Friday, January 20, 2017

RTL-SDR Blog V3 Arrived

I recently bought a new RTL dongle that supports Direct Sampling that allows frequencies less than 40Mhz. In particular, the model I ordered was the RTL-SDR BLOG V.3. DONGLE that was really cheap compared with other solution. It still can't reach the quality of the other more expensive receivers, but it still a step up. The Dongle comes with a long external antenna.

RTL-SDR Blog V.3 Dongle
The RTL dongle.

So, the question now is how better is from my old SDR. I did a check with the RTL power tool to see what is the difference. My old SDR Dongle (Fitipower FC0013) has coverage from 22 to 1100 MHz. The new Dongle RTL Blog V3 a has Rafael Micro R820T has coverage from 24 - 1766 MHz, but it also contains Direct Sampling that allows for High Frequencies. A word of warning here, the reception using Direct Sampling is very bad, especially if you connect the antenna without a filter band or/and preamplifier. I did experiments using the rtl_power, and the results showed much more gain for the new Dongle. All the experiments were done using the internal antenna inside the home. I don't have yet the ferrites installed (post is really slow here), but you can get an idea how the dongles are doing. Here are the plots (click to zoom):

Fitipower FC0013 24-500 MHz Band survey.
Fitipower FC0013 24-500 MHz Band survey.

RTL Blog Rafael Micro R820T 24-500 MHz Band survey.
RTL Blog Rafael Micro R820T 24-500 MHz Band survey.

However, we should be interested in the Signal Noise Ratio rather to actual power received. The new Dongle is more sensitive, but it also gets more noise. I'm waiting for the ferrite to arrived to get a clear view the noise of the new Dongle. Here is a screenshot receiving HF:

Receiving HF with a lot of noise.
You can buy the receivers here: SDR Blog Receiver with Rtl2832u ADC Chip.