Hey everyone,
I've been trying to set up an NTRIP/Android/Bluetooth system for Leica GPS 500 units and have had very little luck finding information on how to do it. I have found that those who possess the information want obscene amounts of money for it, and I just can't justify that expense. So, after figuring out how to do it on my own, I thought I'd do the right thing and write a tutorial on how I did it. This forum seems to be the most logical place to post it. Clearly most of the regular contributors in this forum are using equipment that has all of these functions built in, but for people like myself who are stuck with (or perhaps prefer) the older gear, workarounds such as this are necessary. In the interest of helping people understanding "why" they need to do certain things; this is a tutorial more than an instruction manual. Expect it to be verbose.
You'll need:
*A Leica GPS 500 system
*Some sort of RS232 - bluetooth module such as a Parani SD1000 for example (recommended), or a cheap Chinese BT-232B-E (not recommended. I had trouble figuring out how to achieve two-way communication with that unit. The Parani is the better option.)
*An Android device capable of two-way bluetooth communication.
*An internet connection
*Soldering iron, heat shrink tubing, hot glue gun, etc
First and foremost, you'll need to sort out your cables. There are cables on the market that will give you access to the NTRIP system straight out of the box, but you'll be limited to receiving corrections only. If you're ok with that, then ignore this tutorial and just buy a standard Lemo to PC data cable and a bluetooth module. You'll need to carry around a separate power supply for the bluetooth module itself and your Android app will be limited to what it can do for you. You will not see corrections, coordinate quality or any satellite information on your app.
There are also existing NTRIP systems on the market that have been created by various companies, but they have their limitations. The CellXtrem module costs well over US$1000 here in Europe, requires its own sim card and its own internet plan. It does, however, allow you to continue using the GPS 500 as a data recorder, as it doesn't use the Terminal port. However, I wondered about whether or not a new firmware update would be required in order to run it (I have firmware V5.11 with TP Stakeout built in to it, so different firmware requirements don't interest me) so I emailed them. They never answered. I then emailed their sales guy in the UK. He replied with "I don't know". Those 3 words do not inspire the confidence required to hand over more than $1000.
The TopView Android app and the Carlson system require an external data recorder, because they both tie up the Terminal port on your GPS 500 by requiring a cable to plug into that port. Also, neither of these systems are free. Sure, the TopView Android app handles data recording within the app itself, but the English translations leave a lot to be desired (it's a Spanish app originally) and the designer of the app refused to answer my questions regarding configuration settings on the GPS 500 itself. He demanded that I purchase the cables from him directly before he would answer my question. He insisted that I pay him money for something that I didn't need just so I could use his pay-as-you-go app. In my opinion, demanding that you pay him first so you can also pay him later is a bad business mentality.
The Lefebure NTRIP client is the way to go due to its simplicity, zero cost and user-friendly interface, and the RTKGPS+ app is also free. It offers greater options, but is not so user-friendly. Both offer corrections and various other information on screen.
If you'd like to use your Android app to its full potential then you'll need two-way communication between your GPS 500 and your Android app. This is something that the GPS 500 doesn't support internally as a standard function. It does, however, have the ability to simultaneously send and receive the necessary data streams to achieve full NTRIP via two separate internal functions. The trick is finding a way to make that happen in a neat little package. If this is what you need too, and would also like to continue using your GPS 500 as a data recorder, then read on.
There is no need to provide your bluetooth module with external power and carry around extra batteries and cables. Everything you need is provided by the GPS 500.
So, you'll need a Lemo cable that is able to carry data and power at the same time. The 5-pin Lemo "data to PC" cables that you see on eBay (whether they be genuine Leica or Chinese copies) are unsuitable, because they only carry data signals (RX, TX and Ground). There's a reason for that: the GPS 500 outputs 12V from all of its ports (except the Terminal port. That's 6V, but we're trying to avoid using that port. Using that port means you can no longer use the GPS 500/TR500 as a data collector, which is what TopView and Carlson do.) You don't want to introduce 12V to your PC, so the data cables do not use the power pin. Well, mine don't. Yours might. You'll need to check it.
The 8-pin Lemo "data to PC" cables are also unsuitable at the DB9 (serial port) end, because the bluetooth modules on the market use the "ring indicator" pin in the DB9 connector as their power input. The 8-pin Leica cables do not have that wire connected within the DB9 connector. Neither do the Chinese cables.
So, you'll need:
*A 5-pin 1B Lemo plug that has all the required wires inside. I would recommend a TR500 cable or a GEB171 battery cable. Personally, I had a couple of old battery cables that have the 5-pin 1B Lemo plug at one end and the funny squarish plug on the other end (I'm too lazy to find the part numbers for cables). But be warned: you'll be cutting up those cables.
*Any type of 8-pin Lemo 1B data cable. Anything will do, as long as it is a data cable. You need it for the Lemo plug end only. Again, you'll be cutting up this cable too.
*A standard male DB9 serial port plug. Make sure it has all of the wires inside it.
*A 12V to 6V/5V voltage reducer.
*Some sort of box/case big enough to put it all in.
Regarding the voltage reducer: The Parani manual says that it will run on 12V. However, I have read in more than one internet forum that people who have run them on 12V have burnt them out eventually. So, I thought it would be foolish to not lower the supply voltage. Feel free to not use a voltage reducer if you wish. I bought a couple from the devil himself (Amazon) that reduce DC voltage down to 5V for less than $5 each. It seems like a good investment. Your choice.
Here's the GPS 500, or at least, here are my two GPS 500 units. I drafted this up in AutoCAD and performed my own checks on all the ports. I did this because I decided to change the internal batteries in my units and found that one of them had been repaired internally, while the other one has a power port that doesn't work at all. So, I felt that I needed to do some checking before I started. Only after performing these checks did I cross reference my results with the diagram found in the GPS 500 manual. Both my units coincide with what was found in the manual. You should probably run some tests yourself, just in case someone attacked the internals of yours at some point. If you decide to copy my setup directly, then Port 2 and either Port 1 or 3 are the most logical ones to use, as the remaining port (Port 1 or 3) can still be used for external radios. This allows you to use the NTRIP system and your rover at the same time if you wish (I'm not sure why you would). Therefore, because Port 2 cannot be used for a radio, it is the most "spare" port and should be used as one of your NTRIP cable ports as opposed to buying two Lemo 8-pin plugs and only using Port 1 and 3 for your NTRIP.
NOTE: If you follow this tutorial, then you will be wiring up a DB9 serial com port plug to supply power to the bluetooth module. Remember that fact before you go and connect your new cable to a PC!!! When you are finished, your "Ring Indicator" pin of your DB9 could be supplying more than 5V (depending on your voltage reducer) to a PC circuit that is only designed to accept 5V. It's not up to me to tell you whether or not that will be ok. This is something you need to be aware of. Personally, that's another reason why bringing the supply voltage down to 5V makes sense.
Wire it all together like this:
As you can see, it's actually quite simple.
Here's my finished cable:
GPS 500 Configuration:
*Connect the cable to the GPS 500.
*Turn the unit on as usual.
*Press "CONFIG", then "4 Interfaces".
*Select "1 Real-Time". Press EDIT.
*Set "R-Time Data" to ROVER.
*Set "Data Format" to whatever you want. (Usually "RTCM V3.0")
*Set "Port" to 1, 2 or 3.
* Press "CONT".
*Back in the interface screen, select "3 NMEA Output". Press "EDIT".
*Use Device: "YES".
*Set "Port" to whichever port the other Lemo plug is connected to.
*Whilst still in that screen, press "MESGS".
You'll need to send at least the GGA message to your NTRIP app. Highlight "GGA" (it should already be highlighted) and press "USE". Press "CONT".
*Press "CONT" again to exit that screen.
That's it. Your GPS 500 is now streaming NMEA data out to the bluetooth module and is waiting for you to feed it a RTCM3 correction stream from your Android app. You now have a fully functional NTRIP system on your GPS 500 and, best of all, still have the ability to use your GPS 500 as a data collector. It should all cost you less than $200 (bluetooth included) and only take a few hours of your time.
I hope this helps someone.
On an unrelated note; a special thank you to Lance Lefebure. You are a legend.
Mick.
Micheal D'Aubyn, post: 428509, member: 12101 wrote: That's it. Your GPS 500 is now streaming NMEA data out to the bluetooth module and is waiting for you to feed it a RTCM3 correction stream from your Android app. You now have a fully functional NTRIP system on your GPS 500 and, best of all, still have the ability to use your GPS 500 as a data collector. It should all cost you less than $200 (bluetooth included) and only take a few hours of your time.
I hope this helps someone.
On an unrelated note; a special thank you to Lance Lefebure. You are a legend.
Mick.
Wow. Neat looking package MIke. Brings back memories. Tried to do some of the same stuff with a Bluetooth module back just before I got an ATX 1230. You're the man, umm person!
