Q:
I enjoy my satellite radio. At my home outside Savannah, Georgia, if I go into a parking garage, I lose the signal. When in Vegas, I could be in the middle of a multi-level casino parking garage and get excellent reception. What causes the difference in reception?
A:
It’s no secret that Las Vegas has more security guards than New York City has taxi cabs. All Las Vegas security guards have a two-way radio that they carry as part of their uniform. A security guard without a radio is like Barney Fife without a bullet in his upper-left pocket.
The casino security and surveillance departments use aerial repeaters that amplify the signal to their security guards’ two-way radios. Signals that don’t have the benefit of being boosted with repeaters are to signals that do have the benefit of repeaters as your mom yelling at you at the top of her lungs is to your mom using a megaphone.
But wait, there’s more. Because of the size of a casino property, the security radios need even more of a boost than just the repeaters. Enter the distribution amp. This is comparable to taking a five-watt stereo and adding a 5,000-watt booster.
Now, here’s your answer. So that that the security guards never have a blind spot where they can’t hear or send radio transmissions, on every floor of a big casino’s parking garage is a distribution amp. (The same is true for all the elevators.) The unexpected benefit to satellite-radio buffs is that the repeaters and distribution amps boost the signal to car satellite radios as well.
Update 01 September 2008
Sometimes we rely a little too heavily on experts to answer the highly technical questions; this expert, apparently, committed a few bloopers.
Here's the feedback we've received on the answer from four dissenters. Thanks to everyone who wrote in.
- I'm pretty sure that you were only 50 percent right with the satellite radio question. Repeaters are used but they are not the same ones that the casinos use. Both XM and Sirius have repeaters in major metro areas to fill in the holes that satellites can't reach. There is no way that a repeater could pick up an entire band of frequencies and amplify them all. If you doubt me, Google "xm repeaters" or "sirius repeaters."
- I have never heard of private (casino-owned) radio repeaters helping satellite radio signals. How are casino's repeaters receiving the satellite signal to repeat it? XM Radio (and I presume Sirius, but I can't speak to it) uses ground repeaters in major cities (including Las Vegas). Those special receivers were installed by XM at strategic locations throughout the city. They have satellite receivers on them, and then translate that signal to a stronger radio frequency signal that can be received by in-car XM receivers. These terrestrial signals are used to help in places where there are obstructions (like tall hotels, bridges, and yes, parking garages). Additional information about these ground repeaters can be found here: http://www.xm411.com/phpbb/viewtopic.php?t=616.
- Since geostationary spacecraft are above the equator, terminals on the ground must have a decent view of the southern sky to receive signals from them. This posed a challenge for XM, since listeners in cars often pass by obstacles, such as buildings, foliage or hills, which can block geostationary satellite signals. XM’s solution is a network of repeaters – antennas on buildings and other sites that receive satellite signals from an optimally placed antenna and retransmit them. The repeaters are located primarily in built-up areas, where loss of the satellite signal is most likely to occur. Each XM receiver is equipped to receive signals from both of the company’s Boeing 702 satellites and a repeater simultaneously. As long as one of the sources is available, the radio will play without interruption. In addition, the receivers have buffers that store programming for several seconds, allowing operation to continue even if no signal is available momentarily. Sirius uses a trio of Loral FS1300 satellites in unique elliptical orbits in an effort to avoid the problems posed by geostationary satellites. The orbits, shaped like figure eights, allow the satellites to appear higher in the sky than XM’s, cutting down on the potential for a listener to be out of range of a satellite signal -- and allowing Sirius to have a much smaller number of repeaters. Sirius’ repeater network also avoids the need for specialized antennas that can track the company’s non-geostationary satellites as they move about the sky, Sirius feeds its repeaters using capacity on a geostationary satellite leased from a traditional satellite operator. Listeners can’t tell that the signals they receive via the repeaters do not travel over Sirius’ fleet of satellites. The Sirius satellites each spend about 16 hours over the United States, then whip around the other side of the Earth and return eight hours later for another stint hovering over Sirius’ listening area, according to Ted Hessler, the company’s vice president of space segment and enterprise operations. Two Sirius spacecraft cover the United States at any given time, Hessler said.
- I am sure you have been flooded with emails correcting your answer to the the QOD about Sat Radio reception in garages by now. But just in case you haven't. Your answer couldnt be more off. The Sat signal (digital) and the radio signal (analog) are totally different things and the casino security repeaters have nothing at all to do with it. The person aske
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