They listed all "fixed" devices must be below 75 meters HAAT. A lot of customers fixed CPE could be well above that as well.
On 09/23/2010 01:50 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 > > "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:* wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] > *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/ > +1 617 795 2701 > > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! 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