Digital Radio and Audio Characteristics


Audio as we know it in the traditional analog modes such as FM, AM, and SSB are completely changed by the advent of digital radio. This analogy apllies to all modes weather it be: P25, D-Star, DMR, System Fusion, NXDN and the list goes on. As we knew two way radio from the past we would have to modulate our voice with the modes of: AM and SSB. More modulation equated to more peak power on the voice inflection swings of the human voice. As FM made its way to the market operators were slow to adapt to the change rather then modulating the career based upon voice inflections; the wave form was modulated by the frequency in a new form know as deviation or standard deviation.

Over deviation occurs when we close talk the microphone and exceed the pass band characteristics of the radio and or the system. This led to the experience of clipping or falling out of the pass band. This is a remanent of past that is still with us to this very day.

So you ask your self how does this digital stuff work and how is my voice processed by the system. Our radios have inside of them what is known as a vocoder. A vocoder is a device that takes the spoken voice; and then converts it over the air into digital format of: 10101010101010101010101; then the receiving radio converts the : 10101010101010101010, back to the spoken voice. This affects our audio in the following manner when you raise your voice a bit is sent telling the receiving radio to adjust its gain to a higher volume setting then this resets when the next transmission of another operator happens. This is why we frequently hear one station lauder then the other and visa versa.

So how do we properly operate in the digital mode the answer is very simple. We need to speak in our natural calm voice as we would be when talking on the phone. A good rule of thumb is if you must raise your voice back away from the microphone, if you are naturally a soft talker speak closer to the microphone but not too close as this creates lauder then necessary audio characteristics.

Lastly enjoy learn and have fun. I hope this helps in explaining how digital audio works and how we can best help to improve the digital experience of all