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In 1895, the first form of radio was invented by Gugliemo Marconi. Sending morse code over airwaves to a receiver over a kilometer today, Gugliemo set the stage for what is now a form of communication that exists all around us, in every possible way.
At all times of day, radio frequencies are dancing over, around, and through every one of us as various devices and stations communicate with one another. Most people would recognize radio as being a means for transmitting 90s one hit wonders and bad audio-only advertisements, but there’s so much more to this technology than commercial use.The amazing thing about radio operation is that it is next to impossible to track who is listening in on a station being broadcast. As such, tuning in on unencrypted frequencies is a simple matter of getting the right equipment and pointing at the right station. Some frequencies are more easily accessed with particular equipment, so proper research before setting out to listen in is a must. Setting up antennas and receivers to better boost your ability to listen in on specific parts of the frequency band can also help improve your radio listening experience, wherever you may be.
Because these radio stations are broadcast over open airwaves, anyone can listen in on transmissions from sources like truckers, maritime vessels, search & rescue teams, and even roving satellites. But before we get into any specifics, a word on the legality of radio frequency monitoring.
Legal Considerations
Listening to communications of any kind is a legitimate and time-honored hobby for tech enthusiasts the world over, but as with any information gathering techniques, it’s important to remember to do so without infringing on the privacy of others.
Ham radio operators are usually licensed in their country of operation, so interacting with the government about your interest in radio listening is a must. On top of that, the general rule of thumb for radio listening is that you may listen to just about anything you want that isn’t encrypted, but actions taken on information learned can be punished by the law. This article does not condone invading the privacy of others or any illegal use of information that may be gained over radio.
All that in mind, technology is available that will grant the listener access to encrypted radio channels, such as emergency services and law enforcement. This is why when cruising the airwaves, EU radio operators are very unlikely to passively encounter police chatter or ambulance discussions; in the past decade or so, those conversations have been moved to more secure channels to protect vulnerable peoples. Even with that in mind, technologies such as baby monitors can be accessed with sufficiently powerful radio equipment. It’d be a little weird to access such devices, so they and other sensitive personal radio uses won’t be covered in this article.
In the US, listening to police radio chatter specifically is a protected activity and can be done freely. Apps and devices are specifically designed for listening in on police communications on crimes and emergencies which are 100% legal to listen to from the user’s personal comfort.
Some countries are far more strict about radio operation than others. Before setting out to go on any auditory adventures, consult local restrictions and agencies as to who is allowed to operate amateur radio equipment and on what frequencies.
With that out of the way, time for the real meat and potatoes. What information is accessible via radio?
Frequencies and their Uses
Different frequencies of radio airwave space are reserved for different uses of communications. Don’t expect all channels to always have communications going at all times, be patient for the chance radio transmissions to roll within range of your setup.
Here’s a breakdown of some of the frequencies various services use. Keep in mind, any guide on frequency listings here or in physical form are liable to become outdated even before you read them. This is more of a general reference for what kind of stations and frequencies are available for listening, and will require trial and error to find and listen to.
Note: All frequencies listed are in MHz.
CB Radio: 27.60125 – 27.99125
Short for Citizen Band radio, these frequencies are a non-government accessible radio band for mobile radio communication. Think truckers, boaters, and hobbyists. This communication spectrum used to be popular with professionals like plumbers and electricians, but saw it fall out of favor due to its popularity in the 70s making the channels noisy and difficult to use. There’s more than a handful of novelty country songs about CB radio, making it a classic staple of hobby radio enjoyment.
10m Amateur Band: 28.000 – 29.7000
The widest of the High Frequency bands, radiation from sunspots greatly affects this frequency range. During sunspot minima, radio transmissions can be spotty and difficult to listen in on, and during sunspot maxima they reach farther and have stronger signals. During sunspot maxima, this range can be open worldwide. Some information accessible in this range includes beacons, satellite downlinks, packet radio, slow scan TV, and fax calling.
Analogue Cordless Phones: 31.0375 – 40.1125, 47.41875 – 47.5500
Though rare these days, there are still analog cordless phones which operate in this area of the spectrum. Note that this doesn’t apply to modern mobile phones, which operate on completely different transmission methods. As mentioned earlier about invasions of privacy, whether you should listen in on other peoples’ phone calls is up to you, especially because the people more likely to still have analog cordless phones are the elderly!
GE 5.8GHz Analog Cordless Phone
Low Power Devices: 49.8200 – 49.9875
This range is dedicated to low powered devices, such as toy R/C cars and older walkie talkies. Incredibly short range, this spectrum can be interesting to listen in on especially around Christmas time, as kids open up their toys and start broadcasting the RC controls out into the airspace.
6m Amateur Band: 50.0000 – 52.0000
Reserved for amateur radio operators, this channel space can be found housing uses such as telephony, FM, simplex, repeater channels, packet radio, internet voice gateways, APRS, fax, RTTY and SSTV. Many repeaters, especially in the UK, operate in this frequency band allowing for much further communication reach than smaller transceivers would usually be able to operate.
Low Band PMR: 77.6875 – 86.3750
While reserved in the UK for low band walkie-talkie licenses, this area of the spectrum is also seeing use by taxi companies and agricultural radio communications.
Commercial Broadcast Band: 88.0000 – 108.0000
Hey, it’s the frequencies you probably already knew about before reading this! Commercial broadcast is what your car picks up for FM radio, including local community stations and national broadcast stations. This band is analogue only.
Civil Air TACAN & DME Idents & ILS Localizers: 108.0000 – 112.0000
This portion of the frequency band is reserved for plane landing systems. You won’t hear any voice over these channels, but signals instead. These signals measure slant range of aircrafts by timing the propagation delay of VHF or UHF radio signals. TACAN and DME work by measuring the amount of time it takes for a radio signal to move from the runway, to the plane, and back, giving a measure of distance. ILS works to give an impression of height by creating a vertical beam of radio signal that allows aircraft to determine if their approach distance and height matches what’s necessary for a landing. This allows pilots to approach a landing even without visual contact with a runway.
TACAN & DME Idents & ATIS & VOR: 112.0000 – 117.9750
Much the same as the previous frequency band, but for TACAN & DME & ATIS & VOR instead. Timing signals without voice over the air. Specifically, the swap of ILS localizers for ATIS & VOR provides a different range of information for takeoffs and landings. ATIS (Automatic Terminal Information Service) includes weather reports and other crucial terminal information that may otherwise impede landings and takeoffs. VOR is a radio based technology that allows pilots to determine their heading and bearing relative to the ground station. Measuring the angle of the signal and the direction of the station gives information on a plane’s position completely wirelessly. Similar function, different methods!
International Civil Aviation: 117.9750 – 138.0000
This stretch of bands is for AM radio systems as used for airports and aircraft. An extremely busy set of frequencies, these stations will include approach, radar, tower, ATIS, departure, and other aircraft related needs. Specifically, 121.5MHz is used for international distress and is very much worth monitoring. Even if you’re not near an airport, you can still hear airplane chatter when they fly nearby.
Illegal Paragliders: 143.7500 – 143.9500
Hang gliders, paragliders and motorized paragliders use this portion of the band for air-to-air communications. They often use frequencies without official acknowledgement from radio enforcement authorities, and can be found anywhere around 143MHz.
2m Amateur Band: 144.0000 – 146.0000
A versatile band for licensed users, this band can be used for SSB, SSTV, fax, repeaters, simplex communications, digital modes and amateur satellite. Of note, the international space station downlink can be heard on 145.8000.
UK Police/Fire (Now Defunct): 146.0000 – 156.00000
Before emergency services were moved to encrypted channels to discourage listening in, this is the frequency band where their communications were hosted. This means they can no longer be listened to with any scanner, radio, or SDR receiver. Even if someone were to acquire a lost or stolen radio, they would be locked out of the encryption network rendering them completely useless.
Wide Area Paging: 153.0250 – 153.5000
Be warned; When listening to this frequency band, you’ll be signing up for horrible noises screeching right into your ears. Wide area paging is for services like alarm and security companies, doctors, and emergency services to send signals and information between their services, which aren’t pretty auditorily. SDR dongles with decoding software can be purchased to enable decoding pager frequencies, though.
Short Term Hire:158.7875 – 172.0000
Imagine you’re going to be managing a marathon, and want to make sure all your teams of workers can quickly communicate over the open air. This is the band of frequencies you can rent in the short term to use in such a situation. The good news is that this makes this frequency band worth a listen with its many users and varied functions.
Cobra PX650 BCH6
Search & Rescue: 147.3500 – 161.88125
Allocated to search and rescue efforts, these channels are used for both simplex and repeater based communications. Note that training exercises undertaken by search and rescue usually take place high up in areas such as hills and mountains, meaning their communications can travel a long distance for listening.
Marine Band: 156.0000 – 163.0000
Marine VHF radio equipment is installed on all large ships and most seagoing small craft, with some even being used on rivers and lakes. If you want to learn about maritime OSINT, check out our other article here. You’ll be hearing about summoning rescue services and communicating with harbors, locks, bridges, and marinas. Just like with airplanes, just because you don’t happen to be near a port or hub doesn’t mean you can’t pick up chance communications for passing vessels, especially with ship-to-ship contact.
High Band VHF PMR/Land Mobile/Base: 158.5250 – 181.7000
While these channels used to be more populated in the heyday of radio enthusiasm, now it’s mostly used by taxi companies, security, and numerous other organizations. Back in the day it was commonplace to find doctors, RSPCA, utility companies, and waste collection efforts on these channels. This is also where community repeaters may be found for business use as well.
Trunked Networks: 180.0000 – 203.0000
This section of the spectrum is allocated to trunked networks for bus companies and airports. Many of the uses include MPT1327 trunked networks, primarily for operating multiple handsets on a single network. While its use is less common these days, there’s still plenty of chatter to pick up and listen to even still.
MPT1327 (MPT-IP) Two-Way Radio
Military Air Band: 225.0000 – 399.9000
This portion of the radio air frequencies is reserved for military air use, such as ground, air to ground, air to air, and air to ship communications. Expect to hear not only military from your own country of residence, but also foreign military aircraft transiting to your airspace. Keep in mind that air shows and plane demonstrations are perfect times to listen in and get a feel for what planes are performing!
MOD/USAFE: 402.4500 – 425.0000
Allocated for use by defense and US air forces in Europe, this section of radio frequencies are usually quiet outside of training procedures.
70cm Amateur Band: 430.0000 – 440.0000
An amateur band for licensed users, this frequency band is generally quieter than its 2m Amateur Band counterpart. CW, SSB, FM, DV, and data modes can all be used in this frequency band.
LPD433: 433.0750 – 433.7750
LPD433 stands for Low Power Device 433 MHz, which is exactly what this frequency band is used for. Low powered personal radio devices used without needing a license are operated here, primarily with analog FM signals. This is also where devices such as car key locks operate via radio frequencies.
UHF PMR/Land Mobile/Base: 440.0000 – 467.2000
Combining licensed and unlicensed use of radio needs, this portion of the spectrum can be found housing users such as security, asset protection, taxis, ports, docks, construction, airports, and beyond.
FT-7900R Mobile Dual-Band
PMR446: 446.0000 – 446.1000
Just like LPD433, this part of the radio frequency spectrum is for Personal Mobile Radios at 446 MHz. This means that functions such as small businesses, events, motorcycles, and others will openly host chatter on these channels, making them prime candidates for eavesdropping on various people and networks.
Short Term Hire: 426.0375 – 462.4875
If it isn’t yet clear, there are frequently more than one set of frequency channels for various uses. This way, conditions for clear communication and open availability of radio frequencies can be maintained even at peak use. In this case, the frequencies listed are the same as Short Term Hire 158/172 as explained above.
POLYCON: 417.5000 – 449.7375
Designed as a dedicated radio system used by the coastguard for search and rescue efforts, POLYCON enables helicopter crews to communicate easily. You can hear crews speaking with pilots, winchmen, medics, and other personnel on board. Because the signals are elevated via helicopter, signals can be heard much further out than might be otherwise expected.
Baofeng BF-888S Frequencies: 462.1250 – 469.9500
The Baofeng BF-888S is the radio of choice for many fresh radio operators wanting cheap, ready to use communications. However, more green radio enthusiasts may not be aware that the preset channels are only intended for factory testing and may not comply with local regulations for what channels are okay to operate on. That in mind, their 16 default channels between 462 and 469 are worth listening in on to hear people using the Baofeng straight out of the box.
Local Radio Talkback/Microphones: 470.0000 – 855.0000
Here at the end of the radio spectrum we have communications to and from wireless microphones for video production. These communications are used by TV film crews, news crews, and theater productions. Unfortunately, they are extremely low powered so you would need to be extremely close by to be able to pick them up.
Shure BLX14R/W93 Wireless Microphone System
The Radio Spectrum in Full
In full transparency, this article was written with the intention of making the very noisy (all puns intended) charts of radio frequency obsolete. They list overlapping uses and aren’t particularly descriptive or helpful from a layman’s perspective, or in terms of measuring what the channels actually get used for.
Regardless, if a visual reference of radio frequencies would be useful to you, you can check out an outline of UK frequencies here, US frequencies here, and Singapore here.
What Makes Radio Listening Unique?
While it may not be the newest or most exciting way to gather information from local sources, the appeal of radio has a certain old-school quality to it that’s tough to ignore. Sitting in an enclosed space, surrounded by LED panels and slowly turning a dial to tune in on frequencies not intended for general listening certainly has its own appeal when it comes to informational capture.
Even past the appreciation of the aesthetic it provides, many organizations and groups don’t expect hobbyists to really exist in the modern day, making the conversations taking place ripe for tidbits of information that might otherwise be concealed on more popular channels. Coupled with the transient nature of radio communications both in it usually not being captured for later listening, and the need to be in a relatively close proximity to the communications taking place, there’s an entire undiscovered world of information being freely shared via radio at all times.
In Closing
Radio is generally considered to be an outdated, dead technology. Whether that’s true or not, these communications take place every day all around you. Whether it’s maritime vessels communicating with docks or search & rescue exercises being carried out, you have the option to tune in to these communications simply by owning the right equipment and listening in.