Ask someone who's been observing the XML scene for a few years about XML in the context of cell phones and similar devices (PDAs and so on). What you'll get from them will probably include references to WML, WAP, and various web services. What you most likely won't get from them will be anything regarding XML-based descriptions of cellular and PCS broadcast systems.
The latter is the subject of this month's "XML Tourist."
Mobile Broadcast Regulation in Canada
In the United States, regulating the broadcast spectrum--including the cellular/PCS frequencies--falls to the Federal Communications Commission (FCC) and various state agencies. In Canada, this is the work of Industry Canada's Spectrum Management Services.
"Regulation" in this sense doesn't mean monitoring the content of broadcasts. What's at issue is that only a limited number of radio frequencies are available in a given geographic area for each general type of broadcasting--AM, FM, cellular, and so on. The companies who provide broadcast services participate in frequency auctions to acquire the right to use specific frequency ranges. One way to determine that the assigned frequencies, and no others, are being used by a given provider might be termed "reactive": if that provider's broadcasts interfere with another's, the interfering provider is essentially trespassing on territory "owned" by the other provider and can be subject to fines or other penalties.
Much better than waiting around until someone oversteps their prescribed frequency ranges, though, is to monitor, proactively, the types of broadcasting equipment they're using in the first place. Not all antennas are created equal: some stand 50 meters tall and some shorter or taller; some are positioned on high elevations and others in lower-lying areas; some broadcast at significantly higher power than others; and so on. To take an extreme example, a transmission antenna that is only a half-meter tall and broadcasts a relatively weak signal may not threaten anyone else's transmissions or receptions at all, even if its broadcast frequency spills above or below the assigned range.
With these considerations in mind, Spectrum Management Services has, since fall 2004, required broadcasters to periodically upload data about all cellular/PCS stations and antennas that they operate. The service providers can upload the data either in ASCII text form or--no surprise--as XML.
Here's a portion of the first record in the sample text file available from Spectrum Direct, the Service Management Services website (broken into multiple lines for legibility):
92900001,"Sub. #23-1, Aug/04",James Watson,
6139412262,,watson.james@ic.gc.ca,,
Ottawa ON - 300 Slater St.,ON,83,452428,
754245,80...
And here's the same data in XML form:
<station_data
xmlns="http://sd.ic.gc.ca/station_data_en"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://sd.ic.gc.ca/station_data_en
station_data_en.xsd">
<account>
<company_code>092900001</company_code>
<reference_number>Sub. #23-1, Aug/04</reference_number>
<contact_name>James Watson</contact_name>
<telephone>6139412262</telephone>
<email_address>watson.james@ic.gc.ca</email_address>
<station>
<location>Ottawa ON - 300 Slater St.</location>
<province_code>ON</province_code>
<nad27_83>83</nad27_83>
<latitude>452428</latitude>
<longitude>754245</longitude>
<site_elevation>80</site_elevation>
...
</station>
...
</account>
</station_data>
(Which do you prefer? Me too -- and not just because I'm writing about it!)
As you can see, the data file includes some general information about the company (account) providing this upload; contact name, telephone number, and so on. Each broadcaster might have only one "station"--basically, the location of the broadcast facility--or it might have more than one station (by far the norm). Not shown above is data about the antennas placed at that station. Here's an example of data about a single antenna:
<antenna>
<tx_frequency>1950</tx_frequency>
<upper_tx_frequency>1965</upper_tx_frequency>
<rx_frequency>1870</rx_frequency>
<upper_rx_frequency>1885</upper_rx_frequency>
<bandwidth>1250</bandwidth>
<class_emission>F9W</class_emission>
<tx_power_w>8</tx_power_w>
<tx_ant_manufacturer>ZZ</tx_ant_manufacturer>
<rx_ant_manufacturer>ZZ</rx_ant_manufacturer>
<tx_ant_model_no>PCSS090-13-2</tx_ant_model_no>
<rx_ant_model_no>PCSS090-13-2</rx_ant_model_no>
<tx_ant_height>55</tx_ant_height>
<rx_ant_height>55</rx_ant_height>
<tx_ant_azimuth>120.0</tx_ant_azimuth>
<rx_ant_azimuth>120.0</rx_ant_azimuth>
<tx_ant_gain>16</tx_ant_gain>
<rx_ant_gain>16</rx_ant_gain>
<tx_ant_pattern>8200</tx_ant_pattern>
<rx_ant_pattern>8200</rx_ant_pattern>
<tx_line_loss>3.2</tx_line_loss>
<rx_line_loss>3.2</rx_line_loss>
</antenna>
If the antenna at that station is omnidirectional, there will
be only a single antenna element; otherwise there
will be one per unidirectional ("sectorial") antenna located
there. The elements whose names are prefixed tx_ and
rx_ represent, respectively, the antenna's
transmission and reception characteristics. Element names
referring to "azimuth" define the compass direction in which the
antenna is aimed (0 degrees if omnidirectional, 360 degrees if
directional pointing due north, and so on--the antenna
described above is aimed roughly east-southeast). The
antenna_pattern element has a string-value of 8000
if omnidirectional, 8200 if (like this antenna) unidirectional.
Other elements--tx_power_w,
rx_ant_gain, etc.--spell out various technical
characteristics of the antenna. (Descriptions of all elements are
available in a PDF
document at Spectrum Direct.)
Now, I've no idea whether Canadian cellular/PCS providers find
these data requirements burdensome. But just to head off one
objection--that their systems change very little over time--Spectrum
Management Services provides an alternative form of the
data file. In its XML guise, this replaces all the
station elements (and their descendants) with a
single empty no_system_changes element:
<station_data
xmlns="http://sd.ic.gc.ca/station_data_en"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://sd.ic.gc.ca/station_data_en
station_data_en.xsd">
<account>
<company_code>092900001</company_code>
<reference_number>Sub. #23-1, Aug/04</reference_number>
<contact_name>James Watson</contact_name>
<telephone>6139412262</telephone>
<email_address>watson.james@ic.gc.ca</email_address>
<no_system_changes/>
</account>
</station_data>
|
Related Reading 
XML in a Nutshell |
Thus, even when there have been no changes to the stations described in its previous upload, the broadcaster can continue to follow the periodic data upload cycle.
On receipt, Industry Canada validates each submission. If the submission isn't of the "no changes" variety, its contents are added to an Assignment and Licensing System (ALS) database (completely replacing any earlier data for the same service provider's stations and antennas).
Working with Raw XML Data
While researching the Industry Canada cellular/PCS station data formats, I came across one other tidbit which the agency offers to simplify service providers' data preparation. This is a "stylesheet" of sorts, but one following neither the CSS nor the XSLT standard. Instead, it's a stylesheet expressly intended for use with Altova's Authentic XML editor.
(Altova is probably better known--it certainly was to me--as the developer of the popular XML Spy editor. The Authentic product might be thought of as a free, reduced-feature-set version of XML Spy.)
The XML dialect in which this stylesheet is coded is Altova's own StyleVision Power Stylesheet (SPS) language, typically produced not by hand, but as output from (yes) Altova's StyleVision stylesheet editor. Authentic uses SPS stylesheets to display and manipulate data in a way similar to typical web-based forms.
Here's a portion of the SPS stylesheet provided by Industry Canada for use by cellular/PCS license holders:
<structure version="2"
schemafile="station_data_en.xsd"
workingxmlfile="station_data_en.xml"
templatexmlfile="">
<nspair prefix="n1"
uri="http://sd.ic.gc.ca/station_data_en"/>
<nspair prefix="xsi"
uri="http://www.w3.org/2001/XMLSchema-instance"/>
<template>
<match overwrittenxslmatch="/"/>
<children>
<template>
<match match="n1:station_data"/>
<children>
<template>
<match match="n1:account"/>
<children>
<newline/>
<paragraph paragraphtag="h1">
<children>
<text fixtext="Upload and Account Details:">
<styles font-family="Arial"
font-size="large"/>
</text>
<template>
<match match="n1:company_code"/>
<children>
<xpath allchildren="1">
<styles font-family="Arial"
font-size="large"/>
</xpath>
...
</children>
</template>
</children>
</paragraph>
</children>
</template>
</children>
...
</template>
</children>
</template>
...
<pagelayout>
<properties pagemultiplepages="0"
pagenumberingformat="1" pagenumberingstartat="1"
paperheight="11in" papermarginbottom="0.79in"
papermarginleft="0.6in" papermarginright="0.6in"
papermargintop="0.79in" paperwidth="8.5in"/>
</pagelayout>
</structure>
As you can see, it's something like an amalgam of XSLT (e.g.,
all those template elements), HTML (the reference to
an "h1"), and XSL-FO (the pagelayout element's
contents, obviously describing a physical page rather than layout
in a browser window). While perfectly well-formed XML, it also
departs from convention in several ways, most notably (for me)
in its use of those rather strange nspair elements
up towards the top, each of which makes an element and a couple
attributes do, apparently, the same work as plain old namespace
declarations.
Here's a screen shot of the sample XML data file from the Spectrum Direct site, using their SPS stylesheet, when viewed in Authentic:
See? It's just like a Web form, except that it requires neither a server nor any programmatic validation. The combination of the document's schema and the presentation laid out in the SPS stylesheet (like the select lists for Province Code and Coordinate Format) keeps the data entry clean.
All in all, I'd have to say that the Industry Canada data-collection effort, with its simple XML schemata and SPS stylesheet, fairly puts the lie to complaints (still lingering) that XML applications are too difficult to use -- and provide too little payback -- for small-scale data sets. I've neither expertise nor interest in providing cellular or PCS service in Canada; but obviously, if I did, regularly describing my systems to government regulators would be the simplest of tasks before me!
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We want your property to look great all season long! We try to eliminate your frustrations with proactive service! Our technicians will make at least two, service visits during the holiday season to make sure everything is in working order.
From small to large, we can make any size home look fantastic. Whether it's roofline, landscape, or tree lighting, we will turn your home into a festive winter wonderland.
Our staff of decorators are experts in the field of Christmas lighting and holiday decorating.
We will be happy to provide you with decorating ideas or turn your existing ideas into a reality. Our service department will ensure that your lights stay lit the entire holiday season.
We have a huge inventory of various Christmas lights, extension cords, timers, and other installation necessities available for purchase, and we also offer Christmas Light for sale.
Just because the holiday season comes to an end, doesn't mean our service does! After the holidays, we will come back to your property, take down your decorations, label each item, and store it in our facilities. It's not in your way, and next year, we will return and reinstall!
We offer the following Products and Services:
Christmas Lighting
Full service sales and installation departments
Custom pole-mounted banner sales and installation*
Large animated holiday displays
Custom holiday displays
Leasing and rental programs*
In house graphic arts department
Knowledgeable and helpful year round staff.
call us for free quote 1-818-386-1022
Frequently Asked Questions
Will your Company remove my lights as well as install them?
Absolutely. Our company is dedicated to providing you with a beautiful Holiday display, as well as taking all of the burden out of shopping for necessary materials, installing lights, and removing the lights after the holiday season. We will remove all of the lights and materials that have been used for your display, and carefully put them away in storage bins for next year.
How do you calculate your labor estimate?
There are several factors that contribute to the estimated price of a job. These factors include the complexity of the display, electrical constraints, and of course the length of time necessary to complete the job. We take our time on each and every job, and pride ourselves on providing you with the most professional displays in town.
What happens if I have a problem with my lights?
Our qualified installers are trained to take all of the necessary measures to prevent any problems with your lights. However, if you do have a problem with your display, we have full time service technicians to correct the problem as soon as possible.
Why should I choose you to decorate my house instead of another company or individual?
There are many reasons why you should choose us for your decorating needs. The top two are experience and customer service. Our company has years of experience in the field of decorating homes, businesses and commercial properties. With this experience comes reliability, knowledge, service, and a very high level or quality that is hard for anyone to match. Our customer service is second to none. You can rest assured that every effort is being made to ensure 100% customer satisfaction.
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call us 818-386-1022
call 1-310-925-1720
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