Daniel Eran Dilger
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Podcast: Apple and Location Services on the iPhone

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Gene Steinberg of the Tech Night Owl invited me to talk about the Location Services on the iPhone in a podcast with Macworld senior editor Dan Moren.

You can tune into the live broadcast stream Saturday night from 7:00 to 10:00 PM Pacific, 10:00 PM to 1:00 AM Eastern, at http://www.technightowl.com/radio/. An archive of the show is available for downloading and listening at your convenience within four hours after the original broadcast.

The previous episode I appeared on is available at NOW PLAYING! March 26, 2011 — John Martellaro, Daniel Eran Dilger, and Sascha Segen

The Tech Night Owl LIVE is also broadcast on many local radio stations via the GCN network.

You can also access our show’s Podcast feed, now available at: http://www.technightowl.com/nightowl.xml.

  • gus2000

    Osama Bin Laden’s last words: “I KNEW I shouldn’t have gotten an iPhone!”

  • http://www.informationworkshop.org Mark Hernandez

    Love YOU Daniel, but the Tech Night Owl show, and Gene is so hard to listen to. Ugh. He doesn’t help to clarify things, he just spews out-of-order questions. Like fingernails on a chalkboard to me. (He doesn’t even know how satellite TV works.) Jeez.

    I could have explained the whole thing CLEARLY in a quarter of the time.

    What’s the purpose of a show like this?

    I’m glad I know how to not have Garlic Breath though.

  • thibaulthalpern

    Mark Hernandez, well in a way you a right. The show Tech Night Owl is more homegrown and amateurish than professional. Yes, there is a bit of rambling going on but the show is quite enjoyable if we accept the side-roads and diversions taken. I think that’s okay. Tech Night Owl isn’t meant to be all that polished and pristine like say a CNN broadcast.

  • gslusher

    Re: GPS

    You said that GPS takes a “long time to figure out where you are” and that it’s because the satellites are far away. Both are wrong.

    A GPS receiver can keep up with you car doing 60mph–88ft/sec–otherwise, how could it do turn-by-turn directions?

    Other receivers can keep up with a supersonic aircraft and missiles. They can read out not only position but velocity, in six degrees of freedom. (Car receivers only do two dimensions and often don’t read velocity but compute it from two points. That’s not because of inherent limitations in GPS but to keep the cost down. Aircraft receivers have more capability and cost a lot more.)

    What can take a while is for a GPS receiver to ACQUIRE the satellites at the beginning or if you lose one or more satellites (e.g., you go inside for a while—not a few seconds, but several minutes). Add that to the difficulty getting GPS signals indoors and you have good reason for Apple to use triangulation of cell phone towers & WiFi hotspots to get a rough fix on the iPhone’s location.

    As for being “far away,” the GPS satellites are in a 12,550-mile orbit. That causes a delay of about 0.07 seconds between transmission of the signal and the receipt. HOWEVER, that isn’t why it takes time to acquire the satellites, as the satellite signals are continuous. The reason that aquiring satellites takes time is that the GPS receiver not only has to “tune into” a satellite, it has to download a database that the satellite transmits that describes the satellite’s orbit very accurately. It has to do this for at least 3 satellites to get 2-dimensional location, preferably 4. Then, it has to compute the orbits. All that takes some time. Finally, the receiver computes its location. (It actually USES the delay to do this! It also has to correct for both Special and General Relativity at the same time.)

    FWIW, at one time in the distant past (1984-86), I was in charge of long-range planning for a bunch of Air Force space systems, including GPS. Later, I took a “course” at MIT (online, sort of) in General Relativity that included a guest lecturer explaining how GPS compensates for General Relativity. They actually initially included TWO algorithmes in the receivers, one using General Relativity, the other not, just in case Einstein was wrong. GPS is yet more strong evidence that Einstein was right.