Re: [SLUG] Need advice here -OT

From: Chuck Hast (wchast@gmail.com)
Date: Sun Oct 29 2006 - 07:19:15 EST


On 10/29/06, Pete Theisen <petetheisen@verizon.net> wrote:
> On Sunday 29 October 2006 01:18, Eben King wrote:
> > On Sun, 29 Oct 2006, Pete Theisen wrote:
> > > On Saturday 28 October 2006 00:11, Bob Stia wrote:
> > >> I have a daughter (adult) who is confined to a hopital for a serious
> > >> condition and will be for the next few months. I want to give her a
> > >> computer with internet access.
> > >>
> > >> I have available a late model Mac to let her use. The hospital does not
> > >> have wi-fi in the patients rooms so I am thinking cell phone modem.
> > >
> > > I am using the verizon service with a pcmcia. It runs at about 128 but it
> > > costs $60 per month so it is not a lot of speed for the money. It is
> > > *supposed* to be always on but they will cut you off after while if you
> > > aren't actively using it.
> >
> > How much of an inconvenience is it to reconnect; i.e., is it manual or
> > automatic, and how much time does it take?
>
> Hi Eben!
>
> To begin with, it is not always obvious you have dropped. Then you have to
> take out the modem, reinsert it, let it be recognized and then get back on.
>
> Or, sometimes, you just click connect. Usually the easy one is when you
> disconnected rather than were dropped.
>

What they are dropping is the link between your equipment and the base
station you are linking through, your software is supposed to detect activity
and go bring the link back up, part of the testing of CDMA2000 1xRT
data was how long it took to recover from the dropped link (if it is not
recovered in 45 seconds it is a failure and you initiiat a new call and
start over again. The software handling the interface should bring up
the link again in the background, you should only notice a small delay
and then off it should go. I did all of my testing using the driver supplied
by the manufacturer (on a windows machine) have never used the
Linux software so not sure how it works. CDMA (Verizon, Sprint and
I think Altel) need two computers to test data, one which actually
pings a remote device and gathers RTT, and RF environmental
data and a second one which test the recovery from a dropped
link. In windows the piece that dropped the link was the DUN piece.
It appears that they have kept a virtual circuit type operation rather
than move to a connectionless mode. The DUN times out and
drops the link, a request to send data in the background should
cause the DUN to make the call again.

GPRS/EDGE is treated like a NIC card, there is not really a circuit
to drop, if it misses a packet it retries. So in that sense the GSM
providers have a more natural environment, it is just not as fast
as the CDMA world quite yet. The driver acts like a NIC driver
rather than a DUN driver, it just registers with the network and that
is it, no VC set up nothing to time out, of course if it can not hear
the control channel it will no longer be able to communicate.

Pray that your daughters recovery will be speedy, the computer
I am sure will help that much more. I was just up there last week
in Manhattan, there is also WiFi all over the place, as someone
pointed out.

-- 
Chuck Hast  -- KP4DJT --
To paraphrase my flight instructor;
"the only dumb question is the one you DID NOT ask resulting in my going
out and having to identify your bits and pieces in the midst of torn
and twisted metal."
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