RTK for Fendt VarioGuide with a third-party base, how-to guide

Here is a bit of a mini-tutorial on configuring the current Fendt VarioGuide with RTK correction using either a portable or fixed UHF base (correction source) and the built-in UHF radio. Contrary to accepted wisdom, this will work with more than just a "Fendt" portable base. Its entirely possible to get an RTK correction with a third-party UHF base, so long as the UHF base is within a certain range of frequencies and has matching channel spacing (see more below).

I'll try and keep this hopefully as clear and concise as possible, however if I've missed anything, then let me know and I'll update. I apologise if this all comes across as a bit too "techy". If something isn't clear I'll try to explain it as best I can in layman terms. I'll also try and add in some screen shots and photos.

I'm going to divide this into 3 parts, to help split up the info: (1) General Observations, (2) Configuring the Internal UHF Modem, and (3) Configuring an External UHF Modem.

I'm going to skip configuring RTK using the mobile network (GPRS) modem, as that's pretty straightforward.

Part 1 - General Observations

1. The current VarioGuide is based on Topcon sourced AGI-4 based hardware, overlaid with AGCO/Fendt software and firmware. It is not possible to firmware re-flash a 'white' Fendt VarioGuide receiver with firmware from a 'grey' Topcon AGI-4 unit.

2. In UK/Europe AGCO offers an RTK modem "clip-in" option, that can either be factory installed or ordered and installed any time after inside the VarioGuide unit. The RTK clip-in (or snap-in) module contains three keys things:

(a) OAF (options authorisation file) to unlock/enable RTK within the receiver
(b) Satel Satellite-3AS UHF radio modem. The module for the UK market is limited to a frequency tuning range of between 455 to 459 MHz. It is also firmware locked to a 25 kHz channel spacing/width.
(c) Motorola G24 quad-band GPRS mobile radio modem, for using mobile network based NTRIP correction source. Not really covered here.

3. In UK/Europe AGCO supplies country-specific RTK modules, in which the UHF radio modem has a narrower and fixed 4 MHz tuneable band within the 403 to 473 MHz range. For example in France the RTK module has a tuneable radio range of 442 to 446 MHz (and a fixed channel width of 12.5 KHz). In the UK the AGCO module can tune between 455 to 459 MHz (and has a fixed channel width of 25 KHz). Officially the reason for doing this is to maintain regulatory compliance with each countries radio spectrum laws. The UHF base you're trying to connect to must transmit within these ranges to be able to connect using the internal UHF radio. If its outside this range, then you're out of luck - go to Part 3 below.

The latest Fendt / AGCO part numbers for this RTK module (updated in September 2015, with quad-and GPRS radio. Previously was a tri-band GPRS radio) are as follows:
AGCO: 0054 259 250 000
Fendt: H835.970.190.492

You will also need the "RTK Completion" kit (AGCO Part No. 0054 259 100 000) which has a short coax lead, right-angle TNC-TNC connector, a little UHF Gainflex antenna and a GPRS antenna included.

4. The RTK module will need to have an IMU (Inertial Management Unit) or otherwise known as the gyro-compass module fitted in the receiver in order to get slope/terrain compensation. This is a separately ordered component (Fendt P/N: H835.970.190.400). You will already have it if you have VarioGuide running with HP satellite-based 10cm correction. More on that in the next point.

5. I am told from reputable sources, that its quite possible (but I have not tested myself) to use a non-AGCO RTK clip-in module available from Topcon directly with VarioGuide. The benefit here is that the Topcon clip-in has an unlimited/full UHF tuning range all the way across from 403 to 473 MHz. Its is also able to set and use any configured channel width including 12.5 kHz, 20 kHz or 25 KHz. The downside is that in Europe and UK, Topcon will only sell you the RTK clip-in module together as a kit together with the gyro-compass, so if you've already got a gyro-compass you'd be buying it again. In the states and Australia it is possible apparently to get RTK enabled with just an unlock code/OAF without a physical clip-in radio modem - but you'd still need an external modem of some sort. If someone is upgrading from a standard EGNOS based VarioGuide (no gyro-compass installed) straight to RTK this could be an appealing option over the AGCO/Fendt sourced RTK clip-in for the additional flexibility as stated above.

6. With a laptop and the free Topcon Receiver Utility (TRU) software on a laptop, it is quite easy to plug-in to the tractor using the 9-pin serial connection in the cab, next to the right-side rear pilar to get full access to the VarioGuide unit. This is useful for diagnostics or to change/configure some of the UHF radio setting like the radio protocol etc, which isn't possible or viewable from the tractor terminal screen. Be warned TRU is quite a powerful tool and you could screw up your receiver settings (or potentially brick it) if your not paying attention or you don't 'close' the connection properly when you're done. More on that in the next post.
 

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Part 2- Configuring the Internal (VarioGuide) UHF modem

Take a note of the setting of the UHF base you’re wanting to connect to. In a nutshell the UHF modem on the tractor needs to match exactly the settings of the UHF radio at the base to be able to communicate with it and receive correction data. The key things are:

a) Frequency. This can be set through the terminal in the tractor
b) Radio Protocol
c) Channel width – by default it will either be locked to 25 kHz or 12.5 kHz dependant on the RTK module type ordered from AGCO

Basic settings on tractor terminal
1. Select Signal Type as “Base Station”, the in the Base Type select “Fendt Base” – this is basically telling the receiver to use the internal UHF radio modem.
2. Use the rotary dial to select the “Channel”. This will adjust the frequency to match that of the base’s frequency (anywhere in the range from 455 to 459 MHz.) using the scroll wheel.
3. Select the “Signal Format” to be RTCM3.1, the other choices are CMR+ (for Trimble style bases) and RTCM 2.3.

Radio Settings and Steps using TRU
1. Install Topcon Receiver Utility (TRU). Latest version is 3.0.2 The TRU software is free to use from Topcon
2. Using a 9-pin serial cable connection connect tractor serial port (roof 9-pin female) to laptop. I use a USB to serial converter from Maplin for £20
3. The USB/serial cable should auto-detect the speed of the connection and parity type, but if it doesn’t set the serial port speed etc. to be 38,400 bps, (with None for parity, 8 bit word, 1 stop bit)
4. Open the TRU program and from the Device menu (top left), drop down and select “Application Mode”, then select “Modem Managing”
5. Open the data connection to UHF modem by selecting the Device menu again and “Connect”
6. The modem parameters will be displayed there. There will be three tabs, General, Settings and Functions. Select the Settings tab.
7. Finally when finished don't forget to close the connection by using 'Disconnect" from the device menu before shutting the program or your laptop.

The default settings of the standard RTK clip-in module are as follows, these settings should mirror the UHF radio settings at the base.

- Radio protocol = Satel 3AS (you also have a choice of PacCrest-4FSK, PacCrest-GMSK, Trimtalk450s and PacCrest-FST)
- Spacing = 25 kHz (for AGCO UK modules this is fixed an cannot be changed…unless you have a Topcon sourced snap-in module)
- Satel FEC = On (this is forward error correction, and is switched on by default
- FCS Mode = Off
- TX and RX addressing = Off
- Repeater = Off

Satelline-3AS.png


VarioGuide.png
 
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Part 3 - Configuring an External UHF Modem

There is the “third” way to get RTK correction data into the VarioGuide and I think this has been by and large the default way of connecting to a third-party (e.g. not a Fendt portable) UHF fixed or portable base.

If you want to connect to an existing external base, over which you have no control of the settings (e.g. frequency, channel width etc) and the frequency the base is using falls outside of the range you can receive using the AGCO internal radio (455 to 459 MHz) and/or the base is using a 12.5 KHz channel spacing, then this might be your only bet.

There is a spare serial port on the right hand side of the VarioGuide unit in the roof. See picture below. An external modem (about the size of a packet of cigarettes) is connected to this port using a simple serial connection – 5 wires in total.

Its possible to buy a little Satelline EASy UHF radio modem exactly for this task.

A very basic serial cable can then be made up using a DB15 connector at the modem end and a Deutch DT06-12SB connector at the VarioGuide end, some pins, blanking plugs and an inline 1A fuse for the power supply to the modem from the VarioGuide port.

“External base” is the Base Type setting using on the terminal, you then set the port speed and parity to match the data modem. A special serial port adapter is available to put the external Satel modem into programming mode, its about £35. Modem settings are defined/programmed using free software, Satel Configuration Manager off their website.

VarioGuide (AGI4) Serial Port Pinout.jpg
 
Location
North
Have you considered a career in rocket science?

So much stress all the time trying to figure out where to spend all the salary. Farmers do not have that problem. :)

By the way, some time ago this rocket scientist helped me build the radio link from my own base to the VariGuide receiver, using the internal modem. Thaks a lot.

Have both options to choose now, NTRIP via GPRS or the radio link. This also enables the more rare application that Pheasant Surprise talked about in another thread: transfer the RTK correction signal via internet (GPRS or fixed) and the last mile with a low power radio (portable NTRIP to radio converter). Should be useful if the radio coverage is not sufficient and cellular coverage is patchy.
 
So much stress all the time trying to figure out where to spend all the salary. Farmers do not have that problem. :)

By the way, some time ago this rocket scientist helped me build the radio link from my own base to the VariGuide receiver, using the internal modem. Thaks a lot.

Have both options to choose now, NTRIP via GPRS or the radio link. This also enables the more rare application that Pheasant Surprise talked about in another thread: transfer the RTK correction signal via internet (GPRS or fixed) and the last mile with a low power radio (portable NTRIP to radio converter). Should be useful if the radio coverage is not sufficient and cellular coverage is patchy.
Thanks NF. Very kind of you to say, but I think you're being a bit modest here. You deserve a lot of credit for getting this working!
 
Location
North
Point 5 in the first post. I am using all topcon rtk hardware in mine. The gyro, radio modems etc is all direct from topcon.

But that does not fit under the title: "RTK for Fendt VarioGuide". Equally you could have all Trimble gear. In both cases either using a separate screen or an isobus application on the VarioTerminal I guess?

EDIT: I guess I misunderstood the "all topcon" definition, thought it included Topcon AGI-4.
 
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Richard Smyth

Member
Arable Farmer
But that does not fit under the title: "RTK for Fendt VarioGuide". Equally you could have all Trimble gear. In both cases either using a separate screen or an isobus application on the VarioTerminal I guess?

Using fendt varioguide but the topcon rtk components. Pheasant surprise mentioned he had no experience of using the topcon brand radios as opposed to the agco/fendt gear
 
More for background that anything, just had a look at AGCO parts book online (get yourselves a login, its handy). These are the VarioGuide snap-in RTK module options (and associated tuning ranges) that are offered for sale in Europe:

1. Germany, Switzerland, Spain, Denmark, Austria: 431 - 435 MHz (not sure of the channel spacing)
2. Italy, Netherlands, Norway, Sweden, Belgium: 439 - 443 MHz (not sure of the channel spacing)
3. France. UHF tuning range: 442 - 446 MHz (12.5 kHz channel spacing)
4. Portugal: 456 - 460 Mhz (not sure of the channel spacing)
5. Great Britain and Ireland: 455 - 459 MHz (25 kHz channel spacing)
6. Denmark: 440 - 444 MHz (not sure of the channel spacing)

Basically these limited tuning ranges are designed to coincide with the 'licence-free' part of the UHF spectrum in each country, plus a bit extra, but not too much extra ;)

With my cynical hat on I'd suggest that if AGCO made just the one snap-in fully tuneable 403 to 470 Mhz (like Topcon does) then there might be too much temptation for customers to use any base (not just direct them to their own fairly poxy portable one). Topcon on the other hand really want/need to make their UHF radio as tuneable and interoperable as possible so that it will make their hardware work with as wide a variety of kit as possible. Hence more sales. So there is the difference.

Side note about licence free spectrum; in the UK the 'licence-free' allocation in the UHF-II spectrum is from 458.525 to 458.925 MHz. This gives exactly 15 channels of 25 KHz spacing in that range (there are 3 channels that must be skipped because they're used for other stuff). You can only transmit with a maximum power of 0.5W ERP using these frequencies. Outside these specific frequencies and/or above 0.5W transmit power, then you need to have a Business Radio (usually will be Area Defined if you've only got one fixed mast) licence from Ofcom.
 
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Rik

New Member
Hello
I just bought a fendt 724 with vario guide gsm controler, vario doc pro, and a novatel smart6l antenna
the auto steering works great but with low acuracy.
my problem is: I dont have a licence autorization from fendt for centimeter level acuracy to use the rtk. It is curently in submeeter level.
My local dealer dosen't seem to know a lot about gps systems.
and he is trying to sell me a licence code that costs 5000€ for just a simple code.
To the best of my understanding, the tractor has every hardware and software required to recieve rtk signals by the gsm internal modem conection that already has a sim card instaled and working.
i already have the local rtk signup codes.
but 5000€ for a code??? My god !!!
can you tell me if that's normal or he is trying to rip me of?

gps.jpg
gps.jpg
 
Hello
I just bought a fendt 724 with vario guide gsm controler, vario doc pro, and a novatel smart6l antenna
the auto steering works great but with low acuracy.
my problem is: I dont have a licence autorization from fendt for centimeter level acuracy to use the rtk. It is curently in submeeter level.
My local dealer dosen't seem to know a lot about gps systems.
and he is trying to sell me a licence code that costs 5000€ for just a simple code.
To the best of my understanding, the tractor has every hardware and software required to recieve rtk signals by the gsm internal modem conection that already has a sim card instaled and working.
i already have the local rtk signup codes.
but 5000€ for a code??? My god !!!
can you tell me if that's normal or he is trying to rip me of?

View attachment 668562 View attachment 668562
Your receiver is only in standard trim and licensed for EGNOS, so to get to RTK you need two additional unlocks:
1. Submetre to Decimetre
2. Decimetre to Centimetre

I’ve not seen retail prices lately, but about two years ago now when they introduced the NovATel and Trimble receivers to VarioGuide, the retail price for each unlock was approximately £1800.

So that’s about €4000 on today’s exchange rate for both unlocks, but as said prices may have moved up like they have with metal in the intervening period.
 
Hi I think you only need one unlock code to go from submetre to centimetre on a novatel
You're right Rodney. Apologies I was quoting the Trimble receiver upgrade unlocks.

There is no unlock to decimetre for the NovAtel receiver as it supports neither CenterPoint like the Trimble nor Omnistar HP like the original Topcon receiver. It unlocks straight from EGNOS to RTK.

@Rik - you will probably find the prices will be still roughly in line even though it’s one step unlock, but check your dealer hasn’t included a radio modem or something in that price he quoted.
 

Rob101

Member
Arable Farmer
Hi, I recently purchased a fendt 724 with RTK. I have a SIM card ready to go but I’m not sure where it goes on the fendt. Can anyone assist me?
Thanks
 

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The Health and Safety Executive for Northern Ireland (HSENI) alongside the Farm Safety Partnership (FSP), has named new farm safety champions and commended the outstanding work on farm safety that has been carried out in the farming community in the last 20 years.

Two of these champions are Malcom Downey, retired principal inspector for the Agri/Food team in HSENI and Harry Sinclair, current chair of the Farm Safety Partnership and former president of the Ulster Farmers’ Union (UFU).

Improving farm safety is the key aim of HSENI’s and the FSP’s work and...
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