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mctavjb9

60 karma · joined July 2, 2010

coxe [at] close-haul [dot] com

FPGA designer, wireless hardware entrepreneur, and recovering experimental particle physicist based in Boston, MA

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mctavjb9··on LHC results put supersymmetry theory on the spot
The Worldwide LHC Computing Grid: http://lcg.web.cern.ch/LCG/public/

It's designed to handle up to 15 petabytes of data per year. Data transfers from 11 data centers around the world are handled via 10 Gbps point-to-point optical links.

mctavjb9··on [dead]
Noticeable shaking on the 3rd floor of a concrete building in Cambridge, MA. Some people evacuated. Being a former LA resident, I deemed it minor and didn't bother.
mctavjb9··on How to survive Black Hat and Defcon without getting hacked -- maybe
It depends how you define "secure." There are numerous weaknesses of 2G (GSM) security that were addressed in the 3G (UMTS) standards. The major ones: 1) GSM supports one-way authentication only (handset to network), so man-in-the-middle attacks are possible; 2) encryption is optional, and when turned on by the carrier, only covers the air interface between the phone and the basestation, leaving base transceiver station (BTS) to base station controller (BSC) connections, often a microwave links, effectively unprotected; 3) GSM encryption keys are not long enough to make brute force attacks impractical (A5/1, the strongest version of GSM encryption, has a 64-bit key); 4) GSM does not support data integrity protection, making false BTS attacks like Paget's DEFCON demo possible; and 5) encryption keys and authentication data are transmitted in the clear within a network and between networks when the phone is roaming. (Ref.: 3GPP TS 33.120, 3GPP TS 21.133).

A 3G-only phone isn't susceptible to attacks that attempt to coerce a handset into 2G operation and exploit the weaknesses of GSM security. However, UMTS networks, because they're packet-based, still have to contend with DoS attacks and other Internet headaches.

mctavjb9··on All that is wrong with the Recruitment Industry
"Rarer than a free quark" would save your analogy.
mctavjb9··on Six programming languages built in Cambridge, MA
Oh come on, BostInnovation is not a misnomer. There are plenty of certifiably innovative startups and several well-known VCs on the Right Bank of the Charles. Runkeeper and Cloudant are on the same floor of my former office building in the South End. Flybridge and Spark Capital both have offices in the Back Bay. There's a cleantech incubator called Greentown Labs in the Fort Point Channel district that houses some very innovative companies, as well as all of the Mass Challenge finalists in the Seaport (editorial comments about Mass Challenge aside, many of these companies are IMHO quite novel and interesting). A new ed-tech startup and a micro-VC firm have recently set up shop in the Leather District near South Station. Oh yeah, and there's Skyhook Wireless and Where.com, and well, the list goes on...
mctavjb9··on What happened to all the female developers?
Happily not the case in my family. The Apple II Plus was my Christmas present in 1980. My younger brother (now an MBA) was content playing video games when I wasn't hunched over the keyboard writing BASIC programs with alarming numbers of GOTO statements.

Do you really think that girls are discouraged from using computers in this day and age? I'm always excited to meet women who can code or who show even the slightest interest in learning how to actually program a computer because there don't seem to be very many of us (even in a place like Boston). That being said, most women that I know who are approximately my age or younger are at least reasonably adept at using software that other people wrote.

mctavjb9··on On being a woman and a non-physicist at CERN
I spent 2.5 years at CERN as a grad student in experimental particle physics in the 1990s. I never experienced anything like the condescending head patting or bad pick-up lines the OP refers to. In fact, those years at CERN were the closest thing to a meritocracy that I've experienced in my adult life. I suspect that being a non-physicist is a far bigger impediment to fitting in at CERN than being female. I spent countless hours talking physics over coffee, skiing down mogul-infested inclines in Chamonix, and drinking beer/yelling at the TV during soccer matches with the guys in my (otherwise all male) research group and never felt like I didn't belong. On the rare occasions that guys said or did things that I found to be in poor taste, I called them out on it in a non-confrontational way. Most of the time they weren't intentionally trying to be misogynist swine, they just needed someone to point out to them that they were being insensitive. I've been in the unique position of existing in male-dominated environments for as long as I can remember and have always wondered why more women don't seem to realize how much male behavior can be explained by a combination of cluelessness and insecurity-- it would save my gender much emotional angst.
mctavjb9··on Why We Do Pushups
My knee jerk reaction to this story was "do any women work at this company"? (I'm female and do pushups every day as a component of marathon & triathlon training, so I'm not whining about the hypothetical possibility of feeling excluded.) I understand the intent, but the implementation seems misguided for many of the reasons that others have mentioned. If you want to encourage your employees to stay in shape without marginalizing anyone, offer to subsidize gym memberships or the athletic activity of their choice (e.g., karate classes, participation in a soccer league, yoga etc.) And there are plenty of teambuilding activities that have virtually no threat of joint damage.
mctavjb9··on Terence Tao's General Exam
Definitely my experience. I still have vivid nightmares about the general exam more than 10 years later. It was an 3 day x 8 hours per day written test with no breaks. If you wanted to eat, you had to bring food with you into the test room. Then there was the dreaded oral inquisition. Although I didn't appreciate it at the time, having survived the abject misery of the first 2 years of a physics Ph.D., everything else has seemed manageable in comparison. A few years ago, they changed the format of the written exam to a single 8 hour day. My thesis defense was a total cakewalk. Scheduling it late on a Friday afternoon was probably the single smartest thing I ever did in grad school.
mctavjb9··on How First-Time Entrepreneurs Can Establish Credibility: 3 Case Studies
The fact that "Joey" was annoyed with someone willing to clue him in on social norms that he could easily glean through careful observation is a sad commentary on what seems to be an increasingly pervasive lack of common sense and misplaced feelings of entitlement amongst entrepreneurial wannabes. A frothy market only amplifies the effect. I wonder if it's partially a regional/generational thing. As a native Bostonian on the youngish side of Generation X, this interaction makes me cringe. Another trend that irks me is the use of blog comments for blatant self-promotion. The sage advice to JFDI and establish credibility is basically the translation into startup speak of the mantra of my high school English teacher in 1989: show don't tell.
mctavjb9··on Want to scale? Make sure your LTV is greater than your CPA
David Skok of Matrix Partners has blogged comprehensively on this topic: http://www.forentrepreneurs.com/

The content may seem obvious, but how many startups can you think of that have utterly failed to achieve LTV > CPA?

mctavjb9··on Python for Android | Linux Journal
I can totally relate to the statement: "If, like me, you'd rather eat glass than sit down to write some Java code in Eclipse, it would appear that you are out of luck when it comes to implementing your next project on Android." I've been attempting to educate myself about Android development for a side project. Dealing with Java has been an impediment, as my brain seems to grok scripting languages far more easily.
mctavjb9··on Higgs in ATLAS, maybe
This result should be taken with a large chunk of NaCl until the analysis is internally approved by the collaboration and peer reviewed. Although it's been a while since I got my Ph.D. in experimental particle physics, I do remember that di-photon data sets are subject to significant sources of background from a variety of decay processes that produce one photon + a jet of hadrons, 2 jets, a Z boson decaying to electrons etc. Accurately filtering out and estimating the purity of the data sample is crucial, particularly when claiming the discovery of a new particle. My money is on a some combination of a statistical fluctuation, an inaccurately modeled background, or mis-estimated systematic uncertainty that is creating an artificial "bump." I look forward to being proven wrong and hope that ATLAS and CMS discover something so that high-energy physics doesn't go down in the dustbin of history because it's gotten too bloated and expensive to sustain.
mctavjb9··on Higgs in ATLAS, maybe
Yes, but the LHC is actually running at this very moment and will be operational through the end of 2012. CERN opted to run at 7 TeV and put off the shutdown required to increase the energy to 14 TeV. In fact, the LHC just set a world record for beam intensity: http://press.web.cern.ch/press/PressReleases/Releases2011/PR...
mctavjb9··on Poll: Do you know C?
FPGA designer here. I don't think it's accurate to claim that SystemC is replacing VHDL and Verilog for ASIC/FPGA design. I view SystemC as a niche tool to allow software engineers to dabble in hardware design. I use C for embedded software, but would never dream of designing hardware in anything else except pure HDL. It's a bit like trying to write a letter in a foreign language using Google Translate-- the results are non-optimal and often comical.
mctavjb9··on Enter the MassChallenge competition
I'd be curious to know what the results of this survey question were from companies that made it to the first round but were not selected for the incubation phase. I had the entry fee waived through endorsements last year, but had an experience during the pitch round similar to others who have commented here-- judges who had nothing resembling a clue. I've heard this story over and over and have no intention of participating this year.
mctavjb9··on Facebook client on a SIM, works on any GSM handset
Why do you think OpenBTS is illegal in Brazil? There's a research group at UFPA in Belem that's been quite active in the OpenBTS project. I met two of the guys at the OpenBTS Workshop in Germany last summer. See-- http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5304...

A license for the GSM spectrum used by OpenBTS from the relevant government telecommunications authority is necessary almost everywhere in the world.

mctavjb9··on Ask HN: Peter Thiel's talk at MIT tonight
Yes, it was recorded: http://justin.tv/mitef/b/273997550

Be warned that the audio isn't so wonderful and the running time is 1h41m.

Thiel had some verbal tics that were distracting at times, but the talk was totally fascinating. Off the top of my head, the most memorable points: * The rate of change of innovation peaked at the end of the 1960s and people's expectations/aspirations regarding major technological breakthroughs are far lower/more modest than during the era when men were landing on the moon. (Nixon said that the cure for cancer would take 5 years. We're not going to see a Jetsons robot that does all of your household chores in our lifetimes.) Thiel blames this state of affairs on a dearth of entrepreneurs willing to take the requisite risk. * His investments/mentoring is very Silicon Valley centric, but he did make a flattering comment about the high density of intelligent people in Boston. * If given the choice between investing in a team of engineers and a team of MBAs, it's a no-brainer. * He's steered clear of biotech and cleantech-- too capital intensive, not profitable. * He does not believe that there's a shortage of capital per se, but the sweet spot for game-changing technology companies is >$1M and <$1B. * Rationale for "20 under 20": student loan debt crushes innovation-- people are forced to take high-paying golden handcuffs jobs after graduation. [As a Ph.D. who is well over 20 and was fortunate enough to graduate debt-free, I hadn't considered this point of view. Although I'm still dubious about the whole concept, I can appreciate it.] * If you're in college, LEARN. Don't just go for the credential or the high-paying summer internship, take the hardest courses in a field you find interesting and go work for a startup during your breaks. He cited a recent visit to a business school where 100% of the people he asked admitted to being there to get an MBA and not an education. * Don't network for the sole purpose of starting a company, seek out people who are passionate about the same things you are and let business ventures form organically. * He's skeptical of programs like YC and TechStars because he thinks that they encourage a cookie cutter approach to building businesses that are not really going to change the world, since the barrier to entry for Web 2.0 startups is so low. * Indicators of startup success: 1) CEO pays him/herself <$120K/yr., 2) founding team are not homeowners (although not necessarily in their early 20's). * Best one-liner paraphrased: deciding to marry someone based solely on the mutual desire to get married is not the best idea (said in reference to founding a company with someone one barely knows). * In response to a question about failures, he stated that he doesn't think one learns too much from failure because there's always a scapegoat and it's often difficult to determine root cause.

Disclaimer: views are Peter Thiel's, not necessarily my own and this post is not a comprehensive summary by any means. Search for Twitter hashtags #mitforum and #mitef for 140 character snippets from other audience members and watch for the flurry of blog posts/coverage in the coming days on VentureFizz, BostInnovation, Greenhorn Connect, OnStartups, and Mass High Tech.

mctavjb9··on If you put your hand in the Large Hadron Collider...
Sorry to be a buzzkill, but the LHC beam circulates in an extremely high vacuum. There's no way a hand could even get in the beam without breaking the vacuum, thereby causing the accelerator to shut down automatically. Also, it's cryogenically cooled. Radiation dose aside, the hand would freeze and probably fall off.

http://www.lhc-closer.es/php/index.php?i=1&s=4&p=15&...

Incidentally, when I was working at CERN in the mid 1990's, the Large Electron-Positron Collider (the predecessor to the LHC) was shut down by an act of sabotage involving 2 Heineken bottles placed in the beam pipe. The electrons and positrons (and many physicists) were not happy bunnies. http://blogs.nature.com/news/thegreatbeyond/Beer%20bottles.p...

Update: Now I see that the vacuum point has already been made. There are no heavy ions in the LHC main collider, they're produced by bashing protons into a target in one of the secondary beamlines. Also, antimatter is frequently the byproduct of extremely high center of mass proton-proton collisions.

mctavjb9··on Codec2: GNU low-bitrate speech codec (2400 bits/second)
Here are some suggestions for further reading: http://www.villagetelco.org

Steve Song's blog (Telecommunications Fellow at the Shuttleworth Foundation): http://manypossibilities.net/

http://openmobile.futuretext.com/

There was an article in Linux Journal last December that includes more technical details on the Mesh Potato.

mctavjb9··on Codec2: GNU low-bitrate speech codec (2400 bits/second)
Low bit rate codecs with acceptable quality will be a boon for VoIP over satellite. Satellite Internet service is both bandwidth-limited and hideously expensive-- Inmarsat Fleet Broadband for cargo ships, for instance, typically costs $6/MB. The idea would be to set up local phone networks that employ one of the GSM codecs or mu-law (allowing the use of plain vanilla handsets) and then transcode the voice to a more efficient codec like this one upstream/downstream of the satellite connection to the PSTN.

Incidentally, David Rowe is one of the pioneers of the Mesh Potato.

mctavjb9··on Too Few Women in Tech? Stop Telling People How They Should Feel About It
I read this statement quite differently: the sample size is small, so the author makes an extra effort to learn from the experiences of others that she views as role models (i.e., successful women in tech). Not everyone who seeks advice is by definition an acolyte. The approach of collecting as much potentially relevant data as possible, culling out what is helpful/inspiring etc., and using it to inform future actions seems like a sensible approach to me.
mctavjb9··on Burning Man's open source cell phone system could help save the world
Are you referring to Chris Paget's demo at DEFCON at the end of July?

OpenBTS can in fact be used for nefarious purposes (or to demonstrate the intrinsic insecurity of the GSM standard). It could also in principle be used by law enforcement agencies to track criminals.

mctavjb9··on Burning Man's open source cell phone system could help save the world
As a point of reference, the BOM for last year's Burning Man setup can be found at the bottom of this page: http://gnuradio.org/redmine/wiki/gnuradio/OpenBTSBM2009RF

The default hardware for OpenBTS is the USRP, not the USRP2. The USRP + 2 RFX 900 daughtercards set me back about $1400.

OpenBTS units like these use Intel Atom SBC boards, which retail for <$100: http://www.intel.com/products/desktop/motherboards/d945gclf/...

The bare hardware cost is less than $5K, but perhaps the $10K price quoted in the article includes the tower, rigging, cables, power source, enclosure, Wi-Fi backhaul, etc., not to mention a nice profit margin.

Incidentally, there are some gnarly GSM patent licensing issues that are discussed in the January 2009 entries on the OpenBTS blog.

mctavjb9··on Hacker Spoofs Cell Phone Tower to Intercept Calls
This demonstration is neither particularly novel nor particularly legal.

http://laforge.gnumonks.org/weblog/2010/08/01/#20100801-on_r...

mctavjb9··on XX Combinator
I'm all for women hackers/entrepreneurs self-organizing on an informal level and comparing notes, but I must confess that I have the same visceral reaction to women-only hacker spaces that I did to girls-only math classes when I was in 6th grade. Whatever floats your boat, but I've always believed that it shouldn't be about lacking a Y chromosome, it should be about doing the hacking/learning the math. I may be in the minority of the minority, but I would much prefer to build my business surrounded by people with a diversity of perspectives who could provide flashes of insight that would never occur to me as a typical INTJ scientist (although not a typical 30-something female, clearly). Narcissistic nutcases-- there are plenty of both genders-- are a fact of life.

I believe that the status quo is not going to evolve much through anything that can be construed by naysayers as affirmative action. Rather, women with technical and/or entrepreneurial aspirations need to get over themselves, stop being so concerned about peer pressure or what anybody else will think, do what they love, and prove to others that it can be done. Laura Finton, founder of oneforty and a Tech Stars grad is a great example. She started her company as a single mom with young kids as a solo founder with no programming skills. Even though I'm not a Twitter person at all, I take my hat off to her. She's taking the time to tell her story to the Boston entrepreneurial community and leading by example.

mctavjb9··on Use an Android phone and an USRP (GNURadio) to create a GSM "Cell" (BTS)
Almost all GSM phones sold in the past 4-5 years are quad-band phones-- 850 MHz/1900 MHz (US, Canada, a few other places), and 900 MHz/1800 MHz (Europe, Asia, Africa).

An iPhone in the US, for instance, connects to AT&T for voice calls on the 850 or 1900 MHz bands, depending on what chunk of spectrum the carrier owns in the caller's particular location. If Joe Caller got on a plane to Europe, the phone might roam onto a GSM900 network. But in the US, part of the 900 MHz European GSM band happens to be allocated to ISM.

What people experimenting with OpenBTS in the US tend to do is test with old 900/1800 MHz-only phones that can be procured for a pittance on eBay. That way, they're guaranteed not to connect to AT&T or T-Mobile.

As a sidenote, before the GSM carriers started upgrading to 3G networks, most GSM phones didn't actually have GPS chips. Sprint & Verizon (CDMA) phones did, because GPS timing information is a crucial part of the standard (see http://alumni.cs.ucr.edu/~saha/stuff/cdma_gps.htm for gory details).

mctavjb9··on Are There More Girl Geniuses?
Unlike Switzerland, the American Enterprise Institute isn't exactly known for being a bastion of neutrality. The author's other cause celebre is that people should stop whining about women being underrepresented in math and the hard sciences. Her AEI profile (http://www.aei.org/scholar/56) informs us that she is "preparing to write a book on the lost history of conservative feminism." As a non-white, non-male physics PhD, I can't wait to read that one.
mctavjb9··on Apple letter about iPhone 4
"Bar rendering" debates and the actual signal (yes, a physical quantity!) that the phone sees from the AT&T network are non-issues with a BlackBerry thanks to its wondrous ability to display RSSI directly: http://www.blackberrycool.com/2009/04/22/converting-signal-s...

Someone should write an iPhone app...

mctavjb9··on Use an Android phone and an USRP (GNURadio) to create a GSM "Cell" (BTS)
In actual fact, this demonstration is not breaking any laws (and bears no resemblance to sodomy). There are two GSM bands in the US, 850 and 1900 MHz. Chris Paget, in spite of having a UK domain, lives in the Bay Area. His Android demo used RF hardware operating in the 900 MHz ISM band, which does not require a license provided the transmit power is less than 30 dBm (1W) as per FCC part 15. The maximum transmit power of the USRP hardware is ~23 dBm. Ergo, not illegal.

Other posters have made reference to Special Temporary Authority that one can apply for from the FCC in order to legally operate radio experiments in licensed spectrum. A relevant example is the OpenBTS GSM network at Burning Man-- http://openbts.sourceforge.net/FieldTest3/STAGrant.pdf

The so-called "GSM guard band" between the DECT cordless phone band and the DCS1800 European GSM band being opened up in Western Europe. Unlicensed low-power GSM installations have in fact been legalized in the Netherlands. This swath of spectrum, 1781.7-1785 MHz paired with 1876.7-1880 MHz, was also auctioned off for cheap to 12 companies in the UK by Ofcom (the British equivalent to the FCC) in 2006.

OpenBTS and OpenBSC are complementary but not cooperative (at least not yet) projects. The Base Transceiver Station (BTS) and Base Station Controller (BSC) are different key components in a GSM network. For clarification, see: http://gnuradio.org/redmine/wiki/gnuradio/OpenBTSFAQ#What-is...

OpenBTS currently supports GSM full rate voice and SMS and allows GSM phone to connect to the telephone network via SIP using Asterisk or FreeSwitch. OpenBSC supports GPRS inasmuch as the commercial BTS (e.g., the ip.access nanoBTS) connected to it supports GPRS.