No this isn’t the old “Direct sampling mod” that is out there on the web, this is the easier software mod that doesn’t involve pulling your RTL-SDR apart. As per the direct sampling mod, performance is still shit but with the right antenna it still works pretty well. As you all know these sticks don’t really go below 24 MHz but I have had mine down to around 5 MHz before performance dropped off. I’m not too sure if it is an antenna issue or it is in fact a limitation with the hardware itself but its better than nothing. (Hardware limitation is my guess)
As you can see above, there are a few stations broadcasting around 15.4 MHz. The signal strength isn’t that good during daylight hours and there is quite a lot of noise as I am based in an urban area. Performance can be improved by grounding the RTL device and coax shield at the feed point of the antenna. I have also wrapped my RTL device with a few layers of Aluminum foil which is bonded to the shield of the coax. Also removing the USB connector and soldering a long USB cable minus the shield wire to the device as well as wrapping the USB power lines around a ferrite bead can help with lowering the noise floor by a few dB. Ultimately a decent RTL device with a proper metal case and an up-converter powered from a clean source of DC power is your best bet along with being in a rural area if you want to use your RTL-SDR for HF reception.
The .dll file which you simply add to your SDR# folder can be downloaded here