Applications for GPS in Australia (4)
| This
Page |
eTrex
with more accuracy for geology work
Radio
transmission of GPS position
Bluetooth long range
GPS for portable use.
|
Using
an eTrex in a geology application. Accuracy 5-15 metres.
With
DGPS, 2-3 m
Radio transmission of GPS position- APRS (Automatic Position Reportng
System) |
| Page
1 |
Volunteer
Marine Rescue, Send
your location via mobile phone, Where
is the nearest fuel stop? |
Typical
navigation, Innovation using latest communications, and manage
petrol station
locations. |
| Page
2 |
Whittlesea
Council Fire Management, Shifting
Soils, Counting
and measuring your assets, Understanding
Wildlife |
Emergency
responses, Measuring the drift of our sandhills, GPS helps
locate and value everything from pipes, to parks and gardens,
How many and where? |
| Page
5 |
Birdwatching/atlassing, Differences
in position format. |
Defining and locating
bird habitats and populations, correct methods of reporting
position, |
GPS Civilian accuracy is15 metres or less (without accounting
for selective availability, which was cancelled by the US Government
on 1May 2000).
Find latitude
and longitude of any town in
Australia
Articles written by Kimball Thurlow, Copyright, Johnny Appleseed
GPS, Brisbane.
Geologist using Garmin eTrex, says this:
" I've got a handheld Garmin
etrex (the yellow one) which is a great little device and
mega easy to use. I'm currently using it to record the
positions of unstable rocks in the _____ for our local
transport authority. In some locations I can get an accuracy
down to 5m which is great. However in other spots, where
there is a bit of tree cover or a high rock slope adjacent
to the location, the accuracy goes out to 25m or more which
is too great. We've considered hiring a _____ unit with
the backpack antenna to do these sites; however it costs
an arm and a leg to do so.
I'm therefore looking for suggestions.
I thought that adding a DGPS facility to the etrex would
be the way to go however I don't know if this can be done.
Would this be the best way to go to improve on the accuracy?
Can you suggest an alternative?" |
Well,
the answer is that the DGPS is available for the eTrex,
as a backpack, to purchase, or for hire. Simply a matter
of connecting the eTrex with the supplied cable, and
accuracies of 2-3 metres are achievable. However, where
some of the satellites are obscured, as in the cases
of 25 metre accuracy, it will improve proportionately.
The geologist
now has a backpack fitted up by Johnny Appleseed GPS
with a Garmin beacon receiver. The location of the job
is within 300kms of an AMSA DGPS beacon transmitter.
He is very pleased with the result, achieving the accuracies
he wants. And the additional cost? - about $1200, and
there is no aubscription fee.
Footnote: The
use of an eTrex Summit or eTrex Vista will also give
very accurate elevation readings. So 3 dimensional accuracy
may improve to 2-3 metres all round. |
Radio enthusiasts pick up other radio
operators and stations via radio, and plot them on GPS or computer
map.
APRS (Automatic Position Reportng System)
1. A GPS outputs a NMEA String at 4800 baud RS232
2. A microprocessor receives the string and filters out the $GPRMC NMEA sentence
3. From the $GPRMC sentence, the Latitude, S/N, Lontitude, E/W is filtered
out.
4. A 'packet' is formed and a call sign added
5. The packet is sent to a VHF radio transmitter, which transmitts tones
according to the data fed
6. A receiving station picks up the tones, decodes them and derives the lat
and long
7. The lat and long are displayed on computer or on the MAP page of a GPS.
>>>><<<<
System Hardware
GPS --> Mircoprocessor --> VHF Radio
--> Antenna
Antenna ---->VHF Radio ----> Decoder ---> Computer with
maps
"In the case of the GARMIN GPSMap176 shown on my web page, any stations
heard are
translated into the NMEA $GP????? Write a waypoint command, back to the GPS." from Andrew
VK4TEC See
the GPSMAP176 with radio locations.
Latitude,
Longitude, AMG etc etc etc:
I get many requests to explain the different numbers used by different GPS at
the same location. This is a valid and sensible question, and there are easily
understood answers. You may also wonder about terms such as UTM, GDA, MGA, datum,
position format, grid, and true north. My customers get free assistance with
these, and any other matter relating to their purchase, and the use of the GPS. |
What is GPS? (Explaining
the system of satellites and how it works)
The theory of positioning (How Sir
Isaac Newton and others made GPS possible)
|
Johnny Appleseed GPS