The need: “Make us a (radio frequency) transmitter for training.”
Doing that both cheaply and easily is often not entirely possible:
I’ve tried a number of different approaches but nothing seemed robust enough or cost effective enough for the average tech to produce. There are many RF chips and modules to choose from, but unless you want to take the time to hand solder surface mount components, you’re better off just taping down the button of a key fob.
Enter the Adafruit Feather 32u4 LoRa 433MHz:
At first glance this glorious little, long range transmitter looks like a one trick pony, but it hides a few surprises. The big eye brow raising moment was when I started playing around with the frequency agility of this device. It’s advertised as operating at 433 MHz, but in the example code given by Adafruit, you must specify the frequency. So after moving up and down the spectrum, it was discovered that the frequency actually ranges from 363 MHz to 569 MHz. Another transmitter Adafruit sells has similar characteristics around 915 MHz.
They’ve written an Arduino program that provides all of the functions below, wow!
1 - Transmit a single, set frequency 2 - Burst; specify frequency, length of burst, and how often to activate 3 - Spread spectrum; specify start and stop freq and hop interval 4 - Spread Spectrum Burst - This option allows you to turn your spread spectrum signal off and on like a burst transmitter. 5 - Spread Spectrum, Frequency Hopping, Burst - Allows the user to do everything entailed in option 4, but the signal will randomly jump between two specified frequencies. SIGNAL AMPLITUDE Specify an amplitude level between 5(weakest) and 23(strongest). This transmitter is a beast. Even 5 will blow you away.
We’re glad the Feather is meeting expectations (and has flexibility that isn’t in the product description).
And if you’d like to try this build yourself, check out the Feather, unless you are Boris and Natasha, that is.
Have you been working with Feather? Let us know your project ideas in the comments below!
As Jason notes in his blog:
Transmit responsibly. Using this transmitter could get you in some hot water if you are transmitting too powerfully in the wrong frequency range. Be careful and don’t break the law.