Taking into account the mentioned factors we decided to make an overview of the best smart GPS antennae available on the market today, that provide the best quality at a reasonable price. We consider the accuracy of 20-30 cm as sufficient for most farming operations. Therefore, after many field tests and feedback from our community, we have chosen these 3 smart GPS antennae that can be used to improve the efficiency of your farming operation this season:
- Novatel Ag-Star™ Antenna
- Hemisphere A101
- Trimble AgGPS 162
Table 1: The comparison of characteristics of Novatel Ag-Star™, Hemisphere A101 and Trimble AgGPS 162 receivers
|Novatel AG Star™||Hemisphere A101||Trimble AgGPS 162|
|Receiver Type||L1 GPS||L1 GPS||L1 GPS|
|Channels||12 + 3 SBAS, GPS, GLONASS||12 L1 CA GPS 12 L1P GPS 3 SBAS or 3 additional L1CA GPS||12 + 3 SBAS|
|Update Rate||10Hz||10 Hz||1 Hz, 5 Hz|
|Horizontal Accuracy 2DRMS (95%)|
|SBAS (WAAS, EGNOS)||0.6m||0.6m||0.6m|
|Pass2Pass||+/-18 cm during 20minutes||± 20–30cm||± 20–30cm|
|Interfaces||RS-232, CAN||RS-232, CAN||RS-232, CAN|
|Protocol||NMEA, RTCM v2.3 (DGPS), RTCM v3 (DGPS), CMR(DGPS), CMR+(DGPS)||NMEA, RTCM v2.3 (DGPS), RTCM v3 (RTK), CMR (RTK), CMR +(RTK), NMEA||No|
|Price||€ 1,049.00 exc VAT||€ 1,382.00 exc VAT||€ 1,081.00 exc VAT|
As we see from the table above all compared receivers have similar technical characteristics. The major difference between them lies in the smart mathematical algorithms that are used for improving the accuracy. Each antenna uses its own algorithm:
e-Dif from Hemisphere. eDif is an optional mode where a receiver can perform with differential-like accuracy for extended periods of time without the use of a differential service. It models the effects of ionosphere, troposphere, and timing errors for extended periods by computing its own set of pseudo-corrections.
OnPath®. Advanced Filter Technology that provides consistent accuracy in areas where some satellites may be obstructed. It improves pass-to-pass accuracies even with the absence of SBAS signals.
GLIDE™ combines L1 code and phase data to produce a smooth positioning well suited for applications, such as agricultural guidance, where relative positioning is critical. It works in all code positioning modes, including Single Point, DGPS and SBAS. From our tests, this algorithm shows significantly fewer positioning jumps and less than 1 cm differences between passes.
All of the mentioned algorithms can operate when the SBAS signal is absent. Thus, these smart antennas can be used anywhere geographically and are especially useful where SBAS networks have not yet been installed, such as South America, Africa, Australia, and Asia.
All antennae described in the overview have both good quality and good technical characteristics, but the GLIDE™ algorithm was designed to improve pass-to-pass accuracy even when SBAS correction is working. This makes the Novatel antenna the best for agricultural purposes. Moreover, the Novatel Ag-Star antenna provides a substantially higher accuracy of 18-20, it also has a built-in Bluetooth module and is cheaper than the other antennae.
In conclusion. the Novatel Ag-Star is the best price/quality antenna with smart GPS receiver and sub-metre accuracy currently available on the on the market.