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FCC AM Database

Posted: Mon Feb 27, 2017 8:37 am
by davedybas
Has anyone created an "offline" database from the FCC CDBS records ? I'm looking for a way to create my own. My objective is to be able to search for AM stations within the 3Km distance from a specific bearing. The FCC database has been off line every now and then and it's caused me a bit of a problem getting work done.

My biggest problem is determining how the various CDBS database files relate to each other. ie: am_ant_sys, altc_group_id, am_augs, etc....

Anyone have ideas ?

Re: FCC AM Database

Posted: Mon Feb 27, 2017 10:27 am
by Deep Thought
I wrote mine when they were still on the old VAX system and then updated it in 2000 when CDBS replaced that. One of these days I should re-do it in something that doesn't require DOSBOX to run it. :mrgreen:

The tables and data are text files, and the index associations are published. It's non-trivial to link them all up in something like MySQL but if you have any programming experience it isn't terribly difficult either. If all you are looking for is facility data and not all the other flotsam and jetsam that the ownership records toss in, only a few of the tables are required. ant_sys_id is the primary key for the AM data.

data record descriptions: ... iption.pdf ... eadme.html

data abbreviations: ... table.html

I've attached an older FCC description doc that explains things a little better than the current ones do. Keep in mind it is 14 years old and some fields and tables have been added, changed or deleted. I have also attached a definition file I used to convert the program I had written to use the new CDBS files in 2000. It relates the different FCC tables and fields with the variable I use. It ain't pretty but it works. 8)

Re: FCC AM Database

Posted: Mon Feb 27, 2017 6:29 pm
by davedybas
Hi Deep Thought,

I'm no IT wizard...but I do know a few things. One thing I can't figure out is... how does each of the data files determine what row of data it links to in another file ?

For example : The am_ant_sys file contains about about 82,000 records of data but there are no Call Letters in this database. So I guess there is an "index" or something in that database that can be used to find the Call Letters for a particular record in the altc_group or call_sign_history database ? I'm just not understanding how these separate database files are linked together.

Do you remember ?

Best Wishes,
Dave Dybas

Re: FCC AM Database

Posted: Mon Feb 27, 2017 7:15 pm
by Deep Thought
Since this was originally designed to be an engineering database ant_sys_id is the primary key field (index) in the am_ant_sys table and for any record which contains technical data and each one is unique. A DA-2 station would have two am_ant_sys entries, one day and one night. Usually they are sequential but not always. From there you can call up everything related to that engineering record using that as the search field in the other tables. For example, from an am_ant_sys table record's ant_sys_id field you can find the facility ID number, which then can be used to find all of the non-technical data for the station. There are primary and secondary key fields which branch all over the place. If all you need is a distance search, you can retrieve the coordinates from the am_ant_sys table, do the math to figure out whether it is within 3 km, and then fetch the rest of the data for the records which qualify.

I have a diagram of all this in a binder somewhere from when I implemented the database. I thought it was at the office but it is evidently at home. If I can find it tonight I'll post that It makes this a LOT clearer.

Re: FCC AM Database

Posted: Mon Feb 27, 2017 7:29 pm
by Deep Thought
Using the ant_sys_id #1 (WYCL, Niles, OH) as an example...the data in each record is pipe delimited, making it easy to import into just about anything.

Code: Select all

[This post was turning into a monster so I've attached what I was going to write instead of doing it as a post. Easier to deal with. :mrgreen: ]

Re: FCC AM Database

Posted: Wed Mar 01, 2017 8:21 am
by davedybas
Hi Deep,

Thanks for the insight....and examples. You certainly are a Deep Wealth of knowledge.

Wish me Luck !


Re: FCC AM Database

Posted: Fri Mar 03, 2017 7:10 am
by kkiddkkidd

A number of years ago, I used the CDBS to create a dbase to import into Garmin GPS units that showed both AM and FM stations as you were driving.

Getting all the data linked and indexed is the hard part. I think that I used excel for most of what I created. My data was not easily updateable and I only did so about once a year for the next 4 or 5years. I found that the ownership and a couple of the other files were so bloated and out of date as to be useless.

I wish there was something similar to my dbase on Garmin rx's for smart phones. If there is, I have't found it. I wish we could import the same data into WAZE...


Re: FCC AM Database

Posted: Fri Mar 03, 2017 7:14 am
by w9wi
I'm sure it could be written for a smartphone but...

They're in the process of moving the TV data into a new License Management System database. My recollection is they intend radio to follow suit eventually.

I don't suppose anyone has any idea how far along that project is? (probably not at all...)

Re: FCC AM Database

Posted: Sun Mar 05, 2017 8:43 am
by Lee_Wheeler
I am still using my old EDX DOS based versions of AMGW and AMW but, after the CDBS conversion, it got tricky. The FCC continues to publish and update the old VAX flat files but they wouldn't run on the database conversion program. The files looked the same but they wouldn't convert. I did a hex dump and found out that the old VAX files only used a Carriage Return at the end of each record and the converted files use a Carriage Return and Line Feed.

There are some shareware utilities like DOS2UNIX that convert the file to the original format and the conversion routines run again.

The old EDX stuff still runs and, other than skywave which they never really figured out, it works as good as anything else for groundwave studies. For skywave I can usually get something through the Commission if I cut the field to about 70% of what EDX says the limits are.