[HamWAN PSDR] East Tiger Mountain cell site on the air

[Bart Kus]

Hi Dean,

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.

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.

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.

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.

--Bart


On 6/22/2015 11:04 AM, Dean Gibson AE7Q wrote:
> 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 *0.1W*.  Reports are that it is a bit scratchy, but 
> pumping the power all the way up to *0.5W* gives a reported clean signal.
>
> OK, that's 70cm, not 5cm.  However, I've long been able to access 
> KB7CNN (1292.2MHz) at the same site with *1W*.
>
> All antennae above are omni.
>
> 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 *huge* 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 ...
>
> 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 *four degree* difference.  Google 
> Earth's elevation plot shows a clear path to both East TIger and 
> Baldi, the latter path *barely* clearing the terrain just west of East 
> Tiger.  VE2DBE's Radio Mobile Online ( 
> http://www.ve2dbe.com/rmonline.html ) plot agrees.
>
> 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.
>
> Thoughts?
>
> On 2015-05-31 19:50, Bart Kus wrote:
>> 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!
>>
>> --Bart
>
>
>
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