As a first-year sound engineering student, and a music enthusiast, I was under the impression that I was all done with physics and science.
Little did I know that I would have to understand audio and digital signals as they would affect my career. I disliked how complicated all of this was made to be, and so in this article, I wanted to break down digital and analog signals, what the differences are, and the applications of each.
The difference between an analog and digital signal is that with an analog signal, the waves are continuous (continuously changing) and smooth over time. Within any range of an analog signal wave, there are infinite values. Additionally, analog signals convert information into waves of varying amplitude and frequency. Digital signals on the other hand are represented by discrete columns and convert information into discrete values. They have a finite possible set of values that the signal can be converted into.
Analog vs Digital: A comparison
|Digital Signals||Analog Signals|
|Less stable, but also less prone to noise||Very easily impacted by the effect of noise|
|Digital signals are usually represented as square waves||Analog signals are usually visually represented as sign waves|
|Digital signals tend not to be affected during data transmission.||Analog signals may be affected during data transmission.|
|The accuracy of digital signals tend not to be adversely affected by noise||The accuracy of the analog signals could be adversely affected by noise|
|Equipment comprising transistors, logic gates, and micro-controllers are used in Digital circuits.||Equipment including resistors, Capacitors, Inductors, Diodes are used in analog circuits.|
|Digital signals have two or more states and exist in binary form.||Analog signals are continuous and vary through time.|
|Troubleshooting of digital signals is easy||Troubleshooting analog signals can be challenging|
|Digital signals use less power.||Analog signals use more power.|
|Digital signals use discrete values to represent the data.||Analog signals use continuous values to represent data.|
What is a signal?
A signal in simple terms is a quantity that can present and convey information.
Signals are passed between devices to send and receive information.
Everyday Examples of wave signals include:
Fiber optic cables
Commonly known for pairing signals to your TV.
Send information coded in a beam of light down a glass or plastic pipe.
Radios receive signals via radio waves.
Send and receive voltage signals.
Characteristics of Analog Signals
Analog signals are smooth and continuously changing – there are infinite values they can take even when those values are in a certain range
Analog signals can record the exact waveform that was received and delivered by a device.
Characteristics of Digital Signals
Digital signals exist as on or off pulses.
On pulses are represented as the number 1
Off pulses are represented by the number zero
As the values are more clear cut they are less prone to interference and are more replicable than analog waves, as they do not need to replicate every part of the wave perfectly. They simply need to know that the signal is on or off
Source: Instrumentation tools:
Is analog better than digital?
This is a very controversial topic
Regardless of where you stand on the discussion of the two signals, both digital and analog have their merits. When it comes to discussing the two types of signals and accuracy, analog is more accurate than digital.
Whether referring to a device or a piece of music, analog is more accurate because it provides a better representation of the recorded information. In the case of recorded sound, analog offers the true representation of the sound, whereas digital is not a recording of the actual sound and is not as exact as analog information.
Digital music is getting better and better. High-def streaming sources are definitely getting better. However, when it comes to critical listening-people are analog by nature. The human ear responds to small variations in sound pressure or amplitude when it comes to listening
As a result, because human beings are analog- the interface to people should be analog. When it comes to the critical listening of music, analog reproduction is the better method for reproducing musical content.
Every digital systems utilize audio technology. For example preamplifiers, power amplifiers, and speakers are analog technology. Digital audio will always be limited by the fact that there is a finite amount of samples that you can take per second.
So even if you double the sample rate, you can always keep doubling, but there will always be space between the samples.
Analog on the flip side does not have this issue. Therefore analog tape can catch infinitely small variations in amplitude.
so analog devices such as magnetic tape can capture a smooth representation of the sound wave. Whereas digital, only has a certain value and the next one and can not capture values in between those predefined values.
The major drawback to tape however is the noise floor – because there is always an inherent noise associated with magnetic tape.
What’s easier digital or analog?
It can be difficult to get one’s head around the full signal flow of digital recording until you understood analog recording correctly from a multi-track point of view.
You can not understand or appreciate the digital system until you have understood the analog format.
The analog realm is a physical medium – you can see it and measure it – you can see your analog signals moving, You can see cables and wires and voltage units, etc.
If you can get the analog side of the signal chain nailed, this gives you a better stepping stone into digital.
So a good understanding of analog allows you to easily transition into digital.
You could, I guess get away with understanding digital-only, but if you get a job in an analog recording studio, you have a mountain to climb.
WHY IS ANALOG MORE ACCURATE THAN DIGITAL?
The following section will present a couple of examples of what analog is and why analog is more accurate than digital.
We can relate this to a watch. An analog watch is likely to be much more accurate than a digital one because it uses high-precision movement to measure passing time, and generally, the most expensive watches in the world are analog ones.
When considering sound signals, analog recording is made up of bumps and dips and as mentioned earlier in the article, is believed to be the true representation of the sound at the moment it was recorded. Digital is not a recording of the actual sound, but rather a combination of zeros and ones combined in the form of machine language, it is not as exact as analog information.
Although analog is more accurate, digital is still used because unlike analog, it is non-linear and can be edited or played back at any point. This is a huge timesaver and results in better longevity.
Whilst digital signal trumps analog in various other aspects, accuracy is not one of them. Think of it this way, analog signals correspond the variations of air pressure of the original sound, and digital signals are a series of numbers that correspond to the sound’s continuous variations. Digital signal numbers need to be reconverted to analog signals before they can be listened to.
SIGNALS. WHAT ARE THEY AND HOW DO THEY RELATE TO ANALOG AND DIGITAL TECHNOLOGY?
Technologically speaking, analog and digital can be broken down into signals. A signal is an electrical current that is used to carry data from one system or network to another and we encounter different types of signals in our daily lives.
Whether you are watching television, listening to music, scrolling through your social media, or simply talking with a friend over the phone, both analog and digital signals cannot be avoided.
As we have witnessed throughout the decades, people accept the adoption of technology easily enough, but discussion about the two types of signals can be a delicate one. Examples of digital devices are hard drives, CD recorders, and most processors in a computer. Land-line telephones, VCR’s, photocopiers, and record players are all considered analog devices.
SIGNALS AND SOUND. CONVERTING ANALOG TO DIGITAL AND HOW TO IMPROVE ACCURACY
The accuracy of a converter relates to how many bits, from conversion to conversion, can be duplicated. In other words, accuracy reflects how true the ADC’s output reflects the actual input.
When using an analog-to-digital converter (also known as ADCs) it is important to understand the accuracy of the system, and simply increasing the performance or resolution
of the ADC will not particularly improve the accuracy. ADC errors need to be minimized in order to improve accuracy when converting from analog to digital.
To minimize the ADC errors with regards to the external environment, be wary of the reference voltage and power supply, remove the analog-input signal noise, match the ADC dynamic range to the maximum signal amplitude, and match the analog source resistance.
DON’T CONFUSE ACCURACY WITH RESOLUTION
An easy mistake to make is to confuse accuracy with resolution. The terms accuracy and resolution are not the same but are related and should not be used interchangeably. Think of accuracy and resolution as cousins, but not twins.
Simply put, accuracy is just an error, or how much the value under deviates from its true value. Accuracy error is often also referred to as sensitivity error. Resolution is simply how finely the value measured can be represented or displayed.
Even though a system may have 12 bits of resolution doesn’t particularly mean it will be able to measure a value to 12 bits of accuracy.
It is important to understand that both accuracy and resolution influence the signal chain, and it must be kept in mind that not all components are created equally. Increasing the performance or resolution of a ADC converter will not particularly increase the measurement accuracy. Other aspects such as front-end noise need to also be considered.
SAMPLING RATE AND BIT RATE
When you download digital music, it’s likely that you will be given the option of downloading the same track at different bit rates. The bit rate is the amount of information captured each time the track is sampled.
A higher bit rate means that more information is captured and the analog information is converted into digital information more accurately. Higher quality tracks may have a higher bit rate, but the tracks will be a bigger file and take up far more space on your computer, which means it will also take longer to download.
It’s very common for music to be digitally converted for CDs and MP3 tracks with a sampling rate of 44.1kHz (about 44,000 times per second). The sampling rate needs to be rough twice the highest frequency of sound in your wave, and since human hearing is limited to about 20kHz, that suggests we need a sampling rate of at least 40kHz.
The typical bit rate for an MP3 track is around 128kbps (128,000 bits per second), though higher-quality tracks have a bit rate between 128kbps and 256kbps (up to 256,000 bits per second).
Which rate you choose will depend entirely on the product that you intend to deliver. It can also depend on the type of engineer working on the project. Some engineers trust that today’s sample rate conversion is good enough and it’s not necessary to choose a rate based on keeping the math simple. For these engineers, a higher rate is generally considered better.
Although we live in a digital world, we are starting to see a resurgence in analog technology. From a steady increase in the sales of vinyl records and paper books, to an increasing appeal of physical toys, digitally-minded youngsters are being won over by companies such as Lego, whilst more traditionally digital companies such as Nintendo are also seeing the value of the production of physical figurines.
The resurgence of Analog Devices
The resurgence in analog could be related to the issue of ownership. Digital music and games are instantly accessible through apps and consoles, yet they remain intangible. Analog therefore offers a more personal experience and connection to music, books and games.
In Japan, we have seen a steady increase in the sales of vinyl throughout the past decade, and it doesn’t seem to be slowing down. It won’t be long until the resurgence of vinyl will see the analog form of consuming music overtake CD sales.
The UK is also set to see the best year in three decades with regards to vinyl sales in 2020. In 2019, Rolling Stone said that “Vinyl records earned $224.1 million (on 8.6 million units) in the first half of 2019, closing in on the $247.9 million (on 18.6 million units) generated by CD sales.
The global vinyl market size is projected to reach $481.5 million by 2026, from $208.3 million in 2020, at a compound annual growth rate of 15% during 2021-2026. This figure could however change and swing either way. Considering the current climate and the lack of live music throughout 2019 and 2020, these challenges are likely to affect the projections for the coming decade.