[Shannon Hicks]

What kind of carrier board or adapter board are you using between your PC and the Xbee LTE module?

[Shannon Hicks]

Did you activate the SIM card with Hologram?  If the orange RSSI LED light isn’t coming on, then you aren’t getting any cell reception.  Once you do get cell reception, the orange LED will come on (and its brightness is indicative of the strength of the signal).  And a few seconds after the orange light comes on, the blue light will start blinking, which shows that you’ve successfully joined the network.  The problem we’re having with several of the “dead” LTE modules is that seem to lose the ability to join the network (blinking blue LED) after a few weeks or months in use.   None of them have the issue of no orange LED.  I’ve only seen instances of no orange LED when there was no antenna attached, the antenna had a bad (loose) connector, and using the module where there was no AT&T or Verizon LTE signal.  Have you tried communicating directly with the Xbee LTE module using X-CTU to verify any of its settings or updating its firmware?

[Shannon Hicks]

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.

[Shannon Hicks]

We’re eagerly awaiting the new Campbell turbidity sensors which should be available in late spring or early summer.  In the meantime, there aren’t any other low cost, high quality turbidity sensors that easily interface with the Mayfly except for the Yosemitech ones, which we’re still evaluating for long term performance reliability and accuracy.  Some other people on this forum have used them and might be able to give their opinion of them so far.

[Shannon Hicks]

What is the battery voltage that your Mayfly is recording in your data file?  We’ve had a few random failures of a mosfet on the board that will cause the Mayfly to read the incoming Lipo or USB voltage as being much lower than it really is (see this post: https://www.envirodiy.org/topic/innacurate-lipo-battery-voltage-data/).   Your logger code probably has a line in it that prohibits the bee from transmitting when the battery gets low, so it’s possible that your board has a bad mosfet which is tricking the Mayfly into not transmitting.

[Shannon Hicks]

You might try using a new SIM card or a new LTEBee module.  We’ve had several of them stop working recently for no reason at all.  Sometimes using a brand new SIM card will fix the problem, but other times it requires using a new LTEbee module.  We haven’t determined the cause of the failure yet, nor a solution to get them working again.

[Shannon Hicks]

There’s no reason to remove the CR1220 coin cell battery before shipping the board.  You’re not able to ship loose batteries, or larger multi-cell batteries, but it’s okay to ship one watch battery if it’s installed in equipment, such as being inserted into the Mayfly’s battery holder.   Don’t ship more than one at a time, and protect the Mayfly from rattling around, and protect it from short-circuiting on anything else inside the package.  If you follow those steps, you are allowed to ship it via any US carrier without any certification or warning sticker requirements.

And as Sara said, the latest sketches we use (as found in the current ModularSensors examples) synchronizes the clock every time the board is restarted (assuming you’ve got a wifi or cellular connection), so manual setting of the RTC isn’t necessary.  Or you can just load a DS3231 adjustment sketch, set your clock, then load your logging sketch.  The CR1220 should last 4-5 years under ideal conditions.

[Shannon Hicks]

We finally received the Mayfly boards and other accessories, so we’re working to get everything tested, packaged, and shipped to Amazon as quickly as possible. Everything will hopefully be available online again by this weekend or early next week.

[Shannon Hicks]

All the starter kits I sent to Amazon at the beginning of the month sold out within a few days of being back in stock. I’m still waiting on the shipment from the manufacturer to get all of our products back in stock on Amazon. The holidays kind of mess up the schedules. I’ll post an update whenever I have an estimate on when everything will be available again.

[Shannon Hicks]

We usually use the MB7389 because it has the proper filtering for looking at a single target such as water, and has TTL output, so it’s easy to read with the Mayfly. They make lots of other versions, depending on whether you want to look at snow, or people, or multiple objects at once, and with different outputs (TTL, RS232, PWM, analog, 4-20ma). And they make the MB7589 which has a heater to keep condensation from building up on the transducer, but it uses lots of power and wouldn’t be good for a battery powered station. If you use the external temperature sensor for compensation (which is usually necessary to improve performance) you have to be careful about where and how you mount that, because bad readings with the external temp sensor due to sunshine or other factors, will cause your ultrasonic sensor to over- or under-adjust the reading and cause errors. The ultrasonic sensors don’t work well in small bore stilling wells or pipes with a diameter less than about 6 inches. And the inside of the pipe must be completely smooth with no obstructions or joints, otherwise the sensor will just pick that up and never “see” the water. Even things like a spider on the wall of the pipe or some condensation will cause the sensor to pick that up instead of the water. The Maxbotix manual specifically states that using the sensor in a pipe will void the warranty and they can’t guarantee good performance. Overall, we’ve had too much trouble with reliability and accuracy of the sensors to deploy them widely. I know some other people are using other methods of ultrasonic or lidar sensors for measuring water in storm drains and ditches, but we usually use submersible pressure transducers in our applications so I have not investigated ultrasonic sensors much further. The sensors have a blanking distance of 50cm, so you’ve got to make sure the water won’t get any closer to your sensor than 50cm, or you won’t be able to measure it. The sensors have standard 3/4″ NPT threads on them, so you can find a variety of couplers, elbows, etc in the plumbing section of your hardware store that you can screw the sensor into, so we usually just bought whatever pipes and adapters we needed to put the sensor in the proper location, and then ran the wires through the pipe and out the end and over to the logger box. I don’t think I have many pictures of the installations anymore, but find the threaded pipe section (either metal or PVC) at your hardware store and I think you should be able to put together a mounting bracket for one that will fit your location.

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