Analogue Radio Frequency Scanning
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From the Heritage Minutes collection
The wind howled and icy rain pelted down as the fragile kite swung desperately in the gale over the Newfoundland cliffs, tugging at its 180-metre wire. It was midday on December 12, 1901, and Guglielmo Marconi sat anxiously in the small, dark room on Signal Hill.
"I placed a single ear-phone to my ear and started listening," he recounted. "The receiver on the table before me was very crude... (but) I was at last on the point of putting the correctness of all my beliefs to the test."
Marconi, son of an Irish mother and an Italian father, had been playing with electricity since he was a child. A rebellious student, he hated lessons but loved to experiment and invent. By the time he was nineteen, he had resolved to be the first man to give the world a system of communication based on electromagnetic waves. By trial and error, relying on his own intuition and audacity, Marconi conducted a series of experiments indicating that long-distance wireless communication was possible. One problem remained. Scientific theory of the time asserted that radio waves followed straight lines that would leave the earth's atmosphere and continue into space. Marconi had a hunch, unsupported by any scientific proof, that the waves would be drawn by gravity and follow the curvature of the earth. If he was right, a powerful signal could cross an ocean. Marconi set out to prove that global transmission was possible.
He built a transmitter in Poldhu, Cornwall, in England, and a crude receiver in the Cabot Tower in St. John's, Newfoundland. His experiments proved that rigid antennae could not withstand the North Atlantic winds, so he decided that in Newfoundland he would use a kite to raise the aerial high enough to capture the signal from England.
"Suddenly, there sounded the sharp click of the 'tapper'... and I listened intently. Unmistakably, the three sharp clicks corresponding to three dots sounded in my ear." Marconi's "big thing," as he called it, had come off. The transmission of those three dots, Morse code for the letter S, marked the first wireless link between the Old World and the New.
The following is solely the point of view of the author. Always refer to the law in your jurisdiction regarding a scanner receiver. It is encouraged that you continue your study of the topic in other resources.
What Is Radio Frequency Scanning?
Understanding Scanners
Scanning is a growing hobby that lets you "listen in" on public radio conversations and keep up on current local events as they are happening. You can get into the scanning hobby with only a radio scanner.
A radio scanner is a radio receiver used by hobbyists to tune to a wide range of frequencies in order to monitor two-way radio communications from the various agencies and companies using two-way radio, such as police and fire departments, ambulance services, government agencies, aircraft and amateur radio services. In addition to letting you scan these transmissions, scanners are often preprogrammed with service search banks (such as police, marine or aircraft). By pressing a single button, you can quickly search those frequencies most commonly used by public service and other agencies. In addition, scanners can be programmed to monitor specific frequencies, as well as to follow conversations on trunked radio systems (called trunktracking). Additional accessories, such as headphones, antennas and external speakers can be added to your scanner in order to enhance your listening experience. Also, localized frequency lists give you a place to start listening.
In addition to the enjoyment of hearing day-to-day action as it happens, scanners can also allow you to monitor emergency situations as they are discussed by the people on the scene (rather than waiting for the news reports).
Scanner Receiver is any receiver capable of automatically scanning a frequency band, or several frequency bands, for radio frequency "Radio Frequency" RF signals, or a manually tunable receiver that employs programmable or preset channel frequencies and decodes the messages that are transmitted by other parties on those frequencies.
Analogue scanner receiver is a scanner receiver capable of decoding only analogue signals.
Digital scanner receiver is a scanner receiver capable of decoding only digital signals.
Are Scanner Receivers legal?
In Canada, yes, when the Radiocommunication Act is followed.
Do I Need A Licence To Operate An Analogue Scanner Receiver?
In Canada, no; not for an analogue scanner receiver. A licence is required for a digital scanner receiver.
If Scanner Receivers Are Legal In Canada, Why Does The Province Of [Blank] Ban Their Use In Automobiles?
Automobile use is the jurisdiction of the Provinces and Territories in Canada. Scanner receivers are legal in Canada, but the Provinces and Territories create the rules for driving.
Is Streaming Scanner Receiver Audio Over The Internet Legal?
My interpretation of the Radiocommunication Act is it is not legal in Canada. It is not legal to divulge nor make use of any intercepted radio communication without authorization.
Is A Mobile/Cellular Phone A Radio?
Mobile/Cellular phones are radio-based telephones that are linked by radio instead of wires.
Is Listening to Mobile/Cellular Phones With A Scanner Receiver Legal?
In Canada, yes, when the Radiocommunication Act is followed.
Is It Legal To Listen To Anything On A Scanner Receiver?
In Canada, yes, when the Radiocommunication Act is followed.
Legislation alone cannot prevent people from listening to the radio signals of others. However, if you do intercept someone's radiocommunication, remember that it is an offence under the Radiocommunication Act, to divulge or use the information obtained.
Certain types of scanner receivers are now subject to regulation. Any scanner capable of receiving digitally modulated transmissions must be licensed.
For more information on this subject, or any other question concerning radio, contact your local Industry Canada office. The number is listed in the Government of Canada pages of the telephone directory under "Radio Interference".
(2) Except as prescribed, no person shall intercept and make use of, or intercept and divulge, any radiocommunication, except as permitted by the originator of the communication or the person intended by the originator of the communication to receive it.
(3) Subsection (2) does not apply in respect of radiocommunication that consists of broadcasting, a subscription programming signal or a network feed.
9.1 Every person who contravenes subsection 9(1.1) or
(2) is guilty of an offence punishable on summary conviction and liable
(a) in the case of an individual, to a fine not exceeding twenty-five thousand dollars or to imprisonment for a term not exceeding one year, or to both; and
(b) in the case of a person other than an individual, to a fine not exceeding seventy-five thousand dollars.
Do News Reporters Use Scanner Receivers To Report The News?
If they do in Canada, they must follow the Radiocommunication Act.
Who Listens To Scanner Receivers?
Many people including: hobbyists, enthusiasts, amateur radio (HAM) operators, and emergency service responders.
What Do People With Scanner Receivers Listen To?
That depends on the individual. I listen to many things from aircraft to the weather broadcast. I like to listen to the radio communications from airports, especially during air shows. I like to listen to the marine radio traffic when the Great Lakes shipping season runs. I like to listen to amateur (HAM) radio. I like to listen to the railways.
Are Scanner Receivers Police Scanners?
No. There is no such thing as a so-called, "police scanner". A scanner receiver is able to listen to police radio frequencies because police radio frequencies are part of the Electromagnetic Spectrum where all radio transmissions are found. A scanner receiver is not designed to only scan the frequencies the police use. The radio frequencies police forces use differ widely between jurisdictions, and the spectrum allocations for police forces can change over time.
Is Listening To Police Radio Calls Legal?
In Canada, yes, when the Radiocommunication Act is followed.
Why Would Someone Want To Listen To The Police Radio Transmissions?
Likely for the same reasons some people have an interest in going on a ride-along with an on duty police officer. It puts a human face on the local police force. One learns something that is involved in being a police officer, and a dispatcher, and what police work is like in one's own community; however, with a scanner receiver neither the civilian nor the officer faces any of the problems that may occur with a traditional ride-along.
Some police forces could have an open channel specifically for broadcast of public alerts.
Off duty or auxiliary police officers may have scanner receivers scanning the police frequencies.
Law abiding citizens may simply have an interest in police work.
There are many possible reasons.
Police radio transmissions, and other emergency services, are mostly brief and routine radio communications. They are not the "action packed" radio communications one may imagine them to be.
Similar answers could be given for one's desire to listen to any of the public emergency services.
Emergency service dispatchers may listen to each others' radio calls to stay better informed of what is happening in multiple response situations.
Do Criminals Use Scanner Receivers To Evade The Police?
I have never found any good evidence of this, although it appears some police forces perhaps believe they do, and these police forces therefore encrypt their radio transmissions.
Criminals have long used methods to evade the police, and the police are well aware of these methods, and how to counter them. I find it an insult to police officers that one may say all a criminal needs to do to escape the police, or gain an advantage, is to listen to the police radio communications.
Al Capone reportedly had a police radio receiver installed in his armoured 1928 Cadillac, that he also had constructed to minic a police car, to presumably use to listen in on the police calls. Capone still went to prison; and more than once.
What Does "Encrypted" Mean?
encrypted means treated electronically or otherwise for the purpose of preventing intelligible reception.
Are All Police Radio Transmissions Encrypted?
Some police radio transmissions are encrypted, and some are not. This seems to depend on the individual police force whether or not the police encrypt their radio traffic. Some police forces choose only to encrypt certain radio transmissions, others encrypt all radio transmissions.
What Happens If My Scanner Receiver Tunes Into An Encrypted Frequency?
You will hear nothing intelligible.
Is It Legal To Decrypt An Encrypted Radio Transmission?
In Canada, if you do not have authorization to do so, it is illegal to decrypt, or to listen to, any decrypted radio transmission.
Is It Legal To Listen To An Encrypted Radio Transmission Without Decrypting It?
In Canada, yes. You will hear nothing intelligible.
Do I Need A Special Or Expensive Scanner Receiver To Listen To Analogue Radio Frequencies?
No. You can listen to analogue transmissions with just a basic analogue scanner receiver. Typically, these are scanner receivers that have the word NASCAR® printed on them. They are also generally inexpensive, and easy to use.
Short-wave radio recievers have the frequencies to listen to radio communications including ships, aircraft, and amateur (HAM) radio. A good short-wave receiving aerial is usually required to hear these radio communications, as is a suitable location.
Are Analogue Scanner Receivers Obsolete Because Of Digital Radio
No. It depends on where you are, but there is still a lot of analogue transmissions to listen to. Some areas may use digital signals more than analogue signals, and other areas may use analogue signals more than digital signals. As a general rule, smaller cities and towns tend to use more analogue radio transmissions than digital radio transmissions.
What Sorts Of Things Can I Listen To With An Analogue Scanner Receiver?
With a simple analog scanner receiver, you can start by listening to different analogue transmissions in your area that you discover. Analogue frequencies can include: general radio service (aka, citizens' band, or CB), aviation, amateur radio (aka, HAM radio) marine, railway, commercial, city works, industry, sport, public transit, public weather broadcasts, emergency services, and more. Basically, if it is transmitted openly in analogue, you likely will be able to listen.
What Happens If I Listen To A Digital Transmission On An Analogue Scanner Receiver?
You will hear nothing intelligible.
What Is Simplex?
Simplex is a communication system that only allows transmission of signals in one direction at a time. A two-way radio uses simplex.
Can An Analogue Scanner Receiver Be Used To Listen To A Simplex Radio System?
Yes, if the simplex radio system is analogue.
What Is A Repeater?
A repeater picks up a mobile unit's transmission on one frequency, then rebroadcasts (or repeats) the transmission 5 MHz lower, but at a higher power level than the mobile unit.
Realistic, Pro-25, Portable Scanner, Owner's Manual, 1995.
A repeater is usually on top of a tower, a building, a hill, or a mountain, and generally operates in the UHF range. A repeater greatly extends the radio range of mobile units.
What Is A Trunked Radio System?
A system called trunked radio lets several services use the same set of frequencies in the 800 MHz band without interference. Several frequencies are allocated to two or more services (like fire. police and water departments). As each service transmits, a separate control signal activates other radios in the same service, so only that service hears the transmission. The frequency is selected as soon as the unit begins to transmit, and could be any one of the allocated frequencies.
Realistic, Pro-25, Portable Scanner, Owner's Manual, 1995.
Trunked radio systems are commonly used in larger cities.
Can An Analogue Scanner Receiver Be Used To Listen To A Trunked Radio System?
Yes, if the transmissions are analogue; however, without a Trunk Tracker™ capable scanner receiver, it may be difficult to follow one service's communications on the trunked system, depending on how busy the services are. I follow an analogue 5 frequency trunked radio system with my non-trunk tracking Realistic PRO-25 scanner receiver without much difficulty because of the low radio traffic of the 24 users. Only a few of the 24 users occasionally transmit at or near the same time as other users.
How do I find frequencies in my area?
Among radio spectrum users are broadcasters, taxis, building and other construction trades, air transportation, radio amateurs, marine transportation, telecommunications carriers, electrical power utilities, trucking companies, police, and federal, provincial, territorial and municipal departments and agencies.
Years ago, when most all radio communications were simplex, it was much easier than today. One just found the frequency, and keyed it into the scanner.
Two sources of frequency lists were the Haruteq Scanner Book, and Betty Bearcat Frequency Directory. The Haruteq publication could be purchased from Radio Shack, and the Bearcat publication was included with the purchase of a Uniden scanner. Today, these publications are out of print, and obsolete; however, the old frequency lists are of value because some frequencies are still being used. I have discovered some of the former police simplex frequencies in my city are now used by EMS, and in the winter season also by the Ontario Ministry of Transportation, in what seems to be an analogue trunked system.
Some old forgotten Internet sites can be found that have lists of frequencies from the simplex days.
You can search on your own with your scanner receiver, and I think this is the best way of finding current frequencies. Try scanning a small number of frequencies at a time where you think you may find something interesting in the Radio Spectrum. With some time and patience, you may find transmissions. You will likely discover frequencies in your area that are not listed on the Internet. I have a growing list of frequencies that I have found by scanning.
Look for aerials in your area, on towers, on buildings, and on vehicles. With a little aerial knowledge, you will be able to visually identify the general frequency range of the aerial you see, and will be able to scan those frequencies.
You may want to look up current frequencies on the Internet for your area.
Good Canadian resources are Spectrum Direct and Spectrum Management System Data Search on the Industry Canada website.
VHF Marine Radio Channels can be found on the Canadian Coast Guard website.
Amateur Radio (HAM) information can be found easily with an Internet search.
Uniden scanner receivers have a unique feature called Close Call™ that helps to detect strong radio signals.
A frequency counter will assist in identifying strong signals.
The Pro 25 (20-505 available in Canada only) receives these bands:
29-29.7 MHZ (10-Meter Amateur Radio)
29.7-30 MHz (HF Hi)
30-50 MHz (VHF Lo)
50-54 MHz (6-Meter Amateur Radio)
108-136.975 MHz (Aircraft)
137-144 MHz (Government)
144-148 MHz (2-Meter Amateur Radio)
148-174 MHz (VHF Hi)
406-450 MHz (70-Centimeter Amateur Radio and Government)
450-470 MHz (UHF Lo)
470-512 MHz (UHF 'T' Band)
806-823.9375 MHz (Public Service)
851-868.9315 MHz (UHF Hi)
896.1125-956 MHz (UHF Hi, 33-Centimeter Amateur Radio)
A GENERAL GUIDE TO SCANNING
Reception of the frequencies by your scanner is mainly "line-of-sight." That means you usually cannot hear stations that are beyond the horizon. During the summer months, you may be able to hear stations in the 30-50 MHz range located several hundred or even thousands of miles away. This is because of summer atmospheric conditions commonly known as skip. This type of reception is unpredictable but often very interesting!
A GUIDE TO CANADIAN ACTION BANDS
As a general rule on VHF, most activity concentrates between 153.785 and 155.98 MHz and then again from 158.73 to 159.46 MHz. Here you find local government, police, fire, and most emergency services. If you are near major railroad tracks, listen between 160.0 to 161.9 MHz for signals.
In some larger cities, there has been a move to the UHF bands for emergency services. Here, most of the activity is between 453.025 and 453.95 MHz and between 456.025 and 467.925 MHz.
In the UHF band, mobile units operate between 456.025 and 459.95 MHz and between 465.025 and 469.975 MHz. A repeater picks up a mobile unit's transmission one one frequency, then rebroadcasts (or repeats) the transmission 5 MHz lower, but at a higher power level than the mobile units (that is, 451.025-454.95 MHz and 460.025-464.975 MHz). This means that if you find an active frequency inside on of the mobile units frequency spreads, you can look 5 MHz lower to find the repeater frequency.
The Pro-25 (20-9505 available in Europe/Australia) receives these bands:
66-88 MHz (VHF LO)
108-136.975 MHz (Aircraft)
137-144 MHz (VHF Hi)
144-148 MHz (2-meter Amateur Radio)
148-174 MHz (VHF Hi)
406-450 MHz (70-Centimeter Amateur Radio and UHF Lo)
450-470 MHz (UHF Lo)
470-512 MHz (UHF Hi)
Europe:
806.000-956.000 MHz (UHF Hi)
Australia:
806.000-823.9375 MHz (UHF Hi)
823.9500-850.9800 MHz (UHF Hi)
851.000-868.9375 MHz (UHF Hi)
868.9500-896.1000 MHz (UHF Hi)
896.1125-965.000 (UHF Hi)
Realistic, Pro-25, Portable Scanner, Owner's Manual, 1995.
Uniden BC72XLT
25.0-27.995 MHz Citizen's Band/Business Band
28.0-29.695 10 MHz Meter Amateur Band
29.7-49.995 MHz VHF Low Band
50.0-54.0 MHz 6 Meter Amateur Band
108.0-136.9875 MHz Aircraft Band
137.0-143.995 MHz Military Band
144.0-147.995 MHz 2 Meter [Amateur Band]
148.0-174.0 MHz VHF High Band, Federal Government
406.0-419.99375 MHz Federal Land Mobile
420.0-449.99375 MHz 70cm Amateur Band
450.0-469.99375 MHz UHF Standard Band
470.0-512.0 MHz UHF TV Band
Uniden BC72XLT Owner's Manual, 2004
Why Does The Scanner Receiver Have Gaps In Its Frequency Coverage?
Many scanner receivers sold leave out certain bands because of a lack of interest by most users, no voice communication in those bands, or because of a specific law in the country the scanner receiver was manufactured. For example, broadcast bands, AM and FM radio and TV channels, may be left out because of a lack of interest in listening to those frequencies on a scanner receiver. Frequencies that are usually used to transmit electronic data that have no voice communication may be left out. The cellular band is not included because the scanner receiver was manufactured in the U.S.A. where it is not legal to intercept the cellular band. In Canada, "full band" scanner receivers that do not have gaps in their coverage are available for sale by some retailers. Always be sure to examine the band range to confirm it is full coverage prior to your purchase if this is the type of scanner receiver you want.
What Are Bands?
a range of frequencies or wavelengths in a spectrum (esp. of radio frequencies)
Oxford Dictionary
What does FMN mean?
Frequency Modulation Narrowband. Some radio transmissions are FMN. Not all older scanner receivers are designed to receive FMN. This only means if a scanner receiver is not designed to receive FMN then the audio may be at a lower volume level, or the audio may have static.
Why Do I Hear Morse Code On Some Frequencies?
This could be because of the regulations regarding radio communications in your country. What you may be hearing is the Call Sign that identifies the broadcaster or transmitter. Instead of a person announcing the Call Sign, which is often 3 letters followed by 3 numbers, a computer automatically transmits the letters and numbers in Morse Code. This is fast and effective when the law states transmission of a Call Sign is required on the frequency. Some use a human, or computer voice, recorded message instead of Morse Code. It is not uncommon for the Morse Code Call Sign to interfere with a voice communication because the Call Sign is automatically sent at predetermined intervals to comply with regulations. Radio users who verbally state their Call Sign frequently enough likely do not need to use such a system.
If you can learn Morse Code, you will able to translate those "deets" and "dahs" you hear, and you can identify the Call Sign. With some investigation, you can discover who is using that frequency from their Call Sign.
Some amateur radio operators will at times transmit in Morse Code instead of voice. Communicating solely in Morse Code is something some amateur radio operators enjoy doing.
What Is That Annoying Computer Sounding Noise On Some Frequencies?
It could be one of many things. If you can stand to listen to the computer noise, you may hear a voice transmission, or a Call Sign. Sometimes the noise is continuous, and listening for a voice transmission would be not be of any use.
Which Scanner Receiver Is The Best One?
That depends on the user's preferences. I am satisfied with my old Radio Shack Realistic PRO-25 and my newer refurbished Uniden BC72XLT. Both scanner receivers are analogue, hand-held, and each one does something the other does not.
The Realistic can scan in the 800 MHz and 900 MHz range, and this is preferred for frequency hunting. I find it generally simpler to programme with fewer buttons that need to be pushed.
The Uniden scans the 25 MHz to 28 MHz range, has the Close Call™ feature, can temporarily lock out frequencies during a direct search, has preset frequency banks, and is more compact. Both scanner receivers have the weather band frequencies preprogrammed. These frequencies are the same in Canada and the USA.
Some people prefer base model scanner receivers, other people prefer mobile scanner receivers, and some prefer hand-held scanner receivers. Some people have no preference for a scanner receiver.
How Do I Get Better Reception With My Scanner Receiver?
The aerial is the most important piece of equipment for radio frequency scanning. Without a good aerial, your reception will not be good. Reception depends on things like, the quality of the aerial, the aerial height above ground, the terrain, and the strength of the signal. Obstructions, such as buildings, hills, and trees, can disrupt a signal. Concrete, metal, steel, or other building materials can also block or disrupt the traveling signal. Generally, it is line-of-sight when it comes to the best receiving with your radio frequency scanner. That basically means, the signal does not travel past the horizon.
There are some good resources on the Internet on how to make your own external aerial from all kinds of material from beginner ability to expert ability, or there are external aerials you can buy ready made from stores. The important thing to know for scanner receiver aerials is to have one that is multiple band, meaning it is constructed to receive a broad range of frequencies your scanner receiver can listen to.
I have had this magnet-mount aerial for many years, back from when Radio Shack was in Canada. I find it to be an excellent scanner aerial. It is still available from Radio Shack in the United States.
Radio Shack magnet-mount mobile scanner aerial
How Do I Convert MHz to kHz, kHz to MHz, and MHz to metres?
FREQUENCY CONVERSION
The tuning location of a station can be expressed in frequency (kHz or MHz) or in wavelength (meters). The following information can help you make the necessary conversions.
1 MHz (million) = 1,000 kHz (thousand).
To convert MHz to kHz, multiply by 1,000.
To convert from kHz to MHz, divide by 1,000.
To convert MHz to meters, divide 300 by the number of megahertz.
Realistic, Pro-25, Portable Scanner, Owner's Manual, 1995.
I Bought A Scanner Receiver That Advertised It Came Preset With Service Banks: Police, Fire, EMS, But It Wasn't. Why?
If the scanner receiver is scanning preset Police, Fire, or Ambulance frequencies, usually called the Service Search feature, and this is not what you are hearing it could be because the scanner receiver was manufactured the the U.S.A., and you are in another country; however, radio transmissions do travel across borders, and you may receive these transmissions if you are close to the U.S. border.
In my city, the preset "POL" (police) frequencies are where some private security frequencies can be found, but not the city police. Police frequencies in my city are digital and encrytped. When I am near enough to the U.S. border, the presets seem accurate.
Emergency service frequencies in one country can be different from the emergency service frequencies in another country. Also, allocated frequencies for users sometimes change over time, and so do the radio systems, and this could be a reason.
Preset Amature Radio (HAM). Marine, CB, Weather, and Air frequencies are the same in Canada and the U.S.A..
© Trevor Dailey
This page is revised from time to time.
Resources:
RadioReference: Scanners and Scanning
RadioShack Guide To Shortwave Radios
NRC short wave station broadcasts (CHU)
How to Make the Ultimate AM Antenna
This page is revised from time to time.