RTK Bridge

[squowse]

hillsidesurveyor, post: 353187, member: 7292 wrote: Because of our hilly terrain and lack of cellular reception we have normally always set up a base station over a local NGS point and run RTK via base and radio. We have tried using a network rover via cell phone attached to the pole, but even on top of some of the hills we could not get sufficient amounts of data to get it to work. To maybe bypass the base station setup we were looking at possibly purchasing an RTK Bridge. Has anyone had good experiences with these? Can you set the bridge up on top of a hill so that it can broadcast to the rover down into a valley where no cell coverage exists?

Also if you survey via RTN and have a rover that is capable of tracking Galileo etc, but the RTN stations only track GPS and GLonass, wouldn’t you only be able to then use GPS and Glonass?

With the new receivers and collectors do you even need a cell phone on the rod?

Is there a better solution than an RTK bridge for relaying RTN signals to areas with no coverage?

I am not the most tech savy individual out there so bear with me if these questions seem somewhat elementary.

RTK repeater will do what you want but they are not much cheaper than a base receiver. So you could use your RTN (and/or static logging) to set up a base point and then set up your base there. If you can’t get RTN at that point then a repeater won’t help you.
Ability to receive a cell signal will vary device to device. I have found that the TSC3 is not the best and can be outperformed by a basic 2G phone in difficult areas.

[lee-d]

I don’t use the modem in the TSC3, we use 4G MiFi for RTN.

[Bryan Newsome]

Our RTN Coop mentioned, and I appeared to experience, that AT&T and Verizon are shutting down there 2G capabilities, at least in the Central Texas area. I had a 2G module built into my Trimble R8 model 1 and I didn’t have to carry a phone around. Right at Christmas time I became unable to log onto a wireless network with it. My personal phone can be used as a wifi hotspot so I reconfigured my TSC2 DC to hook up through my phone. My initialization became much faster, I had a stronger signal, but my DC battery drained much faster since I was now using the DC wifi to connect to my phone. This is my personal unit, which I sometimes use. Our Co. has an AT&T myfi unit which we use for the Co. R8 model 2. When we have terrain and no cell phone capabilities down in the ravines, we sometimes use our RTN to shoot a local control control point several times, average the results (and checking the residuals/deltas) and then use that point as a base point and switch to radio/rovers.

[hillsidesurveyor]

Lee D, post: 353190, member: 7971 wrote: I don’t use the modem in the TSC3, we use 4G MiFi for RTN.

Well you lost me there. What is mifi if I may ask?

[lee-d]

I’m not sure the exact model, but they’re called MiFi Liberate and they’re from AT&T

[lee-d]

If you mean “what is it” as opposed to “what model”… it’s a cellular WiFi hot spot.

[norm-larson]

MiFi is a brand name that has come to mean cellular to WiFi internet hotspot. They work very well and I have two models I am testing with external antennas, one Sprint and one Verizon. They are both Netgear units sold under the carriers name and are very similar. Testing is still on going but I haven’t stumped it yet. I need to add that we are NOT in a rural area though. I am using auxiliary antennas of 2.5dbi, 9dbi and 18dbi gain. My MiFi thread

I guess Lee D beat me to the answer …

[shelby-h-griggs-pls]

I bought a Bridge-X last summer, totally ditched UHF radios for RTK. I have reached out in the 5-6 mile range with the built in 900 Mhz radio using as a base-rover setup (open country) and the Bridge-X will pull in a cell signal where a handset shows no bars. The Bridge-x is designed as you imagined, set up on a hill at edge of cell coverage and extend that via radio.

Overall pretty happy with this setup. If you get a static IP for the Bridge-X you can also use it as a means to host your own base over an IP address, meaning you could run your own base and as long as BOTH base and rover are within cell coverage you can continue RTK operations. Additional benefits is the better modem/external antenna of the Bridge-X allows a hotspot for e-mail, etc. in the field where you may be dead with just a cell phone.

Bridge-X isn’t a magic bullet of course since there are still areas where I can’t get a cell signal, BUT I believe is a great option to have just due to the flexibility of modes and operations you can do with it.

The Bridge-X product from Intuicom DOES NOT currently support anything above 3G modes on either CDMA or GSM models, therefore if carriers do shut off the 1G/2G ability it may limit the usage, I suspect there will eventually be a new model, BUT likely to not be upgradable without a hardware change? In reality, 2G and maybe even 1G is all you need to support RT GNSS corrections, so I see their point, at least up until the carriers don’t support the older modes.

SHG

[hillsidesurveyor]

Thanks for the replies

I guess the only reason I was looking into this was to save the cost of buying a base station and just purchasing another rover, but it sounds like some of you still have to break out a base station from time to time when no signal can be acquired. Can a bridge or other device project a signal from the top of a hill to a valley a mile away with a 600′ elevation drop?

Our current setup is a base with internal radio, repeater radio (if needed) and rover. This works great and has never caused us problems, but it would be a great time saver not to have to set up a base station all the time.

[Phillip Lancaster]

Why not run cell and uhf at the same time?

[squowse]

hillsidesurveyor, post: 353298, member: 7292 wrote: Thanks for the replies

I guess the only reason I was looking into this was to save the cost of buying a base station and just purchasing another rover, but it sounds like some of you still have to break out a base station from time to time when no signal can be acquired. Can a bridge or other device project a signal from the top of a hill to a valley a mile away with a 600′ elevation drop?

Our current setup is a base with internal radio, repeater radio (if needed) and rover. This works great and has never caused us problems, but it would be a great time saver not to have to set up a base station all the time.

The ability of the radio to broadcast into the “hole” will be the same whether it is a RTN repeater or base station. (All other things being equal).
The reason I suggested to keep on using a base is that it can be used for other things.

Also with a base, depending on circumstances, you may be able to set it up in the “hole” and save yourself a hike. The RTN repeater will always have to go on the hill and if it loses cell signal you are stopped. Murphy’s law requires that this will be after you have hiked to the most inaccessible part of your survey, the light is fading and it is the last day.

They are handy but for the money we decided against using one.

[Spally]

hillsidesurveyor, post: 353187, member: 7292 wrote: Because of our hilly terrain and lack of cellular reception we have normally always set up a base station over a local NGS point and run RTK via base and radio. We have tried using a network rover via cell phone attached to the pole, but even on top of some of the hills we could not get sufficient amounts of data to get it to work. To maybe bypass the base station setup we were looking at possibly purchasing an RTK Bridge. Has anyone had good experiences with these? Can you set the bridge up on top of a hill so that it can broadcast to the rover down into a valley where no cell coverage exists?

Also if you survey via RTN and have a rover that is capable of tracking Galileo etc, but the RTN stations only track GPS and GLonass, wouldn’t you only be able to then use GPS and Glonass?

With the new receivers and collectors do you even need a cell phone on the rod?

Is there a better solution than an RTK bridge for relaying RTN signals to areas with no coverage?

I am not the most tech savy individual out there so bear with me if these questions seem somewhat elementary.

Hillsidesurveyor, we have numerous customers here in Australia using RTK Bridges for exactly the use case you describe. For best results, set the bridge up high where there is good phone coverage and use it to repeate the RTK data vai its internal radio. If you are surveying in a “hole” try using a directional antenna and focus the transmitted signal to where you are working. We have surveyors here that have one perminantly installed in their truck with a high gain 3G aerial fitted and always use it to “repeat” from their truck. The RTK bridge can also act as a server as well. So if you are outside of an area covered by a Network CORS provider, but you still have phone coverage, you can connect the bridge to the Base and act as a server. You can set your rover to connect to the RTK bridge over the Internet, just as you would with NTRIP, and pass the data that way.

As for your question on GPS/GLO/BDO, basically, when it come to RTK, a rover can only resolve the satellite ambiguities which are in common with the base. So regardless of your rover’s tracking capbilities, if the base is GPS/GLO only, then that is all you can use. And if you are tracking say 8 GPS on your Rover and the Base is tracking 7, but out of that only 6 Sats are tracked by both, then you can only resolve for those 6 Sats.