[aprssig] Object wierdness

[Stephen H. Smith]

Lynn W. Deffenbaugh (Mr) wrote:
> Earl Needham wrote:
>> That sounds a LOT like what we occasionally see where someone will 
>> get home, shut off their mobile, and anywhere from several minutes to 
>> several hours later their "position" will move around the area and 
>> their tracker is SHUT OFF.
>> I don't think anybody has ever actually discovered why this happens.
>>
>>   

I have experienced another cause of this.    

Transitioning a D700 from PACKET mode back to APRS mode can cause way 
out of date posits (cached from the last time it was in PACKET mode) to 
be transmitted.



I normally run a mobile laptop APRS installation with a Kenwood D700 in 
the car.  When I park and shut down the laptop (to remove it from the 
car),   I have the exit de-init routine in UIview command the Kenwood's 
TNC into standalone APRS mode (rather than turning it off).    My 
de-init sets the D700 to beacon at a once-every-30-minutes rate with the 
display dimmed to zero and the canned "Out Of Service" Mic-E message.  

The next time, I install the laptop and start it, all is fine. However, 
when I get to my destination, shut down and remove the laptop anywhere 
other than where I started, the D700 apparently still has the original 
stand-alone location from the GPS cached somewhere in it's memory.   The 
first beacon after shutdown will be a "hyper-jump" back to my home 
location (where the car was parked overnight). 30 mins later, the posit 
will jump back to the current parking location.     

The same thing will happen when I get back home. Shutting down the 
laptop and reverting to standalone operation will do a one-time 
"hyper-jump" back to Home Depot, my girl friend's house, or wherever I 
was parked for a while and then 30 mins later, the next beacon will 
correctly reflect my current home location.  

As a result, after the laptop shutdown and transition to standalone 
mode, I always cycle the D700's power off and than back on to force 
another beacon immediately that will correctly reflect the current 
location.

I have observed a similar effect in the D700 stand-alone mode.   If the 
700 gets an "invalid fix" flag in the GPS data steam, it quits 
beaconing.   However, if the GPS connection is interrupted (GPS 
unplugged, turned off, etc) while a GPS fix was VALID, the last heard 
location, cached in the radio with a "FIX VALID" flag will be used 
indefinitely (like a canned manual GPS entry). 

Seems to be yet more firmware bugs in the D700........

------------------------------------------------------------------------

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Stephen H. Smith    wa8lmf (at) aol.com
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