So, if we have a negative HAAT, is it correct that we are within the
rules.
Say we have a location with -100 calculated HAAT and it can not be above
+75.
Frank
On 9/24/2010 2:11 PM, Brian Webster wrote:
This rule as it is written states that the ground elevation not more
than 75 meters HAAT. Remember that is the not actual ground elevation
of the site, it is the HAAT calculation. See my other email with a
HAAT report pasted within. My office at an elevation of 1420 ft AMSL
actually has a negative HAAT value. I think people are
misunderstanding how HAAT is calculated.
Brian
*From:* wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org]
*On Behalf Of *Fred Goldstein
*Sent:* Friday, September 24, 2010 3:37 PM
*To:* WISPA General List
*Subject:* Re: [WISPA] FW: Transmit Antenna Height
At 9/24/2010 03:03 PM, you wrote:
Steve,
Here is another question to pose to the FCC. Does the HAAT
requirement include receive antennas. In otherwords, can no clients
be installed above the 76 meter HAAT level?
I see no mention of receive-only terminals, though I doubt anybody
asked. But if by receive you mean client (such as a Mode 1 CPE), then
the rules seem to ban those entirely, not just APs, from high ground:
"...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."
They cite to the IEEE's filing, but it didn't call for a ban; instead
it called for wider protection distances based on HAAT:
13.We recommend that HAAT be used to determine the required separation
distance from TV protected contours as described in the Table below.6
The method for calculating HAAT should be the same as was employed in
Part 90 to protect the TV service from PLMRS. In addition, we
recommend no limits on the antenna height above ground for fixed base
stations.7 We further recommend that no changes in the assumption of
antenna heights of 10m AGL for fixed user terminals (CPEs) be made for
the purpose of calculating the separation distance to the TV protected
contour.
That would have been reasonable.
*From:* wireless-boun...@wispa.org [
mailto:wireless-boun...@wispa.org] *On Behalf Of *Fred Goldstein
*Sent:* Friday, September 24, 2010 2:57 PM
*To:* WISPA General List
*Subject:* Re: [WISPA] Transmit Antenna Height
At 9/24/2010 02:16 PM, Tom DeReggi wrote:
There is one other benefit of this.... No body else will be able to
install higher either.
Mounting lower to the ground, its more likely a WISP will be able to
install their own tower, and no longer have to pay huge colocation
costs on a commercial tower.
I predict more houses up on the hill, being the new TVWhitespace towers.
Although, aren't these low channel Whitespace omnis like giant, and
weight a ton?
No, Tom, you missed the poison pill. If somebody lives on a hill,
more than 76 meters above average terrain, then they are banned from
using fixed whitespace devices AT ALL. Not at 4W. Not at 1W. Just
the flea-power portable devices, which are basically wireless mics.
This new rule needs to be changed.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: Brian Webster <mailto:bwebs...@wirelessmapping.com>
To: 'WISPA General List' <mailto:wireless@wispa.org>
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>
[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 <mailto:fgoldst...@ionary.com>
To: WISPA General List <mailto:wireless@wispa.org>
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
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ionary Consulting http://www.ionary.com/
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ionary Consulting http://www.ionary.com/
+1 617 795 2701
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