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Aberration in RTK signal causes kink in sowing line December 5, 2013

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This photo, taken on a farm in the UK on 13 November 2013, shows that the RTK correction signal is not infallible. The explanation I was given by someone “in the know”, seemed logical and plausible. Firstly, if one looks at the small print for the signal provision, it guarantees it only for 95% of the time. The cause of these aberrations, I was told, is the ever-shifting constellation of satellites and a coincidental loss of three or more before new ones are acquired. This can cause a temporary loss of the RTK correction but it should not lead to an error of more than 15 cm.

Although I didn’t ask this, one presumes that if one’s GNSS provider gives access to more than one satellite array (e.g., GPS plus GLONASS), coincidental losses of this nature become less likely.

Can anyone shed more light on this and confirm my assumption?

RTK aberration

Your experiences with delivery of the RTK correction signal January 27, 2013

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We all know that getting a reliable RTK correction signal is essential for running a CTF system seamlessly but equally, integrating it with different vehicles and control systems can be far from easy. This blog is asking you to report your positive experiences, how you have overcome difficulties and who or what has helped you most.

We know there is a lot of dissatisfaction out there but we don’t want this blog to be the home for complaints, rather we want it to be a place where people can find out who is doing their job well and what other  help there is to hand.

It can also be a place for asking questions. We can’t guarantee that you will get an immediate answer but the more people who use this blog, the more likely it is that you will be pointed in the right direction or receive a helpful reply.

So, please start blogging!

Lightning strikes – RTK base stations November 10, 2010

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The obvious place to postion a base station is often the highest point on a farm and if this is remote from farm buildings or any other features of greater height, makes it very vulnerable to lightning strikes. Has anyone any advice about how to reduce this risk? Is it possible for example to create a conductor at the same location without interferring with the radio signal from the base station because this conductor must obviously extend higher than the base station?

Regarding the danger of damage due to lightning, this is one of the very good reasons to have your base station geo-referenced, particularly if you are on controlled traffic or are using it for inter-row operations or bed making, when you want to be able to come back to exactly the same place every time. Ask your supplier how to get your base station geo-referenced. This will allow you to ensure that the replacement station, positioned in exactly the same place, locates itself on exactly the same coordinates as the base it replaces and avoids any “jump” in absolute positioning when you start tracking with your new base station.

Another practical aspect of base station location is power supply. If you are relying on a battery, you will almost certainly have to mount this out of reach of passers by, which of course means that there is some hassle for you to reach it as well. Some base stations can take around 1.5 amps, meaning that a 120 ampere-hour battery will only last 67 hours at the most – less than 3 days!

Have you any practical tips you would like to share with others? Just post a comment if you do.

RTK – all about being precise January 4, 2010

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Satellite navigation is being used increasingly across the world in all sorts of clever ways, not least amongst them being for agriculture. Here we are seeing the enormous benefits of being extremely precise, making sure we have the least amount of overlap between one pass across the field and the next. This cuts down on waste – wasted time, fuel and chemicals and the amount of wear on machines. It also means that we do less damage to crops through double dosing with chemicals. So, this technology is good for the pocket and good for the environment.

Another clever way we are using it in agriculture is to autosteer machines so that they run in the same place year in year out. This means that they don’t damage the whole of the field or paddock but are confined to perhaps as little as 20% of the area. Presently, machines run over, and therefore damage nearly 100% of our fields every season. And, when there can be 12 t on each wheel, this is a lot of damage and soils don’t bounce back overnight, they can take many years to recover. To keep machines in exactly the same place each year, we need to use a very particular satellite guidance technology called RTK (Real Time Kinematic). Given the right technology and the right set up, this can steer vehicles to ± 2 cm accuracy – an incredible achievement that even the best drivers can’t achieve, even for a few minutes.

There is a lot to learn about this technology and the idea of this blog is to share experiences and for people who are having problems to post them on the site in the hope that others can help solve them. There are now many providers of this technology, so I hope they will take part and guide people through the maze that sometimes confronts them.

One way of finding out more is to come to one of our workshops. The next is taking place on 9th February 2010 in the UK and you can find out more by visiting: http://www.controlledtrafficfarming.com/content/workshops.aspx

So, have you tried RTK and has it worked seamlessly for you? If not, tell us what is going wrong or how you solved the problem.