World Headquarters, Beaverton, Oregon, USA
Our business
Design and Manufacture of RF
coverage measurement and mapping
instrumentation
 Emphasis on digital and analog
television coverage measurement
 Specific expertise in automated RF
measurement and analysis of DTV
quality of service
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Our television customers
Transitioning to 8VSB digital service
 Operating analog and digital plants
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New transmission formats
New power levels
New channel assignments
New antenna locations
New government regulations
Cost and people constrained
Antenna Patterns
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Not always as you would expect
6.5 miles from 1000’ AAT
Horizontal Gain
Oded Bendov / Krishna Praba, Television Engineering Handbook, Jerry Whitaker
Vertical Angle Gain
Z Technology measurement systems
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Address specific measurement needs
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documentation
identification
acceptance
confirmation
resolution
DSS5800 DTV measurement system
DSS5800 DTV measurement system
Programmable field
strength meter
8VSB data demodulator
GPS Receiver
Power and
Distribution
Laptop Windowstm PC
AC
DC
DSS5800 DTV measurement system
Programmable field
strength meter
8VSB data demodulator
GPS Receiver
Power and
Distribution
Laptop Windowstm PC
AC
DC
DSS5800 DTV measurement system
Programmable field
strength meter
8VSB data demodulator
GPS Receiver
Power and
Distribution
Laptop Windowstm PC
AC
DC
DSS5800 DTV measurement system
Programmable field
strength meter
8VSB data demodulator
GPS Receiver
Power and
Distribution
Laptop Windowstm PC
AC
DC
Three measurement techniques
1. Drive testing
• rapid accumulation of data
• identification of problem coverage areas
2. Calibrated testing
• used to validate more general data
• communicates very specific values
3. On-site testing
• detailed evaluation of local conditions
Drive Testing
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Rapid accumulation of coverage data
• Calibrated measurement equipment
• 7 ft. antenna height, on roads
• Automatic capture and recording
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Identification of problem areas
• Relative to previous runs
• Poor signal coverage
• Changes in coverage
Drive Test Considerations
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Equipment configuration
• Antenna, Power, Mounting, Calibration
• Convenience and Safety
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Environment
• Location, Obstructions, Reflections
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Operator interface
• Driver Distraction, Information Displays
• Setup & Automatic Collection of Data
Mobile Test Antennas
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Horizontal dipole
• General direction towards
transmitter
• Magnet mount, ~24” above roof
surface
• Calibrated; antenna factors for dBuV/m
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Vertical sampling antenna
• Mag mount 1/4 wave vertical
antenna
• Not true to horizontal component
• Characterized
Mobile Test Antennas
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Omnidirectional antennas
• Generally lower gain, uncalibrated
• Subject to multipath distortions
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Rotators
• Dipoles are broad pattern
• Just need a general direction
• Beware of distracting driver
Antenna Correction Factors
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Measured correction factors supplied by antenna
manufacturer
Add antenna factor plus cable loss to receiver
reading in dBuV to convert to field intensity in
dBuV/Meter.
Example:
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Antenna Correction Factor
Cable loss
Meter Reading
Field Intensity
16.0 dB/m
.9 dB
44.0 dBuV
60.9 dBuV/meter
Calibrate Antenna Setup
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Mount antenna and adjust element length for
frequency as indicated in manufacturer’s table
Connect to measurement equipment with calibrated
cable
Add antenna correction factor for operating frequency
and calibrated losses
Enter system correction factor into meter or PC
application software
Meter or application will read field intensity in dBuV/m
Multiple Frequency Testing
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Same band, one antenna
• Factory antenna factors
• Element length vs. frequency vs. factor
• Characterizing for multiple frequencies
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Multiple Antennas
• Power combiners
• Filters
• System characterization
Multiple Antennas
VHF
UHF
LP Filter
HP Filter
Power
Combiner
dBuV/m
VHF ant correction factor - cable loss - LPF loss - Combiner loss - cable loss = VHF Antenna Factor (sys)
UHF ant correction factor - cable loss - HPF loss - Combiner loss - cable loss = UHF Antenna Factor (sys)
Add antenna factor plus cable loss to receiver reading in dBuV
to convert to field intensity in dBuV/Meter.
Calibration Procedures
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Equipment certification
• NIST traceable antennas, cables, field
strength meter
• Secondary reference
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Equipment setup
• 30 ft. antenna height vs. vehicle rooftop
• Antenna factors recorded with data
Drive Test Procedure
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Set up job
• Frequencies
• Antenna factors
• Signal types
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Adjust antenna direction
• Spectrum display
• Sample measurement
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Start Drive Test
• Hit record
• Drive the route
DVB-T Spectrum & data display
8VSB Spectrum & data display
Signal Level
(voltage)
At Cursor Position
(frequency)
8.8 dB
0.33 MHz (freq)
20 Log(.38)=8.4 dB
Main Tap normalized
To 100%
3 uS
(time)
38% of Main Tap Energy
(voltage)
Example Case: One major reflection at 3 uS
causes a .33 Mhz ripple on the Spectrum Display
Percent
Reflection
(Voltage)
At Cursor
position
(Delay)
Operational Precautions
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Do not operate
while driving
Be aware of
antenna orientation
Stop and enter
comments where
appropriate
Analyze recorded
data later
The Drive Test
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Set up the “job” for signal types and
frequencies
Click F1 “Sample” to check the reception
Click F3 “Record Continuous”
Drive until direction changes more than
~30 degrees; stop and adjust antenna
direction
Click F4 “Stop Measurements”
Take a break and look at the data
Automatic data recording
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Analog: records all setups, time, location,
direction of travel, peak power, antenna
factors, frequencies, etc.
Digital: adds wideband parameters;
integrated power, etc.
DTV systems add data from the digital
decoder; sync/eq locks, tap values, etc.
Clear text data files are easy to read and
export to other applications
Clear-text Data File
Analyzing the data
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Real-time map
plotting
• Colored trail of dots
for any parameter
• Plots value as a
color for each GPS
location measured
• Color may be
automatically or
manually scaled
Analyzing the data
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Map oriented data
• Colored trail of dots
for any parameter
• Tool-tip displays
selected value for
selected location
• Right-click for all
data taken at that
location
DVB-T data parameters
8VSB data parameters
On-Site Testing
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Problem resolution
Difficult locations
Sniff out problems
Using customer
antennas
Site suitability
RF signal measurement products
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Systems designed to meet
specific industry needs
• digital and analog RF field
strength measurements
• automatic signal coverage
mapping
• 8VSB/DVB-T demodulated
data analysis
Our mission
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Address the RF measurement needs of our
customers
Provide economical, real-time assistance
and solutions
Increase the confidence level of the
technical operator
Enable the gathering of historical data for
reference as conditions change
Learn more about our systems
Z Technology, Inc.
1815 NW 169th Place, Suite 3070
Beaverton, Oregon 97006 USA
Tel: 503.614.9800 Fax: 503.614.9898
www.ztechnology.com
sales@ztechnology.com
Factory Contacts:
Guy Lewis, John Purdy, Jim Zook