June 2005
Intermediate to advanced
568 pages
24h 7m
English
Content preview from Mapping Hacks
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Chapter 2, Mapping Your Neighborhood
#18 Why You Can’t Watch Broadcast TV
HACK
Hacking the Hack
The astute reader will have noticed that KQED-TV has not one, but two
antennas listed with the FCC. It happens that the second KQED-TV
antenna on Sutro Tower, a mere 57 meters above ground level, is the sta-
tion’s backup antenna. In the event that the main antenna at the top of the
tower, 500 meters above, malfunctions in an earthquake, the station can
switch over to the backup antenna to give us our natural disaster news. By
how much is KQED-TV’s reception radius reduced when their main
antenna is knocked out? SPLAT! can help us visualize the answer to this
question.
Figure 2-14. KQED-TV’s potential broadcast coverage, including cities
Why You Can’t Watch Broadcast TV #18
Chapter 2, Mapping Your Neighborhood
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81
HACK
First, we’ll make a kqed_backup.qth file, containing the same location as
kqed.qth, but with a different description and antenna height.
KQED (Backup)
37 45 19.0
122 27 6.0
57m
Then we’ll ask SPLAT! to show us the viewsheds of both antennas overlaid.
$ splat -t kqed kqed_backup -c 20.0 -s cities.txt -o kqed_overlap.ppm
Figure 2-15 shows the coverage of the first antenna listed in green, and the
overlap between them in yellow. KQED-TV’s two antennas are well placed
on Sutro Tower. Even if the
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.