[HamWAN PSDR] KU7M and his dBm

Thu May 22 13:03:07 PDT 2014

Bart,

>Would you like some tower climbing / install help?  That's some crazy
uptilt on the antenna picture you showed!

Thank you for the offer, but I think it can wait until I'm healed. This
was 'minor' knee surgery and I should be back to working out in six weeks,
so I'm sure climbing the tower will be doable by then. We are at the very
beginning of tower climbing season....

The crazy uptilt required was the source of most of my headaches. From that
exact location, I will hear nothing with the antenna at the normal 'level'
mount point. You need to tilt it up about five degrees or more before CP
will register.  It never occurred to me that it would have that big of
impact.  Microwaves are weird....

Thanks
Kenny

On Wed, May 21, 2014 at 11:54 PM, Bart Kus <me at bartk.us> wrote:

>  Dean,
>
> I wouldn't limit your potential upside to 3dB with ... "spatial
> modulation".  :)  The vast majority of your path loss is NOT due to
> distance.  If you did achieve clear (or better) LoS, you could be looking
> at 30dB deltas.  Remember we've had Baldi-Tacoma (a far longer distance
> than yours) run at -57dBm during a signal survey.  K7JMM, across the Puget
> Sound (about 3x your distance) is running at -58dBm right now.
>
> Kenny,
>
> Would you like some tower climbing / install help?  That's some crazy
> uptilt on the antenna picture you showed!
>
> --Bart
>
>
>
> On 5/21/2014 9:27 PM, Kenny Richards wrote:
>
>  Dean,
>
>  I'm slightly less mad at you, but still a little peeved. :-)
>
>  The shot to Capital Park from my house goes through quite a few tree's
> in my immediate area. (All within a couple blocks from me)  When I
> originally installed the tower about 10 years ago, I was able to see
> downtown from the top of it. Now I can't, due to the trees of the neighbor
> directly behind me and his neighbor.
>
>  That said, I don't actually have the HamWAN antenna mounted on the tower
> yet. I had to postpone that installation until my knee heals up. (Had the
> meniscus repaired in my left knee last week)  Right now the antenna is
> mounted to a small mast at the apex of the roof. (It is sharing the mast
> with a VHF/UHF vertical)
>
>  I thought that I'd posted links to these pictures before, but I guess
> not.
>
>  Picture of current installation:
> http://www.ku7m.net/drop/KU7M_HamWAN.JPG
>
>  Picture of what I'm shooting through to get to Capital Park:
> http://www.ku7m.net/drop/KU7M_CPView.JPG
>
>  And just because it makes me laugh, the installation from the first
> night it started working: http://www.ku7m.net/drop/DeckAntennaMount.jpg
>
>  The difference in signal strength from the antenna being on the deck
> railing to its current location is ~5 dB. The height difference between the
> to location is about eight to ten feet. When moving the antenna to the roof
> the first time, I had originally installed it on a mast located at the far
> east side of the roof. In this spot I could not hear CP at all. By moving
> the antenna to the mast located in the center of the house (which is about
> 20-25 feet west), the signal appeared and has so far been the best
> location.  I ordered another mast mounting kit for the eve located at the
> far west side of the house. When I'm feeling better I'll install it and see
> if the signal improves again when moving west.
>
>  I don't have many data points on the impact of wind on the signal
> strength. I did check it on Sunday when a system blew through which was
> causing the trees to noticeable move. But I wasn't seeing much change in
> the signal strength. (maybe 1 db?)
>
>  Thanks
>  Kenny
>
>
>
> On Wed, May 21, 2014 at 7:44 PM, Dean Gibson AE7Q <hamwan at ae7q.com> wrote:
>
>>  First of all, Kenny:  welcome!  Now that you have a HamWAN connection, I
>> hope you are no longer mad at me.  Where is your antenna (inside/outside,
>> height above ground, etc)?
>>
>> On a related but more serious side, do you have a direct line-of-sight
>> path to Capitol Hill, or do you go through trees?  The reason I ask is, my
>> path goes through some trees.  When it is windy, that causes my RX signal
>> level (dBm value) to vary about 5 dB (mostly down).  I have wondered
>> whether mounting my antenna higher would help my overall value (of course
>> it would help when it is windy).
>>
>> My average RX signal level is 80 dBm (no winds), and yours appears to be
>> 83 dBm.  However, you are twice as far from your cell site as I am from
>> mine, and since power falls off as the square of the distance, I'd expect
>> (in similar configurations and siting) that you would experience a 6 dB
>> difference.  Since the difference is only 3 dB, that suggests that (all
>> things being equal, which they never are) I might gain *at most* 3 dB by
>> moving the antenna.
>>
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>>
>
>
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