Matt,
What do you have your availability percentages set at in
your network properties of Radio Mobile? For any tree class going above 180
or 200% tells me you have something set wrong in the RF tool somewhere else.
The examples I posted are actually in fairly dense forested areas of
upstate NY. The tree clutter was factored in to the model. Remember also
that in these lower frequencies the tree loss factor drops considerably as
the absorption rate gets lower in the lower frequencies.
Thank You,
Brian Webster
www.wirelessmapping.com
www.Broadband-Mapping.com
From: Matt Jenkins [mailto:m...@smarterbroadband.net]
Sent: Friday, October 15, 2010 12:49 PM
To: bwebs...@wirelessmapping.com; WISPA General List
Subject: Re: [WISPA] WISPA Ex Parte Filing from yesterday
Brian,
I really like your idea for a full duplex system. Your example does not
appear to have much foliage and has rather high density. I feel that TVWS
should be used primarily for the low density with lots of foliage. High
density areas like that could very easily be serviced with higher
frequencies (5.2/5.8)
Would you be willing to look at how effective this would be from a tower
located at 39.184900 -120.963500?
The tree height is on average 120ft. A mix of mostly Pine and some large
Oak. By setting the land cover density to 500% in Radio Mobile, I am still
not able to adequately reproduce the amount of path loss due to foliage when
compared to most links I have deployed in 900mhz.
Thanks,
- Matt
On 10/14/2010 06:16 PM, Brian Webster wrote:
The request was made for the simple reason of being able to use the 40 mw
devices in a split radio architecture. If anyone caught my posting about how
far you can broadcast with 40 mw, it might make more sense. If you transmit
on one end of a link using 40 mw radio you could use a high gain antenna on
the other ends receiver to make up for the low power. Design a radio with a
separate receiver from the transmitter and you can have a multipoint system
that can operate in the first adjacent channels and still work for a WISP.
The key concept is that your transmitter does not use the same antenna as
your receiver keeping the power levels fully legal. The 40 mw devices in the
first adjacent channels do not have any HAAT limits. They are referred to as
mobile devices. There was a potential problem in the rules to make this
work. There was one little statement that said any transmitter and/or
receiver could not exceed the HAAT rules. It makes no sense for a receiver
to have to abide by that since it cannot cause interference. The FCC
apparently agreed.
40 mw transmit into a no gain antenna is legal, a 15 dbi receive antenna on
the other end is legal to. Put one of each in all radio devices and we can
operate in the first adjacent channels, PLUS you can transmit and receive on
separate frequencies thus having 12 MHz to work with.
We need to get out of the thought process of half duplex radios operating in
a single channel using the same antenna. If you can use first adjacent
channels you have a whole lot more capacity in each market than just the 4
watt EIRP non-adjacent channels. Split transmit and receive radios will also
allow you to mix and match high and low power. Use high power for the
downlink and have multiple remote receivers on the low power channels for
the uplink.
See the attached Google Earth file comparing the different channels and
power levels (save it to your hard drive prior to opening in Google Earth).
Remember these TV channels give you 15 to 20 db gain over current unlicensed
bands due to the reduction in free space loss that fact in conjunction with
a 15 dbi gain receive antenna gives you up to 35 db gain to a 40 mw signal
over what one would expect say a 40 mw Wi-Fi radio to broadcast.
The second issue they tried to address was the sites that exceed the 76
meter HAAT rules but would not exceed a total of 106 meters HAAT that you
would in effect have if you build a 30 meter tower on such a site. They
tried to get the erratum fixed to allow for any combination of site
elevation and tower height so long as the total HAAT does not exceed the 106
meters.
Fred do any of the sites you mention exceed the total HAAT of 106 meters?
The FCC said that unless the broadcasters agree that the combination issues
was not a big deal it would have to go out for public comment. The receiver
issue was just a separate point that was talked about in the same meeting.
Please take the time to re-read the FCC notice and use your RF expertise to
think of how one can stay within the rules and design radio systems to take
full advantage of the rules as they are written. I came up with these
thoughts to hopefully get manufacturers to produce devices to take advantage
of the new rules, not just repurpose existing unlicensed gear to operate on
these new frequencies. That would be a total waste of this new frontier and
very spectrum inefficient.
Thank You,
Brian Webster
www.wirelessmapping.com
www.Broadband-Mapping.com
-----Original Message-----
From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On
Behalf Of Fred Goldstein
Sent: Thursday, October 14, 2010 8:28 PM
To: WISPA General List
Subject: Re: [WISPA] WISPA Ex Parte Filing from yesterday
At 10/14/2010 08:16 PM, you wrote:
Fred,
If you don't know how to use this then don't use it. Simple.
Making snarky insults doesn't answer the question. Quite frankly I
have a pretty strong RF and regulatory background so it is not a good
idea to treat me like a dunce. So I'll ask the question
differently. Do I need to create a new petition or did you address
the up-the-hill WISP subscriber issue?
I am looking at potential subscriber locations above 75m HAAT. So I
want WISPs to be able to put a radio there. I'm really confused at
what you're trying to do. Do you really call subscriber units (I'm
imagining the TVWS version of a NanoStation) "receive only" (I
don't), or do you really only want receivers? Which of course don't
fall under those rules anyway.
Thank-you for your opinion and have a good day.
jack
On 10/14/2010 5:13 PM, Fred Goldstein wrote:
At 10/14/2010 06:35 PM, you wrote:
Fred,
Sites with TVWS receiving equipment instead of TVWS base stations
that transmit.
Yes, which is worth precisely zero to a WISP, since we need two-way
transceivers. The only receive-only equipment is what goes with
wireless mics; the mics themselves are transmit only.
jack
On 10/14/2010 3:22 PM, Fred Goldstein wrote:
At 10/14/2010 06:12 PM, you wrote:
Steve Coran (respresenting WISPA), Comsearch, Motorola and Spectrum
Bridge met with Julius Knapp and others from the FCC OET office
yesterday in regard to certain limiting factors in the TVWS
Memorandum Report& Order language. Below is the Ex parte Filing
that was made today.
Rick, when you guys said "to remove the HAAT restriction for
receive-only sites", did you really mean receive-only, or did you
mean the PtP subscriber (slave) station that talks to the "tower"?
I am glad to see action this soon on the 76-meter issue, since it not
only impacts tower locations, but subscriber sites.
--
Fred Goldstein k1io fgoldstein "at" ionary.com
ionary Consulting http://www.ionary.com/
+1 617 795 2701
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