ot: isps

[Geoffrey Mendelson]

On Thu, Apr 23, 2009 at 1:34 PM, nir grinberg <nir at grinberg.org> wrote:
>  The current issue with the
> providers are the fact that their data network coverage is not similar
> to their GSM coverage.  in many locations you will be able to talk via
> GSM, but receive a very poor data connection.

That's because there are three different networks involved here.
Orange runs 3 networks. a 900mHz GSM (voice and data up to 14.4kbps if
they allow it), 1800Mhz (voice, 14.4k data and higher speed data
(GPRS?) ) and a 2.1gHz 3G network. The 900 mHz network covers all of
the State of Israel and the territories, for legal reasons it does not
cover the PA (nudge, nudge, wink wink). The 1800 mHz network has a
shorter range for each cell and covers less. With the shorter
wavelength there are more "dead spots". The 3g network is similar to
the 1.8gHz network in coverage, I have no idea about the number of
cells.

Cell-Com has an 800mHz D-AMPS network (voice and 9.6k data if they
allow it), an 1800mHz GSM network (voice, 14.4k data and higher speed
data) and a 2.1gHz 3G network.
Coverage is similar to Orange's.

As far as signal path, the 1800mHz and G3 networks have the same
problems with signals being stopped by things like paper, "sandwich"
type wood, trees, etc that wifi has. In fact, it's best to think of
them as "wifi on steroids" when it comes to propigation and coverage.
They also suffer from the effects of multipath (reflected signals) and
the fact that the least power of a signal is at a multiple of half of
the wavelength aka "nulls". So you can get a good signal at one
location and 6 inches farther away from the cell get nothing useable.

It also suffers from the effects of antenna orientation (polarization)
so a vertical antenna will get 100 times the signal as a horizontal
one.

So not only is it possible to be out of coverage of the data network,
it's easily possible to be in a "bad location".

Geoff.



-- 
Geoffrey S. Mendelson N3OWJ/4X1GM
Jerusalem, Israel