|
Login |
|
|
Login |
Trip Ericson
My real name is Mark Colombo, but the majority of the people here who would know me, know me under the pseudonym Trip Ericson. As of this writing, I'm a 19-year old college student in my first year at the University of Virginia in Charlottesville. I'm studying Electrical Engineering with a goal of becoming a broadcast engineer or consultant, and I received the Society of Broadcast Engineers' Youth Scholarship in 2007. I have an interest in broadcasting and computers, am an A+ and Network+ certified computer technician and I'm a full-time Kubuntu Linux user. I also hope to one day own my own radio and/or TV station(s), particularly in the county I grew up in, where I've already done the measurements to confirm that an FM radio station would, in fact, fit.
Bruce Myers
Bruce Myers is a software engineer from the Grand Rapids, Michigan area, and he is the wizard behind the coding on RabbitEars. He approached me in an e-mail on March 14, 2008 in response to my message on the front page seeking someone to help me out. He is a software engineer who has been coding since 1985, and has experience in Java, C++, HTML, JavaScript, php. Without him, RabbitEars would still be just a dream.
If you wish to submit "Historical and Ownership Data" or simple subchannel information you will want to just send me an e-mail with that information in it. I'll parse it and load it in by myself. I should warn you though, I can't promise I'll get to it quickly. My priorities are with the technical data, as this is what interests me the most. If I have a lot to do, such updates will very likely have to wait. I get on Ownership and subchannel changes pretty quickly, but historical information, not so much.
If you wish to submit "Technical Data and Screencaps" you will need a bit more information. First of all, any data about facilities comes from the FCC site or from my own handy work if it's something that doesn't appear there, such as WHYY-DT on channel 50. Most of the time, this will be as accurate as I can make it. If it's a problem with the FCC database, it needs to be directed to them and not to me.
If you want to give me screencaps, I accept JPEG and PNG (JPEG preferred) via e-mail attachments. I prefer that they be the original size for 480i, 480p, and 720p images, and scaled down to 960x540 for 1080i images. I also request that you follow the name scheme used by images already on the site--that is, FACID-subchannel_number.jpg. The facility ID can be found in the technical data, the subchannel number is just which subchannel, and the number is just to separate different screencaps by number. For example, here's what a screencap for WVIR-DT 29-3's CW subchannel looks like, namewise:
70309-3_0.jpg
If you wish to submit the other technical details about subchannels, I request that you send me output from the TSReader program in e-mail attachments. You can acquire that here (TSReader Lite will work fine) and once you lock in the station with that program, do an HTML Export, selecting all the checkboxes except for Screencaps and EIT. Then save that file with the same name scheme as used with the screencaps, except use -0 for the subchannel, like this for WVIR-DT:
70309-0_0.htm
If you want to determine whether or not a station is doing statistical multiplexing, watch for the bitrates on the video streams in TSReader to vary by large amounts (greater than 0.1 Mbps) and if they do, that station is doing statistical multiplexing. You can send that detail in the text of an e-mail if you wish.
Q. Where can I find information on the digital transition?
DTVAnswers.Com has a decent amount of information on the subject. I would do an FAQ for it here, except that it's already stated on other sites and stated well; there is no need for me to waste time doing a repeat of what is already available.
Before I begin, make sure you don't miss the important questions about Zones, channels 14-20, LP and CA stations, and channels 2-6 later in this FAQ.
Q. How are these available channels calculated?
Essentially, the FCC mandates that stations keep a minimum distance between themselves and other stations. Rather than calculating field strength, as was done during the digital transition to try to fit all the stations in while ignoring this distance separation, new stations, are required to follow these spacing requirements. What RabbitEars does is measure the distance to each station and use that along with the following numbers to calculate whether or not a station fits according to the spacing requirements. These are the measurements used:
Zone I, VHF: Stations must be 152 miles apart on the same channel, and less than 12.43 or greater than 68.35 miles apart on the adjacent channels.
Zone I, UHF: Stations must be 122 miles apart on the same channel, and less than 14.91 or greater than 68.35 miles apart on the adjacent channels.
Zones II and III, VHF: Stations must be 170 miles apart on the same channel, and less than 14.29 or greater than 68.35 miles apart on the adjacent channels.
Zones II and III, UHF: Stations must be 139 miles apart on the same channel, and less than 14.91 or greater than 68.35 miles apart on the adjacent channels.
Q. What are "Zones" and where are they located?
The FCC divided the country into several "zones" in order to allow stations in the Northeast and Great Lakes region with smaller coverage areas to be spaced closer together, and to try to alleviate interference concerns around the Gulf of Mexico. The FCC seems to have decided that Zones II and III are equivalent as far as digital television is concerned, but Zone I still has stronger limitations on signal strength and, consequently, can fit more stations in a given area. I've created maps of the Zones here:
Zone I consists of all the states and portions of states enclosed by the dotted black line.
Zone III consists of all the states and portions of states enclosed by the dotted black circles, including the entire state of Florida.
Zone II consists of any areas that are not in Zones I or III.
When measuring for available stations, if either your location or the station being measured is in Zone I, the Zone I measurement is used. So if I am in Zone II and I am attempting to measure to a station in Zone I, I measure as though both are in Zone I. But when measuring my Zone II location against another Zone II station, I use the Zone II measurement.
Q. When I do a search, I get stations on channels 14-20 which have call signs beginning with "LM." What are these and how do I handle them?
The FCC has reserved one or more channels in the 14-20 range in several large cities for use by local police and emergency officials. These are shown in the FCC rules as reserved for Land Mobile use only, thus the "LM" indicator.
It is important to note that these reserved frequencies DO NOT conform to the same requirements as digital TV stations do, and must be computed separately. Here are the requirements:
Co-Channel Operation: No stations are to transmit on the same channel as a Land Mobile operation within 155 miles of the given coordinates.
Adjacent Channels: No stations are to transmit on the adjacent channels of a Land Mobile operation within 109.36 miles of the given coordinates.
The FCC seems to have ignored its own rules with regard to some of these reserved channels, but all new stations must conform to these requirements.
Q. How are low-powered and Class A stations handled in all of this?
Low-powered stations are in gray text and can be ignored for the purposes of the available channel search. Low-powered stations receive no protection from encroachment of full-powered stations, and if a full-powered station wants their frequency, they are required to move.
Class A stations, however, do receive such protection. Exactly what protection they receive is unclear to me as of this writing, but they are measured in the table as though they are full-service, and if only a Class A station prevents a station from being listed as "Available," it is listed anyway with an asterisk (*) placed beside it. Further measurements beyond the scope of this search would likely be required.
Q. Why are there so few stations on channels 2-6?
Channels 2-6 have some severe problems which can be tolerated in the analog world, but cause havoc in the digital world. Chief among these is that electrical noise from lightning as well as vacuum cleaners, blenders, and anything else with an electric motor, can and will cause the signal to drop out or disappear completely.
These channels also suffer from a phenomenon called "e-skip" which is when ions in the E-layer of the ionosphere create a sort of mirror which reflects signals that would otherwise go out to space back down to Earth. This allows stations from as far as 1500 miles away to interfere with what you are attempting to watch.
While the power saved by using these channels is undeniably great, the tradeoffs are huge. It is advised to avoid these channels if at all possible.
