Software Defined Radios or SDRs offer a high level of flexibility and adaptability compared to traditional hardware based radios. However adding all these 1s and 0s to the already complex and beautiful art of MHz and dBs can be daunting. We wrote this post to help you start your journey using software defined radios (SDRs) in 5 simple steps.
If you’re scratching your head wondering “what the heck are SDR radios or software defined radios anyways?!?” check out this post that describes SDR radios compared to traditional radios.
Without further delay, here is our beginner’s guide to get started using software defined radios!
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Step One: Get a good laptop with a strong battery
The first step in getting started with software defined radios is the find the right host computer. You will need a decent laptop with a long lasting battery to manage all that software goodness of your SDR. There are a couple reasons for this recommendation, some of which may not be terribly obvious… especially if you’re new to RF engineering.
First, having a laptop with a battery will allow you to take your SDR setup on the go. Many RF signals are difficult to sniff out indoors. GPS is a great example of a ubiquitous but very weak RF signal. The second reason to go for a battery powered laptop is that noise from an AC power supply can wreak havoc on your software defined radio depending on the frequencies you’re interested in operating.
PRO TIP: Add a ferrite chock to any cables that need to be connected to your laptop to help minimize noise interference.
Finally, if the laptop you’re using is your daily driver, it may be a good idea to install and use a good Virtual Machine (VM) to protect your machine.
Step Two: Pick the right Software Defined Radio (SDR) based on your intentions
There are a few key items to consider when deciding which SDR or software defined radio is the right one for you. There are numerous options that span a full spectrum of budgets and functionality. Some of the factors that are important to consider when choosing a software defined radio are budget, receive (Rx) or both transmit (Tx) and receive, frequency ranges, output power (for transmit capable SDRs), etc.
For this beginner’s guide, we’re going to look at two great SDRs for getting started: the RTL-SDR dongle, and the HackRF One.
RTL-SDR
The RTL-SDR is a basic receive (Rx) only software defined radio that is easy on the wallet. It is a great choice for someone brand new to RF engineering and SDRs.
HackRF One
The HackRF One is a very capable software defined radio that is capable of both transmit and receive (Tx/Rx). The HackRF One delivers good functionality for an SDR under $500.
PRO TIP: Pay attention to the type of local oscillator used in your SDR. TCXO will generally perform better than simple XO or VCXOs
Step Three: Make sure your running the latest version of firmware
Like any other electronic device that you own, you should always keep the firmware updated. This is no different for software defined radios. When you first fire up your SDR, be sure to go grab and install the latest firmware. Doing so will likely improve the stability and security of your software defined radio.
For those using the HackRF One SDR, you can find the latest firmware here. If you need help installing, check out this great guide from the folks over at Secure Solutions.
If you’re running the RTL-SDR, you can grab the latest firmware here.
PRO TIP: If your running the HackRF One, a recent firmware updated added the ability to perform frequency sweeps
Step Four: Don’t forget a good antenna for your software defined radio
Some SDR kits, like the HackRF One SDR mentioned above, come with antennas while some don’t. There’s nothing worse than opening up your presents on Christmas morning and then realizing you can’t play because someone forgot the batteries. Don’t let this happen with your software defined radio. Check to make sure your kit includes an antenna, or pick one up if it doesn’t.
As you get more familiar with your SDR and want to start pushing the limits, you may want to upgrade from the included antenna. Some important things to consider when picking an antenna for your SDR is typology (omni-directional, or directional), active or passive, frequencies of operation, etc.
PRO TIP: Pay attention to all of the RF connectors, cables, and adapters (for example: SMA to BNC). Cheap connectors and cables can wreak havoc on sensitive RF systems, especially as frequency increase.
Step Five: Jump start with open-source software defined radio projects
Most of the functionality of your software defined radio is… well… controlled by software. Many of the most popular software defined radios have strong open-source resources to get you started.
These projects can range from creating your own FM radio, to using your software defined radio as a spectrum analyzer. There are even projects to sniff cell phone IMSIs that are near (note: this could have serious privacy and legal concerns, so use at your own risk).
If you’re running a HackRF One, here is a great resource for open-source project files for your SDR. If you’re using the RTL-SDR, here is a link to fun open-source projects as well.
If you’ve already jumped on the SDR bandwagon, we’d love to hear your top tip to help someone get started! Leave a comment below.
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