There are lots of different places you can send your data. ThingsSpeak is just one of several sites available that offer different levels of hosting, depending on how many stations you have, how long they’ll retain the data, and how the data is displayed. You can even create your own mySQL database and free graphing site like I did back at the beginning of the Mayfly project more than 7 years ago. But after adding hundreds of stations, we decided to create the MonitorMyWatershed portal to help with the increasing demand for adding new features, and receiving data from users all over the world. It’s a powerful site, that we’re still constantly improving, but it makes sending and displaying environmental time series data easy. But if you want to send your Mayfly data to any other site, that’s fine too. There are several examples of people in this forum doing that.
Hologram is just one of many cellular SIM card providers. Again, you don’t have to use them, but we recommend them because of their ease of use, and their support of most of the cellular hardware we’ve found that’s compatible with the Mayfly. Not all carrier and SIM card providers allow their cards to be used with the 2G, 3G, and 4G cell boards we’ve tested. The data plans from Hologram cost $0.40 per MB. So your monthly cost will depend on how often you send data, and how big your data payload is. But for most of our stations, the cost is around $6 per month.
I’ve successfully used 2G, 3G, and 4G boards with Mayfly loggers, depending on cell coverage at the many hundreds of locations we’ve deployed stations. We also have boards that transmit their data via WiFi or Xbee radios. I haven’t tried LoRa radios with them yet, but I know several people who have. There are several threads on this forum where I mention the Xbee 900Mhz basestation-ethernet bridge I made that relays any data from the Xbee RF network onto the internet for uploading to the online database. You can also buy commercial RF-ethernet bridges to do the same thing, for twice the money. And they make LoRa bridges that do the same if you’d like to try that.
Jim, I’d recommend just putting XbeePro HP-900 radios on your loggers and build a RF-ethernet bridge if you want to try that route. Or the simplest thing is to buy more GPRSbee 2G cell boards to put on your stations since you still have great 2G coverage at all your sites, then just upgrade their code with the same code that’s running on your other 2 stations that transmit directly to MMW. The code for doing that is on our GitHub repo.