On Thu, 16 Feb 2017 20:44:09 +0000 (UTC), Stijn De Jong
wrote:

So, what I *want*, I can't find, which is an app that scans for all towers,
and simply reports the unique id and signal strength of those towers (which
is how WiFi apps work).

Why can't a cellular app work like a wifi app works (e.g., InSSIDer or
Fritz! Wlan, or WiFi Analyzer, etc.)?

Your smartphone is an SDR (software defined radio) that is capable of
receiving all of the worlds cellular bands and sub-bands, and can
demodulate most any flavor of cellular protocol. However, this is not
a feature that the cellular providers find worthy of providing. Were
they to do so, you would have the equivalent of a hand held spectrum
and protocol analyzer. Such devices do exist, but not built onto a
smartphone platform, which lacks the horsepower to do the job:
http://www.gl.com/protocol-analyzer-for-wireless-and-ip-networks.html

So, you're stuck with only hearing what your smartphone is programmed
to hear, which I think means your cellular providers mode
(GSM,UMTS,CDMA, etc) and possibly filtered to limit reception to your
cellular vendors SID and NID numbers. I gotta play with Netmonitor
later to see if my Verizon phone will "see" Sprint sites. Verizon
roams onto Sprint when desperate. Both are CDMA, but on different RF
sub-bands. So far, I'm only seeing Verizon, but that might be because
I'm in a lousy location.

Also, the reason you can see any wi-fi access point that is
broadcasting its SSID, is that as newer and faster protocols are
added, compatibility with hearing management packets from the older
slower protocols is written into the spec so that the slower protocols
won't collide with the faster protocols. However, that can be
disabled with the Greenfield mode:
http://www.summitdata.com/blog/wi-fi-and-greenfield-mode-functionality/
where an AP can only hear other 802.11n AP's. There have also been
some casualties among the slower protocols, such as where 802.11n
requires that 802.11 and 802.11b speeds NOT be supported. However,
since the broacasts are always sent at the slowest speeds for that
protocol, a higher speed 802.11n AP can always hear if an 802.11 or
802.11b AP is present.

Bottom line. Wi-Fi downward compatiblity and scanning works because
it was designed to work that way. Not so with cellular frequencies,
modes, protocols, vendors, and instruments.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558