Re: [Elecraft] OT: Re: KPA500 mobile?
The tunnel on Taylor Road, Newcastle, CA, which is the best candidate
for a tunnel on a road that may have been part of the old US Route
40 as it officially ends in Utah now. :)
That tunnel runs ENE to WSW or therabouts...
0.103 km or 544.6 feet
62 degrees 49 minutes from south to north
Seems off axis unless the satellite is way off-axis but I had to use
a seriously off-axis sat once when I lived in CA Had to aim the
dish almost due east near the horizon...
We just renewed for her for another 3 years... She's happy, I'm happy.
Waveguide I don't know enough to hazard a guess But at a an
approx 13 centimeter wavelength, sat sigs can certainly travel down a
large tunnel if it enters at a small enough angle of incidence
AND, maybe that water is helping contain the signal in the "guide".
#5 cool to know.
73,
__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389
On 4/15/2017 6:32 PM, Fred Jensen wrote:
> Well, one of the side benefits of this list ... lots of smart and
> knowledgeable people. A summary and then it can pass into the archive
> ...
>
> 1. The first of "my" tunnels is in Newcastle CA [between Auburn and
> Sacramento on the old US40 and Lincoln Hwy route] and was constructed
> sometime around the end of the 19th/beginning of the 20th centuries.
> It's not quite 1/4 mile long. There is no visible wire or radiax in
> it. The hill it runs thru is full of water and you get leaked on when
> driving thru it, even in summer.
>
> 2. In the early 80's, the company I worked for then had a contract to
> rehab the communications for the Bay Area Rapid Transit system. We
> used a 300 ohm twinlead with a hollow core about 2 1/2 in in diameter
> along the ceiling of the tunnels and underground sections. It was 150
> MHz land mobile stuff and the twinlead was fed from a combiner that
> put 5 or 6 transmitters into it [train control, fire, security, etc.]
> It worked very well. Aligning the combiners [which actually looked a
> bit like a still [:-) ] was a bear in the equipment spaces in the tube
> under SF Bay but it worked well. They also wanted 800 MHz simulcast
> throughout the service area, a requirement probably still waiting for
> a real solution.
>
> 3. Other than under bridges, in canyons, beside heavily forested
> roads, and in the garage, where it's obvious the path to the
> satellite(s) is blocked, we don't experience any XM drop outs. She's
> going to drop the subscription, it's expensive and my new Honda
> Ridgeline has become our travel vehicle, but she's had it since 2013.
>
> 4. I've wondered if there wasn't some sort of waveguide effect in
> tunnels. For BART, one of the many problems we had with simulcast was
> that it leaked into the tunnels, even as far as the bottom of the
> Transbay tube. I don't know the XM satellite frequencies but I
> thought they occupied some spectrum abandoned by the Cellphone industry.
>
> 5. [Bonus Factoid]: The pine forests of the Southeast US are opaque to
> 800 MHz.
>
> Thanks for all the ideas and peripheral info.
>
> 73,
>
> Fred ("Skip") K6DGW
> Sparks NV USA
> Washoe County DM09dn
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Re: [Elecraft] OT: Re: KPA500 mobile?
I think that both XM and Sirius were/are using 2.2 GHzor thereabouts.
It's not MSS territory, but it works if you have enough power behind it.
73,
matt W6NIA
On 4/15/2017 4:32 PM, Fred Jensen wrote:
Well, one of the side benefits of this list ... lots of smart and
knowledgeable people. A summary and then it can pass into the archive
...
1. The first of "my" tunnels is in Newcastle CA [between Auburn and
Sacramento on the old US40 and Lincoln Hwy route] and was constructed
sometime around the end of the 19th/beginning of the 20th centuries.
It's not quite 1/4 mile long. There is no visible wire or radiax in
it. The hill it runs thru is full of water and you get leaked on when
driving thru it, even in summer.
2. In the early 80's, the company I worked for then had a contract to
rehab the communications for the Bay Area Rapid Transit system. We
used a 300 ohm twinlead with a hollow core about 2 1/2 in in diameter
along the ceiling of the tunnels and underground sections. It was 150
MHz land mobile stuff and the twinlead was fed from a combiner that
put 5 or 6 transmitters into it [train control, fire, security, etc.]
It worked very well. Aligning the combiners [which actually looked a
bit like a still [:-) ] was a bear in the equipment spaces in the tube
under SF Bay but it worked well. They also wanted 800 MHz simulcast
throughout the service area, a requirement probably still waiting for
a real solution.
3. Other than under bridges, in canyons, beside heavily forested
roads, and in the garage, where it's obvious the path to the
satellite(s) is blocked, we don't experience any XM drop outs. She's
going to drop the subscription, it's expensive and my new Honda
Ridgeline has become our travel vehicle, but she's had it since 2013.
4. I've wondered if there wasn't some sort of waveguide effect in
tunnels. For BART, one of the many problems we had with simulcast was
that it leaked into the tunnels, even as far as the bottom of the
Transbay tube. I don't know the XM satellite frequencies but I
thought they occupied some spectrum abandoned by the Cellphone industry.
5. [Bonus Factoid]: The pine forests of the Southeast US are opaque to
800 MHz.
Thanks for all the ideas and peripheral info.
73,
Fred ("Skip") K6DGW
Sparks NV USA
Washoe County DM09dn
On 4/15/2017 10:40 AM, Clay Autery wrote:
I would think it would depend almost entirely on the orientation of the
tunnel... (and satellite reception azimuth).
First, the longest of those two tunnels is only 425 feet or so. The
other is significantly shorter (southbound).
The tunnels are oriented generally north/south which is the preferred
direction IF you have to monitor geosynchronous satellite transmissions
from overhead... sort of).
You are right on the edge of a large body of water, which while not
brine, has better conductivity than the soil around the lake.
Significant potential for reflections off the high ground on almost all
sides
Don't know where that first tunnel is, so I can't comment. But if you
gotta hear in a tunnel those two would be great candidates...
73,
__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389
On 4/14/2017 10:47 PM, Fred Jensen wrote:
Semi-related curiosity regarding shielding. My wife's car has
Sirius/XM radio. It usually loses contact with the satellite driving
under Interstate bridges and the like. Likewise in the garage. OTOH,
at our previous home there was a tunnel through a small hill, perhaps
1/4 mi long. The XM worked fine through it. There are a pair of
tunnels at Cave Rock next to Lake Tahoe through a granite mountain.
XM works fine through them too. Anyone know why?
73,
Fred ("Skip") K6DGW
Sparks NV USA
Washoe County DM09dn
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Matt Zilmer, W6NIA
[Shiraz]
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Re: [Elecraft] OT: Re: KPA500 mobile?
Well, one of the side benefits of this list ... lots of smart and
knowledgeable people. A summary and then it can pass into the archive ...
1. The first of "my" tunnels is in Newcastle CA [between Auburn and
Sacramento on the old US40 and Lincoln Hwy route] and was constructed
sometime around the end of the 19th/beginning of the 20th centuries.
It's not quite 1/4 mile long. There is no visible wire or radiax in
it. The hill it runs thru is full of water and you get leaked on when
driving thru it, even in summer.
2. In the early 80's, the company I worked for then had a contract to
rehab the communications for the Bay Area Rapid Transit system. We used
a 300 ohm twinlead with a hollow core about 2 1/2 in in diameter along
the ceiling of the tunnels and underground sections. It was 150 MHz
land mobile stuff and the twinlead was fed from a combiner that put 5 or
6 transmitters into it [train control, fire, security, etc.] It worked
very well. Aligning the combiners [which actually looked a bit like a
still [:-) ] was a bear in the equipment spaces in the tube under SF Bay
but it worked well. They also wanted 800 MHz simulcast throughout the
service area, a requirement probably still waiting for a real solution.
3. Other than under bridges, in canyons, beside heavily forested roads,
and in the garage, where it's obvious the path to the satellite(s) is
blocked, we don't experience any XM drop outs. She's going to drop the
subscription, it's expensive and my new Honda Ridgeline has become our
travel vehicle, but she's had it since 2013.
4. I've wondered if there wasn't some sort of waveguide effect in
tunnels. For BART, one of the many problems we had with simulcast was
that it leaked into the tunnels, even as far as the bottom of the
Transbay tube. I don't know the XM satellite frequencies but I thought
they occupied some spectrum abandoned by the Cellphone industry.
5. [Bonus Factoid]: The pine forests of the Southeast US are opaque to
800 MHz.
Thanks for all the ideas and peripheral info.
73,
Fred ("Skip") K6DGW
Sparks NV USA
Washoe County DM09dn
On 4/15/2017 10:40 AM, Clay Autery wrote:
I would think it would depend almost entirely on the orientation of the
tunnel... (and satellite reception azimuth).
First, the longest of those two tunnels is only 425 feet or so. The
other is significantly shorter (southbound).
The tunnels are oriented generally north/south which is the preferred
direction IF you have to monitor geosynchronous satellite transmissions
from overhead... sort of).
You are right on the edge of a large body of water, which while not
brine, has better conductivity than the soil around the lake.
Significant potential for reflections off the high ground on almost all
sides
Don't know where that first tunnel is, so I can't comment. But if you
gotta hear in a tunnel those two would be great candidates...
73,
__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389
On 4/14/2017 10:47 PM, Fred Jensen wrote:
Semi-related curiosity regarding shielding. My wife's car has
Sirius/XM radio. It usually loses contact with the satellite driving
under Interstate bridges and the like. Likewise in the garage. OTOH,
at our previous home there was a tunnel through a small hill, perhaps
1/4 mi long. The XM worked fine through it. There are a pair of
tunnels at Cave Rock next to Lake Tahoe through a granite mountain.
XM works fine through them too. Anyone know why?
73,
Fred ("Skip") K6DGW
Sparks NV USA
Washoe County DM09dn
__
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[Elecraft] OT: Re: KPA500 mobile?
I would think it would depend almost entirely on the orientation of the
tunnel... (and satellite reception azimuth).
First, the longest of those two tunnels is only 425 feet or so. The
other is significantly shorter (southbound).
The tunnels are oriented generally north/south which is the preferred
direction IF you have to monitor geosynchronous satellite transmissions
from overhead... sort of).
You are right on the edge of a large body of water, which while not
brine, has better conductivity than the soil around the lake.
Significant potential for reflections off the high ground on almost all
sides
Don't know where that first tunnel is, so I can't comment. But if you
gotta hear in a tunnel those two would be great candidates...
73,
__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389
On 4/14/2017 10:47 PM, Fred Jensen wrote:
> Semi-related curiosity regarding shielding. My wife's car has
> Sirius/XM radio. It usually loses contact with the satellite driving
> under Interstate bridges and the like. Likewise in the garage. OTOH,
> at our previous home there was a tunnel through a small hill, perhaps
> 1/4 mi long. The XM worked fine through it. There are a pair of
> tunnels at Cave Rock next to Lake Tahoe through a granite mountain.
> XM works fine through them too. Anyone know why?
>
> 73,
>
> Fred ("Skip") K6DGW
> Sparks NV USA
> Washoe County DM09dn
__
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