How to Fill out the Technical Part of the LPFM Application
By Prometheus Radio ProjectAna Martina, Paul Bame, Will [email protected]
Call in number 213-416-1560 | Access Code: 954 162 871
- How to find a transmission site- How to secure Reasonable Assurance- Filling out the form 318 @ CDBS- Info for the Tech Box- How to find an engineer- Q & A
Agenda
How to find a transmission site
The transmission site, also known as the tower site or antenna site, houses the equipment that broadcasts your
FM radio signal out to the world!
Webinar: Finding a Viable Transmission SiteWednesday, August 21 @ 6PM EST
Area of Coverage: How far will it go?
How to find a transmission site
Transmission toolkit
http://www.prometheusradio.org/transmission#transmissiontoolkit
How to secure Reasonable Assurance
Dear [LPFM APPLICANT ORGANIZATION],
Based on our discussion this confirms that, should your FCC construction permit application be granted for a low-power FM non-commercial authorization with antenna at coordinates [XX XXXX.X N XXX XX XX.X W], [I/WE] have space available at [MY/OUR] tower, and would be willing to enter into a lease of tower space with you, subject to final determination of a rental rate based on market conditions at the time.
Sincerely, ___________________ [INDIVIDUAL and/or OWNER]On behalf of [FACILITY/TOWER OWNER/ORGANIZATION][FACILITY-ID ###### or ANTENNA ASRN ######]
Date ___________________
Info for the tech parts of the application
1. Channel2. Antenna Coordinates3. Antenna Structure Registration Number4. Site Elevation5. Tower Height6. Antenna Height7. Power and Height Limitations8. Exhibits
http://prometheusradio.org/cdbs
Filling out form 318 @ CDBShttp://prometheusradio.org/cdbs
Filling out form 318 @ CDBS
Your account number
Filling out form 318 @ CDBSConsolidated Database System (CDBS) online filing system.
User's guide https://licensing.fcc.gov/prod/cdbs/forms/prod/cdbs_ug.htm
Filling out form 318 @ CDBS
Select FCC 318 – application for Construction Permit for a Low power FM Broadcast Station
Filling out form 318 @ CDBS
Form instructions | http://www.fcc.gov/Forms/Form318/318.pdf
Filling out form 318 @ CDBSSection VI – LPFM Engineering
Tech Box
#1: Channel
If you don’t already know the channel corresponding to your frequency, you can convert using the formula: channel = 201 + (frequency - 88.1) / 0.2
Channel numbers range from 201 to 300.
Check!! channel numbers are from 201 to 300 -- do not use frequencies, like 98.1, in box #1
-The FCC requires there be an available frequency in your area in order to apply for a Low Power FM station.
-The transmitter and antenna can only be assigned to an exact geographic location, and you have to specify a location in your application that meets FCC requirements.
-The frequency must not be in use and must not interfere with other stations.
Channel Search
Rfree: Channel Finder Tool
You will be able to see what channels are clearly available at a location, what frequencies may be available with an engineering waiver, and what nearby locations may have more channels available.
http://radiospark.org/rfree
Rfree: Channel Finder Tool
http://rfree.radiospark.org
FCC channel finder toolhttp://www.fcc.gov/encyclopedia/low-power-fm-lpfm-channel-finder
Rfree the channel finder tool
RFree’s tech box will compute the channel number for you.
#2: Antenna Coordinates
● Tells the FCC the proposed location of your antenna
● Must use NAD27 geographic coordinates
● Current GPS technology used NAD83 (WSG84) so you might need to convert to NAD27 before you fill out this section
● Converter available on the FCC website.
● The RFree tech box converts for you (see also the RFree [Change-Location->Latitude, Longitude] page).
● FCC antenna tower registration system uses and expects NAD83 coordinates, so you will need to convert, or let RFree do it automatically.
#3: Antenna Structure Registration Number
● Towers taller than 62 meters (200 feet) located near airports are registered with the FAA.
● If you are NOT using one of these towers, (because you are putting your antenna on the roof of your building or a small tower) check the box “Not Applicable”
● If you are using space on an existing registered tower, confirm that the tower is registered using the FCC antenna database and check the box “FAA Notification Filed with FAA.”
● Height of the ground at your antenna location
● All heights must be in meters -- rounded to the nearest meter. RFree will supply an elevation automatically -- you should verify it against another reliable source like a topographic map, surveyor, or perhaps Google Earth.
● If you are using a registered antenna, your elevation should be close or identical to theirs from the registered antenna database. If you are co-locating with another FM station, you can use their elevation from FCC records.
#4: Site Elevation
● This is the height of the highest point of anything on your tower -- the highest thing which could hit an airplane
● This helps determine if you need to register your antenna with the FAA
● If you are using a registered antenna, the FCC may reject your application if box #5 is different than the registered antenna’s height
#5: Tower Height
● FM antennas can be from 1 meter to over 3 meters from bottom to top
● Provide the height of the “radiation center”, usually the vertical center of your antenna. If you have two antenna bays, it is the point halfway between them
● To be certain, use the specifications from your actual antenna
● To make an estimate, a one-bay antenna will be around 2 meters tall and a two-bay will be 4 meters tall, and so forth -- two meters per bay.
#6: Antenna Height
● Check “yes” unless you intend to violate the law and disregard the power levels the FCC allows on your construction permit, in which case they will disregard your application!
#7: Power and Height Limitations
RFree, myLPFM, the FCC’s LPFM channel finder, and commercial software, will tell you whether your location is far enough away from other stations that you won’t cause interference.
#8 & 9: Interference
The only correct answer is “Yes”. Supply exhibit 14 if your proof of compliance is more complicated than the worksheets.
#10: Environmental and Safety
Rfree Tech Box
Exhibits
Yellow = Interference = Exhibit
Exhibits in Tech Box
Exhibits in Tech Box @ RFree
Exhibits in Tech Box @ RFree
Exhibits
8(a). Interference to Other Stations and Exhibit 11
8(b). Interference to Translator Inputs and Exhibit 12
9. Interference to TV Channel 6
10. Environmental and Safety
How to find an engineer
Radiospark
RF Engineering skills
Questions
