mobile base station

Brisel · Aug 11, 2015

What do you advise on lightning conductors @Robt ? Later this year I may have a site on the highest hill for 20 miles for a wireless broadband repeater & my private 2 way radio station base unit (167 - 172 MHz 10w). I could be open to offers to host a base station...

Wombat · Aug 11, 2015

Pheasant Surprise said:
I'm in the process of building my own mobile and putting in place building blocks for a (future) fixed RTK base. Insofar as you can give advice on a public forum, I'd appreciate if you think there is anything wrong in my thinking or approach. I don't think there is anything bodgy or dodgy here, but always willing to listen and learn.

Licensing. Wouldn't ever contemplate (illegally) running a high-power fixed based without an Ofcom license. An Ofcom license is quite straightforward to do (did it online). In my experience Ofcom are approachable if your are clear with what frequency(ies) and channel(s) you require. It cost me £75 a year for a single 12.5kHz channel for a Business Radio Area Defined Licence in the UHF2 band. Anything above 1 W needs a licence. I found the trickiest part in all this was finding out and then matching and getting an overlapping frequency allocation with RTK receiver/rover and the base radio. Manufacturers don't necessarily give that information out readliy. Didn't really have a problem then getting that desired base frequency in that range allocated and licensed with Ofcom though.

Radio and UHF antenna. On my area defined licence there is an ERP power restriction of 50 W, with no antenna height restriction. I propose to use an approved and well known radio like Satel or Pac Crest. The SATELLINE EASyPro 35W is looking to be the one I'll use. Then a base frequency matched 3 dBd collinear omni-directional antenna (see example attached from Radio Structures with 3 year warranty). Programming the radio at a slightly lower 25 W output with the 3dBd omni antenna I should be within the overall output power of Ofcom licensing regs at 49.88 W. Could probably up that slightly to take into account cable/connector loss. Planning to use a decent grade of coaxial cable like RG213 from radio to antenna to minimise signal loss/attenuation.

GNSS receiver. Is there technically any reason why its not possible to use something like a Topcon HiPer V as both a mobile and fixed base receiver? All the ports are there, external antenna, power supply etc. Plenty of channels, supports dual constellations and dual frequencies, has adequate H & V accuracy. Use an permanent external power supply for fixed base use and internal battery as mobile base. Hook up a decent fence-type GNSS antenna. What's not to like.

Power Supply. A permanent 240V to 12V switching power supply can be added to the base. Needs to be about 150-200 watts output I reckon but I'll be double checking the specs of radio and receiver. UPS/battery backup not really that difficult, could use something like an APC/Schneider unit from Amazon and tuck it away in a waterproof but vented enclosure. Most of our supply cuts last up to an hour or so and we have diesel backup anyway. Serial interface cables with ODU connectors can be bought or made up easily enough if you know where to look.

Enclosure. IP6X weatherproof cabinets (am using a schneider electric one) from RS components or electrical wholesaler.

GNSS Antenna. Last but not least fixed GNSS antenna, mounted in a reasonably high, stable, but non-shaded position, that is immovable as possible. Fence type dual constellation and frequency antenna for best reception and reasonable price/performance. Connect using RG58 cabling, try and keep distance to receiver as short as possible.

Masts. Ive not really covered masts, but if you use a lattice mast or a modular tilting column, the likes from Altron or Radio Structures at 15m+ that to me that is a decently well engineered solution.

Have been chatting to lots of people over the last 6-12 months. There are lots of helpful guides and tools out there which help, e.g.
Pacific Crest, Guide to Wireless Data Links: http://www.pacificcrest.com/library/BRO_Guide_Wireless_Data_Links.pdf
PCC range estimator tool: http://pacificcrest.com/resources.php?page=range_estimator
ERP/EIRP converter: http://www.satcomresources.com/ERP-EIRP-Converter

(By the way thanks for the offer of an RTK signal, but the one of the reasons I'm building my own base is to have control of my own signal and not have any annual subscription charges)

What ever base you use if you are making it fixed get it surveyed to a true Lat/long point. Then if you move it the lines your previously created will be referenced to a true lat/long not an averaged base position.

Robt · Aug 11, 2015

Brisel, email me [email protected]

croppers · Aug 11, 2015

@Pheasant Surprise very interesting thanks for sharing

croppers · Aug 11, 2015

@Robt what's your view on repeaters?

Robt · Aug 11, 2015

@pheasnt surprise.
You are clearly clued up. If I can be any help. Let me know.

Quick question, why do to need both mobile and fixed base? Do you cover a large area

Brisel · Aug 11, 2015

Robt said:
Brisel, email me [email protected]

Will do. I'd had better get the planning permission for the mast first! There are 3 Trimble base stations locally - a private one, a Class one & a local Fendt/Amazone dealer has one. Time for a Topcon or JD one?

Steevo · Aug 11, 2015

Brisel said:
Will do. I'd had better get the planning permission for the mast first! There are 3 Trimble base stations locally - a private one, a Class one & a local Fendt/Amazone dealer has one. Time for a Topcon or JD one?

If we're turning this into a "Suitable mast location thread" then I might have somewhere for one too if any manufacturers are interested.

Pheasant Surprise · Aug 12, 2015

Brisel said:
What do you advise on lightning conductors @Robt ? Later this year I may have a site on the highest hill for 20 miles for a wireless broadband repeater & my private 2 way radio station base unit (167 - 172 MHz 10w). I could be open to offers to host a base station...

Be good to know too. If I can get mast here under PD or with PP (or whatever planning the council deems fit) I would look at:

a) earthing the mast itself using decent thick flexible copper strapping going to an earth rod, driven in away from the mast foundation

b) fitting an RF Inline Cable Surge Protector on the coax cable from the UHF antenna (the highest point on the mast) and then cabling from the earth lug on the protector to the earth rod. Would have thought some 6mm sparks cable would be OK?

Any other thoughts/suggestions @Robt

Pheasant Surprise · Aug 12, 2015

Robt said:
@pheasnt surprise.
You are clearly clued up. If I can be any help. Let me know.

Quick question, why do to need both mobile and fixed base? Do you cover a large area

Couple of reasons really.

1. Cost. Mobile base is by far the cheapest and most reliable way into RTK (excluding renting an NTRIP signal, which just won't work here as we have so many mobile reception black spots). Besides which don't fancy paying an annual sub any more. The return on having your own RTK signal is twice as good the more machines you run, as your investment period reduces whilst on the other hand a rented signal goes up for each machine/receiver. Its a no brainer. So for now I'll setup on the highest hill here to get line of sight as best possible.

2. Flexibility. Want something modular that can be either (a) kept as permanent fixed base (radio, mast, power supply etc) and not have to worry about setting up/tearing down OR (b) just unplug and move easily (the self contained mobile base) should I ever want to.

3. Speed. Would like get up and running, although have Omnistar HP correction sub which expires in December, don't want to get held up in a planning mire over mast with local council with PD and PP stuff. As you know not the easiest of things to get sorted. Also with best will in the world its going to take me a while to get mast up and everything in properly.

SilliamWhale · Aug 12, 2015

I got kitted up with rangepoint rtx from trimble for about £5k and like Steevo I don't think I see a need for RTK now unless wanting to drill between rows

Steevo · Aug 12, 2015

SilliamWhale said:
I got kitted up with rangepoint rtx from trimble for about £5k and like Steevo I don't think I see a need for RTK now unless wanting to drill between rows

Glad to hear it! Did you go EZ-Ster or EZ-Pilot in the end?

I know you won't regret making the move.

Northern farmer · Aug 12, 2015

SilliamWhale said:
I got kitted up with rangepoint rtx from trimble for about £5k and like Steevo I don't think I see a need for RTK now unless wanting to drill between rows

Where did you upgrade from? If you upgrade from EGNOS to Rangepoint RTX, I'm sure you would not want to go back. If you upgrade from rangepoint rtx to RTK, you would unlikely want to go back. An investment and/or a yearly fee may be an issue for each step, impossible to say when it is worth the additional cost.

RTK is not only for drilling between rows. Do you have 2D offset calibration on your screen today? Even if you had, you may find it boring to fix drift every now and then.

Nothing wrong if one finds EGNOS or rangepoint sufficient. But one should not assume it being sufficient for all others. I've never heard of a driver who wants to go back to something less accurate after running on RTK for a while?

SilliamWhale · Aug 12, 2015

[QU

Northern farmer said:
Where did you upgrade from? If you upgrade from EGNOS to Rangepoint RTX, I'm sure you would not want to go back. If you upgrade from rangepoint rtx to RTK, you would unlikely want to go back. An investment and/or a yearly fee may be an issue for each step, impossible to say when it is worth the additional cost.

RTK is not only for drilling between rows. Do you have 2D offset calibration on your screen today? Even if you had, you may find it boring to fix drift every now and then.

Nothing wrong if one finds EGNOS or rangepoint sufficient. But one should not assume it being sufficient for all others. I've never heard of a driver who wants to go back to something less accurate after running on RTK for a while?

I don't think I did assume it would be sufficient for all others. I just said its very good other option and it accurate.

T C · Aug 12, 2015

Northern farmer said:
Where did you upgrade from? If you upgrade from EGNOS to Rangepoint RTX, I'm sure you would not want to go back. If you upgrade from rangepoint rtx to RTK, you would unlikely want to go back. An investment and/or a yearly fee may be an issue for each step, impossible to say when it is worth the additional cost.

RTK is not only for drilling between rows. Do you have 2D offset calibration on your screen today? Even if you had, you may find it boring to fix drift every now and then.

Nothing wrong if one finds EGNOS or rangepoint sufficient. But one should not assume it being sufficient for all others. I've never heard of a driver who wants to go back to something less accurate after running on RTK for a while?

I have gone back from RTK to Rangepoint.
My RTK was accurate at placing the tractor but was let down on the steering side - had it on both electric steering and hydraulic valve.
Rangepoint on trimble autopilot steers the tractor much better and pass to pass would be hard to tell.

Steevo · Aug 12, 2015

Another benefit to Rangepoint is that it is available anywhere. RTK (depending on the system) is usually only available near your local mast. Not ideal for those with land spread around or contractors etc.

Northern farmer · Aug 13, 2015

SilliamWhale said:
[QU
I don't think I did assume it would be sufficient for all others. I just said its very good other option and it accurate.

Sorry, I did not mean to say you said so. My intention was more to state that "very good and accurate" means very different things to different farmers.

T C said:
I have gone back from RTK to Rangepoint.
My RTK was accurate at placing the tractor but was let down on the steering side - had it on both electric steering and hydraulic valve.
Rangepoint on trimble autopilot steers the tractor much better and pass to pass would be hard to tell.

Very interesting, I'll leave this for the real experts but you must have had different HW or something incorrectly set. A more accurate signal cannot make the same HW behave worse.

Steevo said:
Another benefit to Rangepoint is that it is available anywhere. RTK (depending on the system) is usually only available near your local mast. Not ideal for those with land spread around or contractors etc.

Yes and no, a geostationary satellite may not be easy to pick everywhere (specifically very far to the north). RTK base does not necessarily need any mast, my base covers my country and most of others (although of course the signal is not useful too far away). A pity many of you do not have sufficient cellular coverage like I have.

Contractors at my place use network based NTRIP but I accept your point for a contractor in a country with poor cellular coverage. Not that one would not want the RTK accuracy but it isn't good if the correction signal availability is poor.

T C · Aug 13, 2015

Northern farmer said:
Sorry, I did not mean to say you said so. My intention was more to state that "very good and accurate" means very different things to different farmers.

Very interesting, I'll leave this for the real experts but you must have had different HW or something incorrectly set. A more accurate signal cannot make the same HW behave worse.

Yes and no, a geostationary satellite may not be easy to pick everywhere (specifically very far to the north). RTK base does not necessarily need any mast, my base covers my country and most of others (although of course the signal is not useful too far away). A pity many of you do not have sufficient cellular coverage like I have.

Contractors at my place use network based NTRIP but I accept your point for a contractor in a country with poor cellular coverage. Not that one would not want the RTK accuracy but it isn't good if the correction signal availability is poor.

Sorry may be a vague post but I changed brands between RTK and RTX. My point is the best signal with a substandard steering solution can be similar to a poorer signal with better steering.
My advice is to check the whole package not just the hype.

Robert Ramsay · Aug 13, 2015

Steevo said:
Another benefit to Rangepoint is that it is available anywhere. RTK (depending on the system) is usually only available near your local mast. Not ideal for those with land spread around or contractors etc.

That is the beauty of EssentialsNet. The coverage is over all the arable area (pretty much) on one licence and with full RTK accuracy.

Brisel · Aug 13, 2015

Robert Ramsay said:
That is the beauty of EssentialsNet. The coverage is over all the arable area (pretty much) on one licence and with full RTK accuracy.

Where does the correction signal originate from? Satellite?

Edit: Sorry. I was thinking of the RTX Rangepoint correction signal.

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