Just to follow up on this thread for those who care:
I finally got around to ordering (and then got around to installing) a
Wilson Electronics DB Pro with a directional (Yagi) outdoor receiving
antenna and an omnidirectional indoor antenna. It is a dual band
"transciever", essentially taking in whatever signal it finds in those bands
from the Yagi and retransmitting them (after amplification) on the omni (to
be placed at least 20 feet away and not in "front" of the Yagi).
I'm testing against T-Mobile on an iPhone4 (not 4s). My wife is still on
ATT with her iPhone 2g (soon to be replaced with a 4s), I'll do some testing
there as well. For those of you who followed the earlier thread, my
location near Otowi bridge on NM 502 at the Rio Grande has almost zero
effective cell coverage. We are down low and all the known towers
(espanola, pojoaque, white rock, pajarito mountain) nearby are either
marginally line of site or completely blocked by intermediate topography.
My goal is to get good enough coverage to delete my wired landline service
(which we hardly use even with cell phones not working)... I expect to use
my wireless (900Mhz from Tewacom) with Skype to provide a backup alternative
to the Cell coverage. I'm testing Google Voice to integrate it all (hah!).
Using the aforementioned "field test mode" on my iPhone4 I was able to
verify that I was getting a modestly better signal... using the RSSI
(received signal strength indicator) measure in the field test mode, I was
able to roughly map the net strength of signal to my phone with and without
the repeater turned on.
The Yagi is about 15 feet above the ground (a permanent installation will b
ecloser to 20) facing roughly due East which is both my best guess as to
where the tower I'm most likely to use is, and corroborated by some ad-hoc
direction testing with the RSSI. The Omni is roughly in the center of my
30'x30'x20'(tall) stucco-mesh-frame faraday cage of a house.
At the location of the Yagi, my signal strength is roughly the same whether
the system is on or not (not surprising as one step in the installation is
to reduce the retransmit strength until there is no detected interference).
At the opposite end of the house, the signal is similar with the system on
and virtually zero without it (far end of my faraday cage of a house)...
at ground level, I normally see from 0 to 1.5 bars which means I get the
occasional incoming call that i can't answer and can rarely call out (to the
point of never trying). With the system on I get a very usable signal
equal to 3 bars... As I wander away from the house outside, the
rebroadcast signal drops off fairly quickly but it appears I might get
useable signal on most of my 1.5 acre property where previously I had a few
hot spots where I might get enough to catch an incoming call for a few
seconds.
I am testing with data as we speak and so far, so bad... in fact, the whole
signal dropped out in the middle of my attempt to get to my favorite
speed-test site (speakeasy.net) and of course, when I got there, I am told
that my favorite method requires Flash 7, apparently not on my
Safari/iPhone4 (not surprising). So I'll have to find a better solution for
testing... meanwhile anecdotally, Google Maps loads at least as slow as I'm
used to *anywhere* without wifi. Well, fortunately I don't care so much
about Data, or at all at home where I have WiFi.
Overall I'd say the Wilson system works well, mostly as expected and seems
to meet my needs/desires. Internet research suggests that Wilson is the
best system with only a few spurious compliants while all the other options
have many complaints (though many of those sound spurious as well?!).
FWIW, it is also worth noticing that Wilson Electronics is a small-town
company out of St. George Utah... the quality of their engineering,
packaging, documentation, online support rivals that of any large scale
consumer product supplier I know of. That said, there may be little going
on in St George beyond shipping... the parts and primary packaging may come
directly from China and there may be nothing more than a small warehouse in
St. George, but indications are that the engineering and support may
becoming from there as well. A business article linked from their website
suggests that they sell 200,000 units per year and hired 50 new employees in
the last quarter... clearly a big deal for a small town like St. George.
Let me know if you are interested in more specifics.
- STeve
Gil -
Thanks! Very Interesting!
My iPhone does have a "field test mode" (*3001#12345#*) which does expose
the alternate towers that it sees (and might use). I see no indication
anywhere that I could influence it's choice, nor have I been able to find a
concise description of the algorithm/heuristics likely used to decide. The
most obvious of course, would seem to be signal strength, but that ignores
issues such as congestion.
Since GSM is a Frequency Division Multiplex hybridized with Time Division
Multiplex, it seems like there would be almost immediate feedback to the
mobile device as it tries to connect as to whether there even *was* an
available time/frequency slot to use... the heuristic could be as simple as
"try the strongest signal you see, if it is full, try the next, repeat".
Along with a dB indication of (useable?) signal there is something called
RSSI (received signal strength indicator) which seems useful for recognizing
how much interference in the band there might be. It tops out at about 50
underneath a tower but is as low as 5 when still useable. Multiple towers
competing and/or possibly other sources of interference run this number up
without running up the "useable" signal.
There are two very cryptic numbers, C1 and C2 which from the mumbo jumbo
I've found, might relate to the heuristic which I was seeking above... but I
don't know yet... this is subtle and complicated stuff and it appears that
short of finding a professional training course, there isn't much
information laying around for the motivated layman.
See what we have become in this Internet/Google/Wikipedia age? We DO
expect a LOT!
Depending on the phone there might be a # code to get it to search for
more frequencies. Might take a bit of diging though. My oold Cinguluar
phone for instance used #689# that let it borrow other towers in
range. I'll check for the potenial andriod # codes to see if there's
something simillar.
On Fri, Oct 7, 2011 at 12:45 PM, Steve Smith<sasm...@swcp.com> wrote:
I'm hoping *someone* out there knows more about this than I do, though
none
of the earlier discussion seemed to bring any of that out.
I took up Gary Nelson's question about Cell Towers/Coverage, my own
frustrations, and the other resulting conversations to do a little
research
and see if I could learn more and maybe even fix up some of my own
problems/challenges.
I'm testing iPhone 2, 3G, 4 against ATT and T-Mobile SIMS right now.
Mostly
at my house (very marginal signal if any) but will be doing other
places.
I'm looking at Cell Repeaters (primarily for my home, but maybe also
mobile). I'm therefore *mostly* sorting out GSM related issues, but
there
is a lot of overlap in general RF issues, repeaters, tower locations,
etc.
I started trying to write up what I know (so far) and discovered that
(as
often is the case) the more I know, the more I know I don't know. My
3rd
Class Radiotelephony license from 1974 and a BS in Physics provides
just
enough background to get me in trouble. I wrote a long, rambly overview
of
what I know (dominated by what that made me realize I *didn't* know) and
decided most of you don't care.
So, if there are others trying to make actionable sense (or merely slake
your curiosity) about the issues of Cell Reception and the potential use
of
Repeaters, ping me and we can discuss offline. Maybe once we learn
enough,
one or more of us can write up a (more) concise "lessons learned".
My long-winded ramble was useful (to me) already, as trying to explain
it to
the larger crowd caused me to dig just a little deeper than I was for
more
"practical" reasons. Now to get my nose back on the practical
grindstone.
- Steve
--
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FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
