I need some suggestions. I have built a meteorological sensor mast needed to cross a race circuit. Since I cannot string cable across the track surface I need to use a wireless transfer method. I attempted to buy XBee modules but Digi (manufacturer of XBee modules and the suburb immediately beside my location) suggested I contact Digi-Key. Digi-Key (in Thief River Falls, MN) suggested I contact Digi. The modules are back-ordered with no information re: availability.
I’ve already built 2 directional antennas for 2.4 GHz but they could be modified. I currently have a Raspberry Pi 4 without an external antenna connection and an Adafruit Metro Grand Central also without WiFi or an external antenna connection. I may need to buy other replacement microcontroller boards and shields but which ones?
Any suggestions would very helpful.
Any of the small LoRa radio/MCU sub-GHz modules will work over that range, if the line of sight is unobstructed.
Wireless serial modules like the HC-12 are very simple to use, but use a 1/4 wave (17 cm) straight wire antenna, rather than the ridiculous little spirals that are supplied with most of them. See for example https://www.allaboutcircuits.com/projec … er-module/
Thank you jremington. This has been frustrating since each of the potential solutions have been backordered and without fulfillment dates. Consequence of supply chain issues? Who knows. The antennas I have built are double biquad mounted on satellite TV dishes. Making sure the dimensions are close as possible has been a challenge. But the potential gain and the directionality look like a good fit for this situation.
In this case the line-of-sight has no trees, bushes, buildings or cows (??) to interefere. If necessary I could re-configure the antennas for other frequencies if necessary. But first I need to choose transceivers for this situation. Thanks again. I’ll give it a shot and let you know how this works out.
If there are other suggestions out there, please let me know.
The antennas I have built are double biquad mounted on satellite TV dishes.
A heroic effort, but totally unnecessary with a LoRa module. There are plenty available for purchase now.
In addition to the HC-12, modules like these are nice, support higher data rates and have reasonably powerful MCUs on the board, which are USB-ready, and can be used for HID, sensor interfacing or data processing as well: https://www.adafruit.com/product/3078
Now THAT sounds like some great ideas!
There’s another significant issue I needed to face with this project. Unlike standard North American race circuits that are bowl-shaped, Europlean-style circuits follow irregular shapes and have elevation changes. While North American tracks followed horse racing practice and later bicycle design, Europeans designed their circuits using public roads. Irregularly-shaped tracks used in road racing circuits generally follow that practice.
The track at Brainerd is somewhat different. Its shape is very irregular but it’s as flat as a table top. There are no trees in the infield and almost no vegetation. All that makes line-of-sight much easier for wireless communication. The overriding important issue is that every track has several radio and wireless communication networks. Frequencies for transducers in the cars to keep track of timing and scoring are vitally important. Most important of all is the network used for safety and accident production. Interfering with either of those networks would be a disaster so the directional focus of antennas is vital. The 2.4 GHz choice is partly to avoid the 700 MHz to 1000 MHz bands for the other networks. Of course, all the cell phones are an issue but the FCC rules also need to be followed.
Thanks for the suggestions. I’ll let you know how this works out.