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I'm not very experienced in wireless space.

I wish to communicate with an Arduino device stationed at the back of my property, roughly 1500 meters away. I have line of sight, although blowing trees may temporarily get in the way.

Running cable is not feasible with regard to cost, distance and terrain.

I have no problem with a directional antenna on my end, but that is less appealing at the device's end as I want to keep it as light, small, and low-power as possible. If directional at both ends is required, I can make it work.

Wifi? Zigbee? Certainly not bluetooth. Cellular? Something else I should look at?

At the remote side, my hope is that it can run on battery alone, for at least the order of months. I currently have it running at ultra low power of only 54 uA for all but 9.6 minutes of each day. Roughly 100mA for those 9.6 minutes, while it is gathering sensor data and making decisions on what data to send. As it is, on battery I can run it for nearly 10 months on a 5Ah battery. I have no idea how much the wireless equipment will impact that. If I need to add a solar panel, it wouldn't be the end if the world. Still, energy efficiency is a consideration.

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  • \$\begingroup\$ Does data need to travel both ways are can you just have a blind transmitter at the remote end? What data needs to be transmitted and how often? \$\endgroup\$ – Andy aka Jul 23 '16 at 18:15
  • \$\begingroup\$ Both ways. Very little data. As simple as a single 8-bit binary. Ever hour. The wireless notwithstanding, it currently takes 24 seconds to wake up, read sensors, process and ready to send. I don't know how long the sending actually takes, and that's going to impact my battery calcs. \$\endgroup\$ – bcsteeve Jul 23 '16 at 22:21
  • \$\begingroup\$ WHY both ways. Really, really justify this to yourself and me \$\endgroup\$ – Andy aka Jul 23 '16 at 22:55
  • \$\begingroup\$ It has to give me sensor data and I have to tell it when the data is what I'm looking for (I trigger it to launch a balloon). I could program it to be self sufficient so it auto-launches at the right conditions. But the balloon and related equipment is expensive and I don't want to risk some coding mistake resulting in a poorly timed launch. Besides, I want to watch :) Why? Does it make a big difference if it is 2-way? What am I missing? \$\endgroup\$ – bcsteeve Jul 24 '16 at 3:22
  • \$\begingroup\$ A potential issue with two-way is that you have to have the receiver at the remote end powered up for non-trivial amounts of time since it won't know exactly when you are transmitting to it. Possible workaround are synchronizing clocks and having a schedule of when it will receive, or restricting yourself to answering back immediately after it transmits to you. You might be able to cover the receiver power needs with a solar panel, at least in the long time average... \$\endgroup\$ – Chris Stratton Jul 24 '16 at 4:19
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Also consider LoRa sub-G RF modules: long-range, battery powered (ULP), ISM band, affordable price. Many modules are available (though chipset mostly by Semtech, seems also Microchip is offering recently). Quick search returns:

https://www.cooking-hacks.com/documentation/tutorials/extreme-range-lora-sx1272-module-shield-arduino-raspberry-pi-intel-galileo/

http://modtronix.com/inair9.html

http://www.seeedstudio.com/s/LoRa.html

https://www.loriot.io/modems.html

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You could try the CC1310 Launchpad ($29) and EasyLink Network processor SW, which allows you to connect to the Launchpad over UART and use AT modem commands to send RF data. The LRM (long range mode) will support more than 1500m. It will be lower power than your current solution with standby currents of 0.6uA and 12.9mA to Tx at +10dBm.

The CC1310 Launchpad is available here: http://www.ti.com/tool/launchxl-cc1310

Instructions on software (building and downloading) is here: http://www.ti.com/tool/cc13xx-sw

If you want to avoid step 1 and 2 (installing TIRTOS and CCS) you can use CCS Cloud: http://dev.ti.com/tirex/#

More info on the AT modem interface can be found here: http://processors.wiki.ti.com/index.php/SimpleLink-EasyLink#rfEasyLinkNp_AT_Network_Processor_Example

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  • \$\begingroup\$ Very interesting! I hate to start over on what I've already done, but it very well might be worth it and I'll take a hard look at this. Thanks. \$\endgroup\$ – bcsteeve Jul 23 '16 at 22:23

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