[Evan]

Hi Shannon, thanks for responding!

I have registered my SIM with Hologram and the antenna is securely connected. You mentioned somewhere to be careful about the ufl connectors on the antenna coax line, and youre not kidding, smallest coaxial Ive seen.

It could totally be where I am working, though I receive LTE on my cell so I assumed the modem would too. But, I use a different carrier than the Hologram network rides on, maybe?

I imagine the RSSI indicator to act as the solar indicator on the Mayfly. *Cue me walking around staring at the adapter to find the optimum signal.* Thats good to know.

I have not yet tried reaching out directly to the modem, I will dig into that now and report findings.

Apparently my attachments didn’t make it through. If anyone is interested, Ill share what Ive got, but I think the program is sound.

Thanks again
-Evan

[Evan]

Hi Shannon

I am not opposed to MMW at all, I had intended to use it from the beginning. I am familiar with Matlab and liked that its embedded, and if I go telemetric with my loggers, my funding will only allow for 4 loggers, so that worked out.

I am finding that there is a lot that is new to me trying to get online, so progress has been slow. I may jump back over to MMW if I cant get speak to work.

I definitely opted for Hologram, this is my first time through this and I leaned on the suggestions made about it.

Thanks for the heads up about monthly cost, that’s really not too bad.

 

[Evan]

Hi Jim

Thanks for your response. I’ve got a decent logger program using the Mayfly that saves everything to a microSD, thanks to the resources here. But you’re right…why should I have to go alllll the way to the sensor site to see my data?
I’ve done some looking into the LoRaWAN myself, and if my sites were closer to one another, I would’ve for sure gone that route. I didn’t think it was too expensive?
Check out this gateway: https://www.digikey.in/product-detail/en/laird-wireless-thermal-systems/RG191/RG191-ND/7356131
only $250!
And the Sodaq Explorer boards work well: https://support.sodaq.com/Boards/ExpLoRer/.
I still would like to do some LoRaWAN, and if I do, these are what I plan to use.

The Hologram site is indirect about pricing, intentionally, so I believe. I have signed up for the “Maker” plan, whose first SIM is free. If I can get this thing working, I intend to buy three more, for a total of 4. Because there are only four free channels with ThingSpeak, and my funding is drying up, and I believe four is all I can make. If I get that far, I will for sure, let you know what the cost seems to be. I only intend to measure four times an hour, so I don’t anticipate high rates of data transfer. But, having never gone this way, I guess I will see!

But I am having a tough time getting this going…

The recent change:
“Add waitForWarmUp() for modem in examples” is hanging up when compiling. It does not like this added command. Is this necessary, I see it was added to all modems?
~line 286 –> logging_to_ThingSpeak.ino

I can comment it out, and I get past there, but it isn’t much longer until it is upset about the bits I pasted in for the Xbee3 LTE-M modem:

#include <modems/DigiXBeeLTEBypass.h>

const long modemBaud = 9600;  // All XBee’s use 9600 by default

DigiXBeeLTEBypass modemXBLTEB(&modemSerial,

                              modemVccPin, modemStatusPin, useCTSforStatus,

                              modemResetPin, modemSleepRqPin,

                              apn);

// Create an extra reference to the modem by a generic name (not necessary)

DigiXBeeLTEBypass modem = modemXBLTEB;

It gets upset about the dangling “apn” stating that: “identifier “apn” is undefined.”

Is this the Acess Point Name?

Is there something I am missing? I have been scouring the boards before asking to no avail.

Any help is appreciated

-Evan

 

[Evan]

Because my original goal is not to measure conductivity, but presence only, I am hesitant to buy an off-the-shelf variant, and I think that it would be awesome to make my instrument.

Right now, precision is more important to me than accuracy. Though, if it seems possible and I can consistently obtain realistic values, that may change.

You’ve given me a lot to chew on, and I will for sure be reaching back out about this. My electrical know-how threshold has been met with Wien Bridges and low power op amps.

The cable I’ve got isn’t shielded, but is essentially power tool cable and is rated within the SOOW category. I think my only concern with it at the moment is how tasty the local fauna will find it when they’re deployed.

[Evan]

Wow, thanks a lot for the literature, and also for the new resources. Public Lab seems to have some really good stuff and I will for sure be lurking around there.

I see that DC voltage is not recommended for use in conductivity measurements for electrochemical reasons, as well as 5v is high and is not required for successful conductivity measurements.
With this, I see that using AC voltage, sine waves, is the practice. I have found a few things online about duping sine waves with microcontrollers, but nothing that seems to be solid. Have you had any practice with this? Can the Mayfly be used to produce low-voltage alternating current?
If so, what other mechanisms are needed? Look-up tables?
I am quickly reaching the ceiling on my know-how. Can this be done?

Initially my aim was to produce an inexpensive, yet robust, logger that will spend significant amounts of time deployed and could detect and record the presence of water. But it would seem that I am working towards measuring TDS, which I am very much okay with. If at the end of this project I can’t seem to make a reliable, and deployable TDS sensor, I would have at least made a device that can determine the presence of water.
The majority of the time, these sensors will not be exposed to water and will spend most of their time loitering in dry stream beds, at least that’s what we think.

I was pleased to see that temperature is a critical metric when determining TDS. I initially planned to use temperature sensors to determine the presence of water, so Ive got a few on hand. Lastly, my current probe consist of one DS18B20 with the electrodes straddling it. The temp sensors are cheap Asian market style, 5 for $10 sorta thing. They seem to work well and follow the oneWire library set.
I am assuming the metal casing around the senor is stainless, is it possible that the temp housing could be providing ions the electrodes.

For the probe housing, I am currently using 1.5″ PVC parts. That decision was solely driven by the size of the cable and the pass-thru gland needed to achieve a water-tight seal from the enclosure. I was worried about voltage drop, so I sized way up to 18awg, from the 22(?) of the off-the-shelf jumpers/sensors parts.

[Evan]

Hi neilh

Thanks a lot for your response.

Good idea with the titanium rod. How would you cut that?
Right now, I plan to use PVC to anchor the array to streambeds. I haven’t put the first one together yet, but I intend to use a coupler and end cap that will accommodate a cable gland big enough for my 5-conductor, 18awg cable. The housing for the sensors has been the most challenging part of the build so far. Ultimately I hope to make it as small as possible, but right now, it’s quite hefty.

I intend to validate its precision with gradient testing, where the salt concentration is increased in each sample, the value measured, and recorded.
I want to produce an inexpensive probe that is sensitive enough to consistently detect varying conductance ranges, both in the lab and field.

If I cant make something that is robust and consistent between measurements, Ill probably use one of these:
https://www.adafruit.com/product/3397
It does add some cost to the unit, but its small size and sensitivity make it an attractive avenue for me.

I’ve also thought about throwing a handful of DS18B20s onto a bus together and using the measured delta in temperature to determine water depth.
–

[Evan]

Hi Shannon

Would it possible that I complete a large purchase of them? I am working on building an intermittent stream monitor and intend to deploy as many as possible.

I have a few questions regarding the kit, and some if its components.
If possible, can we discuss further Shannon? Via email?

Thanks a lot
-Evan

[Evan]

Welp…I figured it out, I think?
Its happy now, not sure what I did other than give it some time?

Thanks anyways!

[Author]

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