Yeah... that will help. In my neck of the woods, its possible the only available channels might be in the lower channels anyway.
Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: Brian Webster To: 'WISPA General List' Sent: Thursday, September 23, 2010 7:41 PM Subject: Re: [WISPA] Transmit Antenna Height But what if you are able to use spectrum around 200 or 300 MHz? That certainly goes through trees. Brian From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Tom DeReggi Sent: Thursday, September 23, 2010 7:32 PM To: WISPA General List Subject: Re: [WISPA] Transmit Antenna Height Yeah, that really sucks. Many areas needing served have thick forest/trees easilly 70ft tall. A 90ft height, just wouldn't allow enough of the signal to have open air, and the signal would be going through trees most of the full path. In 900Mhz, the difference between having the tower side over the tree line and below the tree line can be the difference between a quarter mile coverage and a 7 mile coverage in our market. All be it, 700Mhz does have better NLOS propogation characteristics than 900 does. I would have liked to see that height doubled. However, admittedly, it will allow much better spectrum re-use in areas that have a limited number of channels available. Spectrum reuse is one of the best ways to serve more people. Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: Fred Goldstein To: WISPA General List Sent: Thursday, September 23, 2010 4:36 PM 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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