FMSCAN - frequencies for any place and transmitter maps
What's on my FM dial?
The FM band looks different wherever you go. If you only a move into the next city there will be
different stations on other frequencies. FMSCAN can calculate what to expect.
It's a free tool.
Whether you just want to take a closer look at your stations at home or you are about to travel
some distant spot - this tool helps to explore FM and AM radio.
The Network Maps section makes it easy to find frequencies of a specific station if you're moving through a certain area.
This has been automatized with the RDS technology. But RDS often fails with weaker stations. Setting the frequency
manually might deliver you many more stations than RDS would find.
FMLIST - the database
Part of the data come from public sources.
In addition to that FMLIST includes many observations from
people who like to listen to distant stations (DXers). These hobbyists are also the most intense users of the database.
Combining all this information makes FMLIST unique. In Southern Europe for example you won't gain much from the
FMLIST has become very comprehensive over the years. It should contain almost any FM frequency in Europe.
AM coverage is world-wide. The current coverage can be obtained by clicking on
FM Coverage and AM coverage.
There are also links on the start page.
GŁnter Lorenz started the FMLIST project in Germany in the late 80ies. FMSCAN and FMMAP have been on the internet since 2000.
From 2004 many international contributors have joined the project.
FMSCAN - Frequencies for any location
Your own location
FMSCAN needs the coordinates for the place for which the automatic bandscan will be processed.
Amateur radio locators can be used, too. On a mobile device you can use the GPS if the geolocation API is supported.
This will work on most Android devices. If GPS is off or you are using a PC/Laptop a rough location will be estimated by
the IP (this will be done by the browser, not by FMSCAN).
But you don't need neccessarily to know longitude and latitude. Just type in your location and select the
Other options for the location serach
You can also use GoogleMaps. If you want to check out a remote SDR-receiver from Globaltuners, the Perseus network or
SDR there is a list of locations. The 'click on map (fmscan mapserver)' option is left as a historic feature from the early days :-)
It will display two sequential maps: fist the world map. Click on the area you are looking for.
The second map will zoom there. Click again on the spot. Now your coordinates will be inserted automatically.
Of course it is also possible to enter the coordinates manually. If cookies are allowed in your browser's preferences,
locations will be saved. They should appear in a list when you return to the location serach.
Everything fine? Then click on the "generate" button. After a few seconds the frequency list appears.
The strong stations are marked green. There is also a second list with the strongest frequency of each program.
This helps if you want to set the memory of your radio. They are ordered from the strongest to the weakest.
- MHz: Frequency followed by polarisation and status (h: horizontal, v: vertical, c: circular, m: mixed, P = planned, I= inactive)
- Cty: country code by the International Telegraph Union
- Program: Program name
- Transmitter: location of the transmitter (in brackets: region code)
- Pdir: effective power towards the selected place in kilowatts
- Pmax (FM/TV): effective power of the transmitters's main beam
- TPwr: Transmitter power (without antenna gain)
- Dist: distance to the transmitter
- Azi: azimuth from receiver to transmitter in degrees
- dbĶV: signal strength relative to 1 microvolt on a non-directional FM antenna outside
"f" stands for fading. That means: the signal strength gets stronger and weaker all the time and often
disappears for a few seconds because it is beyond the FM horizon. Fading depends much on the weather.
Click on the list !
Clicking on the fields will display more information depending on the column
With a click on 'info' at the very right you can get all the basis data for the entry at once glance. Where available you will find
play icons to the livestreams.
Other clickable columns:
you can choose between
- a list of all stations in the area (different radius options)
- draw single frequency maps for the area
- list all frequencies of this program
- display a network map with frequencies for the program
List all frequencies and programs of this transmitter, view photos where available and see the position in a google map. Further options:
- View transmitter map of surrounding area with various scale options
- List all transmitters...: frequency list of all surrounding transmitters
- links to other maps
360-degree patterns for power (ERP), height (FM/DAB/TV) and a cross section of the signal path (FM/DAB/TV)
Interpreting signal strength
How many "dB" are enough for good reception? This depends very much on the receiver and the antenna.
Some sufficient levels for FM:
Even if the signal level is sufficient, neighbouring channels can interfere. If a station 0.1 MHz apart is
only a little stronger, all receivers will face problems. Most car radios and tuners will cope
with a difference of 0.2 MHz a equivalent signals. Cheap receivers still have problems if a station 1 MHz
apart is only a little stronger than the chosen signal.
- 70 dB receivers inside a steel building or in a cellar
- 65 dB cheap alarm clock radios indoor
- 60 dB portable radios or tuners indoor with non-optimized antennas
- 55 dB car radios and portable receivers outside
- 54 dB used to be the reference for clear stereo reception with a 3 element roof antenna
- 40 dB good car radios moving
- 30 dB good car radios standing on a good spot (if you move there will be noise every now and then)
- 20 dB communication receivers with a dipole antenna on a good spot
How strong must a transmitter be?
1 Watt is already enough to cover a village, 1 KW is sufficient for a major city (if the antenna is high enough),
100 KW usually reach up to 120 km with a permanent signal. Behind this horizon, signals are rather weak and they begin
to fade. A directional antenna can pick them up and provide sufficient but fading signal levels.
The effective transmitter power is a product of the electric power of the transmitter and the directional pattern
of the antenna. Most bigger transmitters are combined with antennas concentrating the power like a flat plate.
No signals are needed above and below the antenna, all the power should cover the area.
This is why the effective power often exceeds the transmitter power.
Click on "expert options" to change parameters.
Change location: chose another place or map center
reduces the list to the selected options. In combination with "list all stations" this can work as a database query.
Most fields can reamain empty (common sense rules). Then they would take no effect.
- country ITU country code (f.e. "G" for Great Britain)
- region region code
- program program name
- exact match refers to the program name: "BBC" without "exact match" would put out BBC Radio 1, BBC Radio 2 etc.
With "exact match" the program name should be exactly as written in the databse f.e. "Leicester Sound FM".
- search for networks guides through all possible choices for regions and programs
Frequency: the range of the query in MHz or just the single frequency. The database lists stations on FM from
the East European OIRT band (65-74 MHz), some Japanese stations (76-92 MHz) and the international FM band (87.5-108 MHz).
It's useful to limit the number of calculated signals in advance. If the preselection is too large the script would run into a timeout.
For the lists there are three modes of pre-selection:
shows all stations with a level of at least the threshold value. The radius around the receiver location will be set automatically, depending on propagation conditions (only FM/TV/DAB), time and date (MW/SW) and threshold. Default radius for FM with normal conditions is 200 km.
You can determine a radius around a target location. All transmitters in that area will be displayed. The target location can be different from the receiver location. This makes sense if you want to check the signals of stations i.e. around London which you can receive in Newcastle. The radius mode now also works with larger values calculating with great circles (or over the poles).
If you click on set, the boundaries of this selection will be transferred into the coordinates fields below.
This is for simple rectangular boundaries and will list all transmitters in that area. You can enter longitude and latitude directly or select a continent or country to get the approximate corresponding values. Please notice that this is a very rough and purely geographical method- most countries and continents are not rectangular. If you want to limit the selection by country borders it's better to use the country code on the left.
Program list (SCAN):
will show a list of the strongest frequency of each program below the scan.
dist/azi/dB: The coulums for distance, azimuth and signal strength will be displayed.
If you just want a list of all frequencies of a program independet from your own location you can uncheck this option.
dBmax/dBdist: in addition to the signal strength, two other values will be displayed in brackets:
this would be the signal strength if the transmitter was in sight (no attenuation at all).
Even under extreme positive conditions the signal can't be much stronger. The only execption is if different paths
in the same phase add themselves up, but this can't gain more than a few dB anyway.
this is the signal loss only by distance (not by topography). It is relative to the signal at 1 km distance.
So 2 km would have 6 dB loss, 4 km would have 12 dB, 8 km - 18 dB etc.
RDS-PS-Code (the 8 character display in car radios) containing the program name.
RDS-PI-Code will be displayed. These are 4 Hex-figures that help to identify unknown stations. Most receivers
use it in the background. Some communication receivers can display it as a more or less hidden function.
HAAT (height above average terrain)
The effective height is the average height of the transmitter antenna above the surrounding terrain in 3 to 15 km
radius. For the calculation of the signal strength this value is usually more relevant than the height above sea level.
Just like we have two power columns, there are also two HAAT columns. One for the effective height towards the receiver
and one for the maximum HAAT of all directions.
Sometimes the second value is smaller than the first. That appears illogical. In these cases HAATmax is probably
the average of all HAATs. The data is not always so consistent.
Regional programs will be displayed.
inactive, temporary aqnd planned stations will also be displayed
Every summer stations appear on FM from distances between 900 to 2600 km.
Reception of one station lasts only a few minutes, signals change rapidly.
If you are in Central Europe for example, one minute you can receive a station from Madrid, half an
hour later stations from Valencia appear, later from Italy and so on. This phenomenon is
called sporadic E or E(s) and is caused by reflections in the ionosphere (150 km above).
With the Es index option, the bandscan only lists stations that are likely to appear under these
conditions. The peak propability is assumed at 1800 km, strong stations within 1200-2100 km also listed
at the top. Stations that are closer to the equator are preferred.
Meteor-Scatter-Index: This is another way of receiving distant stations. Once a meteor enters the atmosphere (happens all the time)
it leaves a ionized trail behind for a few seconds. This causes reflections of FM signals in a distance of about
800 km. These signals are very weak and can usually only be picked up with directional antennas and sensitive receivers.
With the MS index option, the bandscan only lists stations that are likely to appear under these
This refers to the most frequent overspill caused by inversions in the troposhere (up to 15 km).
Light tropo enables repeption up to 200 km, strong tropo or ducts (intense inversions into one direction)
lead signals up to 1200 km, or even further under conditions like above the Mediterranean Sea.
Under normal conditions the tropo index is 0, extreme overspill can be simulated with a value of 9.
Look up the Hepburn tropo index for today's conditions.
All scheduled Times (AM)
will list all stations no matter if they are transmitting at the given time or not.
Time and Date
have two effects:
- If the button is active a filter will just list stations which have scheduled broadcasts
at that time. This is especially important on SW. Only time and weekday will be considered for this, using the
current schedule information. Historic schedules are not available.
- Time and date will always be used for the propagation prediction also considering day/night power patterns and
the solar cycle.
only signals above this level will be displayed
weaker signals (SCAN):
in most cases it makes sense just to list the strongest staions on each frequency. The
weaker ones won't be received anyway. This value sets the range below the strongest station.
If it has a strength of 50 dB and the weaker stations value is 10 dB, stations down to 40 dB
will be displayed. You can deactivate this by setting the value far up.
Maximum number of stations in the list. The limit is 10.000.
- omni: no directional antenna. In this case the other antenna values don't matter.
- H-directional: directional antenna with horizontal elements
- V-directional: directional antenna with vertical elements
The relative height (HAAT) will automatically be calculated for the receiver's location (QTH).
In other words: the topography around the receiver will be taken into account in 10 degree sectors when a scan is generated.
If you click on QTHAAT a seperate window will open showing the height values of the receiver.
antenna above ground
this value will be added to the height above sea level when calculating the receiver's HAAT.
Receiver HAAT (FMSCAN / TVSCAN):
relative antenna height of the receiver (see HAAT above). This value will only be used if you don't use QTHAAT.
- gain: would be about 5dB at 3 elements, 7 dB at 5 elements, 11dB at 14 elements
- F/B: front-back-ratio. usually about twice as high as the antenna gain
- Azimuth: in degrees 0=north 90=east 180=south, 270=west and everything in between
- opening: opening angle in degrees at - 3 dB
Transmitter maps (FMMAP / MWMAP):
With a few clicks you can display the coverage and frequencies of any program
additional expert options for maps:
- Radius: from the center to the top or buttom in km
- Pixels: size width x height
- Concentrics: circles around the map centre
- Country/region/program: filter for specific programs (look above)
- Frequency: only stations in the frequency range (or single frequency)
- Min. power: minimum power
- incl.inactive: inactive, planned and temporary stations will be displayed
If checked, circles and ellipses will appear on the map indicating how far the signal can be received with a
certain threshold level. Big threshold will result in small circles.
Actually, this is not in perfect accordance with the bandscan's signal strength calculation.
The calculation includes antenna height and power patterns.
Landscape ranges from 1 (flat) to 6 (mountains).
- Font size: relative size for the transmitter/program labels
- Loc chars: maximum no. of characters for the location name
- Split: detailled descreption of the location will be left away
- Prog chars: maximum no. of chars for the program name (unless 8 char-RDS-PS is unknown)
- location: display name of transmitter location
- frequency: display frequency
- programs: display program name or RDS-PS
- power: display power
- pol: display polarisation
Understand how the maps are being drawn
After creating the background map, dots for all transmitter locations appear on the map.
They can't be overwritten by labels. After that the labels will be drawn. The labels grow step by step starting
with the most powerful signals (100 KW at transmitter ABC as example).
Only if there is still space left after all programs down to 10 KW have been
labelled, a 10 KW program from transmitter ABC will be labelled, too.
If a map looks confusing in the end or too many labels are missing, you should enlarge the size.
The limit is at 5000 x 4000 pixels.
Immediate access to expert options
There are links in the start menu. Here you find also links to single frequency scans and maps.
Single frequency maps
make sense when you receive an unknown distant station on a given frequency.
is based on experience and a little physics. The signals have an initial strength
of 96,4 dB at 1 KW and 1 km of distance. Double distance will lead to a loss of 6 dB.
Double power means +3dB. Taking only this into account, you would have the signal
strength if the transmitter was in sight. But it rarely is.
Topography (trees, buildings...) causes signal loss. FMSCAN calculates with a
linear loss of 22 dB up to the double horizon. This horizon depends on the
effective height of the transmitter antenna and the receiver's antenna height.
Beyond the double horizon signals begin to fade. They are already very weak and
can only reach the receiver by reflections (inversions, planes). Up to 350 km distance
the signal loses additional 15 dB per 100 km, beyond 350 km they decrease by 25 dB
per 100 km. So much about normal conditions. If you have tropo, loss is reduced.
This gives a reliant prediction for rather flat areas. In the mountains however
signals can be reflected more than once. A prediction is more difficult here.
We don't work with 360-degree-height patterns for the receiver's location yet. So
for the calculation it remains unclear whether you have free sight to the North, East
or South or a steep hill to the West.
If transmitter data is missing, default power is 1kW, default HAAT is 100 or 200 m
depending on the power.
Medium wave and long wave
Click on the AM links. The prediction takes time and season into account.
AM reception in the day and the night is totally different. Daytime reception is
limited up to 1000 km (LW) or 300 km (MW). In the night you have strong signals up
to 3000 km.
The TV database is only ready for Central Europe yet. In the Band-I (47-87 MHz) worldwide transmitters are listed.
But due to the rapid changes by digital television it's hard to keep up with the data.
Is a very nice tool with day- and time-specific bandscans for shortwave.
press info May 2011