Sirius (at least) has terrestrial transmitters that are used to full sat
voids, like tunnels or parts of the San Francisco or NY financial
districts, or tall mountains near an interstate highway. The smaller
blockages are probably deemed a minor inconvenience, especially if
they're out inthe countrysideor in unpopulated areas. I used Sirius in
the early 2000s, and used to experience regular dropouts of 4 seconds in
several locations on my commuteto/from work. Each of these areas was
under a highway or freeway.
Not sure if your tunnel was private or not. If it was, it wasn't
covered by surface transmitters unless by accident. There is a tunnel
in LA that basically runs under LAX, and I never lost signal there. It's
probably hit or miss on what's covered terrestrially.
XM (I believe) bought Sirius out, sometime in the last decade. Both
services operate on the abandoned telco S-bandif I understand
correctly. I hear XM isn't doing so well financially, but that was
probably a couple of years ago. May not be current on this.
73,
matt W6NIA
On 4/14/2017 8:47 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
On 4/14/2017 2:50 PM, Phil Kane wrote:
On 4/14/2017 1:13 PM, KENT TRIMBLE wrote:
The assumption has always been that the driver and passengers are
riding
inside a Faraday Cage and therefore are safe from RF radiated by an HF
antenna, regardless of where located and regardless of power level.
When I take my 2011 Ford Focus through the car wash, I put the mag-mount
VHF antenna inside the car but it is still connected to the radio. I
have no problem picking up the usual 2- and 3/4- meter repeaters that
way. So much for the "Faraday Cage". :)
73 de K2ASP - Phil Kane
Elecraft K2/100 s/n 5402
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Matt Zilmer, W6NIA
[Shiraz]
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