Amature Radio Using an RTL-SDR

     I recently began exploring the world of amateur radio by purchasing a software-defined radio (sdr) which allows one to view a wide band spectrum of radio frequencies (RF). Mine goes from 70 MHz to about 2300 MHz. Although this is just shy of being able to see wifi, there is an sdr that has this capability for about 20 times the cost (HackRF One) and is for the time being far too costly given the general uncertainty involved with sdr.

     The uncertainty I'm referring to is what happens when you ask for an inexpensive device that can detect a range as wide as 100KHz-6GHz (I think this is the hackrf one range). This is an extremely tall order. In fact most radio devices have rapidly degrading specs when pushed outside of the range they were designed to operate within. I can think of two good reasons for this, the first being cost, it is more cost effective to fabricate a chip designed to operate at a narrow frequency band rather than having wideband capable devices and only using a small portion of it. The second reason is that the radio spectrum is highly regulated (thanks FCC). In fact once you get started in transmission it becomes very easy to break federal law, for the time being I'm staying away from any significant form of transmission and am at no risk of breaking the law though. Because of this, and the fact that most radio equipped devices are two way transceivers (with broadcast and receiving capabilities) having RF chips that can only operate within their legal range is a logical result.

     I think I remember reading somewhere that rtlsdr was originally used to receive DVBT signals however someone along the way found out that these devices have reasonable performance far outside the range of DVBT bands. The radio works by converting the radio signal into a datastream that goes over USB to software on the host computer which is ultimately responsible for demodulating and processing the datastream. This allows for the creation of software tools which implement new or more expansive protocols and analytic methods.
I don't have any really original or new results however I've been messing around with it enough to have a good amount of neat things you may be interested in.
Today for instance I set up an elevated V-shaped dipole antenna to receive NOAA satellite transmissions. This ended up working to some degree, I could visually observe a signal in the spectrum however the recording of the signal malfunctioned generating 100+ wav files instead of one wav file containing the same information. Because of this I don't think I got a large enough recording when the signal was strongest (when the satellite was near the horizon). Nevertheless, I was able to collect one large file which when fed into wxtoimg (https://wxtoimgrestored.xyz/) generating the following image.

Don't get me wrong, I don't know that this is actually an image, just that this is the result of decoding and assembling the data collected in the recording of a broadcast and fitting it to a map of the area it is supposed to represent. To be clear, the colored components were placed in the image during processing and not by the satellite.

Come to think of it, I might have made a mistake attempting to receive a good image in the middle of the night rather than doing so during the day when the sun could illuminate the earth. Nevertheless the image is a thermal infrared image and pretty featureless to my untrained eye.

I'll post an update about this later if I get a better quality image.

Below is an output generated by wxtoimg of the satellites (NOAA only) which will be passing over San Diego in the coming days.

Here is the satellite tracking application I am using.