For the installation of mine differential GPS solution with two RasPiGNSS Aldebaran modules two special GPS antennas are needed. The antennas are no classic GPS mousse with a USB connector. This antennas are special receiver modules with which only a GPS signal could be received. In each case for the base station and for the mobile unit a GPS antenna is needed. As recommended from www.drfasching.at I bought for the base station the antenna “Tallysman™ TW-2410” and for the mobile unit I bought the “Tallysman™ TW-4421” antenna. With this antenna setup for the base station and the robot car the installation should work perfect. Hopefully the GPS positioning takes place very quick with this kind of antenna modules.
The picture below shows both models from Tallysman™. The antenna right in the picture with the bigger footprint is the Tallysman™ TW-2410 antenna.
The more expensive model Tallysman™ TW-2410 GNSS antenna is able to receive the frequencies GPS L1, GLONASS G1 and SBAS (WAAS, EGNOS & MSAS). This type of antenna is very good for Precise Point Positioning (PPP) applications because of the footprint of a 57 mm diameter the receiver power is very good. The smaller and cheaper model Tallysman™ TW-4421 antenna is a good choice for the mobile unit the robot car. This small antenna is very good in urban areas with tall buildings and many reflections. With the smaller footprint the antenna is much more resistant against GPS signal reflections from trees and buildings. I assume that the base station always has a free sight to the sky and horizon. No tall buildings or trees are next to the base station which could jam the GPS signal.
I bought the GPS module RasPiGNSS Aldebaran with both antennas from www.drfasching.at as well the support to buy the best antenna setup for my application.
The following technical specifications are from the official Tallysman™ TW2410/TW2412 website:
|Architecture:||Dual, quadrature feeds|
|Size:||57 mm dia x 15mm H|
|Enclosure:||Radome: ASA Plastic, Base: Zamack white metal|
|Attachment Method:||Magnetic w/pre-tapped 4 x 6-32 UNC|
|Environmental:||IP67, REACH, and RoHS compliant|
|LNA Gain:||28 dB|
|Supply Current:||15 mA typ, 25mA Q maz (85C)|
|Supply Voltage:||2.5 to 16 VDC nominal (12VDC recommended max.)|
|Noise:||1 dB typ.|
|Axial Ratio at Zenith for both L1 and G1:||<1 dB|
For more details about the antenna please visit the Tallysman™ homepage via the following URL (link).
The antennas are connected directly to the RasPiGNSS module via the external antenna connector. The antenna is very simply connected with the GPS module with the screw. With the 3m cable the antenna could be mounted far away from the Raspberry Pi with the RasPiGNSS module. For the mobile unit the cable may be a little bit too long. But I also have the idea to use the antenna in my car or on top of a tractor of a friend. In this case the cable length of 3m is hopefully sufficient.
Both antennas look very stable, they receive a very clear and good GPS signal. They are very easy connected with the RasPiGNSS module. The antenna itself has the protection class IP67 and they could be mounted outside. For the Raspberry Pi and all the other electronic components I bought a case from IKEA. It is a cheap lunch box for 6,- € which is waterproof. The lunch box is big enough to put the power bank with all the other electronic into the box.
Article list - GPS module RasPiGNSS:Precise GPS GNSS positioning with a Raspberry Pi and the RTKLIB – introduction
Precise GPS GNSS positioning with a Raspberry Pi and the RTKLIB – theoretical setup
Precise GPS GNSS positioning with a Raspberry Pi and the RTKLIB – GPS antenna setup
Precise GPS GNSS positioning with a Raspberry Pi and the RTKLIB – software installation
Precise GPS GNSS positioning with a Raspberry Pi and the RTKLIB – configuration RTKLIB base station
Precise GPS GNSS positioning with a Raspberry Pi and the RTKLIB – configuration RTKLIB mobile unit
Precise GPS GNSS positioning with a Raspberry Pi and the RTKLIB – XBee serial data transmission