[aprssig] Misc. Ramblings
sparkfel at qwest.net
Mon Aug 6 23:56:22 CDT 2007
Although not directly related to APRS or Ham Radio, I recently got bitten
by the R/C bug again and have bought an MPX Easy Star RTF electric glider
and have a Honey Bee FP helicopter on order. At some point in time I
intend to add a video link to the Easy Star. I intend on crashing the heli
into little bits learning to fly it. ;)
Both come with an old-school 72 MHZ radio set complete with plug-in
crystals (although I intend on getting a Hitec synthesized transmitter at
some point). While poking through my local neighborhood hobby shop I came
across something I hadn't seen before. They are selling 2.4 GHz R/C
controllers for both surface and air models. Futaba and a company called
Spektrum RC are offering a 2.4 GHz system.
Their respective web sites are pretty skimpy on technical details, but the
Spektrum RC system uses DSSS with dual receivers (on their high-end
system), both with diversity reception to prevent signal shadowing.
My first thought was "Not another product adding to the RF clutter on the
2.4 GHz band..." But what the heck, why not? Everyone else is doing it.
Anyhow, it's nice to see the R/C world getting out of 1950's technology and
stepping up to the 21st century.
I find myself ready to buy a new HT in the next week or so. I'm leaning
towards an Icom IC-91AD. Any reason I should look at something
else? I've had a TH-D7AG...
If I hook up a GPS to it and transmit my position on one of the D-Star
repeaters in San Diego, will anyone see my position? If so, is the data
forwarded to the Internet or back to 144.39?
At work we've been using Verizon EVDO as an end-to-end link for law
enforcement purposes (live video) FOR OVER A YEAR and for about the last
six weeks we've been seeing more and more EVDO to EVDO connections no
longer working. Verizon denies any problem and says they are doing no
port blocking, but we've been seeing it all over Southern California with
many government and private security agencies. Even VNC and FTP no longer
work EVDO to EVDO. If one end is anything other than Verizon EVDO it works
great, but if we have video originating on an EVDO connection and a police
car with a laptop with EVDO - no video, no VNC, no FTP. Plug that same
laptop into a DSL or cable modem it works great. We were told it may
relate to older EVDO cards, but we have the same problem with Rev-A
cards. Is anyone else seeing this? If anyone else is seeing this or has
an insight into what's going on, please contact me privately
at: mark at sensorwave.com
We have escalated a trouble ticket at work and I know at least one major
Police Department in Southern California has also escalated this issue with
Verizon. Sprint tells us they'ed love our business.
I'm also doing a GPS provisioning project at work, and ordered a few USB
GPS units for evaluation. I got a couple GlobalSat BU-353 GPS pucks that
have a SiRF Star III receiver, and all I can say is, "Holy Cow!" These
have to be the most sensitive GPS receivers I've ever seen. They lock onto
several satellites at my test bench at work, which is uncommon for any
consumer GPS receiver. And they were only about 50 bucks each, to boot.
I also heard that the FAA decommissioned WAAS corrections on satellites 122
(#35) and 134 (#47) sometime last month. Apparently not all WAAS GPS
units can properly look for or acquire data from the remaining two
satellites feeding differential corrections to the Americas (#45 &
#51). Some can be fixed with new programming or a firmware upgrade and
some will have to be junked if you want WAAS. Something you might want
to check on your particular GPS...
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