On Sun, 26 Jan 2020 20:12:27 -0800, "Paul Hovnanian P.E."
wrote:
Jeff Liebermann wrote:
Are you near one of these cities? If so, I might be able to find the
location of the local paging transmiters using 929.6125 Mhz.
Oops. I forgot to include the URL:
http://old.ambientdevices.com/cat/150cities.html
Looks like Seattle is (or was) listed as having coverage.
I ran an FCC database search on the 929.0 to 930.0 MHz pager band, centered
on Seattle (close enough to my location to cover reasonable transmitter
sites). No sites are licensed for exactly 929.6125 MHz. But with a wide
bandwidth front end, close enough might work.
The FCC database is rather difficult to use. I don't want to ruin my
evening by trying to find something in there.
This might be of interest. See Pages 7 and 21
https://labs.ece.uw.edu/funlab/funlab_CRdata/Seattle%20TVWS/radardata_v2.ppt
Looks like the Univ Washington Medical Center uses 929.6125. I doubt
that UWMC is sending weather info on their paging system. It's
probably coming from some other provider on the same frequency. Or,
the previous provider of weather data sold the frequency to UWMC some
time in the past. If I could find the license, I could lookup the
history.
Mo
http://cloud.spok.com/coverage/LocalOne-way/SEA.pdf
There is no actual wire antenna on/in this thing. Basically just a little
brass bar soldered to the reciever board (a one turn loop). Next time I go
over to visit, I'll bring my unit and see if it loads as fast as theirs.
Is there a ceramic trimmer capacitor near the brass bar? Something
that small for 900 MHz is going to have a rather high Q and require
tuning to get it on frequency. I think you'll find the tuning
adjustment to be rather critical.
It is interesting that, when I do get updates, it does a pretty good job,
loading a 7 day forcast for 150 cities in the USA. But then it goes brain
dead and the forcast data ages out. So it does work in fits and starts
(without me having to smack it). When I power it down, the on-screen clock
re-acquires the current time within half an hour. The pager company probably
broadcasts a time signal for all its customers in a somewhat more reliable
manner than the weather data.
Flex Time is usually sent once per minute and is typically off by as
much as 30 seconds. I presume it varies with type of pager and
transmitter maintenance. How your weather station handles time
signals is unknown.
On a hopeful note: If the pager company is still maintaining their stuff, I
live about a mile from a major hospital and medical complex. Doctors being a
major customer for paging services, I seriously doubt that a viable paging
company would let their service go to s**t in this area.
The hospital might be handling their own paging. See previous mention
of UWMC.
I wish I had 900 MHz RF gear to do some testing. Most of my work is down
around 60 Hz.
Thanks for the RTL-SDR and Radio Reference links. I'll do some playing with
those when I get a chance.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558