Understanding the difference between digital and analog signals can be a bit challenging when determining their suitability for specific applications or industries. In this week’s Two-Way Radio Tip, we will delve into the distinctions between analog and digital technology and explore their respective advantages and disadvantages in the context of two-way radios.
Analog technology was the pioneering technology when two-way radios were introduced to the business world in the mid-1930s. Even today, analog remains the primary form of wireless communication technology. However, an increasing number of large industries that rely on two-way radio technology are adopting digital technology.
How Analog Technology Works
Both analog and digital radios transmit signals over a radio channel using carrier frequency waves, typically Very High Frequency (VHF) or Ultra High Frequency (UHF). (Editor’s note: Next week we will delve into the differences between VHF and UHF.) In analog radios, signals are sent via frequency modulation (FM), encoding a voice signal within the carrier wave. These waves are “sinusoidal,” meaning they consist of continuous, smooth oscillations. As the voice modulates, it alters the frequency of the wave. The receiving radio then demodulates this frequency to recreate an understandable voice message. In essence, analog technology produces an actual representation or “analogy” of the voice, which is the origin of the term “analog.”
When it comes to two-way radios, you can understand how analog technology functions by observing how the analog signal degrades as the radio moves farther away from the transmission point. A typical analog signal progressively deteriorates as it approaches its maximum range, eventually becoming indistinguishable white noise. In contrast, digital signals will abruptly cease once they reach their farthest transmission point.
How Digital Technology Works
Digital technology differs significantly from analog technology. Instead of encoding voice signals as representations on a carrier frequency wave, information is translated into a binary format consisting of zeros and ones, with each bit representing two distinct amplitudes. Unlike analog signals, digital signals do not convey a smooth, continuous signal. Instead, they are transmitted in non-continuous block segments, resulting in a precise and square signal. Thanks to this technology, digital two-way radios offer superior voice quality and do not degrade into white noise when reaching their maximum range. Instead, the signal simply drops off.
To better understand, the differences between Analog and Digital technology as it relates to two-way radios, we have created the following comparison chart:
Analog versus Digital comparison chart
| Analog | Digital | |
| Signal | Analog signals are a continuous, sine wave which can allow the radio to transmit a truer version of the vocal message. However, analog can have a difficult time penetrating physical obstacles. | Digital signals pick up processed signals which convert sound waves into mathematical bits. Digital radios can produce as much as 20% more coverage and are better at pushing through walls and concrete. |
| Carrier Wave | Produces a sine wave, which is a smooth, continuously oscillating wave. | Produces discontinuous square waves. |
| Power | Analog radios draw more energy, which can limit the battery shift life. | Digital radios use energy much more efficiently, increasing the lifespan of the battery. Digital radios can also be more powerful, where 1 digital Watt can be as powerful as 4 analog watts. |
| Technology | Analog radios use frequency modulation (FM) waves. These waves produce clear voice transmissions but cannot filter out other noises around the sender. They are also not able to transmit signals past a few miles. | Digital radios work by picking up a processed signal which turns sound into patterns of digits (numbers) rather than the radio waves. The digital signal creates more opportunities for feature-rich technology and can generally travel further. |
| Data Transmissions | Analog signals can experience noise deterioration during transmission cycle. | Digital radios have built-in error correction which reduces background noise, static, etc. |
| Compatibility | Analog radios are unable to work with digital two-way radios. | Digital two-way radios can be compatible with both digital and analog technology. This allows users to perform a digital migration, where you have digital radios working in analogue mode, until there becomes the time when all radios in the fleet are digital. |
| Cost | Analog radios are relatively inexpensive and easy to use. | Digital radios offer more capabilities so can be more expensive, but like most electronics the digital parts get cheaper and more efficient year after year. |
| Future | While analog two-way radios have been a mainstay for years, they have all but exhausted their possibilities as far as features. Manufacturers are no longer making analog only radios. | Digital radios will slowly take over the radio communication market because it provides many additional features, and better coverage. |