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[aprssig] Misc. Ramblings

Mark Fellhauer sparkfel at qwest.net
Tue Aug 7 04:56:22 UTC 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...

73,

Mark
KC7BXS










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