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ARSA Now Has Easy Access To Many Historical AM Coverage Maps

S

Schroedingers Cat

You may have to register, but it's easy.

ARSA (Airheads Radio Survey Archives) Now Has Easy Access To Many Historical AM Coverage Maps.

Go to Stations In the Category column. Enter Call Letters. When the call letters show up, click the call letters. The coverage map will appear on the right side of page. Click on the map to enlarge.

It looks like the collection on worldradiohistory.com, but easier to search.
 
Schroedingers Cat said:
You may have to register, but it's easy.

ARSA (Airheads Radio Survey Archives) Now Has Easy Access To Many Historical AM Coverage Maps.

Go to Stations In the Category column. Enter Call Letters. When the call letters show up, click the call letters. The coverage map will appear on the right side of page. Click on the map to enlarge.

It looks like the collection on worldradiohistory.com, but easier to search.
Click to expand...
What the website address?
 
Schroedingers Cat said:
You may have to register, but it's easy.

ARSA (Airheads Radio Survey Archives) Now Has Easy Access To Many Historical AM Coverage Maps.

Go to Stations In the Category column. Enter Call Letters. When the call letters show up, click the call letters. The coverage map will appear on the right side of page. Click on the map to enlarge.

It looks like the collection on worldradiohistory.com, but easier to search.
Click to expand...
It has coverage maps of some stations but many have no maps and the maps don't differentiate between daytime and nightime reach. It looks like the stations just made up the map to exagerate the areas covered.
 

ARSA | The Radio Surveys / Record Charts Site

An historical archive of Radio Surveys & Nostalgia.
las-solanas.com

It looks like a work in progress. When ARSA first started, it didn't have many record surveys either. The large market stations had almost complete collections, but the smaller market stations just had a handful. Now there are almost 200000 record surveys from 4738 radio stations.

M-3 Map conductivities in many areas are inaccurate, and that's what the consulting engineers used to make the maps. They may overestimate or underestimate coverage depending on the area. Also, usually the 0.5 mV/m contour is shown, and the engineering consultants often put the 0.1 mV/m contour on it. Today, neither is adequate because of inferior receivers for AM BC and electrical noise. It is probably more valuable for DXers and Radio History aficionados.

fccdata.org and Radio Locator use the same M-3 Map data, but no more than three contours for AM stations. Usually, only Class I/Class A stations had protected skywave contours. Many Class II and Class III (Class B) stations with powers of 5000 watts or more at Night have usable skywaves, especially those with 20000 watts or more at Night. The skywaves on fccdata.org also overestimate the usable skywave for all but veteran DXers. But plenty of those Class B's have skywaves in excess of the typical NIF of old stations.

Remember also to put in the call letters of the station at the time the map was made, often the legacy call letters.
 
Last edited:
rparky54 said:
It has coverage maps of some stations but many have no maps and the maps don't differentiate between daytime and nightime reach. It looks like the stations just made up the map to exagerate the areas covered.
Click to expand...
Back before deregulation, stations could be sanctioned for maps that were not clear. The first requirement was to label the field strength of each contour.
 
rparky54 said:
It has coverage maps of some stations but many have no maps and the maps don't differentiate between daytime and nightime reach. It looks like the stations just made up the map to exagerate the areas covered.
Click to expand...

I have seen lots of "coverage maps" that were intended for advertising sales kits, that were more wishful thinking than actual measured signal levels. Most of them looked like someone plopped a coffee can on a map, and then drew a circle that included prime advertising clients.
 
awsherrill said:
I have seen lots of "coverage maps" that were intended for advertising sales kits, that were more wishful thinking than actual measured signal levels. Most of them looked like someone plopped a coffee can on a map, and then drew a circle that included prime advertising clients.
Click to expand...
Of course, few stations have their RF coverage on a sales sheet today. Stations tend to focus on audience delivery, not maps.
 


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