RF Modulation: Crash Course For Hackers

When you’re looking to add some wireless functionality to a project, there are no shortage of options. You really don’t need to know much of the technical details to make use of the more well-documented modules, especially if you just need to get something working quickly. On the other hand, maybe you’ve gotten to the point where you want to know how these things actually work, or maybe you’re curious about that cheap RF module on AliExpress. Especially in the frequency bands below 1 GHz, you might find yourself interfacing with a module at really low level, where you might be tuning modulation parameters. The following overview should give you enough of an understanding about the basics of RF modulation to select the appropriate hardware for your next project.

Three of the most common digital modulation schemes you’ll see in specifications are Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), and LoRa (Long Range). To wrap my mechanically inclined brain around some concepts, I found that thinking of RF modulation in terms of pitches produced by a musical instrument made it more intuitive.

And lots of pretty graphs don’t hurt either. Signals from two different RF dev boards were captured and turned into waterfall and FFT plots using a $20 RTL-SDR dongle. Although not needed for wireless experimentation, the RTL-SDR is an extremely handy debugging tool, even to just check if a module is actually transmitting. Continue reading “RF Modulation: Crash Course For Hackers”

DIY ESP8266 Development Board

Those small, super-cheap, ESP8266 modules are being installed everywhere, creating all sorts of frivolous internet connected thingamajigs. But consider this period as a training ground of sorts, as hackers smarten their chops on figuring out how to get the best out of this IoT gravy train. Right now, getting the ESP8266 to work requires a fair amount of work and to make things easier, [Abdulgafur] built a ESP8266 development board.

The dev board lets the user connect the ESP8266 to a PIC micro controller as well as to a host PC. In addition, it hosts several peripherals such as a 2×16 LCD display, 4 push buttons, couple of indicator LEDs and some GPIO’s broken out to a header. PC communication is via a FT232RL USB-UART converter over a Mini-USB connector. There’s also a few bi-directional level converters to translate between 5V and 3.3V and pull-up resistors for the ESP8266.

As of now, the dev board only supports the ESP8266-01 module. A nice upgrade would be to add support for other ESP8266 modules too. Maybe a separate, 3d printed, pogo pinned, test fixture for the other modules. If you plan to build you own version, [Abdulgafur] has the schematic, PCB and BoM available for download, although we couldn’t spot the PIC code, so you might have to ask for that. And it would be a good idea to remove the GND copper pour from under the ESP8266 footprint.