ten of these signals in five mirror-image pairs to restore the beehive fuse to its exact original location:
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RLE: here Plaintext: here
Every 1440 ticks, the transmitter in Summers' telegraph creates a composite lightspeed signal made up of ten of the elementary signals, with information encoded in the position of the final component signal relative to the other nine. At the receiver end, a delay of 60 ticks in the appearance of that final signal is decoded as a '1' bit, whereas the normal location counts as '0'.
Most of the difficulty in designing a workable lightspeed telegraph is the problem of creating these signals with glider collisions at the upstream end of the beehive wire, and then detecting their presence at the downstream end without causing a catastrophic chain reaction that destroys the wire. In fact, a small segment of the wire at each end is destroyed when each signal is sent. The missing beehives are restored as part of the period 1440 cycle.
In 2010, Adam P. Goucher constructed a version of the telegraph using only stable circuitry, such that a single incoming glider produces the entire ten-part composite lightspeed signal that restores the beehive chain to its original position. The signal is detected at the other end of the telegraph and converted back into a single output signal. This simplification came at the cost of a much slower transmission speed, one bit per 91080 ticks. In this case, the sending of the entire ten-part signal constitutes a '1' bit, and not sending the signal means '0'.
In February 2017, Louis-François Handfield completed a high-bandwidth telegraph using periodic components. The same ten signals are sent, but information is encoded more efficiently in the timing of those signals, improving the transmission rate to one bit per 192 ticks. Specifically, the new transmitter sends five bits every 960 ticks, by adjusting the relative timings inside each of the five mirror-image paired subunits of the composite lightspeed signal.
Further improvements to the transmission rate are possible, with several possible encoding methods, but these would likely require very complex receiver components that would be quite difficult to design.
- Jason Summers' jslife-oversize pattern collection. Retrieved on October 28, 2020.
- Adam P. Goucher (February 8, 2010). Very large 'awesome' patterns (discussion thread) at the ConwayLife.com forums
- Louis-François Handfield (February 19, 2017). Re: High Bandwidth Telegraph (discussion thread) at the ConwayLife.com forums