The modulation basics series uses Software Defined Radio (SDR) as the main hardware used for radio learning. SDR is very convenient for learning, since we can quickly experiment easily with different techniques without buying or building new hardware.
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There are a few common options for beginner SDR device. These will be sorted from least expensive to most expensive.
The RTL SDR is the device I started with, and is capable of following through all the modulation basics projects. This device is capable only of receiving. However, this is not a limitation for learning. Broadcasting often requires additional licenses from your government, so our courses focus only on receiving and decoding initially.
The kit above comes with an antenna as well. A good antenna allows you to receive better signal, with less noise. An antenna is also crucial for being able to receive AM and other lower frequency signals.
A lower cost option for those that want it. Without an antenna, you can often receive nearby FM radio stations reasonably clearly. This product could also be a good option if you already have a compatible antenna, or plan on building your own antennae.
This device was designed by the team over at Great Scott Gadgets. While I haven’t used it myself, many radio experimenters find the hardware quite capable.
There are two main things that set the Hack RF well above the RTL SDR in capability.
First is the much wider frequency range. The RTL SDR can operate only from 500khz to 1.7ghz with 3.2mhz of bandwidth. Essentially this means that after tuning to a frequency, you can also pickup frequencies within this range as well. Some forms of modulation actually require this, as information is sent across a spectrum of frequencies.
The Hack RF One has a wider frequency range at 1mhz to 6ghz. It also has a greater bandwidth at 20mhz.
The feature many people choose the Hack RF for, however, is the ability to transmit. For people that know they want to send data in the future as well, the Hack RF could be a good upfront investment.
Once you have selected and received your device, you’re ready to search for a nearby FM station.
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