AN OVERVIEW OF
with an emphasis on the Maritimes
By William H. White
Aero Radio Enthusiast
last updated March 15, 2020
This page is in a state of ongoing construction. It is not yet complete, but enough is done to post it in case it is of interest. I do plan to add diagrams and more lists, but as always I am not sure when I will get it done. Check back and more might have been added.
Aero radio is spread over the radio
spectrum from LF (Low Frequency), used by radio beacons to the upper reaches of
UHF (Ultra High Frequency) used by satellite navigation and communications systems.
Aeronautical radio is made of two separate components. One is aeronautical radio navigation, and the other is aeronautical radio communications. For simplicity I will refer to them from this point as navigation and communications.
I will describe each of these in turn, with brief descriptions of their subcomponents. In all cases the intent is to provide some basic information, which you can use as a basis for further research if you feel inclined. As this is primarily a radio enthusiast website, I am providing radio frequency information as much as possible. Please let me know if there are errors or omissions. The intent is to give an overview, not to be a precise and complete discourse. You can contact me at marscan1 AT gmail.com.
While it is possible to listen to some aspects of radio-navigation systems, most aero enthusiasts do not, and therefore this description will be brief. My descriptions are not intended to be complete or definitive, and those who are interested should do further research.
In the early decades of flying the predominant radio assisted methods of navigating were via Low Frequency beacons, operating in the 190 to 535 kHz range. The two most common types of beacons were Ranges and NDB's.
Radio ranges were the predominant method of flying the airways of North America from the 1920's and into the early 1950's . A ground installation consisting of four towers in a square arrangement transmitted the Morse code letters A and N along two or four lobes. The areas where two lobes overlapped formed a sort of beam. An aircraft with a simple receiver could head away or towards the beacon. If it was on the beam the receiver would detect a steady tone formed by the merging of the A and N lobes, but if off the beam slightly to one side or the other, one of the two letters would be heard. At one time there were around 400 of these ranges in the United States and as well many in Canada, and to all intents and purposes these defined the airways along which aircraft travelled when visibility was less than ideal. These ranges were totally replaced by VOR's beginning in the 1940's, so that by the 1960's none were left.
NDB's or Non-directional beacons have been around for many decades. In the case of the Radio Ranges, the installation on the ground was complex, but the receiver in the aircraft was simple. With NDB's the opposite is the case. An NDB ground installation consists of a a transmitter feeding into a single vertical antenna transmitting equally in all directions. The receiving installation in the aircraft is more complex, especially in regard to the antenna which must be able to to detect the direction to the beacon. These remain popular, especially in smaller aircraft, or as a backup, but are steadily declining in use. There were many hundreds of these at one point but in the modern era, closures are slow but steady. There are several remaining in the Maritimes, mostly in the vicinity of airports and commonly in line with a major runway. These beacons transmit one to three Morse code characters, and are named either by that ID or by a plain language name. For example the two NDB's on the approaches to Runway 05/23 at Halifax are called the Split Crow and the Bluenose NDB's, both named after popular taverns. NDB's remain a popular hobby focus for radio enthusiasts searching for long distance reception (DX), as these low power beacons can be heard at very long distances in the right conditions.
This is a typical panel display in an aircraft. The display can be set to show the true bearing, or the bearing relative to the aircraft's current heading (which is the most common mode if an aircraft is homing in on a beacon).
NDB's in the Maritimes. Most of these are in line with a runway at a major airport. A few may simply be at the airport. The name of the beacon is followed by the frequency in kHz, followed by the Morse Code ID that is transmitted. Note that an LF receiver is required to listen to these. It may be possible to hear the Miramichi beacon on a regular AM radio as its frequency is just below the bottom end of the AM broadcast band. As for all other parts of the radio spectrum, you can purchase an SDR instead of a traditional receiver, and connect it to your computer, and obtain the necessary software, but you will still need a good antenna!
I myself have not listened for any of these local area beacons listed below, or for the ones farther away. But I do want to say that listening to the NDB at Comox on Vancouver island more than 60 years ago is what started me on my never-ending radio enthusiast life. The location is followed by the frequency in kHz, then the morse code ID.
Yarmouth 206 QI
Pleasant Lake 230 AC (ne of Yarmouth)
Greenwood 266 YZX
Aylesford 341 GF
Split Crow 364 ZHZ (Miller Lake/Fall River)
Bluenose 385 ZNS (Dutch Settlement)
Sydney 263 QY
Moncton 224 QM
Saint John 212 SJ
Alpine 397 ZST (sw of Saint John)
Fredericton 326 FC
Miramichi 520 F9
Bathurst 363 1F
Charlo 207 CL
Sable Island 277 1B
Here are some others along the Gulf of St Lawrence in Quebec, in Newfoundland (island) and in Maine
Spruce Head, Maine (nr
Rockland) 356 SUH
Burnham, ME 348 BUP
Milnot (Millinocket) ME 344 LNT
Portland, ME 301 PH
Gaspe, QU 232 GP
Port-Menier (Anticosti I), QU 360 PN
Havre-st-Pierre, QU 344 YGV
Chevery, QU 276, YHR
Blanc Sablon, QU 220 BX
St Anthony, NL 356 AY
Gander, NL 280 QX
You might note that even though these beacons are all within a fairly localized part of North America, that there are a couple of instances of beacons having the same frequency. I find this quite surprising as there are an abundance of frequencies unused in the region. Keep in mind this duplication when listening, and also take note that there of course is a lot more duplication of frequencies if you take all of North America and the World in general into account. That is why you need to have a chart of Morse Code letters and numbers handy.
If you think you would like to pursue the hobby of detecting NDB's at a distance, there are several on-line resources. you could start with this dedicated NDB group.
These are low power beacons operating on 75 MHz. They are always located on the final path to a runway. It is possible to have an outer marker, a middle marker, and an inner marker, but it is much more common in marker installations to have just one or two, with the outer marker being most common. Often there will be an NDB collocated with an Outer Marker. Marker beacons transmit a signal straight up in a sort of oval beam that is wide across the flight path but narrow along the path. When an aircraft passes over or nearly over the outer marker there will be a beeping sound and a visual signal on the instrument panel to show that the outer marker has been reached. There are similar indications when the other markers are crossed but the beep frequency will be higher, and a different colour of light flashes. This is definitely an older technology, and there are fewer and fewer of these in the United States as the years go on, and there have not been any at all in Canada for many years.
VOR (Very High Frequency Omni Ranges). VOR's are the very high frequency counterpart of the older radiobeacons. These operate in the navigation portion of the VHF aero band (108 to 117.975 MHz). VOR's began to take over from low frequency beacons back in the 1940's and were until the end of the century the predominant means of navigation. Today they are being supplanted by satellite-based navigation methods but are still very very common. VOR installations transmit a complex signal that when coupled with a VOR receiver in the aircraft indicates quite precisely the direction to the transmitter. They are not much affected by weather or other atmospheric conditions. VOR's are often combined with TACAN, or with DME (described below). The VOR has a rotating beam that interacts with the receiver in the aircraft to indicate a direction. Some VOR's have a voice broadcast component, and can be referred to as BVOR's. These broadcasts would typically be of weather and related information. As far as I am aware there are no BVOR's in our Maritimes region, and may possibly be a USA-only variation. The VOR at Halifax is on 115.1 MHz and is located northeast of the airport along the Old Guysborough Road. If you are close enough you will hear its YHZ identification in Morse Code (-.-- .... --..) Other VOR's in the Maritimes are as follows:
Sydney YQY 114.9
Yarmouth YQI 113.1
Charlottetown YYG 113.8
Moncton YQM 117.3
Fredericton YFC 113.0
Saint John YSJ 113.5
Cap de la Madeleine YGR 112.0
The vast majority of VOR's in Canada also have a distance measuring component, referred to as DME, and are properly referred to as VOR-DME's. A very few are plain VOR's, such as at Springbank, Alberta, while another very few are combined with TACAN (see below) and are referred to properly as VORTAC's.
TACAN or Tactical Air Navigation is a military-only air navigation system. It operates in the 960 - 1215 MHz portion of the Ultra High Frequency segment of the radio spectrum. It provides a more precise direction to aircraft than does the VOR, and it always also includes a distance measuring component, so that in one device a pilot will ascertain both distance and bearing to a TACAN station. Typically TACAN's are found at or near military airfields, and commonly on board naval ships have an air component. For example any aircraft carrier would have a TACAN, but it is also likely that our Canadian frigates, which carry a helicopter, would also have TACAN.
In the Maritimes there are TACANs at Greenwood and Shearwater
A VORTAC is a station that has a VOR and a TACAN colocated. There are a very few in Canada. One of the few examples is at Sherbrooke, Quebec. In a VORTAC there are separate bearing (direction) determination systems, but both the military and civil aircraft use the military distance measuring equipment, which is more precise than the civil version. VORTACS are much more common in the USA as compared to Canada.
ILS or instrument landing system is found at many airports but not necessarily on all of the runways. It is an integrated system made up of a VHF localizer beacon and a UHF glide path indicator. Essentially a beamed transmission is sent up the recommended flight path. The receiver in the aircraft will indicate if the aircraft is left or right of the correct path based on the transmission of the localizer. It will also indicate if the aircraft is above or below the recommended approach slope, based on the transmission of the glide path component. The glide path indicator can only be used in one direction as it is aimed up the slope of the glide path. Therefore if one runway requires full ILS in both directions there will have to be separate facility for each end of the runway. The localizer on the other hand can transmit in both directions as it is essentially sending out a vertical beam that can work in both directions. In this case if there is an ILS for one direction of a runway, but not for the other, there can be a localizer approach to the runway from that other direction, but without a glide slope indication. This is referred to as a Localizer Back Course. Note that there are installations that in fact do not have the glide slope indicator at all, so that there is just the localizer in one or both directions.
This diagram shows the essentials of an ILS system, but also shows the 3 marker beacons that are obsolete in Canada and becoming fewer and fewer in the USA.
Localizers transmit on frequencies between 108.1 and 111.95 MHz which appears at first glance to be a spacing between channels of 0.05 MHz, but localizers can only be on frequencies with an odd number following the decimal. For example 109.9 is a valid localizer frequency but 110.6 is not. There are forty separate channels which are numbered in straight-forward progression starting with Channel 1 at 108.1 MHz and Channel 40 at 111.95 MHz
Localizer frequencies are paired with glide path frequencies in the range 329.15 to 335.0 MHz. A particular localizer frequency is always paired with a particular glide slope frequency. For example, in Channel 1, 108.1 MHz is always paired with 334.7 MHz but note that this latter frequency is not the lowest one in the glide path range. In fact the glide path side of things seems to have no rhyme nor reason, other than the fact that a particular one out of the 40 always goes with the same Localizer frequency.
At Halifax runways 14 and 23 have ILS, whereas 05 has a localizer back course (not always in operation) Strangely, runway 32 has no ILS or localizer available even though it is a very busy runway.
YHZ: ILS Rwy 14 is 109.1
MHz Identification is IHZ, ILS Rwy 23 is 109.9 MHz Identification is IJG,
Localizer Rwy 05 is 109.5 MHz Identification is IGX
NOTE THAT YOU CAN LISTEN TO THESE NAVIGATION AIDS, but all you will hear are the identifications in morse code. At Halifax you most likely should be able to hear IHZ ( .. .... --..) all or most of the time, because although Runway 14 might not be in use, there is a related DME function that can be used by aircraft using other runways. As for the two aids on 109.9, these are mutually exclusive. In other words they cannot both be on at the same time as they are on the same frequency. You will hear on 109.9 either IJG (.. .--- --.) or IGX (.. --. -..-) depending on which runway is in use. I have heard on occasion situations when the wind is quite light but one direction of the runway is in use, but a pilot asks for the opposite direction. ATC has replied that they will have to change the localizer from one direction to the other and it will take a minute or so. As a ground observer you should not expect to hear these landing aids at any great distance, though in the world of radio there are strange conditions at times. Even while sitting at the main observation area on the Old Guysborough Road, I have found the signals to be somewhat faint, depending on which aid it is.
Frequency pairing in ILS.
This hard-to-read list shows the channel number followed by the localizer
frequency followed by the associated Glide Path frequency:
Localizer Glide Path MHz MHz 1 108.10 334.70 2 108.15 334.55 3 108.30 334.10 4 108.35 333.95 5 108.50 329.90 6 108.55 329.75 7 108.70 330.50 8 108.75 330.35 9 108.90 329.30 10 108.95 329.15 11 109.10 331.40 12 109.15 331.25 13 109.30 332.00 14 109.35 331.85 15 109.50 332.60 16 109.55 332.45 17 109.70 333.20 18 109.75 333.05 19 109.90 333.80 20 109.95 333.65 21 110.10 334.40 22 110.15 334.25 23 110.30 335.00 24 110.35 334.85 25 110.50 329.60 26 110.55 329.45 27 110.70 330.20 28 110.75 330.05 29 110.90 330.80 30 110.95 330.65 31 111.10 331.70 32 111.15 331.55 33 111.30 332.30 34 111.35 332.15 35 111.50 332.90 36 111.55 332.75 37 111.70 333.50 38 111.75 333.35 39 111.90 331.10 40 111.95 330.95
Note that aircraft on autopilot can automatically follow the indications from an ILS system right down to the minimum height. This requires the aircraft to be vectored to intercept the ILS signals at an angle of no more than 30 degrees. This is where the concept of aircraft landing themselves comes from, though in practicality, pilots need to be able to see the runway and take over at the very end.
GROUND CONTROLLED APPROACH (GCA) is a system by which the pilot is essentially talked in by a controller who uses a precision radar system having vertical and horizontal components This type of radar is called Precision Approach Radar or PAR. This tends to be, or perhaps entirely is, a military thing. Here in the Maritimes there is GCA at both Shearwater and Greenwood. At Shearwater the GCA or PAR frequency for the talk-in is 134.1 MHz with other frequencies listed being 118.1, 289.4 and 346.6. It is likely but not entirely clear that GCA is also used aboard naval ships.
It is hard to classify GCA as being "navigation" vs "communications" as it very much voice oriented.
RNAV (Area Navigation, formerly Random Navigation) This navigation that is independent of the ground-based beacon system but yet is as accurate if not more so. Modern RNAV is based on GPS determination of location, bearing and velocity.
GLOBAL POSITIONING SATELLITE (GPS) is the current standard in aero radionavigation. GPS as a term generally refers to the system of satellites operated by the US Military but other countries have similar systems. Some GPS receivers can use the usual USA satellites with augmentation from other countries' satellites. All satellites broadcast at the same two frequencies, 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal). There are other frequencies used only by the military, or are proposed for future uses. The US system is used not only by the military but also by many millions of civil users for a multitude of applications.
Because GPS or "satnav" can indicate position vertically and horizontally with great accuracy and almost instantaneously, it can also provide bearings and directions to any defined location. This includes waypoints, airports and even can guide aircraft into a landing. GPS could take the place of practically all other methods of navigation, if all aircraft were to be equipped with the necessary receivers, and if pilots were all trained to use them. Most airline navigation is done by way of GPS, also referred to as RNAV, and this includes most of the approaches.
GPS-equipped aircraft still are directed towards beacon locations but not by use of the beacons themselves. For example, an aircraft that has just left Halifax might be told by ATC to proceed towards the PQI (Presque Ile) VOR but the pilot will not be attempting to pick up the signal from that VOR and home in on it. Instead he or she will use the published location of the VOR as the reference point and head toward it. This of course means that the aircraft can be sent towards any location that is in its on-board database, such as those imaginary waypoints. An example would be if the aircraft is sent towards ALLEX, which is near Grand Manan Island. There is no navigation beacon there, but with GPS there is no need for there to be a beacon, just a location.
In good visibility it will still be common to hear pilots to use a visual approach, which means they want to do the flying themselves. Other times it remains common for aircraft to make ILS approaches.
SECONDARY SURVEILLANCE RADAR (SSR) is the type of radar used by ground-based stations to keep track of airborne targets. The older primary radar emitted radio signals that would be reflected off any encountered target. This target would be depicted on a screen as a "blip" with a distance and direction from the radar station. There would be no identification of the target other than one determined by the radar operator. Secondary radar on the other hand depends on the target having a radar transponder. When the radar signal hits the aircraft, the transponder sends out a signal of its own that includes identification, speed and altitude. Air traffic control assigns a specific temporary code to each aircraft in its zone. This is known as the squawk code. Use of the code allows for positive identification of each signal that is generated by an aircraft's transponder. The interrogatory signal sent into the airspace by the radar station is on 1030 MHz, with the return signal from the aircraft being on 1090 MHz.
TCAS (Traffic Collision Avoidance System) [Pronounced Tee-Cass) TCAS is a sort of mobile Secondary Surveillance Radar in that it uses the same frequencies and mechanism. An equipped aircraft sends out interrogatory signals on 1030 MHz, and responses from other aircraft come back on 1090 MHz. This happens several times each second. The return information contains the other aircraft’s identity, position and speed. One's own aircraft is doing the same thing. The on-board unit builds a three dimensional map of the surrounding aerial traffic, and then by extrapolation determines if there is a potential collision threat. If there is there will be an audible alarm, perhaps a synthesized voice, that will sound in both aircraft.
TCAS then negotiates a mutual avoidance maneuvre involving a change in altitude, and how fast or severe that change must be. At present TCAS does not dictate changes in direction or forward speed. For example one pilot could be told to immediately dive, and the other to immediately ascend.
ADS-B (AUTOMATIC DEPENDENT SURVEILLANCE-BROADCAST) is a very common system today in which an aircraft continuously broadcasts its position and other information to any suitable receiver in its vicinity. The position is three dimensional, in that it also includes altitude, and is determined by GPS. This also determines speed and direction which are also transmitted. Also included are identification details. Because this does not depend on being interrogated by a ground-based radar station it can be considered to be independent. This has also meant that the signals can be picked up by hobbyists and has led to the proliferation of sites such as FlightRadar24 and Planefinder, and today anyone with a smartphone can install an "app" that allows identification of almost any aircraft that can be seen.
Most larger aircraft are equipped with ADS-B. There are two levels of ADS-B. ADS Out is the transmission of information to whoever can pick it up. ADS In is the reception of such information. An aircraft equipped with ADS In can directly see the traffic around on the panel.
Many aero enthusiasts today have their own ADS-B receivers and contribute their reception on-line to the various websites such as FlightAware and FlightRadar24. I use those sites "all the time" but I myself do not have a receiver. If I live long enough I will likely join in on this fascinating part of the hobby.
I have posted this page before being finished with my communications overview, as I did not want to wait any longer to get the navigation part (above) up on-line.
I am certain that most aero enthusiasts who listen to radio are far more interested in the communications aspect as compared to the navigation aspect described above. My overview of aero communications will be much shorter as I have essentially covered a lot of the details in my other pages.
HF Long Distance Radio
In the modern world aero communications begin in the radio spectrum with HF SSB long distance radio. To translate, this is the hihg frequency radio in the band or sub-bands that extend from around 3 MHz to 30 MHz. The usage of HF for aeronautical use remains but is slowly being replaced by satellite communications. Commonly HF is used for trans-oceanic flight, when aircraft are outside the range of land-based VHF radio.
This map shows the VHF coverage along the US East Coast and out over the North Atlantic, and from the east side as well. It does show that there are major gaps that must be covered by other means. Those of you who are Canadians might be interested to know that the coverage shown extending from the south tip of Greenland is a remote transceiver for Gander Radio, not from Danish authorities.
For those of us who live along the east coast of North America, and listening to aircraft heading out across the Atlantic, it is common to hear our regional ACC or ARTCC instruct a pilot to change to New York Radio or Gander Radio HF and give a set of frequencies, which are expressed in kHz. For example "United 783 contact New York Radio 8803 Primary, 5646 Secondary" There are several sub-bands of aero frequencies and generally speaking at night those in the lower middle part of the 2-30 MHz band are used. In daytime it is the higher part of the band, and this is all dependent on the propagation characteristics of HF radio and the need for signals to bounce off the ionosphere to get aroudn the curve of the Earth.
You will need a communications receiver rather than a scanner in order to hear these communications, and you will have to be able to decypher SSB (single-sideband transmissions). If you buy a radio advertised as a shortwave receiver it might only have the shortwave broadcasting sub-bands and probably will not have SSB capability. Note that you can purchase an SDR dongle and install software on your computer to do the same thing, but you will still need a good antenna.
There are a few aspects to HF aero comms. The one that is commonly considered is the ATC coverage of regions beyond VHF coverage. Over the North Atlantic, New York has coverage off the east coast of the USA and Nova Scotia, whereas Gander Radio has coverage farther north and all the way to halfway across. On the other side Shanwick and Santa Maria take over. There are other stations covering other regions, and it is possible to hear these from around the world if conditions are good, and you have a good receiver and antenna. Note that some of these ground HF stations are privately owned such as New York Radio operated by AIRINC, and some are government owned such as Gander, operated by Nav Canada (a Canadian crown corporation). Aircraft over these oceanic areas are not under actual control, but they are monitored for position, and therefore aircraft do transmit position and speed reports periodically. Invariably the crew does not listen to the radio frequency constantly in case the ground station calls. Instead a signalling system call SELCAL is employed Each aircraft gets a code, and when this two-tone code signal is transmitted, the receiver on the specific aircraft becomes live and communications are established. This is why a casual listener willl hear a lot of two-tone sounds.
Note that there are also ACARS or data signals going back and forth on HF frequencies, and you can use a decoder along with your receiver to have these displayed. ACARS is explained in the VHF section of this article. HF ACARS operates in the same bands as voice but on different frequencies.
Associated with HF two-way communications are the VOLMET stations. These are broadcasters of weather information and usually transmit at fixed times, perhaps twice per hour. In our area Gander and New York are the VOLMET stations, and broadcast weather for airports of arrival along our eastern areas. Because they transmit at specific times and you can tune and listen for them, VOLMET is a popular long distance radio hobby niche, even for those who have no interest in aeronautics. When I lived in BC I heard VOLMET from Japan, Hong Kong, Australia and Wake Island, in addition the normal ones in Oakland, Honolulu and Anchorage. For whatever reason I have not in the decades since I came to Nova Scotia pursued any HF radio listening so cannot comment on what you would hear from this region. Note that there are also military VOLMETS, such as from Trenton, Ontario. Here s a sample frequency chart with specific broadcasts, for the Shannon, Ireland VOLMET, which is commonly heard in our region.
I should say also that there are HF aspects to ATC over land where the areas are sparsely populated. Here in Canada the Arctic and sub-Arctic have considerable HF usage, due to the low number of VHF stations. On e feature of the Canadian north are Airport Community Radio Stations with one or two HF radio frequencies.
Finally, many airlines and military have HF aero frequencies used for more private or specific communications with aircraft. In commercial airline circles this can be referred to as LDOC, for Long Distance Operational Control. In the USA most airlines contract their communications to AIRINC and rely on phone patches. Those movies in which you see a technician at an airline company talking a pilot through a problem are not really talking through a radio and antenna on the roof, rather they are on the phone and patched via AIRINC and its long-range network. Here in Canada you can listen to offshore or northern SAR missions via HF radio. There is a station associated with Halifax military and the JRCC located on the Halifax base. When I last checked some time ago their main frequency was 5718 kHz, but again, if you are interested you should do some research. For this and other specific issues you could email me and I may have links to pass along to you.
As I do not intend at this point to say much more on this subject, i can only advise that you search online for more information. But check back and I may have expanded my comments and links when you next visit. The following are the HF radio sub-bands allocated to aero radio:
2850-3155 kHz 6525-6765khz
There world is divided into areas with families of frequencies assigned. A family is a group of frequencies that includes at least one frequency from each of (or most of) the available sub-bands. In other words any one family will have a frequency in the 8 MHz sub-band and another in the 3 MHz sub-band. Here is a map of the world that is so small in scale that you will not be able to actually read it, but it will give you some idea of the divisions. Note that not all areas of the world are in a region. Regions have standardized abbreviations, so that for example the North Atlantic is NAT.
Here is a more localized map for the North Atlantic and Caribbean. Note that there are sub-families for NAT.. so there are NAT-A, NAT-B etc. These sub-families are based partially on geography but also partially on the registration country of the aircraft.
Here is a list of the frequencies included in NAT-A, and as well a list of the ATC stations that monitor them.
3016.0 - 5598.0 - 8906.0 - 13306.0
Canarias, Gander, New York, Paramaribo, Piarco, Santa Maria, Shanwick
For more frequencies, for other NAT families, and for other families around the world, check at Canairradio.
Check the link below as well:
The following sections will be written as I find time to do them. In addition I will go back and add and correct the preceding section.
VHF Radio (118 - 137 MHz) Civil Airband
This is the main area of interest for aircraft enthusiasts sitting out at the airport with a radio in hand so they know what is going to happen next. Many of my other pages detail the specific frequencies in use around the Maritimes. When I do write this section it will be about the band in general and how it is divided up into sections, and as well the special purpose frequencies in use throughout Canada and the United States.
UHF Radio (225-400 MHz) Military Airband
This band is used exclusively by the military, with the exception of a very small segment used by civil navigational landing aids as described in the preceding navigation section. Although this band is commonly referred to as an airband, it is also used by naval ships for intercommunications and as well in recent years, a section has been given over to military terrestrial trunking systems.
The most common area of interest in our region for this band is the aerial refueling carried out over Nova Scotia by the United States Air Force, and which has several specified frequencies. I have elsewhere on this website a special page dedicated to this aspect.
Satellite Radio Communications