This document discusses the future of wireless telemetry technology and the applicability of licensed versus unlicensed frequency bands. It argues that licensed VHF frequencies between 218-219 MHz will be better suited for wireless telemetry over unlicensed spread spectrum frequencies. VHF waves can reach distances of 10 miles compared to a maximum of 1,500 feet for spread spectrum, and the infrastructure costs for VHF would be much lower. The document also outlines several potential markets for wireless telemetry like utility meter reading, oil and gas monitoring, and mobile asset tracking.

1. wireless intelligence sm
August 18, 2001
This paper assumes a technical audience with a basic awareness of RF technologies for the
purpose of wireless data communication. The subject matter discusses the future of wireless,
wide-area telemetry technology in the US and worldwide, as well as the applicability of licensed
versus unlicensed (spread spectrum) frequency bands for telemetric applications.
The Case for VHF Wireless Telemetry
by Cynthia Carter
We predict that looking back 20 years from
now the most disruptive use of wireless (RF)
data communication technologies will not have
been for the purpose of extending human
communications with ubiquitous voice and
Internet bandwidth.
Instead, it will be for the purpose of real-time
data communication among intelligent
networks of machines, ERP systems and broad
value-chain processes.
The volume of machine-to-machine
communication will one day come to eclipse
that of communications for human
consumption. And a great deal of the data
collected, especially from remote, mobile, and
hazardous endpoints, will be collected
wirelessly.
The Players – Licensed VHF spectrum vs.
Unlicensed UHF spread spectrum
As the reader is aware, the RF spectrum is a
continuum of inversely related properties of
bandwidth or carrying capacity in one
dimension, and effective range of coverage as
the other dimension. For practical purposes, the
continuous spectrum has been subdivided into
discrete quanta of bandwidth exhibiting similar
physical properties and behavior. Frequencies
between 30 and 300 MHz are grouped into the
VHF (Very High Frequency) range.
Frequencies from 300 MHz to 3 GHz (3,000
MHz) are referred to as the UHF (Ultra High
Frequency) range.
As will be demonstrated from a post mortem
analysis of failed telemetry ventures to date
including CellNet and Metricom, the primary
success factor in a wireless telemetry project is
careful consideration of bandwidth selection for
transmission of data.
Frequencies available in the US for telemetry
applications are found in the VHF and UHF
bands: specifically from 218-219 MHz (VHF),
and portions of the 700-900 MHz and 2.4 GHz
(UHF) ranges.
Current state of the technology
Most of the pioneering work in wireless
telemetry has been done in UHF frequencies.
Not coincidentally, here are found the
unlicensed, public spread spectrum frequencies.
Spread spectrum frequencies in the 900 MHz
and 2.4 GHz ranges, have dominated the
wireless telemetry industry to date for the
simple reason that they have always been freely
available for public use, while licensed
frequencies have not.
While spread spectrum frequency has inherent
properties that indicate its use for certain
applications, it is not proving to be applicable
across a broad range of telemetric applications,
as witnessed by the respective failures of
CellNet Data Systems and Metricom Ricochet.
To date, the downfall of spread spectrum has
been its high capital requirement in terms of
WAN infrastructure to support necessary data
rates. The relation is essentially a function of
signal strength over distances and interference

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with objects within an environment.
Interference with environmental objects such as
buildings, hills and trees makes spread spectrum
a strictly line-of-sight technology, with a
practical range (according to a spread spectrum
service provider) of up to 1,500 feet indoors
and line of sight to the horizon outdoors --
roughly the extent of a large yard (or small city
block at best).
Spread spectrum is also subject to severe
limitations in transmit power in the US, so to
minimize interference with transmissions of
competing users.
While these inherent technical limitations can
theoretically be overcome simply by adding
more repeaters to boost the signal, the
economic burden of supporting more repeaters
remains a long term practical challenge for
spread spectrum users.
Propagative case for VHF
Unlike UHF, VHF is not line of sight. VHF
waves are not absorbed by environmental
objects, but continue to reflect until they reach
a listening target. This property, combined with
the ability to transmit at a much higher power
level, gives VHF waves a dramatic advantage in
coverage area compared to spread spectrum.
For comparison, devices using unlicensed
spread spectrum devices are limited to 1 Watt
of power or less, while 218-219 MHz VHF
devices are licensed to transmit at 2 watts each
and can be increased to 20 Watts if necessary.
While spread spectrum is limited to an effective
range of a city block, 218-219 MHz waves can
reach distances averaging 10 miles or more on
most terrains, and up to 25 miles at higher
power. Recent tests in Bakersfield, CA, show
excellent performance.
Economic case for VHF
The order-of-magnitude advantage in effective
range results in a very sparse WAN requirement
to support 100% coverage of a geographic
market for 218-219 MHz versus spread
spectrum, even when collector sites are
overlapped to achieve a higher level of system
redundancy (see Figure 1).
To illustrate, Table 1 compares the cost of
building a WAN infrastructure for automated
utility meter reading (AMR) to serve the Kansas
City Metropolitan Service Area utilizing CellNet
Data Systems (CNDS) spread spectrum versus
a DataNet system deployed at 218-219 MHz.
Where CNDS needs 6 collectors per square
mile at an estimated cost of $3,500 per collector
($21,000 per square mile), DataNet can place
one collector per every 100 square miles at a
cost of $42,000 per or $420 per square mile.
Comparing these figures with the CNDS spread
spectrum system, the costs for a DataNet
system for the same 4,988 square mile area are:
Table 1: Comparison of CellNet Data Systems spread spectrum vs. DataNet 218-219MHz for
Automated Utility Metering – Kansas City MSA
Spread spectrum VHF
Collectors required per sq. mi. 6 .01
Sq. miles in MSA 4,988
Total collectors required 29,928 50
Cost per collector $3,500 $60,000
Total infrastructure cost $104,748,000 $2,997,921
Households in MSA 605,000
Businesses in MSA 113,926

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Total endpoints 1,792,312
Infrastructure cost per endpoint $58.44 $4.17
Endpoint cost, installed $40 $25
Retrofit cost, per endpoint $175 $26.17
Per meter monthly cost to read $1
Payback period 14 yrs > 4 yrs
*These numbers are for purpose of comparing technologies, actual numbers will vary.
.
Markets for Wireless Telemetry
Vertical markets for wireless telemetry are
categorized as: monitoring (industrial,
municipal, commercial vending, HVAC),
security (residential and commercial), mobile
location, and Automated Meter Reading
(AMR).
AMR
The utility industry is diligently searching for a
cost-effective solution to automate meter
reading. Prior to its bankruptcy in Feb. 2000,
CellNet Data Systems installed over 4 million
metered endpoints and accepted orders for
more than 8 million. Itron, the market leader
for AMR services, claims to have over 13
million meters adapted to its walk-up and drive-
by wireless metering systems.
This is compelling evidence that the utility
industry is interested in wireless AMR.
However, to date the industry is still searching
for a cost-effective solution that can be
deployed on a large scale.
Total per-meter billing expenses can range from
$7 to $12 per year. In the final analysis, CNDS
failed because it was unable to persuade utility
companies to spend more than $1 to $1.50 per
month over a 12-15 year contract period to
replace traditional meter reading expenses with
automated service.
Monitoring
Petrochemical is an emergent, interested
vertical user. As of this writing, Texaco has
committed to retrofitting several thousand oil
well heads in 3-4 US MSAs with wireless
endpoint devices to report on state. Reports to
date are favorable.
Security
Security alarm applications are the most
forgiving business model for spread spectrum
technology, this attributable to the premium
service rates users are willing to accept for
security services. Spread spectrum technologies
are in widespread use among security service
providers. No security service is 100% reliable
without a wireless component complete with an
uninterruptible power source.
This is a secondary market because service
aggregator users are likely to remain satisfied
with installed spread spectrum technology in
which they’ve already invested.
Mobile location
Given the growing interest in employee
monitoring online, this trend is certain to
continue as technology becomes available to
monitor the activities of mobile workers.
Potential applications range from municipal and
private service fleets and municipal
transportation to freight transport.
Using low-installed cost endpoint devices,
managers can monitor location and status in
real time via convenient Web browser interface,
revealing the location of favorite donut stores
and prime napping spots.
This will remain a secondary application in the
absence of an aggressively entrepreneurial third-
party service aggregator willing to undertake the
construction of a wireless WAN for its own
use.
Future Scenarios
Regarding the future relationship of spread
spectrum and licensed spectrum for telemetry,
there are two possible outcomes. To the

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question of which is more likely, the answer is
both.
Figure 1 VHF Only First Hop
Scenario 1: Replacing spread spectrum –
Figure 1 depicts high power VHF devices
replacing low power spread spectrum devices
for the “first mile” hop (broken red lines).
High-bandwidth land lines (solid blue) complete
the link to a network operations center.
Figure 2 VHF Augmenting Spread Spectrum
Scenario 2: Augmenting spread spectrum –
Figure 2 depicts data being transmitted via
spread spectrum to an aggregation point, and
then forwarded to a 218-219 MHz transmission
network. High-bandwidth land lines (solid blue)
complete the link to an operations center. This
has the effect of multiplying the density of
transmitting endpoints that can be supported by
a wireless telemetry network.
Impediments to Adoption of VHF
Once built, a wireless telemetry WAN can
support multiple concurrent user applications.
The difficulty lies in getting any single investor
or end user interested enough to undertake the
buildout for their own use.
Utility companies would seem to be obvious
candidates. However, most of those who are in
a position to invest in technology have already
committed to large scale spread spectrum
applications such as CellNet, or technologies
using their own installed infrastructure. With
limited marketing investment to date, 218-219
MHz remains a well-kept secret in the utility
industry.
Perhaps the largest obstacle to adoption of 218-
219 MHz technologies in the US market
remains competition with a confusing array of
intriguing alternatives, beginning with the
densest installed base of wire, cable and fiber in
the world. It is difficult to pitch a buildout
project for a new wireless technology when
underutilized cellular bandwidth and subsidized
spread spectrum bandwidth seem plentiful.
Targeted marketing efforts would help remedy
this by identifying and focusing on those
applications for which 218-219 MHz
technology shows the most immediate
economic advantages.
Conclusion -- Beyond the Obvious
We have only begun to scratch the surface by
mentioning a few million potential endpoints in
the US. There are billions of endpoints to be
monitored worldwide –potentially dozens or
hundreds per capita.
History is full of disruptive technologies such as
indoor plumbing, microwave ovens, CDs and
MP3s that change the status quo forever.
Amusing as it may be, we got along fine before
them; now we can’t live without them.
Remotely monitoring and manipulating objects
by a human operator using a Web interface is
just a beginning. The real power of the
technology kicks in when the output is plugged
back in to the network that produced it as
input.
Envision a future, aggregated, artificial
intelligence organized at the network or systems
level, as opposed to the popular vision of an
ever-increasing intelligence at the machine level.
Ask, what is one machine – no matter how
complex – going to do with all that intelligence?
In our alternative view, machines, as consumers
of information, will remain thin clients,
possessing only as much native intelligence as
needed to function as data-producing sensory
organs. It will be the domain of systems
functioning at the network level to aggregate
this data, determining the higher-level state of

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complex processes and directing local response
back to the machine level.
The role of a wireless telemetry WAN would be
to provide a “dome of connectivity” over
defined service areas. Local domes can be
interlinked via fiber trunk to provide a sub rosa
channel for the free flow of machine-to-
machine data, analogous to human cognitive
processes.
As a flexible, self-routing network, the Internet
Protocol poses reliability and economic
advantages over fixed, point-to-point
networking, particularly at the last (or first)
mile. The TCP/IP protocol was developed for
just this sort of connectivity among human
users. Enterprise systems are already using
HTTP and SMTP to exchange electronic data.
We are committed that one day user-defined
XML-based electronic “dialects” will eventually
kill EDI altogether, making the Internet the de
facto platform for systems integration.
UDP is an alternative Internet protocol that
theoretically can provide a lower overhead
requirement for addressing packets. This is an
area for technical exploration.
We have outlined a vision of a likely future in
which clouds of semi-intelligent endpoint
devices transmit information via Internet
protocol to receptive intelligences existing
anywhere on the globe. The picture that
emerges is of one or, more likely, several global,
distributed machine intelligences comprising
millions or semi-intelligent endpoints linked by
a common wireless protocol.
In Business @ the Speed of Thought, Bill Gates
predicts “the average consumer will come into
contact with at least 100 telemetry points on a
daily basis without ever knowing he or she has
done so.”
And this, mind you, from the man who also
predicted the average consumer might be
interested in a computer.
* * *
Cynthia Carter (Ccarter@DataNetUS.com) is president of DataNet, Inc., a Chicago-based firm
dedicated to the development of commercial applications utilizing VHF wireless telemetry. More
information can be found at the DataNet website: http://www.DataNetUS.com/. Ms. Carter can be
reached at +1.773.665.5001.