My guess is that they are experimenting with WCDMA transmission in otherwise unused cellular channels in these bands. This implies some degree of cognitive radio capability (listen for quiet channel before transmitting), or other interference avoidance schemes (of which I cannot imagine other than cognitive radio).
This is certainly not radar as another poster above suggests, but rather some kind of 3G-speed data communications. Drone sounds like a likely application.
I think Amazon is working on some kind of radio link and wants to test in a variety of cellular bands for determining effective coverage/propagation based on frequency choice. But radio propagation is well understood, so it seems they're more just looking for somewhere convenient to experiment. As Bruce notes, the ISM bands are available, but they're horribly noisy (with youze allz WiFi for instance), and I agree with his point about being unsuitable for radar due to wavelength being too long.
Opportunistic sharing of cellular channels was the basis for CDPD (developed in the early 90's), but that was not successful. I don't think its failure was due to an issue in the RF realm as much as in being able to provide an adequate quality of service for data users vis-a-vis the cost of delivering the service at that time. Cellular data has gone way beyond what CDPD could do, and therefore has supplanted this spectrum sharing approach for the most part.
Not so hot for Datapoint, whose flagship terminal was now facing competition based on their own instruction set and designs.
I went to work for Datapoint in 1978. Was put to work writing software for the 1500 which, ironically, used a Z80 processor. So Datapoint actually used their own design two generations removed. (i.e. 8008 -> 8080 -> Z80)
The 1500 wasn't all that successful because it was tooaffordable. Datapoint salesmen preferred selling the 5500 and 6600 which were much more profitable (commission-wise).
They actually have some architectural details that can be traced to the 4004's successor, the 8008.
If this is true then it is coincidental. The 8008 was originally designed by Datapoint and came in "sideways" to Intel. The 8008 was not an evolution of the 4004.
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