[Make-wifi-fast] Car tire tracking

[David P. Reed]

The XTRX probably can do LTE transmission and reception. Of course LTE's protocols are the real barrier - compared to 3G, it's like SS7 vs. manual switchboards. There's a lot of code to write to do all the LTE functionality - certainly bigger than your Linux Internet stack. It doesn't come with PA's capable of transmitting at LTE power levels, but its LNA's probably are fine. The current XTRX CS doesn't have reference clock stability needed for LTE (its reference clock is 500 ppb). The next version called the XTRX Pro, scheduled for delivery in January, does (100 ppb). This is important for reliable OFDM on a shared channel. Software types generally don't pay attention to this issue as much as they should.
 
The reason I got the XTRX is that it is very small, mini PCIe sized, and also USB 3.0 compatible with a small carrier and metal housing.
 
I have also got an order in at CrowdSupply for a LimeNET Micro, same kind of modest price, but it has its own computer, a Raspberry Pi compute module. It will be delivered in a few months, when they start manufacturing. The performance characteristics are not in the XTRX's professional category, but it's super portable and general purpose, andwith the Pi's multicore ARM processor is very fast for DSP, while being self-contained.
 
I can legally self-certify and operate both of them as MIMO transceivers in SDR modes as a licensed Amateur, in a large set of wideband modes and bands at whatever power I like (up to 1.5 kW, if I add a PA that can do that), as long as I live within the "no commercial use",  "no music" rules, identify my transmissions every few minutes, and share nicely.
 
That's what the worldwide Amateur Radio licensing regime affords to us in Hacker Culture (not the modern definition of scary criminals, but the meaning of Hacker that we used at MIT in the 1970's). Transmitting outside the Amateur bands is, of course, not legal for me to do, as is listening to cellular communications bands. (I'm not sure what other SDR researchers are doing - my informal survey suggests that many students doing SDR are transmitting illegally, as they don't have licenses and their equipment isn't certified. The stuff I want to do is very QRP and very wideband so disturbing any FCC licensee sharing the band is very unlikely anyway.
 
 
-----Original Message-----
From: "Dave Taht" <dave.taht at gmail.com>
Sent: Wednesday, November 21, 2018 4:06pm
To: dpreed at deepplum.com, "Make-Wifi-fast" <make-wifi-fast at lists.bufferbloat.net>
Cc: "David Lang" <david at lang.hm>
Subject: Re: Car tire tracking



On Wed, Nov 21, 2018 at 9:17 AM David P. Reed <dpreed at deepplum.com> wrote:
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> Schneier wrote in 2008 that some TPMS's have unique identifiers in the tire pressure sensors, and that the government requires that they be registered! https://www.schneier.com/blog/archives/2008/04/tracking_vehicl.html
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> He seems to be a reliable source, but I'm skeptical that the tires radiate bluetooth signals for a lot of reasons. However, that doesn't make it less troubling.
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> Now I am motivated to develop a software receiver that can tell me my tire pressure sensor info. Good use for my new XTRX that just arrived, serendipitously, today.

Pretty cool. Does it also already do LTE?

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> Gotta find the specs of the radio system (hopefully NOT bluetooth) somewhere. If the gov't requires it to be a standard, it's probably open to the public.
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> And then I can have fun hacking other people by sending fake tire pressures for their tires!

Heh.

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> RTL-SDR probably can handle receiving what I suspect is the actual coding, though it's can't handl bluetooth frequency hopping.
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> -----Original Message-----
> From: "David P. Reed" <dpreed at deepplum.com>
> Sent: Wednesday, November 21, 2018 11:48am
> To: "David P. Reed" <dpreed at deepplum.com>
> Cc: "David Lang" <david at lang.hm>
> Subject: Car tire tracking
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> I think everyone who works in "wireless", especially mobile wireless, should become well aware of privacy concerns.
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> Privacy isn't just about secrecy, but about how information gathered by sensors is used by others. Now that it's trivial to gather terabytes of personally sensitive information and analyze it, we have to live in a Surveillance Society whether we like it or not. My own thinking (admittedly anarchist-libertarian) is that Norms need to grow, because Laws can't. Engineers (the ones who design and maintain systems) have professional responsibilities for the societal impacts of their systems. THey are not allowed to subcontract that to the people who specify or regulate their output.
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> So if we know how to, or can invent a way to, maintain privacy better for all (users and bystanders), we really must.
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> The shareholders/owners of profit-maximizing companies won't, and the government (even the elected one) won't.
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> Which is why I am following up on tire pressure gauge unique addressability. Anonymous car presence detection is a whole 'nother thing.
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> By the way, Dave, I'm sure you know that the WiFi MAC is the technology standard of choice for inter-vehicle communications in the Transportation departments and ministries of the world. One thing to argue for is to require MAC address randomization and periodic (every 10 minutes?) changes.
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> Convoying in the Smart Car and Autonomous Car industries is an important design goal. That requires some kind of "addressing" but it really should be non-unique, anonymizing. That follows the standard Principle of Least Privilege in systems architecture, which every engineer of information and control systems should have at front of mind for new designs.
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> Fortunately, nearly all users of the 802.11 protocol assume that the MAC address can dynamically change, and the hardware in the 802 standard devices all seem to support it.
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> IPv6 actually supports (and IETF best practices encourage) randomization of the lower 64 bit half of the 128-bit address, with the upper 64 bits being the coarse grained routing mechanism, including subnetting. So one can indeed randomize at the IPv6 level for privacy, given the design that allows multiple v6 addresses per interface. You can have different "personae" in IPv6.
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> This good-privacy-in-the-design can get broken by thoughtless engineering.
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> That's why I spread the word.
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-- 

Dave Täht
CTO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-831-205-9740
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