Living in the modern age of cell phones, the new generation will not be familiar with the QRN. QRN is the background noises coming from natural sources that interfere with the radio waves. The QRN produces a buzzy sound in your radio signal. You tend to hear a very distorted sound. Often, people do not know about it, and they find themselves in trouble on how to remove this. Different radios give different intensities of QRN depending on their type. Ham radio is usually good at getting minimal QRN.
QRN usually comes from the disturbance or interference of lightning. The signal transmission, propagation, and reception are affected. It is quite unpleasing to the ears. You will try to get rid of the QRN as soon as possible, or the other way, you will not be using your radio.
There could be multiple factors leading to the formation of QRN in radio signal transmission. The atmospheric noise is a major contributor to the formation of QRN. A wide range of frequency disturbances is created (mostly between 100kHz to 20Mhz). RF noise is thus produced. Aurora, although a delight to see in the polar regions, does affect QRN. They produce low-level frequency changes, which are mostly below 0.1MHz
Radio signal transmission is affected intensively by geological activities. Earthquakes and erupting volcanoes increase RF noise, eventually increase the QRN. Cosmic rays are also a major contributor to increased QRN. All these come from space. The electromagnetic waves coming from the sun reach earth after about 11 years, commonly referred to as the sunspot cycle. The other galaxies, stars, and planets also produce these waves that interact with radio waves on the earth. Hence, produce increased QRN. Snow static and rain static also aid in increasing QRN. Although it sounds a little dumb, yes, it does produce QRN.
If you want to combat QRN to attain a smooth working of your radio, you will have to make some efforts. You might need to involve your neighbors in this task. Firstly, place your SDR play unit about 6 feet away from your PC. Make use of ferrite beads at the ends of the USB cable. Turn on soft filters in your radio and also lower your IF gain. Sound card EQ bands help to reduce the sound hiss. You can also try adjusting the bandwidth using the red lines present in SDR play and the AUX SP panel.
You might have to wait for a little to observe better transmission of the radio waves. If the issue persists, you can go for a balun-type long antenna wire. It should have a short 35 coax run. It improves the efficiency of the waves coming. If your QRN is not lowered after all your efforts, try switching the radio type. Short wave and two-way radios offer decreased QRN.
On the whole, QRN is an unwanted phenomenon, but we can not neglect its importance. It helps us understand the interaction of natural waves with our radio waves. One can not avoid QRN as it is a natural phenomenon, but we can reduce it to max levels by taking appropriate steps.