Digital Signal Overview for Amateur Radio Enthusiasts

There are a small number of enthusists who have a proper understanding of digital signal processing and what it means in the ham radio world. Manufacturers often brag about the fact that their product can process digital signals and operators who have used it know the value of it. However, the ones who don’t understand the real deal behind the digital signals are the amateurs.

Understanding the Basics of Digital

To understand what digital signal processing means and what it does, you will need to have a good guess what anything ‘digital’ does in the first place. In order to completely understand what digital means in the ham world, the simplest approach will be considering the RF waveform. The RF signal in simple words is an Alternating Current signal. This means that the electrons flow between the circuit in a back and forth direction. While the flow of the electrons is in a forward and backward direction, the voltage that passes through reverses its polarisation. The reversal in the polarisation helps with the flow of electricity in one direction and then in the other, thus giving it the name ‘Alternating Current’. In simple speak, voltage is referred to as positive and negative and is depicted in waves. The height of the wave is the voltage of the signal that passes.

When the waveform is looked at from the digital side, the data fed into the wave is more numerical thus giving it a square-like shape in the waves. The greatest thing about the digital waveform is that every dissection point of the wave is easily measurable making it robust for processing information. The digital wave will be able to comply with the intentions of the user making it fast and efficient. A processor that is used in the digital signal processing of radios is like a computer in itself. The only difference between a computer’s processor and the radio processor is the speed at which it can process digital/numerical signals. When processing digital signals, it cannot function by itself. There has to be a continuous conversion between digital and analog to maintain the clarity of the receiver’s audio. The digital signals will be flawed if they are received directly by the receiver on the other end. Circuits, filters and other tools are used in the conversion of the digital signal into analog waveforms for better reception.

Application of Digital Signals

The digital signals that are used in ham radios are used in many ways and have numerous purposes. Digital Signal Processing or DSP is applied soon after the intermediate filter stage. The Intermediate Filter along with the DSP is used in real-time to perform any of these functions:

  • Undesirable mixing products are weeded out of the passband
  • Noise is removed by algorithms that are contained in the DSP
  • Any offending signals are identified and filtered
  • The width of the bandwidth can be modulated to fit the different operating modes like AM, FM, CW or Digital
  • The operator processes filter shapes and effects

Advertisement

Comments are closed.