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Hi Dean,<br>
<br>
I think it would help in discussing these comparisons if you were to
express the RF power not in terms of absolute power, but in terms of
power spectral density (W/Hz). The 1W modem is set for 5MHz
bandwidth when communicating, so its PSD is 0.2uW/Hz. Your 0.1W
handheld is set for 25kHz bandwidth, so its PSD is 4uW/Hz. That's
20x higher power density. If the noise floors of both spectrums
were equal (which they aren't) that would mean a 13dB increase in
the ability of the FM radio to discern a signal, compared to the
modem.<br>
<br>
So 70cm FM has a lot going for it here. It has better NLoS
propagation combined with a theoretical 13dB PSD boost. On the flip
side, you have the 30dBi gain of the modem dish helping you to
compensate for those losses.<br>
<br>
This weekend I'll be running our first tests of the 900MHz gear in
NLoS conditions. I did some lab tests on it over the weekend, and
it looks like @ 5MHz bandwidth it transmits just about 1W. The
signal, being OFDM, isn't very tight, so we'll have to be very
careful with 900MHz repeater co-location. We'll also have to watch
out for colocated 800MHz users.<br>
<br>
Regarding you linking to ETiger, there's a bunch of trees in the
way, but give it a try! The mountain tower unfortunately does not
clear the surrounding tree line. If someone feels like donating a
60ft tower for up there, I'm sure that'd help. :) Also, keep in
mind that due to the tree issue, ETiger was only installed as a
single sector site. Sector 3, aimed at 240 deg. Have you tried
aiming @ Haystack yet? Nigel just moved and is linked up to it now
from Everett. We need to do some tree pruning @ that site to raise
its signal levels.<br>
<br>
--Bart<br>
<br>
<br>
<div class="moz-cite-prefix">On 6/22/2015 11:04 AM, Dean Gibson AE7Q
wrote:<br>
</div>
<blockquote cite="mid:55884E45.8020605@ae7q.com" type="cite">
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Recently I noticed that I can access the WA7HJR (444.65MHz)
repeater on East Tiger, from my home in Mill Creek, with the Icom
and Yaesu handhelds at <b>0.1W</b>. Reports are that it is a bit
scratchy, but pumping the power all the way up to <b>0.5W</b>
gives a reported clean signal.<br>
<br>
OK, that's 70cm, not 5cm. However, I've long been able to access
KB7CNN (1292.2MHz) at the same site with <b>1W</b>.<br>
<br>
All antennae above are omni.<br>
<br>
Meanwhile, my connection to the Paine site has dropped in the last
month from -77dBm to -84dBm. If last year is any indication, I
have about 30 days until I lose the connection to Paine for
another six months. Originally I thought this was due to seasonal
foliage growth, but since reception didn't come back until late
February, I think it's something else. Just to one side (a couple
hundred feet) of my direct path to Paine, is a <b>huge</b> water
tower just south of 132nd Street, and I'm wondering if that was
serving as a reflector when it was full, and not so much as it
emptied during the summer (or maybe partially resonant or energy
absorbing?), and not refilled until the winter. That hypothesis
fits the timeline better than foliage ...<br>
<br>
Anyway, when I get the time this summer, I will try moving the
5shpn & antenna to the south side of my house and try to
connect to the HamWAN site at East Tiger. Using Google Earth, I
see that the bearing from my house to East Tiger is 156 degrees.
I also see that the bearing to the Baldi site is 160 degrees, a <b>four
degree</b> difference. Google Earth's elevation plot shows a
clear path to both East TIger and Baldi, the latter path <b>barely</b>
clearing the terrain just west of East Tiger. VE2DBE's Radio
Mobile Online ( <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://www.ve2dbe.com/rmonline.html">http://www.ve2dbe.com/rmonline.html</a>
) plot agrees.<br>
<br>
This brings up the subject of common sector frequencies.
Theoretically, the narrow beam of my antenna dish (isn't it about
3 degrees?), coupled with East Tiger being only 28.3 miles away
compared to Baldi at 47.8 miles, I would think would resolve any
interference.<br>
<br>
Thoughts?<br>
<br>
<div class="moz-cite-prefix">On 2015-05-31 19:50, Bart Kus wrote:<br>
</div>
<blockquote cite="mid:556BC881.8070409@bartk.us" type="cite">We
put a new cell site on the air this weekend. It's @ East Tiger
Mountain, and radiating @ 240 degrees (Sector 3) only. It's
linked directly to the Tukwila datacenter, and has a second link
to Snohomish DEM ("Paine"), but that's not yet configured for
routing. This site is 1500ft higher than our existing Mirrormont
site, and will serve to replace it. It's superior location and
superior connectivity are a double-win. Mirrormont has been
re-configured to be on the Sector 2 frequency temporarily so as
not to conflict, but will go off the air at some point in the
near future. If you're in the coverage area try to give it a go
and report back! <br>
<br>
--Bart <br>
</blockquote>
<br>
<br>
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