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8 Different Types of Surveillance Technology

Surveilance terchnology used for security of your family and properties.

It’s hard not to have a complicated relationship with surveillance technology. On the one hand, it can be used to protect people and property. On the other, it can be used to oppress.

Knowing the various types of surveillance technology doesn’t make the relationship any easier, but it does make it easier to adapt to a world increasingly full of it.

Related: 4 Different Types of GPS Technology

What Is Surveillance?

Surveillance is the process of gathering information by monitoring the signals emitted by a subject. The evolution of surveillance follows the types of signals that present relevant information.

Most animals reflect light and create vibrations as they take actions, so visual and audio surveillance are common in nature. As humans have started creating a variety of signals, we’ve also created ways to receive them – even when we’re not meant to.

The very first surveillance technologies were devices that enhanced human senses already tuned to these signals. Spyglasses and ear trumpets were both invented in the midst of the Renaissance Period.

The dramatic improvement in visual range was quickly adopted by sailors who could see to the horizon on the open sea. From there, surveillance technology has undergone an increasingly rapid transformation in forms and capabilities. 

1. Wire Surveillance

A man preparing to tap a wire to used for surveying suspects through wire.

The telegraph was the first new signal type that humans began to send. The telegraph dramatically sped up the rate of communication across vast distances after Morse built the first line from D.C. to Boston in 1844.

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It wasn’t long before people began wiretapping, or physically connecting a wire to another to intercept the signal, including the Union and Confederacy splicing into each other’s signals during the Civil War. The long wires provided ample opportunities to sneak an off-shoot to their own receivers.

Wiretapping spiked in relevance after the invention of the telephone. More information was being shared more rapidly, and both private and government entities had motivation to tap into and control that information.

The New York Police Department employed wiretapping against criminals using phone lines in 1895 in the first known government use of the technique.

The U.S. Supreme Court narrowly ruled that wiretapping was legal in Olmstead v. United States, 1928. The decision applied more broadly than just the wires themselves, so it starts an important legal history. Despite reversing the ruling in 1965, a law just three years later reauthorized its use by law enforcement.

Now, wire surveillance is fading into antiquity, just as wires themselves are. Wires are still necessary for a number of applications and can be tapped similarly to telegraph wires, but there are easier and more effective ways to surveil in most situations.

The term is still used when discussing modern wiretapping, but it typically refers to intercepting any telecommunications without regard for the method.

Related: 6 Different Types of Wireless Technology

2. Surveillance Cameras

A man installing a surveillance camera outside his front door.

Visual data is generated by photons, presenting clear information over longer distances than most other signals. A network of cameras linked to a bunch of monitors in a dark room is one of the first things that comes to mind when picturing a surveillance system.

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The first surveillance cameras were novel, but their actual usefulness was limited by video quality and recording logistics. In 1927, inventor Leon Theremin created and installed the first surveillance system for the Kremlin in Soviet Russia. Since that first simple surveillance setup, cameras have come a long way.

For decades, closed-circuit television (CCTV) held onto a reputation for poor quality video outside of high-priced installations thanks to the common 640×480 resolution. The recent development of Analog HD has vastly improved the quality of analog CCTV systems.

The digital revolution brought higher quality cameras and larger storage to match, though analog TVs remained popular for CCTV due to their reliability and security. 

A digital surveillance system can be relatively cheap and set up shortly after purchase by an untrained amateur. Popular models have nightvision, high-definition video and audio recording, internal and Cloud storage, solar charging, and more. 

3. Audio Surveillance

Two agents wearing headset for surveying their audio they investigate.

Audio surveillance began to rapidly evolve in the 20th century as scientists developed a greater mastery over electricity and signals. Telephones translated the audio into electric signals, but they couldn’t hear what was going on if they weren’t in use.

Early electronic equipment was large, so it wasn’t nearly as easy to hide. Even hearing aids of the time required large pieces of equipment. Since people could stay quiet when they saw the device, audio surveillance technology lagged behind cameras.

The one exception was the parabolic microphone. A dish around the audio receiver enables a parabolic microphone to capture audio from hundreds of feet away.

Despite being a bit bulky, the long operating distance makes it possible to stealthily listen to conversations. The sound quality is not the best, and it can be blocked by a thick wall or something else in the line of sight.

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Audio bugs began to appear at the end of World War II. The United States ambassador to Moscow received a replica of the U.S. seal in 1945.

The ambassador took it to the residence and hung it up, where it would stay until 1952. A lucky happenstance caused a radio operator to hear a conversation in the residence, eventually leading to the discovery of an audio bug inside the seal.

The clever device, created by the same Leon Theremin who made the first surveillance cameras, used the size of the seal to mask its own bulk and only powered on when radio signals were directed at it. The same technique is used in modern radio frequency ID (RFID) chips. 

The audio bug benefited more from the development of transistor technology than the parabolic microphone.

Smaller parts and better design continuously shrunk and improved the bug to the point that consumers can now spend about the cost of a video game to buy an audio bug that’s barely larger than a few coins with Internet connectivity and exceptional battery life.

A stealthy recording device that looks like a pen can record hundreds of hours of audio, as was critical to the plot of the film Zootopia. The most advanced microphones are now smaller than you can see without a microscope.

Many people have brought audio surveillance into their home by choice. Amazon’s Alexa keeps a log of all conversations with the virtual assistant by default, though there is an option to disable the feature.

Despite assurances that Alexa doesn’t listen when she’s not supposed to, the assistant has been known to still record conversations after being told not to, activate at odd times, continue recording after a command is finished.

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4. Internet Surveillance

A man doing internet surveillance at his office.

Although the increasing use and capacity of other surveillance technologies is worrisome, Internet surveillance is a different type of threat. The Internet is a wonderful tool; you’re likely only reading this article right now because of it. It’s a relatively affordable form of entertainment, social interaction, and information all rolled into one.

That makes us more likely to invite it into our home than if a company offered to install video and audio monitoring that they controlled. The number and types of Internet surveillance threats are always increasing, but here are some of the most important varieties to know.


If you use the Internet, you have almost certainly been tracked by cookies and encountered at least one warning that a website uses cookies to function. It’s possible to use the Internet without accepting cookies, but the overall functionality will be severely limited.

These pieces of information can follow the way a browser travels across the Internet. The information exchange allows websites to do things like keep you logged in or track the activity linked to a certain IP address. 

We accept these cookies because of their utility, but accepting cookies comes with risk. For example, knowing that a random IP address visited a store and purchased something from an account may seem innocuous, but other cookies may link that IP address with other accounts.

Since humans have a tendency to reuse passwords across websites, typical browsing habits can quickly link a compromised password to other accounts.


Internet surveillance, malware on the intermet.

Computers may seem smart, but for now they can only respond to commands. They feel no sense of loyalty to their user, so a piece of programming can make your computer share all of the information it generates.

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Malware refers to a number of different types of programs, like viruses and worms. Apps that spy on you can be considered a form of malware, but their specific delivery method warrants extra care.

Keyloggers were one of the first types of surveillance malware. The technique was in use before the Internet was created, but the ability to quickly transmit stored data was quickly adopted as an improvement.

Since computers were less likely to be online, keyloggers could collect inputs over time while the computer was offline. Consider how often people type important information like their social security number and payment card information into a computer, and the increased spread of keyloggers in the Internet era makes sense.

Devices are now more likely to be connected to the Internet at all times. Many laptops have audio and video recording devices built into them, and others have peripherals that stay attached.

Malware can take control of a computer and configure it to appear to be sleeping while the microphone and camera stay active, recording or transmitting data to the malware’s owner.

5. App-Based Surveillance

App-Based Surveillance used for contact tracers.

Smartphones have additional connectivity features that can be used to surveil a person to an extreme degree. While many apps can spy as a form of malware, others intentionally allow someone else to spy on the phone.

Companies and governments are likely to install some of these apps onto all of the devices in the office and the ones issued to employees. Someone with access to the device can also install them. In either case, the installation would not be obvious. 

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Users also intentionally give some apps the permission they need to monitor their activities. Even with the best intentions, a company whose app collects data from GPS, Internet activity, texting, and audio calls may lose all of that information in a security breach.

Whenever an app asks you for service permission, you should be aware of the risk before you click accept.

6. Aerial Surveillance

High Technology used for aerial surveillance to view places for an aerial vision.

Airplanes and helicopters in the air provide a much better vantage point for visual surveillance. Early after their invention, plane crews would fly over the target area and report back the location of enemy troop movements.

Advancements in radio technology let the crews report back at greater speeds. Improvements to the helicopter then made it a more viable option for surveillance supporting ground activities in areas where they don’t have to worry about anti-air attacks, such as law enforcement outside of warzones.

Some of our largest strides in aviation came from a desire to build a better surveillance plane. The SR-71 Blackbird was developed in 1966 to fly at high speeds and altitudes, and it remains the fastest plane to exist more than two decades after its retirement. 

Once, proper aerial surveillance was something that was out of reach for all but government entities, like the military or police force. Now, anyone can purchase a drone and have a floating camera.

They’re a bit noisy and conspicuous, but the price and operating cost are far below that of a helicopter for similar functionality. Enforcement agencies and militaries have been employing drones for similar reasons, though the more robust models cost more than the consumer versions.

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7. Satellite Surveillance

A satellite in space used for satellite surveillance.

Beyond the sky, you can still find more surveillance technology. With powerful cameras, satellites can see what’s happening on the surface of the planet from orbit.

Their vantage point is better than any possible within the atmosphere, allowing a single satellite to see details across vast regions. Not everyone can just launch a satellite into orbit, though, so control and usage of these satellite cameras are incredibly limited.

Satellites are also a critical component of cellular phone service. In normal cell phone calls, the radio signal is not encrypted between the tower and the satellite.

Intercepting the signal at this point is possible with the right equipment, effectively tapping into the wireless pathway. Using end-to-end encryption greatly reduces the risk of interception, though it won’t stop an app with audio permission from recording the call.

8. Scent Surveillance

K-9 police dog investigating a suspicious bag.

Smells are chemical signals that can linger in an area long after the primary source has been removed. Nature has had a better grasp on chemical analysis than humans for some time, so we still use nature’s scent technology for surveillance. Namely, we train dogs and other animals with a keen sense of smell to alert us to specific chemicals.

Breathalyzers that detect alcohol are the most common scent surveillance tech in use. Low public support for drunk driving and few other uses make it easy to incorporate breathalyzers into law enforcement policies without raising privacy concerns.

Police carry breathalyzers for field tests, and vehicles can have ignition interlock devices linked to breathalyzers. New advancements in breathalyzer technology allow breathalyzers to potentially detect a wider range of substances. 

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