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[aprssig] questions on Los Angeles area propagation

Stephen H. Smith wa8lmf2 at aol.com
Thu Nov 10 08:15:47 UTC 2005


jimlux at earthlink.net wrote:

> OK.. so I've been fooling around a bit with a low powered tracker (5W 
> into either the rubber duck or a trunk lid whip) on my way to and from 
> work.  (W6RMK-5 if you're interested) Some interesting observations.
>
> 1) There's no good way to tell if you're not getting in because of 
> terrain or because of congestion.  Is there some way to look at all 
> the packets received and transmitted by one of the high digis (i.e. 
> W6SCE-10)?  From that, I could figure out what that digis channel 
> occupancy is, and match it up against my presumed transmission attempt 
> times.
>
> 2) If I am getting blocked by terrain, the existing coverage of the 
> San Fernando Valley is horrid.  We're not talking about windy canyon 
> roads here but major freeways cutting across the north and east sides 
> of "the valley", the 118 and 210.  I expect to get hidden going 
> through the Verdugo hills (about a 5 mile stretch of the 210, and the 
> part of the 210 from Tujunga to JPL is a notorious hole, about which 
> something has already been discussed.  However, as I traverse that 
> gigantic swath across the northern SF valley, which is literally flat 
> as a pancake, I'd expect to have a more even distribution of packets 
> into the system.
>


The only full-time digi that sees the entire SFV is W6SCE on Oat Mtn.    
The problem is that Oat probably sees more of the populated parts of 
Socal than  any other mountain top.  It's an absolutely stupendous 
360-degree view that I love to take visitors to see.  I've spend many  
 From the Oat Mtn ridge line you can see southeast through the Cahuenga 
Pass to downtown L.A and beyond to nearly all of northern Orange County, 
all of the valley is at your feet to the south, nearly all of the basin 
south of the I-10 Santa Monica Fwy beyond the Santa Monica Mtns is 
visible (on a clear day you can see Catalina behind Palos Verdes behind 
the Santa Monicas), look down into the Simi Valley to the west, see the 
Oxnard/Camarillo/Ventura plain on a clear day to the southwest (it's 
also line-of-sight to the Santa Barbara coast), see up I-5 nearly to the 
top of the Grapevine including all of the Saugus/Santa 
Clarita/Newhall/14 Fwy area, and east clear to the San Bernardino/ 
Riverside areas and beyond to Beaumont/Banning/Cabezon.  On clear 
mornings, you can clearly see the twin peaks of San Gorgonio and San 
Jacinto on the way to Palm Springs.    In other words, this digi sees 
"half the world" at once and is almost continually captured by higher 
powered mobiles everywhere in southern California.  

 Low-power trackers and underpowered handhelds just don't stand a 
chance.   What you really need is a WIDE1-1 fill-in digi relatively on 
the ground in the center of the valley (somewhere around Sherman Way and 
the 405).  Being in the valley instead of thousands of feet above it,  
it would only hear valley mobiles, and could then retransmit with enough 
power to take Oat Mtn away from the 4 neighboring counties.


Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
Home Page:          http://wa8lmf.com

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