Topcon AGI-4 upgrade to RTK

[Richard Smyth]

No 2g here in Australia. I have 2 topcon units running 3G and a Trimble 382 also 3g

 

[Northern farmer]

3G being swapped to 4G here but our AGI-4 units run fine from 2G. Our 2G/3G capable AGI-4 modems stay on the 2G network more or less all the time. Could also be the network strategy to keep low bit rate users on 2G.

The older AGI-4 modems were 2G only, not sure if you would see 3G mentioned at all in that case. Anyway if you can connect to your NTRIP caster, it makes no difference if the correction data comes over 2G or 3G as long as the latency remains low, about one second. Any decent 2G network should manage that easily.

It does take some time for the modem to connect (easily 60 seconds), even network registration is surprisingly slow with these modems but once you see the cellular network signal on the VarioGuide screen and the NTRIP client having registered to the NTRIP caster, it should only take a few seconds and you see the RTCM stream coming (latency changing to a low number) and then a few seconds to RTK fix.

 

[bartdereu]

3G being swapped to 4G here but our AGI-4 units run fine from 2G. Our 2G/3G capable AGI-4 modems stay on the 2G network more or less all the time. Could also be the network strategy to keep low bit rate users on 2G.

The older AGI-4 modems were 2G only, not sure if you would see 3G mentioned at all in that case. Anyway if you can connect to your NTRIP caster, it makes no difference if the correction data comes over 2G or 3G as long as the latency remains low, about one second. Any decent 2G network should manage that easily.

It does take some time for the modem to connect (easily 60 seconds), even network registration is surprisingly slow with these modems but once you see the cellular network signal on the VarioGuide screen and the NTRIP client having registered to the NTRIP caster, it should only take a few seconds and you see the RTCM stream coming (latency changing to a low number) and then a few seconds to RTK fix.

Thanks allot, this clears allot of question marks i've had !!

The modem in my receiver has a build date of 2018 , so i guess its not that 'Old' .?

i've also learned that a M2M Sim card does a better job in staying on a solid 3G network, while a regular sim tries to stay on the cheapest . Not sure if this is true,
but i've heard that most tractor drivers here have a M2M sim card in their reciever.

Still have no clue why the signal is still on roaming.. not that it's bad , we don't get extra charged for roaming data here.

 

[Northern farmer]

Thanks allot, this clears allot of question marks i've had !!

The modem in my receiver has a build date of 2018 , so i guess its not that 'Old' .?

i've also learned that a M2M Sim card does a better job in staying on a solid 3G network, while a regular sim tries to stay on the cheapest . Not sure if this is true,
but i've heard that most tractor drivers here have a M2M sim card in their reciever.

Still have no clue why the signal is still on roaming.. not that it's bad , we don't get extra charged for roaming data here.

RAN (radio access network) selection is a very complicated task but the mobile terminal has very limited freedom there, it is 100% network controlled in practice. The only option basically for the mobile to influence RAN selection is to report partial RAN support. Say if you wanted to keep your mobile in a 3G network, the mobile may report only 3G being supported. The drawback would be that it loses service completely if it moved to an area that is only covered by 2G (obviously more complicated for mobiles that support more radio access technologies, like 2G/3G/4G/5G, including variants within each RAN mode.

The mobile station is not even aware of the service cost at 2G versus 3G but the network is. I doubt any service plan makes any cost difference between radio access technologies, the same cost per minute for calls and the same cost per databyte on all technologies. There may well be service plans with lower priority and lower quality of service level which may result to 2G selection over 3G. In this NTRIP case my guess is that the low requested data rate makes the network to command the mobile to move to 2G even if 3G was available.

For NTRIP 2G is no worse compared to 3G in service quality assuming both have good coverage. The main thing to try to avoid is changes between 2G and 3G because of the longer interruption in data transfer. Even this is not very critical except perhaps if the change happened very frequently for some reason.

I cannot remember if VarioGuide allows the tractor operator to select 2G only versus 2G/3G both supported but the Topcon X30 screen with the AGI-4 GNSS receiver does (but no option to select 3G only, not seen necessary).

The fact that you see your VarioGuide modem using a roaming network is likely caused by a 2G network being shared by two or more cellular operators. A more modern mobile device (with a modern SIM card) would recognise this scenario and not indicate a roaming state. The PLMN code on the 2G network is likely different from the home PLMN code on the SIM card and the AGI-4 modem does not recognise the additional SIM card fields indicating other PLMN codes to be considered as HPLMN.

The AGI-4 modem from 2018 is not old, I'm sure it does support 2G and 3G. Then again I've never seen any 4G capable AGI-4 modem product. Seems they have discontinued the product development and leave their customers to count on third party products that offer 4G (or 5G) connectivity via the external modem connector of the AGI-4 receiver.

 

[bartdereu]

Wow, you guys carry allot of knowledge on this ! Thanks allot for the explanation !!!

 

[Richard Smyth]

RAN (radio access network) selection is a very complicated task but the mobile terminal has very limited freedom there, it is 100% network controlled in practice. The only option basically for the mobile to influence RAN selection is to report partial RAN support. Say if you wanted to keep your mobile in a 3G network, the mobile may report only 3G being supported. The drawback would be that it loses service completely if it moved to an area that is only covered by 2G (obviously more complicated for mobiles that support more radio access technologies, like 2G/3G/4G/5G, including variants within each RAN mode.

The mobile station is not even aware of the service cost at 2G versus 3G but the network is. I doubt any service plan makes any cost difference between radio access technologies, the same cost per minute for calls and the same cost per databyte on all technologies. There may well be service plans with lower priority and lower quality of service level which may result to 2G selection over 3G. In this NTRIP case my guess is that the low requested data rate makes the network to command the mobile to move to 2G even if 3G was available.

For NTRIP 2G is no worse compared to 3G in service quality assuming both have good coverage. The main thing to try to avoid is changes between 2G and 3G because of the longer interruption in data transfer. Even this is not very critical except perhaps if the change happened very frequently for some reason.

I cannot remember if VarioGuide allows the tractor operator to select 2G only versus 2G/3G both supported but the Topcon X30 screen with the AGI-4 GNSS receiver does (but no option to select 3G only, not seen necessary).

The fact that you see your VarioGuide modem using a roaming network is likely caused by a 2G network being shared by two or more cellular operators. A more modern mobile device (with a modern SIM card) would recognise this scenario and not indicate a roaming state. The PLMN code on the 2G network is likely different from the home PLMN code on the SIM card and the AGI-4 modem does not recognise the additional SIM card fields indicating other PLMN codes to be considered as HPLMN.

The AGI-4 modem from 2018 is not old, I'm sure it does support 2G and 3G. Then again I've never seen any 4G capable AGI-4 modem product. Seems they have discontinued the product development and leave their customers to count on third party products that offer 4G (or 5G) connectivity via the external modem connector of the AGI-4 receiver.

topcon have a new receiver close to release so wouldn’t surprise if there is no development on agi4 anymore.

which external modems work with 4g on the agi4. Need to know as 3G is being switched off here in 2022

 

[Northern farmer]

topcon have a new receiver close to release so wouldn’t surprise if there is no development on agi4 anymore.

which external modems work with 4g on the agi4. Need to know as 3G is being switched off here in 2022

Very good if development is ongoing. Is that a new receiver model or SW improvements to the existing AGI-4 HW?

The external modem interface is a serial interface. Any modem with a serial interface works. A cheap option would be a simple bluetooth serial adapter on the AGI-4 port and an NTRIP client on a 4G/5G smart phone feeding RTCM data to the GNSS receiver. There is also an expensive third party device that just plugs into the AGI-4 connector.

 

[bartdereu]

Very good if development is ongoing. Is that a new receiver model or SW improvements to the existing AGI-4 HW?

The external modem interface is a serial interface. Any modem with a serial interface works. A cheap option would be a simple bluetooth serial adapter on the AGI-4 port and an NTRIP client on a 4G/5G smart phone feeding RTCM data to the GNSS receiver. There is also an expensive third party device that just plugs into the AGI-4 connector.

That's exactly what i thought. My knowledge in serial communication and microcontrollers is pretty good, and whenever we'll get into trouble because 2G or 3G gets obsolete i'll try to figure this one
out.

 

[Richard Smyth]

Very good if development is ongoing. Is that a new receiver model or SW improvements to the existing AGI-4 HW?

The external modem interface is a serial interface. Any modem with a serial interface works. A cheap option would be a simple bluetooth serial adapter on the AGI-4 port and an NTRIP client on a 4G/5G smart phone feeding RTCM data to the GNSS receiver. There is also an expensive third party device that just plugs into the AGI-4 connector.

new receiver model I was told a couple of weeks ago. The agi4 has been around a long time.

Ntrip via the phone won’t work for me as limited service in some areas and even with a phone booster I don’t get service. The modem in agi4 with external antennae does however

 

[Ian01]

We run 2g only on roaming SIM with agi-4's, find it more reliable than allowing it to switch between 2g and 3g, tiny amounts of data required so 2g is more than capable

 

[bartdereu]

Found out something that was pretty interesting. It seems that (for sure in Europe) the 2G signal will not go offline anytime soon, at least not before 2025, while the 3G network will
come to an end in a short amount of time. They do that because allot of systems still rely on it (about a million devices in the netherlands only) . Besides that i've read that USA, Australia
and allot of Azian countries have 2G already disabled.

 

[Richard Smyth]

We have not had 2g in Australia since 2017. I thought it was much longer ago than that but apparently not. Apparently 3G has been around since 2003. Quite surprised about that

 

[bartdereu]

This might be a solution :

Beacon v3.0 • DigiFarm VBN

digifarm.com

 

[jh.]

How will loss of 3g affect these RTK systems still coming out just now using 3g sims. Will they automatically take a 4g or 5g signal or will upgraded parts be needed on kit that might only be a few years old.

Edit, just read a few of you saying the 3g systems can switch to 2g .

 

[bartdereu]

Ya, i think the problems will be the biggest in regions that don't have 2G left

 

[bartdereu]

Hi all,

today i had some serious issues with the TOPCON AGI4 reciever, it did a very bad job in keeping a constant high accuracy;

On the vardio terminal i saw that it took long (about 4-5 seconds) to recieve new data after the NTRIP Login data was sent, and once
i got the new data , the signal lag started to gain to sometimes 100 seconds . Sometimes it even got stuck in the 'Plugged in' message.

What exactly is the signal lag? does that mean the signal from the NTRIP that doesn't come in ? do i have a bad data signal ? Or is
it the signal from the GPS sattelites itself? But i've been in trouble with 15+ sattelites and no fix.

The cellular signal is always 3 or 4 out of 5 strips, but i'm still on 2G with roaming . Could that have something to do with it?

And yes, there were some trees around the fields where the trouble started , but i've had allot worse fields with no issues at all.

In the way it's working now, this reciever is useless.

 

[Northern farmer]

The signal lag is delay on the NTRIP data (from the message timestamp to the arrival at the tractor).

I have an old modem on our Fendt and it only supports 2G. I know your modem handles 3G too. Unfortunately it is too difficult to take the SIM card from the VarioGuide receiver to try on a cell phone. Perhaps the SIM card provider has only 2G national roaming and their own 3G/4G network has no local coverage. The SIM card operator might be able to explain this. Anyway, I have never seen a spot with less than 5 bars on 2G on the varioguide signal strength indicator. I sometimes see lag figures higher than 0 to 2 seconds but that must be from 2G cell change, not frequent and takes a few seconds. I wonder if your 2G cell is too loaded from other traffic. You should try with a cell phone NTRIP app at the same location with a similar SIM to see if the correction stream comes fluently.

By the way, do you have the correct VarioGuide antenna, the one for a GSM modem, not the one intended for the Satel radio (at some 400 MHz range)?

Would be useful to try the external VarioGuide modem for NTRIP just to see if it behaves better from a 4G network.

Very infrequently I've seen NTRIP signal issues but recently I've seen positioning issues with the AGI-4. At times with very low number of satellites the receiver starts to pulse shortly to RTK float and back to RTK. Feels like external interference but don't really know what this is.

 

[bartdereu]

The signal lag is delay on the NTRIP data (from the message timestamp to the arrival at the tractor).

I have an old modem on our Fendt and it only supports 2G. I know your modem handles 3G too. Unfortunately it is too difficult to take the SIM card from the VarioGuide receiver to try on a cell phone. Perhaps the SIM card provider has only 2G national roaming and their own 3G/4G network has no local coverage. The SIM card operator might be able to explain this. Anyway, I have never seen a spot with less than 5 bars on 2G on the varioguide signal strength indicator. I sometimes see lag figures higher than 0 to 2 seconds but that must be from 2G cell change, not frequent and takes a few seconds. I wonder if your 2G cell is too loaded from other traffic. You should try with a cell phone NTRIP app at the same location with a similar SIM to see if the correction stream comes fluently.

By the way, do you have the correct VarioGuide antenna, the one for a GSM modem, not the one intended for the Satel radio (at some 400 MHz range)?

Would be useful to try the external VarioGuide modem for NTRIP just to see if it behaves better from a 4G network.

Very infrequently I've seen NTRIP signal issues but recently I've seen positioning issues with the AGI-4. At times with very low number of satellites the receiver starts to pulse shortly to RTK float and back to RTK. Feels like external interference but don't really know what this is.

Hi, thanks for your clear answer.

Indeed my modem should support 3G , but i can't select it , it just doesn't show up. What i'm going to try is to order a test machine-to-machine SIM card from another
provider and see if i have any luck with that. I tried a NTRIP app and the flow is clearly not the issue.

Good point is the antenna, i see on allot of other tractors that they have another type of antenna, the one i have is like the image below and it came with the radio module.

And i see more antenna's like this (not the correct connector i know , couldnt find a better image) :

maybe i'd have to try these things out and see what improvements i can get.

I'll get back when i've done that

thanks

 

[bartdereu]

Hi All,

been a while since i posted something here, but i wanted to give a status update.

I've changed the SIM card to another provider and i have to say the fixes are allot faster now. It does loose signal now and then but
it picks it up again allot faster then before. Latency is always 1s , so that's good. The Roaming notification is also gone, so that must have
been a network issue.

Funny thing is that the reciever sometimes goes to 3G. When he does that, it shows 3G on the GPS's RTK settings page, but on the varioguide
screen (where you see the field and lines) , it shows 4G on the left top corner. Since this radio doesn't do 4G, i guess that must be a bug?

 

[Mikesuper]

Hi there,

I live in France and I have a DEUTZ FAHR 7250 TTV tractor equipped with a TOPCON AGi 4 GPS in egnos.

I would like to switch it to RTK NTRIP.

Can someone tell me where I can find the used RTK modem?

Thank you in advance for your help.