Wednesday, July 20, 2011

How the tracker works

Some people were interested in the tracker function and yesterday I gave a url to get you started on understanding the way this works.  And here is the actual hardware
I am using on the bike.

The thing on the left is a handheld VHF ham radio that usually has a rubber antenna on it.  It is removed so I can hook up an external antenna to it for better range.  This external antenna is what got lost immediate upon the start of the trip and got replaced in Portland, Oregon.

The next thing to the right, in the middle of the picture is a device called a tracker that receives data from the simple GPS, which is the small, square thing below and to the right of the tracker. The purpose of the tracker is to capture the GPS data, to arrange it into a packet of information that is standard and to convert that digital data into specific audio tones that a two-way radio can transmit and receive.  The output of the tracker goes to the microphone jack on the radio.  The tracker also listens to the radio to see if someone else is transmitting at the moment using the same cable as the microphone.  The blue cable with a ed and black thing on it is for 12 volt power to supply the tracker and GPS.  The radio runs on its own battery and can be charged in place or at night in the room or campsite from either 12 volts or 110volt house power.

Once I transmit a packet of information containing location, temperature, voltage of the bike system it goes out into the air.  If someone running what is called a digipeater (digital repeater) hears the packet, it gets repeated over a large area.  If a special station called an iGate hears it gets sent to various internet databases like the one we are using to track my movements. If no-one hears the packet it is lost forever.  That is why there are some places the map is a straight line for a long distance when no-one hears the signal.

Trakers are invaluable in emergency work as one could be placed on first responder vehicles to keep track of where they are, or on search and rescue dogs, or persons on foot in a high risk area.  From that data a dispatcher can see who is nearest a person in trouble.  These things can and are being used with commercial 2 way radio systems as well.

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