Looking for a simple explanation of how the internal radios in receivers work and maybe some tips on how to tweak the settings so the receivers operate as smoothly as possible.
The situation today:
I was working on a highway project in a quickly developing area.?ÿ On the way to set up my base I passed a couple other receivers that were being used by some dirt contractors grading out new subdivisions along this highway.?ÿ Normally I can reach well past the limits on my project even without an external antenna from this point but today I was having all kinds of hell maintaining a radio link as close as 500 feet from the base.
At one point I drove back to the base and changed my radio frequency because I thought these other contractors must be trampling on the one I was using.?ÿ That seemed to work for a while but then as I was nearing the end of the day it went to hell again.
So my thoughts and/or questions are:
1.) My understanding is that these radio frequencies are completely unique and if I'm the only one using 464.500 (for example) then I should have zero problems maintaining a solid radio connection, even if other receivers are operating nearby.?ÿ Is this correct??ÿ To put it another way, if I'm using 464.500 and another receiver 1000 feet away is using 464.250 and another receiver a half a mile away is using 464.725, can there be "noise" that spills over and affects my radio?
2.) I thought the radio or channel ID did something to help with this??ÿ If I have my receivers set to channel ID 7 and someone nearby is using the same frequency as me, doesn't the ID keep our instruments talking to the proper counterparts?
3.) I'm using Trimble gear and late in the day I ran into a problem where my rover battery died, I popped in a fresh one but when I tried to start the rover again the data collector hung at the "building base list" screen.?ÿ I don't run into this problem often but it mostly seems to happen when there are other receivers in the area.?ÿ Does anyone know what can cause a problem like this??ÿ Is it a radio problem or am I barking up the wrong tree?
Sounds to me like typical 'crap on the frequency' issues. Something is jamming you - and it might not just be another gps.
1. with modern radios channel spill should not be a problem.
2. base station id should - in theory - allow multiple stations on the same frequency - but in practice it doesn't work - each station has so much data to send there is no time left for the other.
3. that is typical behaviour when the gps can't work out what is happening on the frequency - its getting garbage.
My best hint is to carry a small scanner to check there is nothing transmitting on your frequency before you start your base.
You are being walked on and probably not by GPS radios. Your radios are subservient to other users and should shut down to allow those users to communicate. Older Trimble radios had a speaker and you could hear conversations. The ones I listened to usually were "I can hear you, can you hear me", over and over. Cell phones have reduced the interference, it used to be much worse. Your radio is the lowest form of communication in terms of importance. You should have a scanner, they can help, but anyone can jump in at anytime so their help is limited.
My best hint is to carry a small scanner to check there is nothing transmitting on your frequency before you start your base.
This is my recommendation too. Before setting up the base, run through the frequencies you have been allocated on your FCC license and pick the cleanest one. Frequency bleedover is still a thing, and if someone in your area is operating on adjacent frequencies with a high output, it can impact your setup. I don't think the internal radios (and even the external radios) have much filtering rejection built into them. Like @mightymoe said, our radios are at the bottom of the priority ladder.
Even when I am running on the internal radios, I like to use a high-gain whip antenna if I have one available, and boost that sucker up as high as I can. It's not as good as an external radio/repeater but it helps quite a bit. I would just use the whip that came with my TDL.
2. base station id should - in theory - allow multiple stations on the same frequency - but in practice it doesn't work - each station has so much data to send there is no time left for the other.
One can indeed run multiple bases on the same frequency, but they must have differing transmit delays. A couple of our offices run dual bases by default, and I used to run them a lot in the past. You have to set the broadcast up correctly - different IDs and different transmit delays.
If someone else is already operating on that frequency, they probably don't have a delay set up. Pick another frequency for both your sake and theirs.
Some areas are just bad for UHF radios in the 450 freq range. Operating in the shale fields in TX, we ran into a few areas with ham radio operators who had some seriously powerful gear - as in, antennas large enough to require special permits. Once they fired up their gear, it was game over for RTK within a certain radius.
Our office is right near a naval base here, and we work for the port right outside the base property. It's not uncommon for both RTK radios and comm radios to get completely jammed when we're working that close in. (Sometimes have to use cell phones instead of comm radios.) Can't tell if it's intentional jamming - one of the former Navy guys says its entirely possible. But again, they get priority over us, so we just have to deal with it.
Radios are the Achille's heel of RTK in populated areas.?ÿ Years ago I switched for UHF to spread spectrum for RTK.?ÿ That option was eliminated with my newer gear (without cobbling something together) and I have had to go back to UHF in remote areas.?ÿ Most populated areas where the UHF frequencies are packed tend to have cellular coverage.?ÿ In these areas I use the cellular network to broadcast corrections via IP.?ÿ I save the UHF for less populated areas.?ÿ Unfortunately the loss of 3G is going to have me scrambling to find a way to connect my base to the internet without adding a data collector.
That being said, I'm working on a relatively remote dam site and yesterday my UHF went fuzzy.?ÿ I think it might actually be electrical interference with transmission lines.?ÿ Luckily, the last area I have to work in has enough mobile coverage that I will start broadcasting over IP today.
It's funny about remote areas. I've been working where I have to drive 10 miles to get cell coverage. There are almost no houses, no towns, yet I keep getting walked on. I think it's people with radios in the area since there isn't cell coverage. There were county crews working on a county road, delivery trucks, I know there's a little oil activity. Anyway, whoever it is walks on me for a short time then I'm back up. I really doubt it's a GPS user. I have more issues there than in the city.?ÿ
The local Trimble dealer mentioned the IP thing to me several months ago.?ÿ It sounds like a nice way to go but from what I understand about it you need to keep a wifi brick at each receiver to make it work.?ÿ This sounds like more hassle than I'd be willing to put up with right now, but if they were to integrate a wifi card into the receiver in the future then it's something I'd be up for testing.
@bstrand?ÿ
Current Trimble receivers already have SIM card slots. Drop cards in the base and rover, and run your corrections through NTRIP.
Configuring the base and server can be a little tricky, but it can definitely be done without an external device.
This thread made me realize that maybe Camp Atterbury (9 miles from my home office, but maybe roughly only a couple~few miles from the two jobs I was struggling with earlier this year) might have something to do with the base-rover-radio trouble I was having. ?ÿI don??t recall spending much time or effort with the radio scanner and trying different frequencies. ?ÿI think I was too easily frustrated and spoiled with my typical quick connection to the Indianan RTN. ?ÿ
Besides, whenever they upgrade the Indiana CORS to handle more constellations, I believe my canopy efforts will improve. ?ÿWhenever that happens??
?ÿI think it might actually be electrical interference with transmission lines.
Down here its not just power lines that can fritz you in rural areas - electric fences, particularly those that pulse, that are a major source of interference.
I once had a rural job in a small valley where I could not get RTK to work on any of our frequencies. What should have been an easy job with GPS turned into a mission to complete with total station.
@bstrand?ÿ
It's also part of their bigger plan...
The Alloy base solution.
We bought one.
It's the future.
Not sure if it's a good future.
Yet.
Apparently you can edit the receive frequencies on the Trimble radios.?ÿ Have to bring it to the dealer to edit the transmit frequencies.
?ÿ
It is ludicrous that you need to take a trimble receiver in to the dealer to add frequencies.?ÿ
@rover83?ÿ
Connections and cables still some of the weakest links in a base/rover setup
