GPR uses a small radio wave transmitter and antenna -
the frequency is high and is similar to cell phones. It ranges 100 MHz to 2000Mhz
-- Cell phones are about 900 Mhz
(Its does not interfere with cellphones. BUT cell
phones and radios do interfere with radar)
GPR Antenna are shielded so you don't get effects
from building and things around them (at least usually)
Signal about 1 to 10% the level of a typical
cellphone about .05 to .5 of a watt (cell phone output is about 3watts)
Radar wave 100,000 km /sec cf about 300,000 km / sec
in air .. It travels very fast!
This is what a pipe looks like
when imaged with GPR
How it goes together
The radar
system
receives and transmits the signal within the same
antenna
Typical GPR antenna
Operator scanning for targets
The antenna interface to a digital sampling system
The timings are very precise as time windows are on
order of 10’s on Nano secs
This is an example of a typical radar setup
when running the antenna behind the vehicle but on the ground
(actually on a major expressway in SE Asia)
How it works
The Antenna transmits a cone of energy into the
ground
The signal returns after it reflects off layers in
the ground
We then store this data as a scan
We collect between 10 to 100 scans every meter
Radar works in a similar way to
normal radar, its just scanning the ground not the
air
when imaged with GPR
Typical GPR antenna
