I found one link that describes basically this service for AM/FM radio reception in the I-90 tunnels. It is section 7.3 (right near the end) of this link:
http://www.wsdot.wa.gov/sites/default/files/2012/06/26/I-90TunnelSystem.pdf And, cellular service will be ultimately in all of the tunnels under Seattle and already exists in the oldest downtown tunnel as described here: http://www.seattletimes.com/seattle-news/transportation/seattle-transit-tunnels-will-finally-get-cellphone-signals/ 73, phil, K7PEH > On Apr 15, 2017, at 8:14 AM, Jim Stahl <[email protected]> wrote: > > OTOH, this can be a feature of tunnels, not a bug. Several years ago I was > riding on the “BikePike”, an abandoned section of the PA Turnpike east of > Breezewood that has become a bicycle route featuring two old tunnels. > Although closed off to motor vehicle traffic, we noticed a pickup parked > outside the entrance to one of the tunnels. A few hundred yards into the > tunnel we encountered a minivan with lots of high end electronic test > equipment. Turns out the guys were doing tests on some military equipment, to > determine that it was RF quiet to prevent detection by enemy forces. We > didn’t ask a lot more, lest they would have had to shoot us :-) > > > 73 - Jim K8MR > > >> On Apr 15, 2017, at 10:43 AM, Phil Hystad <[email protected]> wrote: >> >> A number of tunnels are “wired” for broadband radio reception. A bit of >> years ago when they were building the I-90 stretch between Bellevue and >> Seattle there are two major “tunnels” on each side of the I-90 floating >> bridge (across Lake Washington). The tunnel on Mercer Island is actually >> not a tunnel but a covered section of the freeway but the tunnel on the west >> end is through the hill (known as the Mount Baker tunnel but not because it >> is under Mount Baker but because it is under the Mount Baker neighborhood of >> Seattle). >> >> So, a news article at the time described how the technology was employed to >> provide radio reception for AM, FM, and also cellular communication. I >> don’t remember reading about Sirius/XM radio though. I do know that my HF >> mobile operations come to a halt through those tunnels. As signals drop off >> after a 100 feet or so from the opening and don’t come back until the other >> side. >> >> Unfortunately, I can’t remember anything of the details of how this was done >> but I suspect wide-band amplifiers and wires and top-side wide-band antennas. >> >> 73, phil, K7PEH >> >> >>> On Apr 14, 2017, at 8:47 PM, Fred Jensen <[email protected]> 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 > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
