Antenna Structure Registration) 

and Tower Maps

Summary of Tower Maps

Tower Maps is compiled directly from site owners and managers. Tower Maps updates site files on a daily basis of co-location sites.  Tower Maps maintains a high level of quality control to ensure the best possible and most comprehensive data source. Tower Maps excludes government site that do not offer lease space.

FCC and Tower Maps

(Click on image for enlargement)

Questions and Answers

Question: Is Tower Maps a repacking of the FCC data?
No, Tower Maps is not developed from the FCC Antenna Structure Registration (ASR) data.  

Question: What is the FCC data?
The FCC Antenna Structure Registration (ASR) Data is maintained by the FCC from those site owners or carriers who submit FCC ASR registration forms.  The FCC data is free and it is what it is. The FCC data is neither complete, not always current.  It is available in flat tables and needs to be reworked for use in GIS. The FAA data is focused on aviation hazards and height obstructions above 200 feet. 

Question: How complete is the data?
Tower Maps is estimated to include over 98% of all commercially viable antenna sites.   This estimate for Tower Maps is based on over 10 years experience of researching and compiling antenna site data.  Tower Maps does not include site such as single tenant rooftop arrangements.  The completeness of the FCC data is substantially less than that of Tower Maps, based on visual overlay of the two data sets.  The ASR file currently contains 104,000 records (as of August 2006) although many are not useable collocation sites.

The FCC believes that 28% of all registrations are not yet filed. The LBA Site Assessment Project estimates that 70% are not filed or are in error. (http://www.lbagroup.com/Wireless_University.php)

Question: What is the source for Tower Maps data?
Tower Maps is compiled directly from over 450 site owners data files.

Question: Are rooftop sites includes in Tower Maps and FCC data?
Tower Maps includes commercially managed rooftop sites.  The FCC ASR data does not include these as they are concerned with the "structure" registration.

Question: What sites are not included in FCC data?
There are many sites that are included in Tower Maps that do not appear in the FCC ASR data.  This includes not just the small tower owners, but also the large ones including Sprint Sites, American Tower and others.  The lack of FCC registration does not appear to be an issue of company size or tower age.

Question: Aren't all towers properly registered with the FCC?
Simply stated, no.  As to why these towers are not properly registered is unknown. These are obvious violations.  Enforcement of the registrations by the FCC is, no doubt, a difficult task.


Question: How is data maintained for current ownership?
Tower Maps is updated on a daily basis.  The files are then compiled directly from over 450 site owners data files for monthly update release. When a site is bought and sold, over time the record shifts from the original owners to the new owner.  One will find that there are "duplicate" sites in Tower Maps.  The FCC data simply reflects the antenna site original application and records are not updated.

Question: Is there a quality assurance review for spatial accuracy?
Tower Maps data for consistently prepared for using decimal degrees in NAD83 projection.  Data received in NAD27 are reprojected.  All sites are plotted and checked for transposed or unrealistic latitude and longitude.  Check plots are prepared and sent back to site owners such that the site owner can correct coordinates.
The FCC data does not appear to a Quality Control review or update process.

Question: Are there duplicate records in Tower Maps?
Yes, Tower Maps data does include some duplicates.  There are two primary reasons for this.  One is a site which recently changed ownership.  Historically Tower Maps has worked to flush out "sold sites".  This includes scraping tower companies that have been purchased by the larger tower companies.  It has been noticed over the years that this process can take month or years.  It is also noticed that after the transition, there are often error introduced.  The second reason is that several companies work together, co-listing one another's sites.  When Tower Maps is able to identify the true site owner, duplicate records are removed. 

Question: Are there error records in Tower Maps?
Unfortunately yes, Tower Maps makes all reasonable efforts to check and scrub the data, but is reliant on the site owners providing accurate data.  For example, one site purchased by American Tower was noticed to be on the wrong site of the road as seen in aerial photo (TerraServer).  AT then attempted to correct the location, but placed is 21 miles in the wrong direction.  This was confirmed in internet postings.

Question: What value does Tower Maps provide? 
Tower Maps is value-added data providing the data subscriber with an accurate, complete and current listing of available antenna sites in a consistent GIS-ready data package.  

Question: Where does one obtain FCC data?
You can download the FCC ASR data files in ESRI GIS shapefile format free (10 MB zipped)...... click here
You can purchase this data from Percon if you wish......  click here and click here


  Tower Maps FCC ASR
Estimated percent completeness 98% + Unknown
Rooftop sites Yes No
Record correction and maintenance  Yes Unknown (Presumed no)
Frequency of update releases Compiled daily, released monthly Posted about weekly or bi-monthly
Data quality review Data flagging and check maps prepared Unknown
Last updated:  August 18, 2006

For more information call us at 540-822-5092 or e-mail info@towermaps.com

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