I am looking at Reach M+ to possibly use it in the frame of my master thesis. I have an application where this device could be perfect for. Nevertheless, I still have some open questions (not found in docs or forum) of which I hope you can help me out.
About the application:
We plan to build a GPS stations (=rover) which will be positioned in the wild. As we need cm-accuracy for our position, we will use typically a base and a rover. Furthermore, we want to carry out long-term measurements of the position (approx. about 2 weeks), and since our rover will be powered by a battery, it has to be very energy efficient. We don’t need such a high measuring frequency, as the rover won’t experience high velocities/ accelerations. Something between 0.1 Hz and 0.2 Hz would be adequate. On the other side, the rover might be positioned well far from the base, up to 5 km / 3.1 miles, which is why we might need a LoRa antenna for communication with the base. This application will only be a proof of concept. If we succeed, we plan to build a whole fleet to create a dense field of GPS stations in the wild. This is why the application should be cost-efficient as well and I wouldn’t want to use Reach RS+.
Questions:
As we need to be energy-efficient and don’t require very high measuring frequencies, it would be beneficial to switch the whole system (neither the GPS nor the LoRa antenna should receive/ send data) to a “Sleep-Mode” for any arbitrary time range. Is this possible with the Reach M+?
Can the GPS measure its position with a lower frequency, for instance 0.1 Hz?
Is it possible to use 2 Reach M+ both as base and rover, which communicate over LoRa antenna?
For retrieving data from the rover (at approx. 3-5 km distance), do we need a further LoRa Radio Antenna to attach to the computer, or how would that work? Obviously, the data can’t be logged via Wlan.
Do you need real time accuracy, or would post processed do?
The M+ is power hungry by micro controller standards,
It also does not cope at all well with being enclosed for weatherproofing. Too much heat is generated.
I suppose there’s there’s an answer about what Reach M+ could be made to do, and there’s the answer about what it can do straight out of the box. I’ll go with the straight out of the box answers:
You could switch Reach M+ on/off with an external timer circuit.
The slowest sample rate that the software will allow is 1Hz.
Yes, each Reach M+ (base or rover(s)) can be paired with an optional LoRa radio module. This is used for RTK and only transmits correction messages (RTCM3).
Log files are usually retrieved over short-range Wi-Fi or by USB cable, not transmitted over long ranges (unless you are in a cellular coverage area, and I think not.)
I don’t really need time accuracy, post processing would do it, but then it depends if there’s enough storage to save the data over 14 days.
Thanks for this input: I read about it in earlier discussions/ short calcs and already took it into account: Since this application would specifically be used in rather cold environments, I was thinking the generated heat could be beneficial.
Thank you for your feedback and sorry for my late reply, after your inputs I had to do some clarifications first and get some more understanding of these products.
This is the actual plan regarding the GPS station: As postprocessing the data will be sufficient, I don’t need any LoRa antenna. I will build an external PCB that 1) has an integrated timer circuit, 2) stores the data received from Reach (via USB) on an SD card, 3) transmits the stored data via XBee to my computer.
At this point, I’m wondering if the Reach M+, or even the Reach RTK might be “overengineered” for my application: As I will do postprocessing with RTKLIB, I think there’s no necessity to have an RTK receiver, especially since the (power-consuming) Intel Edison is built in for the real-time computation of the position (which I wouldn’t need in that case). Is this assumption correct, or what is the exact role of the Intel Edison?
Being this is the Emlid community forum, we like to promote the use of Reach devices. What you get with M+ is a tiny Linux based computer with a GNSS receiver and the easy to use software and support of the community. Surely you could use M+ for your application.
However if your ideal device diverges from M+ enough that you are wiling to put together a more compatible hardware design, there is nothing stopping you from that.
Even if you don’t choose Reach devices for your final product, maybe you want to get a set so that you have a working design to start with and then find out what you can eliminate for your final hardware.
So, you ask what is the role of the Intel Edison here? For starters, the Intel Edison system-on-module was discontinued not too long ago, and so the new M+ uses the Neutis N5 system-on-module. Its role is many, from networking and bluetooth, to input/output hardware, plus data storage, cpu processing, web server, the ReachView application, etc, etc. It can pretty much do anything except make you breakfast in the morning, which - might be more than you need, but it is very versatile. Check it out at the link above.
