Radio: MeshTastic GPS Messenger, Open Time of Flight LIDAR, Rowhammering DDR4 with TRRespass
jdb10987 at yahoo.com
Thu Mar 12 12:16:45 PDT 2020
Jim Bell's comments interspersed:
On Thursday, March 12, 2020, 02:42:08 AM PDT, grarpamp <grarpamp at gmail.com> wrote:
>Open Hardware scanning laser rangefinder based on Time-of-Flight
principle. No standalone laser rangefinder modules were used in this
LIDAR, so its schematic and firmware are fully open.
For a few years, I have been following the Bosch laser distance measuring unit that has been sold in Home Depot stores.
And there appear to be a few other manufacturers as well. (I can remember, back in the mid-1980's, when ultrasonic rangefinders seemed neat.)
One thing I wonder is how much of a 'hard limit' the maximum range is. Optical rangefinders tend to be rather strongly limited by the reflectivity of the target. One way to drastically increase that range is to use a 'corner-cube' reflector, most often seen as a super-reflective molded plastic module often used on or near roadways, or on the back and sides of a car. Such reflectors have the useful characteristic that they send a great deal of the incident light back in the direction form which it came. Do a little research in a parking lot at night with a flashlight, and you will find the retro-reflectors. They are called a "cooperative target". They can increase the returned signal by a factor of 100's, or even 1000's.
So, I wonder if those short-range rangefinders could operate with much-longer distances if they were used with a retro-reflector?
It is quite possible that my isotopic dielectric invention will greatly improve performance in the area of resisting rowhammer. One major figure-of-merit in the DRAM chip design is the ratio of the bit-cell capacitance to the bit-line capacitance: bigger is better. The way a DRAM bit line works is that it is connected many hundreds of bit-cells, gated by row-address lines. Initially, the bit line is fully charged, and then the row address is turned on, shorting the specific bit-cell to the bit-line.
There may be many hundreds of bit-cells potentially connected to a given bit-line, but of course only one at a time. So, if the bitline is charged to, say, 3.0 volts, and the bit-cell is also charged to 3 volts, doing that connection changes little. But if the bit-cell is charged to 0 volts, doing that connection drops the bit-line voltage slightly. This voltage difference is amplified during the read cycle, and then written back into the cell at the end of the cycle,
What is needed is an increase in capacitance of the bit-cell, and a decrease in the capacitance of the bit-line. My invention can do both.
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