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RTL-SDR vs NESDR – which one should I buy?

In this post we take a closer look at two popular SDR dongles – and . We will explain the differences between the two and make recommendations on which one to buy.





is one of the most popular SDRs on the market today. In fact it is our top SDR pick for those looking to get started with SDR on a tight budget.





is based on the same chipset, namely the . As a result, internally they feature the same radio receiver technology. These two SDRs are able to receive signals in the frequency range of 25 MHz to 1750 MHz. Also, their performance specifications in this frequency range is identical.








What’s the difference between the RTL-SDR and the NESDR?





There are a few main differences. Without further ado, let’s get right into the details:





DIMENSIONS





is narrower than . This means that you can insert NESDR’s into the USB ports of side-by-side. You can’t do that with .









So is that an issue?





Not really. In fact we recommend not to plug the SDRs into the USB ports directly. There are a couple of reasons for that.





Firstly, any RF noise from the laptop or will get picked up by the antenna and show up in the output of the SDR. This is something that is very undesirable. Our recommendation is to use a USB cable to physically separate the USB dongle from the laptop. And in that case, the wider is not an issue.





Secondly, if you drop your laptop with a USB dongle attached, it will stress the USB port and potentially damage it.





CLOCK OSCILLATOR





has a TCXO (Temperature controlled crystal oscillator) has an accuracy of 0.5 ppm (parts per million), while has an accuracy of 1 ppm. What does this mean and what’s the impact?





Let’s say you tune to a frequency of 1 GHz with both SDRs. With , there will be a frequency error of up to 500 Hz. In the case of the RTL-SDR, the frequency error can be as high as 1000 Hz or 1 kHz. This means that the signal you’re monitoring can be offset from where you’re tuned to. If you’re trying to detect and/or demodulate the signal, this will result in errors.





DIRECT-SAMPLING MODE





The frequency range of the tuners used in and is 25 MHz to 1750 MHz.





implements a direct sampling mode whereby signals at the RF input can be fed directly to the analog-to-digital converter (ADC). This means that you can view signals in the range of 500 kHz to 28 MHz.





Here is a video that shows High Frequency or Medium Wave AM broadcast radio being received with







processing HF and MW signals



It’s important to point out here that the performance of in this direct sampling mode and frequency range below 28 MHz is not as good as performance in the range 25 MHz to 1750 MHz. In fact the team at Nooelec recommends the use of the for viewing signals below 28 MHz.





BIAS TEE





has a built-in bias tee that can be enabled by software. It provides 4.5 volt and up to 180 mA of current. We have covered Bias Tees in previously. A bias tee allows you to power – for instance, one that is mounted close to the antenna on the top of a tower.





Conclusion





In this post we have looked at both and from Nooelec. The main differences between the two are captured in the table below.





Dimensions3.54 x 0.39 x 0.39 inches5.12 x 2.56 x 0.43 inches
TCXO accuracy0.5 ppm1 ppm
Direct SamplingNoYes
Bias TeeNoYes




If you are looking for a low budget SDR that goes down to 500 kHz for HF monitoring is the one you should buy. Or if a bias tee is required for remote operation – once again, should be your pick.





However, if you’re looking for better frequency accuracy although with a limited frequency range, buy . If you want to monitor the entire frequency range down to 300 Hz we recommend buying the upconverter as well.




















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