RTK base station Antenna advice needed.

[kayn1n32008]

OK, that's good info.

If you haven't waterproofed all the connections, make sure you do it. You need more than just electrical tape.



I usually go for better antennas, but "better" doesn't necessarily mean more gain. Gain is only part of the equation, you need to consider the radiation pattern, down tilt, etc.

Height usually increases range, but longer coax will reduce it. If you are going to go for a 100 foot high installation, and the radio will be at ground level, you need something better than LMR-400. 1/2" Heliax would be the minimum.

But as we keep suggesting, I don't think more gain/more RF power is the answer here.

If the topology is fairly flat, you shouldn't need 100 foot high antenna to get the range you are expecting.

At 100 feet, you will have clear line of sight out to the horizon at 19.7 miles. If the antenna on the tractor is at 10 feet, you can add another 6 miles. So, you should see about 26 miles of range if everything is working well.

At 45 feet, line of sight to the horizon with a 10 foot high antenna on top of the tractor should give you almost 20 miles of range.

Again, all dependent on the topology.
So, no wet coax, good antenna, a bunch of LMR-400, it's still suggesting that you've got at least two issues:
1. Co-channel interference. Try one of the other frequencies you have and see if range improves.
2. Still chance of a faulty component. Again, a tech with proper test equipment could help you confirm your equipment is good.

Don't rule out an issue with the tractor end of all this. Could be a bad antenna, bad antenna mount, bad coax, bad coax connector or an issue with the receiver. Issue with the receiver could be that it's gone deaf, or it's getting interference from the tractor, other radios, noise via the power feed.

I really think that a good tech with about an hour of time could locate the issue quickly and save you a lot of time and money swapping out equipment.

Yep. You really need to get the data link receiver sensitivity checked. LMR400 isn't really adequate for this either, neither are PL259 connectors. You should be using N connectors through out, except on the survey receivers. Use the mating connectors and not adaptors. If needed use high quality jumpers, with out barrel connectors where possible.

 

[KevinC]

Yes the arrestor has SO-239 ends. This was the arrestor recommended to me from the store that sold me the antenna. I made it work by putting PL-259 connectors on the LMR400 cable.

Not doubting your abilities, but are you sure the PL-259's are installed properly?

As others have said, you need a professional to look over everything.

 

[Shulerfarm]

Not doubting your abilities, but are you sure the PL-259's are installed properly?

As others have said, you need a professional to look over everything.

I am going to answer a few people's questions on this thread.
Yes, I can see distance and signal strength on my monitor in the tractor. At 7 miles it goes from 0% to 10% every few seconds. Not great by any means but works.
The PL-259 I put on myself. I had a 50' LMR400 cable with factory type N ends. I cut this cable at 41' and attached PL-259 to install the polyphaser. Stripped back the layers to the appropriate length, folded the outer layer and crimper the barrel on, soldered the center wire to the tip, heat shrink b/w connector and cable. Looks store bought.
Yesterday tried a handheld radio programmed to my frequency. Could hear the pulses coming in as static on the handheld. Cut my base station off and no other traffic was on that frequency. I probably chased them off with a continuous signal broadcasting 24/7. The handheld could hear the base up to 4 miles if you pointed the antenna a certain way. (No am on base)
When I get some time I will try some different things including creating an interference with the hand held and see how it effects the signal on the tractor.
I am not happy about being on this general use itinerant frequency. Construction crew could be using this frequency right down the road from me. Think about disruption I might be causing them.
Photos of operators manual on radio test. Notes the reflective power under 5 is great. Mine is 02 without a amplifier. Last photo is example of what you can see in the tractor.

 

[clbsquared]

Does your base station ever lose power? The only reason I ask is because you have it set to “Absolute”. If you never lose power that’s great. I found that when my base lost power (weather related and other “out of my control” related issues) it took anywhere from 24-48 hours to do the survey. Obviously that led to reception and accuracy issues. I have mine set to “quick survey”. It doesn’t affect the accuracy at all and after a loss of power, it’s back up within minutes of power being restored.

 

[Shulerfarm]

Does your base station ever lose power? The only reason I ask is because you have it set to “Absolute”. If you never lose power that’s great. I found that when my base lost power (weather related and other “out of my control” related issues) it took anywhere from 24-48 hours to do the survey. Obviously that led to reception and accuracy issues. I have mine set to “quick survey”. It doesn’t affect the accuracy at all and after a loss of power, it’s back up within minutes of power being restored.

I have all the straight. What I did was put my receiver from the tractor on the post that supports my base station receiver. Powered it up and turned it onto the dealer network frequency that I have been using for the past 13 years. It locks into a location. Record the lat, long, and alt. Swap receivers and type in these values under absolute base. By doing this none of my boundaries or AB lines move. Easy and perfect. No need to do the 24 hour survey. If you do a 24 hours survey it is important to record these values for future use if you have to replace equipment. The first week of planting this year I set up a mobile base in the back of a pickup and used Quick Survey mode. Worked OK but some of my boundaries were off. (This was expected) I use headland offsets for planting swath control, so boundary accuracy is very important.
I would strongly recommend you do the absolute base for 24 hours. It should remember these values after power outage. I know it will if you type the values in. This will be consistent and accurate forever. The quick survey is something new each time it powers up. It just averages out the gps data over a few minutes and sets the value. Can be slightly (+/- 12") off each power up. Altitude or vertical can be much worse. Fine for a days worth of work but not great for consistent longterm operation.

 

[clbsquared]

I have all the straight. What I did was put my receiver from the tractor on the post that supports my base station receiver. Powered it up and turned it onto the dealer network frequency that I have been using for the past 13 years. It locks into a location. Record the lat, long, and alt. Swap receivers and type in these values under absolute base. By doing this none of my boundaries or AB lines move. Easy and perfect. No need to do the 24 hour survey. If you do a 24 hours survey it is important to record these values for future use if you have to replace equipment. The first week of planting this year I set up a mobile base in the back of a pickup and used Quick Survey mode. Worked OK but some of my boundaries were off. (This was expected) I use headland offsets for planting swath control, so boundary accuracy is very important.
I would strongly recommend you do the absolute base for 24 hours. It should remember these values after power outage. I know it will if you type the values in. This will be consistent and accurate forever. The quick survey is something new each time it powers up. It just averages out the gps data over a few minutes and sets the value. Can be slightly (+/- 12") off each power up. Altitude or vertical can be much worse. Fine for a days worth of work but not great for consistent longterm operation.

It was originally set to Absolute. Frequent power outages in my county proved to be a problem with it. It’s been on Quick Survey for the last six years. My boundaries and A/B lines have never moved. I strip til about 1200 acres of cotton land a year, so I know how important it is for that line to not move. The planters run directly in the middle of the bed every time.

 

[Shulerfarm]

I am glad that is consistent for you. I wondered if after power outage if absolute base mode would perform a 24 hours survey each time. Probably doesn't. I know it does not if you type in the lat, long, alt. Everytime you power it up it will be perfect, ready to go in two minutes. No survey. As I mentioned before I "meshed" mine to the dealer tower. The dealer "meshed" their towers together (if they were reasonably close to each other) a farmer could switch towers at anytime with the exact same results in guidance/location.
Viewing a thread - Absolute base / Quick survey RTK

 

[speedway_navigator]

I hear data on 464.500 and .550 when surveyors are in the neighborhood. It looks like they use that link from their portable device back to the tripod mounted GPS unit to measure offsets. I asked a few guys about a license, got the deer in the headlight look.

 

[kayn1n32008]

I hear data on 464.500 and .550 when surveyors are in the neighborhood. It looks like they use that link from their portable device back to the tripod mounted GPS unit to measure offsets. I asked a few guys about a license, got the deer in the headlight look.

The 'tripod mounted GPS' is a reference station. The portable one is the rover. The data link is from the reference station to the rover, it is correction data and is one way only.

The reference station is 'told'(either a 'here' command, or previously determined and corrected coordinates) where it is, these are 'known coordinates'.

The reference receiver calculates its position using the GNSS(Most receivers use GPS, GLONASS, Galileo and Beido satellite constellations)receiver. There is almost no single constellation RTK systems in use any more.

The calculated coordinates are compared to the known coordinates, and generates a correction that is sent over the datalink to the rover. The rover then applies that correction to the positions it calculates to get sub-centimetre accurate measurements.

These are stored as vectors from the reference station to the rover. Once the survey is complete, the data collected by the rover and the static data(usually its collected, and it must be for 'here' command coordinates) is post processed.

Even survey GNSS receivers are only accurate to a horizontal and vertical accuracy of 2-5m. Post processing will bring that accuracy to 1cm or better.

With all legal surveying, anything you survey, needs to be related to something existing to 'tie' it to the 'real world'. There is a hierarchy of evidence that you need to follow to properly relate your survey to the real world.

For some things like quantity(volume of material moved/stocked/placed) measurements, it doesn't really need to be tied to real world.

 

[kayn1n32008]

I asked a few guys about a license, got the deer in the headlight look.

That's not surprising. Most surveyors are using company equipment, or rental gear. Quality, survey RTK equipment is incredibly expensive. Like $50k+ for a reference, rover and data collector. Not including software for the data collector or tripods, rod, high power datalink radio, antenna or power source.

 

[speedway_navigator]

I asked a surveyor if he was aware which GPS systems he was accessing since as you noted there are more than just our system to use, he was not aware. He said he had a job pending but could not find a local reference point. We had seen new markers in the woods just off a fairway of a golf course near us and told him, he thought those could be what he was looking for.

I called our county surveyor's office when I saw the new markers to see why they were there. The guy who answered was the one who put them in, he was concerned and asked if the golfers were complaining. I said no, the golfers need any excuse they can find to blame their bad scores on so don't worry about it.

 

[speedway_navigator]

saw this right after my previous post

Venezuela embraces Russian GLONASS in challenge to US satellite dominance

Russia is accelerating the expansion of ground correction stations for its GLONASS satellite navigation system across Latin America, with Venezuela ...

www.intellinews.com