eFarmer has developed FieldBee – the new generation of the RTK GPS system, the cost of which is much cheaper than existing solutions on the market. At the moment, we are taking pre-orders.
We are receiving a lot of emails and calls with questions regarding the RTK system. In this blog I will try to answer them.
For those who are reading me for the first time – I am Alexey Bogatyryov – CTO of eFarmer. All of the following information and recommendations are based on my knowledge gained as a technical engineer with over 10 years of experience in precision agriculture.
How do RTK and GPS work?
Let us first clarify the principles of operation of GPS and RTK.
At an altitude of about 20 000 km there are moving satellites which are continuously sending several kinds of radio signals to the ground. Satellites are aware of their position in space and time. They send radio signal with the coded coordinates of the satellite and the time of sending the signal. The receiver, in our case – FIeldBee records the time of signal reception and the position of the satellite at the time of sending the signal. Based on the data from multiple satellites we can determine the location of the receiver.
Why poor accuracy? The radio signal travels a distance of about 20 000 km through the ionosphere and other atmospheric layers with different densities, and in the vicinity of the ground signal is reflected from buildings, houses, trees, and that introduces an additional error.
How to get high accuracy? Logical decision – to use several receivers. For example two receivers, one at the point with known coordinates (a base station RTK BEE station), the other on a moving object – FieldBEE. Both receivers simultaneously carry out measurements, the base station calculates correction to the observed measurements and send them to the receiver, which applies correction to the measured coordinates. Next, the base station after a while calculates corrections and re-send it to the receiver, this method is called the RTK (real time kinematics), which allows to achieve centimeter accuracy in a real-time.
Correction transmission methods
The methods of transmission correction significantly affect the range of communication between the receiver and the base station:
- Radio channel. Direct connection: base station-radio channel-receiver. In this configuration, the base station transmits corrections without delay and data loss if there is no source of interference in the radio channel. It is the most stable way to pass the corrections. But it has limited range of – up to 2km with direct visibility.
- Through the Internet. The Internet channel is used to communicate: base station -> wifi router -> Internet -> connection server -> Internet -> 3g modem of an Android device -> eFarmer app -> Bluetooth -> FieldBEE. This method of transmitting corrections has a range of up to 10 km. But because of the large number of steps in the transmission chain, increases the probability of packet loss/delay. In this case, it is important to provide a stable internet connection between all participants or to switch to the radio channel.
Your questions answered
Now, after we figured out in the theoretical part, let’s answer your questions.
1. What does the range of 2km and 10km mean?
Depending on the method of transmission of corrections by radio or the Internet, the FieldBEE RTK system can be:
- Stationary. In this embodiment, the base station is mounted on a roof of a farm (for example). Connected to the Internet via wifi and via the Internet it transmits the correction to a FieldBEE/s, that is/are located on the tractor or handheld. This method makes it possible to operate in RTK mode, at a distance of 10 km.
- Mobile. In this case, the base station is mounted on a tripod on a edge of a field. It allows for RTK mode with 2km range in direct visibility.
2. How does the accuracy of the system on the distance to the base station?
The accuracy depends on the distance to the base station, regardless of the transmission method.
Table. Accuracy of RTK system depends on the distance to a base station.
|Smartphone||FieldBEE||Field BEE RTK||Field BEE RTK||Field BEE RTK|
|Distance to base station||–||–||10km2 to 10km||< 2km|
3. How much money do I need to pay for the correction?
This question is asked by people who know that some companies charge for the correction signal.
We do not sell correction services. Our kit uses a base station. After buying that, you can always use the correction without restrictions. You can also purchase the base station to share the cost with your neighbors, thereby, saving on initial investments.
By the way, if your area has access to a free correction signal, you can use FieldBee receiver and connecting to this service to receive RTK accuracy.
FieldBee supports RTCM 3.x correction format, this means that you can subscribe to a paid service providers correction signal in your particular area. In this case you need to find out where is the nearest base station to your fields is located. It should be closer than 10km.
4. Why FieldBEE RTK is much cheaper than similar solutions?
Yes, it is the fact that we were able to create a RTK system that cost 5 times cheaper than a similar example from JohnDeere, Trimble, Raven, Leica. Why is our price a great deal cheaper?
First, we apply new generation microchip technology. Second, we use a smartphone for signal processing instead of expensive smart antenna. Third, we sell the equipment directly, without intermediaries and laying moderate margins so that we could create new and innovative products for farmers around the world.
With RTK BEE Station you will receive 0-4 cm accuracy at a price much cheaper than the competition. By purchasing the base station you do not have to pay for corrections.
We are very pleased that in 5 days from the start of pre-order campaign, we have received more than 100 orders for the RTK base station. What more important for us is your feedback, we recently received this message from our Irish customer:
“I think you are on a winner with reducing the price and getting an annual subscription. Gives your company a secure future and makes the initial investment for the farmer more affordable. I’ll pass on your info to my local group… Keep up the good work. Happy Christmas”
We promise you that we will continue our work. After the start of antennae production, we are preparing to introduce the autosteer, that will be compatible with our products at a price you will like.