Unfortunately XLR is not allowed in the UK as far as I’m aware
1 Like
There’s a pretty obvious hack to fit a Digi XBee Extra Long Range Radio to an Ardusimple simpleRTK2B V1. It requires a small piece of 2mm pitch Prototype PCB, 2 x male 2mm pitch headers, 2 x female 2mm pitch headers, 1 uF and 100 pF capacitor, jumper wire to 3V3 power source.
Assume pin 1 is at the top of the XBee Headers. Put an over-size piece of 2mm pitch Prototype PCB over the XBee headers held in place with male header strips under the board. To the left of the headers run female headers on the top connecting pins 2-Tx, 3-Rx,10-Gnd,11,20.
Pin 1-3V3 needs to be powered with a jumper wire off the main board from 3.3V. To help reduce noise, Digi recommend placing both a 1 uF and 100 pF capacitor as near to VCC as possible.
ArduSimple LR and XLR Radio Kits are about double the component cost from other suppliers (eg XB9X-DMUS-001 and XBP9X-DMUS-001 respectively for US castellated module with U.FL antenna connector, antenna and IPX U.FL IPEX cable).
ArduSimple fit the modules to an adapter like GitHub - faludi/xbee-smt-tht-adapter: XBee SMT -> THT Adapter, including XBee PRO SX. Digi has good PCB design and manufacturing instructions which should be carefully read including attention required for layout (eg grounding, heat dissipation and RF performance) and solder reflow requirements if they are to be sourced from other suppliers.
Very good observation! I guess there was a method to the Digi madness when they switched to this silly SMD form factor.
The pins line up perfectly with the XBee headers, you can see them poking through in the ArduSimple radio boards:
But you’'d be wrong not to sit the module on a board.
I have wires soldered to the pads and it works fine. It will also work fine with the pin header as @m_elias says. Ground, 3.3v, TX, RX, Reset will all connect as they should. The Digi instructions don’t really apply here. We’re not using reflow ovens and surface mount soldering. RF performance is about antenna placement which again doesn’t apply here, since a pigtail attaches to an external antenna. Plus if we fry a unit it’s no big loss. Not really sure what you’re going on about.
The other side of the xbee socket has only one connection on the SimpleRTK and that’s another ground. However on the SX module it lines up with the ioref pin, which is itself not connected on the SX module (it’s unused). So probably would be fine here. If not, leave that pin out when doing the other side which really is just about mechanically holding the module the socket.
Personally I would leave off the TX pin also. You really don’t want your rover talking on the airwaves if you forgot to turn off the outbound traffic on UART2.
Specifically, heat kills electronics and the higher the transmission power the more heat produced. It gets bloody hot in Australia which leads to interesting things often fixed with a fan. The specs use the board the module is sitting on to dissipate heat (ie it’s not accessible) - Recommended footprint and keepout.
The recommended footprint includes an additional ground pad that you must solder to the corresponding pad on the device. This ground pad transfers heat generated during transmit mode away from the device’s power amplifier. The pad must connect through vias to a ground plane on the host PCB. Connecting to planes on multiple layers will further improve the heat transfer performance and we recommend doing this for applications that will be in transmit mode for sustained periods. We recommend using nine 0.030 cm diameter vias in the pad as shown. Plug vias with epoxy or solder mask them on the opposite side to prevent solder paste from leaking through the holes during reflow. Do not mask over the ground pad.
Of course it will work if the right connections are made but that doesn’t mean the module isn’t being used as a slow burn fuse. It will depend on the actual environment where it is used, so a base station sitting on a pole will be different from a module in an air-conditioned cab.
Maybe there are more practical ways of handling heat dissipation (eg using a properly fitted heat sink and thermal paste, wire, adapter board with thermal past etc).
Oh sure. But except for a tiny bit of heat dissipation through the ground plane the Ardusimple radio modules aren’t going to be any cooler. The point is you can get the equivalent to the Ardusimple modules with just a header soldered on. There’s precious little by way of heat dissipation you can do to these modules short of putting active cooling on the can.
The ardusimple modules do have a nice SMA (or maybe it’s RP-SMA) connector on there board which is more robust than a pigtail.
And it’s not just the radios that you have to worry about overheating. There’s the GPS receiver itself. I recommend putting the whole works indoors and just have the antennas outside. That’s what I do. I’ve used a 1 watt transmitter pushing through a 50’ coax cable up to an antenna for years without issues, loss-wise.
On my new set up that I’m going to work on this summer, I’ll have the GPS antenna on the roof of my shop with a 30 foot cable on that, and then the 900 Mhz digi transmitter will be on a 50 foot cable up to the top of a mast, with the radio module and the GPS receiver all inside mounted to the wall.
If I understand correctly, putting my simpleRTK2B in a watertight 8x8 electrical box sitting 5 feet on a mast above my house is going to heat up to much? I’m in central Saskatchewan and we do get warm in the summer, but not like down south. I have a usb adapter inside as well, which would create it’s own heat. Any suggestions?
I had mine in a waterproof enclosure outside for a couple of years and seemed okay in Alberta heat. At the moment I have it inside my shop.
I have a XLR SIMPLERTK2B and have some areas that the corrections come and go.
The mobile phone does work in the areas that lora doesn’t so is there a way to receive corrections in my home office which is in range of the XLR putting the corrections online as a backup instead of building antenna higher which may not be possible.
I have a spare LR SimpleRTK2B rover, could that be used somehow?
Yes that’s essentially what I do. Use a 3.3v Serial to USB adapter, such as this one. Only Vcc, Gnd, Tx, and Rx are needed. Then I use the open source ntripserver program on a raspberry pi to connect to the serial port and then push it up to rtk2go.
So do I connect that adapter to my base station or to my rover to get the correction messages it gets from the base station?
I have also got a couple of dragino arduino lora shields, could something like that receive corrections data to be sent to rtk2go?
Maybe I misread what you’re doing. What I understand is that sometimes you can’t get a clear connection to your base station, so using a cell-based internet connection would work. To do that you need a way of getting your base station messages to rtk2go. What I described was one method to do that without physically connecting to the base station. Instead a receiver nearby, attached to a computer, picks up the 900 MHz broadcasts and sends those to RTK2go. This is on the base station side, or near the base station. If the base station is already close to a computer you can connect the USB to serial adapter directly to the uart2 TX line that is already feeding the XLR radio.
On the rover you’ll need a means of getting it from the phone to the F9P. This could be something as simple as a bluetooth serial adapter board that connects to the F9P’s uart RX pin, just like the roving radio unit does. I use a sparkfun silver bluetooth adapter. You could have the 900 MHz receiver connected to uart2’s RX line and the bluetooth connected to uart1’s RX line. Then the F9P would take messages from whichever source had valid data on it.
Hope that helps a bit.
Yes that’s about it.
Just want to fill in the radio black spots with RTK2go.
The base station is within radio range but not WiFi of my computer.
So I will need to connect a computer or raspberry Pi to a receiver
Find the network ID to connect to base corrections
Use NTRIP to push data to RTK2go
Agopen signed in to RTK2go
Have I got the basics right?
I am a bit out of my depth but it is always a good day to learn.
Thanks for your help.
You don’t necessarily need a full computer. I suppose an ESP32 board could listen on the radio and make a connection to the NTRIP server if you were inclined to write a program to do it or found someone that could help put together a sketch or some firmware (see below).
But yes, you’ve got it about right. At least that’s what i do. You need the network preamble ID and the hopping id to be the same on all your radios (rovers need to match the base station).
The raspberry pi part is tricky since you don’t have any experience there. Maybe someone has an ESP32 sketch that would do the job with just a radio receiver and an ESP32 connected together. Maybe the ESPRTK folk would be willing to tackle that. Wouldn’t hurt to reach out to them. They already have most of that functionality in their product. Would just be a matter of stripping out some things since you already have the F9P broadcasting RTCM over the air from your base station.
Okay, at least I have a starting point now.
I will reach out and see what I can come up with.
Thanks again for your help.
I can assist somewhat with running ntrip server on linux on a pi with my systemd start script. But that presupposes some linux knowledge. ntripserver has to be compiled from source. I don’t have the time and resources to make a ready-to-go SD card image for the Pi, which would be nice. I guess another avenue to explore is to reach out to @Stefan regarding his RTK Base Raspberry pi base station. He might have the means of modifying his existing image to do what you want to do with just an SD card image to boot on the Pi.
It is looking more and more like its not a plug and play afternoon upgrade for me but certainly worth pursuing.
I have limited Linux knowledge but did experiment with it a few years back.
If I was able to get WiFi with yagi to my base station would your first suggestion be more (plug and play)?