Leica RX1250: Tether to Phone?

hello Jim,

make sure your phone has some remote sim option enabled.

also the rx1250, as far as i know, has no default option for a samsung phone, which would list the set of AT commands used by the samsung phone. so you will more than likely need to add to the list a new 'samsung' device to interface with that has the correct AT commands listed.

in my experience, and verified by my local leica support, life is a lot easier if you have an older nokia phone. if i was in your situation... actually i am in your situation! we use a 1200 rover run by an RX1250 and connect to ketwork RTK. i have re-commissioned one of the old office phones, a nokia e51, to live with the GPS and connect to the NTRIP caster. it is now the dedicated GPRS modem and lives in the instrument case.

if i were starting again i would do it this way again. i would just go and buy an older nokia like an e51 or 6120 and run them as a dedicated GPRS modem. these older nokias are often acknowledged as having the best 3G network reception of plain phones without using an external antenna.

please tell me if i have misunderstood your question.

> If I were starting again... i would just go and buy an older nokia like an e51 or 6120 and run them as a dedicated GPRS modem.

I'm just getting my feet wet with network RTK, so bear with me if I seem unclear on some of the concepts. What I have available is an IP address for an NTRIP caster, a Samsung phone running Android, and a Leica ATX1230/RX1250. I also have an NTRIP client on the phone, as well as an app to turn the phone into a WiFi hotspot. I'm trying to figure out how to get the caster feed to the RX1250 without dedicating a phone to it. I don't care which NTRIP client I use - the one on the phone or the one in the RX1250 - and I don't care if the connection is via bluetooth, WiFi or even cable. Lots of variables! Lots of head-scratching! Might work, might not.

no problems jim.

first things first: rx1250 doesn't do wifi. ain't happening. bluetooth or bust.

secondly: NTRIP client on the phone is unnecessary. between the 1250 and the NTRIP caster, everything will be taken care of.

the GPRS modem (phone) just provides the internet connection, nothing else.

our company has long been tethering phones to rx1250's and TCRP1250's. we all used nokias. those who changed to smartphones (samsung s2 and iphones) don't do it anymore. doesn't mean it can't be done though.

gschrock mentioned the modem commands, which is same thing i already mentioned (AT commands).

the rx1250 comes loaded with a short generic phone list: nokia phone, seimens, motorola, sony & CDMA phone. these phone choices have the generic AT commands the phone type will need to connect to, communicate with, and disconnect from the internet while acting as a GPRS modem. use one of these brands of phones of a similar vintage to the rx1250 and your life is easier.

you can also create your own custom device (phone) and enter the appropriate AT commands for your phone. you will need to find a list of AT commands that your phone uses and enter them when you create your custom device. if you look at the existing phone list and edit one of the default phones you will see which commands you will need. without this, again, it probably ain't happening. if it does happen it will be pure dumb luck that the commands used by one of the default phones matches the commands used by your phone and allows you to connect.

for an example the nokia 'Init 1' string looks like 'AT&FE0^MAT+CREG=1^M'. the 'Connect' string is 'ATD*99***1#^M'. you will need to find your samsung equivalents and enter them to enable internet communication to happen.

i don't know which samsung phone you are using but the galaxy s2 & s3 don't need apps to be a wifi hotspot (in australia at least); it is an included function of the phone already.

keep asking questions if you need.

I researched this to death and determined that the only way to do this w/ smartphone is to "root" the phone. I haven't had time to attempt this however. I'm still using the old phone as described above.

> I researched this to death and determined that the only way to do this w/ smartphone is to "root" the phone. I haven't had time to attempt this however. I'm still using the old phone as described above.

i had hoped that this was not needed as it surely would invalidate the warranty we have on our phones.

out nokia e51 is just part of the kit, just like the radio modem is when doing RTK with our own base. it is possibly actually a preferable solution to have 1 dedicated phone when multiple users are involved because searching for, and connecting to, a new device every time a different user goes out tests the temperament of the instruments and users both.

> Hi Conrad,
>
> Thank you for the clarifications. I am quite bummed to hear that the 1250 will not do WiFi. That means the users are at the mercy of the tangle of GPRS connection settings. Most of the popularitry of those little "MiFi" (portable aircard WiFi hotspots) is that users do not have to worry much about changing/changed settings; one size can fit all the kit, no discrete "pairings" needed.
>
> FWIW linked here is a partial list of some carrier settings and this guide might be a good start.

g'day gschrock,

it could be a tangle if you want to use a phone other than those listed in the default, i agree, but the system 1200 has been out for a while and unfortunately smartphones may not have been invented then, certainly not wifi hotspots. bluetooth tethering was pretty good tech at the time.

i really don't see it as a big deal though. mini wifi hotspot vs small phone. the phones that will do it easy, like nokia e51 e52 6120 e63 etc. are readily available, and CHEAP. cheapest bit of kit you will ever buy for a leica. price a radio modem or cellular modem for the system 1200 and you will see what i mean.

cheers.

> Too right, Wasn't agruing the point, and not trying to discourage Jim, but the carriers up here can be a pain to deal with first time, and then there can be surprises in how the streaming plans are handled. There was big gotcha a while back where one carrier added accelerators and every one of the users on our RTN of that specific carrier went dark all at the same time ("strewth!"). It took a week of each one painfully going thorugh support to get opted out. So it is not a surprise that those that can are mostly going MiFi.
>
> But once cellular it is set up (and someone keeps good notes) it is a cheap piece of kit as you said.
>
> Tough part of dealing with the carriers is finding anyone in support that understands that you are trying to use the phone esweentially as a modem; they can tell you how to install and app, but mention AT or APN and they go blank.;-)
>
> As an aside: I run an RTN up here in this WA, but spent most of my youth in the other "W.A." down your way.

wow, that accelerator stuff sounds nasty.

W.A. these days sometimes seems like another country. other side of the continent, 'mining boom', inflated wages, inflated house prices and the occasional crackpot talking of secession.

Thanks for all the tips. I appreciate the suggestion about buying an old phone and dedicating it to RTK service, but one of my goals in this endeavor is to keep the cost to a minimum. My need for RTK is sporadic, and adding the monthly expense for a redundant phone/data service isn't a direction I currently want to go.

I haven't given up the fight, but I keep running into roadblocks. Latest among them: my username and all of the network mountpoint names contain a "_" (underscore character). I have yet to find a way to get the RX1250 to cough one up. I've searched the manuals and tried all the shift/function keys I can think of, to no avail. Doing NTRIP on my smartphone would allow me to avoid that problem, so for now I'll continue to explore ways of tricking the RX1250 into thinking that it's connected to a radio rather than an NTRIP caster.

hello jim,

underscore if definitely there. just move to any input field you want to edit and start editing by pressing the red return key. you will notice [F1] to [F6] now have all the usual characters above them (capital A-Z etc) if you now press the yellow down arrow a few times you will see that the display above the [F1] to [F6] keys now are cycling through different character sets. underscore belongs to the set four down arrows away.

in australia we have data-only, monthly sim cards available for purchase from major carriers with no contracts, everything just expires at the end of 30 days. something like 1GB for $30 or so. $30 is just under 1/6th of our hourly charge out rate for a 2-man crew. that makes working at the problem worth just under 10 minutes of our time each month we want to use it. it wouldn't be worth the hassle to us to devote any more time to it than that if it was our problem. on the other hand, if you are anything like me, a habitual fiddler and occasional tech-head, then you probably like the challenge and will not stop until you've spent many nights 'hacking' to blazers trying to make it work. i might even grab one of the guys samsungs and have a quick go myself.

good luck jim.

> My need for RTK is sporadic, and adding the monthly expense for a redundant phone/data service isn't a direction I currently want to go.

I've been using RTN/RTK for over 6 years now. I use a T-mobile account and the same phone I bought 6 years ago; I'm on the third battery for it. I pay 30 bucks a month for the service, it's unlimiled internet only and I can text too, but I don't.

I use it on almost every job I do; there have maybe been 2, where I didn't. When I first got it, I timed myself; I was up and running inside of 2 minutes from turning the key on the van and all the gear was still in the box.

I work in Western Washington, where there is lots of canopy, so I don't get to use it a lot. But when I do, I'm still amazed at the results I get and how quick I can get it.

Doug

Have you tried calling Leica support j/k I know that is a waste of time. Are you wanting to connect to the Leica Smartnet or setting up your own NTRIP network. I was told best practice would be to send the corrections to one of your servers and then have the correction broadcast from the server IP. Reason for that suggestion was to have a constant IP for a base connection.

> Are you wanting to connect to the Leica Smartnet or setting up your own NTRIP network.

I have access to the California Real Time Network (CRTN), but there are currently only 2 stations in my area, so basically I'm only looking at single-base RTK. I'm interested mostly because it would save me having to mess with setting up and protecting a base station.

Thanks to Conrad I got the character set problem resolved, though not the Internet access matter. The RX1250 bluetooth is still giving me trouble -- I can see the RX1250 from my phone and see my phone from the RX1250, but getting them to pair has been an unsuccessful struggle. I did get the phone to pair with a bluetooth radio hung off the clip-on connector in a test configuration (i.e., wires everywhere!), but the data sent from the NTRIP client on my phone apparently wasn't formatted correctly for the RX1250. It recognized the feed as RTK corrections, at least to the extent of complaining whenever I disconnected the phone's NTRIP client, but the 3D quality indicator never got below 2 meters.

Someday I would like to hear a conversation of a RTK Network Position (basically a virtual base position) and using the nearest single base line. I lean towards a single baseline solution from a fixed station that I can recreate if needed. When you use a RTN solution it is a one-time deal which can never be duplicated.

hello Robert,

are you offered MAC/MAX corrections in your RTN? this differs from VRS in that the baseline data is ultimately connected to a single base station. to be repeated over and over and over again!

cheers.

No GPS can be truly recreated. The orbits change, the models, no two fixes are completely the same.
Think about how people use the sun or stars for measurement, those move too.
The idea that RTK is any more recreatable than network is missing a very big point. If you measure something with one method or technology and then measure it again with the same or another, you are simply reemasuring in a relative manner from one spot to another by another means or under different conditions. And whether or not you get the same results, especially when the conditions or tool changes, that is the true test of your measurement.
Do you retrace a survey done with a solar compass and link-chain as the original did, or do you use a total-station?
All GPS measurement rely on models for sources of error, it does not nmatter if it is RTK, MAC, VRS, or whatever. There is a lot of filtering happening in your RTK measurements before you even see a result. Some of the battle over this or that type of GPS was marketing over competing methods.
There are going to be people who utilize indepenedent masurements, like with different tools and methods as a true test of a measurment, and there will be those who do not. That is OK, there are tools for everyone.

> Someday I would like to hear a conversation of a RTK Network Position (basically a virtual base position) and using the nearest single base line. I lean towards a single baseline solution from a fixed station that I can recreate if needed. When you use a RTN solution it is a one-time deal which can never be duplicated.

A few weeks ago I rented a network rover from a regional Trimble dealer that maintains a VRS/VSN network. In the field I appeared to be getting some sort of network solution, but when I brought the data into TBC, all the points showed up as single vectors from individual CGPS stations. The network is on NSRS2007/GEOID03 and I set my TBC project up for NSRS2011/GEOID09. I never recalculated to do a direct comparison between the VRS versus postprocessed positions, so I don't know how closely they agree.

> The RX1250 bluetooth is still giving me trouble -- I can see the RX1250 from my phone and see my phone from the RX1250, but getting them to pair has been an unsuccessful struggle.

The pairing thing has really got me puzzled. This evening I was able to get the RX1250 to pair with my phone, but it almost immediately "unpaired" itself. The phone pairing is stable with other BT devices, so I'm assuming that there's something about the RX1250 BT that doesn't like my phone. I even went into the WinCE BT utility and added the phone's MAC address to the Trusted category, but if that had any effect I didn't notice it.

The Leica manual mentions that the RX1250 wants to be the master device, and says that a pairing request from another device will be met with a PIN popup. I've only seen that once in all the pairing attempts I've made. (My phone doesn't have a master/slave setting that I've been able to find, so I guess I should explore that a bit.) I did notice that after a number of pair/unpair events the RX1250 failed to find the AX1230 receiver, which I've been running on another BT port. Maybe I crashed the BT subsystem. 🙁

The system's owner (a colleague) has been connecting the AX1230 to the RX1250 via cable. Is the RX1250 BT implementation known to be unreliable?

>
> The system's owner (a colleague) has been connecting the AX1230 to the RX1250 via cable. Is the RX1250 BT implementation known to be unreliable?

jim,

in my experience the RX1250 BT implementation is fine. i personally have never needed to get the cable out of the box to connect RX to AX. if a pairing seems to be taking too long or looks like it may not happen then we turn it off and on again. works every time.

cheers.

From Derek Graham on Aug 23rd:

Not my area of expertise upon which to opine.
It's Sunil Bismath's though:
http://www.library.mto.gov.on.ca/webopac/zoomrecord.asp?recordkey=8649b92d-e800-4843-88...
Click on attachment
Attachment: cvvd - Utilization of Network RTK GPS in MTO Highway Surveys.pdf
His comments at the end are particularly interesting with regard to comparison to other jurisdictions.
Cheers,
Derek

The conclusions are good food for thought. The tests were done on a netwrok that was at the time fairly incomplete, and the spacing of the stations was longer than most networks.

And there are a lot of studies and guidelines at this site.
As I understand the reason why network was developed over ten years ago and spread over so many countries is the degradation of results over baseline length for single base, the ability to add better orbit data to network, and the network stations could be active parts of national CORS systems. There is some good reading in the links.