Background: Last night (and the night before) I was playing with my RTL-SDR and GNU-Radio again. Working with my FM Receiver, (which was working previously by the way), I detected that last night I was not getting any output? No matter where I tuned, I only got noise.
This had me flummoxed! This GNU-Radio flow-graph was working not more than a couple of months ago. What changed since then? The version of GNU Radio is the same (GNU Radio Companion 3.7.11). The Dongle is the same NooElec RTL-SDR Dongle.
CubicSDR: I then, just as a sanity check, decided to compare with CubicSDR. With Cubic-SDR and the same RTL-SDR Dongle connected to the same front panel USB, I immediately got an output when tuned to the right Radio-station frequency.
Connect to Motherboard's USB: Then just to test, I turned off CubicSDR. Unplugged the RTL-SDR Dongle from the front panel of the PC and put it in one of the four USB sockets that are directly attached to the motherboard and can be reached from the backside of the PC. I restarted GNU Radio and executed the same flowgraph for the FM Radio. And this time I got an output. I could listen to some radio stations.
So, it seems the front panel USB sockets are maybe not providing enough power for the Dongle to work? I googled how much power the Dongle draws? and apparently it varies from model to model.
Does running a GNU Radio flow graph stress the Dongle more, so that it has to draw more power from the USB? Because the CubicSDR was working without a problem when the RTL-SDR Dongle was connected to the same front panel USB where GNU Radio flowgraph was not giving any output. (The flowgraph is the same as in my first question, also shown below at the end of this post).
I am looking to buy, then, an USB extension set, to power the RTL-SDR externally. (As I am worried, it might be drawing too much power and could possibly damage the Motherboard, as happened to this guy's phone? And also to have the Dongle running stably.)
On a further note, if it is indeed a power issue, then it is a tricky little pitfall that a n00b like me can fall in. Because you get no error, no warning. The flowgraph runs. Everything seems to be working, except you get no output. You can never be really sure, if your flow graph has a bug or your Dongle is not working. How (IF it is even at all possible) can one be sure that the Dongle at least, is working correctly when testing different flowgraphs, applications, etc?