Episode 816 – Time Division Multiplexing

This time on the show Darren continues his series on the Public Switched Telephone Network with Time Division Multiplexing and some of the more interesting elements of T1 signalling. signaling.

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  • tz

    Very good introduction. One minor note is that the 8 bit A/D D/A isn’t linear, but uses a compander (compressor/expander) which is another reason modems must use all that weird stuff. Also where the analog-to-digital happens (miles away in the country, next door in the city), and ISDN – which is what broadcasters still require since it is low, guaranteed latency would round the discussion out. For historic info, those towers with horn antennas at 35 mile intervals.

    Actually latency itself would be a good topic, because most know about bandwidth but not the rest of QoS.

  • zob

    Actually in Europe you had (and still have) 56kBps maximum on the analog modems. You have to use a “home side” digital box to have a real 64kBps channel.

    Except for Germany, which has almost only real 64kBps digital channels.
    Means also that to be DSL compatible, Germans have small converting boxes on top to multiplex it properly.

  • unixndata

    Long time watcher , first time poster. And i have to say i really enjoy your show atm.

    The last two ep’s have been really good , knowing things that are not directly related to your field ( me linux and windows admin) is a really good insight due to not going out of my way to find information like that.

    Keep up the good work Darren , oh and btw your vid on rooting the droid made me get a x10 andriod ftw.

    Peace out and keep up the good work.

  • Stocker

    Greetings from denmark(europe)

    The 32 timeslot E1 consist of 30 * 64kbit of data channels and and 2 start/sync channels of also 64kbit. which brings the total bandwidth up to 2mbit. the start/sync frame is in timeslot 0 and sync fram is channel 16.

    This type of connection is only used for larger companies which require alot of incomming telephone calls. This product goes by the name ISDN30.

    As for internet we use Coax(docsis-x) from the tv-companies, telephone-companies use twistedpair telephone wires for adsl and also fiber optic.

    The infrastructure in Denmark is that nothing can be above ground, so everything is in the earth and that is the main reason that some parts of our country they are still abit behind though 98% of our country is “online”.

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  • frequencydrive

    I love this kind of stuff. The hardware behind the software. Compression, signal analysis is good stuff. Keep’em coming.

  • iondream

    Excellent segment, really enjoyed it. I worked in telecom and got a basic intro, but it was lacking. Yours is much better, and makes me confident enough to hit the books. Thanks for a great segment, and please continue. It really allows a complete view of technology as a whole, and answers questions that naturally come up when exploring the higher level tech we use everyday.

  • uw

    Great show!! really enjoyed the last two shows. i would say its not completely off topic, u have to know the old to understand the new. keep it up!

  • Wags

    Just found this when I fired up W7 media centre for the first time.
    Dealt with telco stuff for years, but the ILEC analog to digital stuff was a bit abstract to me when I first started off in more periphery jobs back in the day.
    Now dealing with packet cable. Fantastic explanation of everything that the last employer did a terrible job with way back when.

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