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Comment Re: Not really needed for drones (Score 1) 24

The FCC application lists the desired modulation type as 4M14G7D. FCC describes this as a 4.14 MHz (maximum) bandwidth emission that transfers data over a modulated wave using Two or more digital channels signal (wow that really narrows things down).

Best match I can find to this modulation type is WCDMA, aka UMTS (3G cellular). I didn't verify that all of the requested bands support this signal type, but several of them certainly do.

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.

Comment Re:TFA completely left out Datapoint. (Score 1) 74

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).

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