Make sure to comment to the fcc about this. Get involved and ensure your voice is heard.
"Fred Goldstein" <[email protected]> wrote: >At 9/23/2010 04:50 PM, Brian Webster wrote: > >>If you are on a high mountain and there are also a lot of other high >>locations around you your HAAT number could still be low. If however >>you are on a high mountain and the rest of the area all the way >>around your site is much lower, your HAAT figure will go up. Sites >>built on side hill locations with the hill rising above in part of >>the radius will greatly reduce the HAAT number. >> >><http://www.fcc.gov/mb/audio/bickel/haat_calculator.html>http://www.fcc.gov/mb/audio/bickel/haat_calculator.html > >A subscriber's house is wherever it is, and under the new rule, they >are just not allowed to subscribe if it is more than 76 meters >AAT. This doesn't have to be on top of the high mountain. If you >have RadioMobile, you can click around some potential sites and use >its US-mode HAAT function. I found a lot of places that would be >shut out. Try the "hill towns" in Berkshire County, MA, or just to >its east, so see what I mean. Heck, these are so hilly and woody >that the VHF channels look most attractive. (Not that they're >available; only one upper-VHF is actually vacant there.) Only a >handful of channels meet the white space criteria there to begin >with. I have the FCC's contours showing in MapInfo so I can click >anywhere on its map and see which contours I'm within. And of course >for co-channel, I have to look for contours about 10 miles beyond. > >If a significant number of subscribers are shut out, not to mention >the necessary access points to reach them, then we're stuck again on >900 MHz, which is pretty busy. So even with a white space access >point to reach the low houses, we'd need the 900 too to reach the >high houses. How silly. > >> >>"How is the HAAT determined? A HAAT value is determined by taking 50 >>evenly spaced elevation points (above mean sea level [AMSL]) along at least >>8 evenly spaced radials from the transmitter site (starting at 0 >>degrees [True North]). The 50 evenly spaced points are sampled in >>the segment between 3 to 16 km (formerly 2 to 10 miles) along each >>radial. The elevation points along each radial are averaged, then >>the radial averages are averaged to provide the final HAAT value. >>Terrain variations within 3 km (2 miles) of the transmitter site >>usually do not have a great impact on station coverage." >> >>Brian >> >> >> >> >> >> >>From: [email protected] [mailto:[email protected]] >>On Behalf Of Fred Goldstein >>Sent: Thursday, September 23, 2010 4:36 PM >>To: WISPA General List >>Subject: Re: [WISPA] Transmit Antenna Height >> >>This item alone may be the show-stopper, the poison pill that makes >>it useless to WISPs in much of the country. >> >>In places where the routine variation in elevation is more than 75 >>meters, there will be houses (subscribers) that are more than 76 >>meters AAT. I notice this in the areas I'm studying, both in the >>east and in the upper midwest. >> >>In a place like Kansas, nobody is >75m AAT. But in the woody >>Berkshires of Western Massachusetts, the UHF space is needed to get >>through the trees, and a significant share of houses are >75m >>AAT. Also, if you want to cover a decent radius, the access point >>needs to be up the hill too. 75 meters isn't a mountaintop; it's >>just a little rise. >> >>It makes no sense to absolutely ban fixed use at a site that is 100m >>AAT if the nearest protected-service contour is, say, 50 miles >>away. A more sensible rule would be to follow broadcast practice, >>and lower the ERP based on height, so that the distance to a given >>signal strength contour is held constant as the height rises. Hence >>a Class A FM station is allowed up to 15 miles, and if it is more >>than 300 feet AAT, then it is allowed less than the 3000 watts ERP >>that apply at lower heights. >> >>Maybe the lawyers want to have more petitions to argue over. >> >>At 9/23/2010 04:07 PM, Rich Harnish wrote: >> >> >>65. Decision. We decline to increase the maximum permitted transmit >>antenna height above ground for fixed TV bands devices. As the >>Commission stated in the Second Report and Order, the 30 meters >>above ground limit was established as a balance between the benefits >>of increasing TV bands device transmission range and the need to >>minimize the impact on licensed services.129 Consistent with the >>Commission's stated approach in the Second Report and Order of >>taking a conservative approach in protecting authorized services, we >>find the prudent course of action is to maintain the previously >>adopted height limit. If, in the future, experience with TV bands >>devices indicates that these devices could operate at higher >>transmit heights without causing interference, the Commission could >>revisit the height limit. >> >>66. While we expect that specifying a limit on antenna height above >>ground rather than above average terrain is satisfactory for >>controlling interference to authorized services in the majority of >>cases, we also recognize petitioners' concerns about the increased >>potential for interference in instances where a fixed TV bands >>device antenna is located on a local geographic high point such as a >>hill or mountain.130 In such cases, the distance at which a TV bands >>device signal could propagate would be significantly increased, thus >>increasing the potential for interference to authorized operations >>in the TV bands. We therefore conclude that it is necessary to >>modify our rules to limit the antenna HAAT of a fixed device as well >>as its antenna height above ground. In considering a limit for >>antenna HAAT, we need to balance the concerns for long range >>propagation from high points against the typical variability of >>ground height that occurs in areas where there are significant local >>high points we do not want to preclude fixed devices from a large >>number of sites in areas where there are rolling hills or a large >>number of relatively high points that do not generally provide open, >>line-of-sight paths for propagation over long distances. We find >>that limiting the fixed device antenna HAAT to 106 meters (350 >>feet), as calculated by the TV bands database, provides an >>appropriate balance of these concerns. We will therefore restrict >>fixed TV bands devices from operating at locations where the HAAT of >>the ground is greater than 76 meters; this will allow use of an >>antenna at a height of up to 30 meters above ground level to provide >>an antenna HAAT of 106 meters. Accordingly, we are specifying that a >>fixed TV bands device antenna may not be located at a site where the >>ground HAAT is greater than 75 meters (246 feet). The ground HAAT is >>to be calculated by the TV bands database using computational >>software employing the methodology in Section 73.684(d) of the rules >>to ensure that fixed devices comply with this requirement. >> >>130 The antenna height above ground is the distance from the antenna >>center of radiation to the actual ground directly below the antenna. >>To calculate the antenna height above average terrain (HAAT), the >>average elevation of the surrounding terrain above mean sea level >>must be determined along at least 8 evenly spaced radials at >>distances from 3 to 16 km from the transmitter site. The HAAT is the >>difference between the antenna height above mean sea level (the >>antenna height above ground plus the site elevation) and the average >>elevation of the surrounding terrain. >> >>67. In reexamining this issue, we also note that the rules currently >>do not indicate that fixed device antenna heights must be provided >>to the database for use in determining available channels. It was >>clearly the Commission's intent that fixed devices include their >>height when querying the database because the available channels for >>fixed devices cannot be determined without this information.131 We >>are therefore modifying Sections 15.711(b)(3) and 15.713(f)(3) to >>indicate that fixed devices must submit their antenna height above >>ground to the database. >> >>68. We continue to decline to establish height limits for >>personal/portable devices. As the Commission stated in the Second >>Report and Order, there is no practical way to enforce such limits, >>and such limits are not necessary due to the different technical and >>operational characteristics of personal/portable devices. >> >> -- >> Fred Goldstein k1io fgoldstein "at" ionary.com >> ionary >> Consulting <http://www.ionary.com/>http://www.ionary.com/ >> +1 617 795 2701 >> >> >>-------------------------------------------------------------------------------- >>WISPA Wants You! 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