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"You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat."
Sending data over long distances is like magic, and now you can be a magician with this range of powerful and easy-to-use radio modules. Sure, sometimes you want to talk to a computer (a good time to use WiFi) or perhaps communicate with a Phone (choose Bluetooth Low Energy!) but what if you want to send data very far? Most WiFi, Bluetooth, Zigbee and other wireless chipsets use 2.4GHz, which is great for high speed transfers. If you aren't so concerned about streaming a video, you can use a lower license-free frequency such as 433 or 900 MHz. You can't send data as fast but you can send data a lot farther.'
Also, these packet radios are simpler than WiFi or BLE, you dont have to associate, pair, scan, or worry about connections. All you do is send data whenever you like, and any other modules tuned to that same frequency (and, with the same encryption key) will receive. The receiver can then send a reply back. The modules do packetization, error correction and can also auto-retransmit so its not like you have worry about everything but less power is wasted on maintaining a link or pairing.
These modules are great for use with Arduinos or other microcontrollers, say if you want a sensor node nework or transmit data over a campus or town. The trade off is you need two or more radios, with matching frequencies. WiFi and BT, on the other hand, are commonly included in computers and phones.
These radio modules come in four variants (two modulation types and two frequencies) The RFM69's are easiest to work with, and are well known and understood. The LoRa radios are exciting and more powerful but also more expensive.
First there is the 900 MHz radio version, which can be used for either 868MHz or 915MHz transmission/reception - the exact radio frequency is determined when you load the software since it can be tuned around dynamically. We also carry an RFM69HCW 433 MHz version here. These are +20dBm FSK packet radios that have a lot of nice extras in them such as encryption and auto-retransmit. They can go at least 500 meters line of sight using simple wire antennas, probably up to 5Km with directional antennas and settings tweakings
For more details, check out the product pages for various models at
- http://www.adafruit.com/product/3070
- http://www.adafruit.com/product/3071
- http://www.adafruit.com/product/3072
- http://www.adafruit.com/product/3073
PCB files for the Adafruit RFM/LoRa Radio Breakouts. The format is EagleCAD schematic and board layout
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Designed by Limor Fried/Ladyada for Adafruit Industries. Creative Commons Attribution/Share-Alike, all text above must be included in any redistribution. See license.txt for additional information.
