RF Power Meter Selection
Who we Are
Kevin King Bird Technologies Group Mili Military & Government &G Sales Manager
Lynn Strube Bi d T h l i G Bird Technologies Group Application Engineer
Who We Are Bird Technologies Group id h l i • Bird Electronic Corporation 68 years and counting • TX‐RX founded in 1976 • Bird Technologies Group (BTG) was created with the merger of two RF communications industry leading brands, Bird Electronic Corporation and TX RX Systems. • Our most recent acquisition X‐COM Systems
Bird Electronic Corporation Bird’s core competency is RF Power Bi d’ t i RF P Measurement and Management Markets • • • • • •
Government & Military Semiconductor Broadcast Medical Equipment Medical Equipment Wireless Service Providers Wireless Equipment OEM’S q p
TX‐RX • • • • • • •
Public Safety Communications Antennas Duplexers & Triplexers Field Services TX RX TX‐RX Filters Signal Boosters Combining Systems
X‐COM‐Systems • • • • • •
RF Capture / Playback Waveform Generators Waveform Generators RF Data Analysis NTDS Switching h Engineering Services 16 TB disk memory standard 32 TB or more available • 32 TB or more available
Power Meter Selection‐ What We Will Discuss‐ •
Review of power meter types i f
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What about this modulation stuff?
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Difference between modulation and Channel Access
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Pulse Power Considerations
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RF power meter lab
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Power Meter Selection‐ Key Criteria •
Frequency Range
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Power Range
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Signal Modulation Type
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Channel Access Format
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Peak / Pulse Power Considerations
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Frequency Range / United States Frequency Allocations
3KHz
300GHz
Frequency Range / Bird Technologies Group Bird Electronic Bird Electronic • Frequency measurement range 250KHz to 12Ghz • Monitoring & analysis 100KHz to 3.7 GHz g y TX‐RX • 30 MHz to 1 GHz X‐COM Systems X COM Systems • Recording & playback of the spectrum at 6 GHz bandwidth and up to 32 Terabytes of information, frequency limited only by spectrum analyzers selected for use.
Bird Electronic Bird Electronic
Power Range / Bird Technologies Group
• A radio frequency power meter is an instrument q yp used for the determination of the level of energy flowing in a transmission system • Power measurement range from 25mW to 250kW • Using an additional directional coupler then the power measurement range is in the millions of watts, transmission line dependent. watts, transmission line dependent.
A Few Words About Modulation • • •
There Are Really Only Three Methods For Encoding Intelligence On There Are Really Only Three Methods For Encoding Intelligence On An RF Carrier Amplitude, Frequency, or Phase – (or Combinations of These) Amplitude modulation or AM works by varying the strength of the transmitted signal in relation to the information being sent transmitted signal in relation to the information being sent
A Few More Words About Modulation FM and Phase Modulation are Both Forms of Angle Modulation d h d l h f l d l
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Angle Modulation is modulation in which the angle of a sine Angle Modulation is modulation in which the angle of a sine‐wave wave carrier is varied by a modulating wave such as Frequency Modulation (FM) or Phase Modulation (PM) FM with its digital correspondence frequency‐shift keying (FSK) i h i di i l d f hif k i ( S )
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PM with its digital correspondence phase‐shift PM with its digital correspondence phase shift keying (PSK) keying (PSK)
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Careful Selection of Power Meters is Required for These Signals
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Signal Display
Challenges of Digital Modulation
• High peak to average power ratio (Crest Factor)
10 dB Po ower
Peak / Average Power Ratio Power Ratio
Time
A Few Words About PSK Modulation • • • • • •
Constellation Diagrams‐ C ll i i A new way to understand modulation d d d l i 8‐PSK Signal Is shown on constellation diagram below X‐Axis is In‐Phase, Y‐Axis is shifted 90° Notice positions of symbols in I‐Q plane Length of vector from origin represents symbol power 8 PSK symbols all have same power Constant Envelope Modulation 8‐PSK symbols all have same power‐ Constant Envelope Modulation Q
I
A Few Words About Modulation • • • •
16 QAM Constellation Diagram is Shown Below 6Q C ll i i i Sh l Notice the different power levels of the symbols This is a form of Non‐Constant Envelope Modulation These waveforms require special consideration when making power measurements
What About Channel Access Methods? • • • •
Channel access methods refer to the techniques used to share frequencies Ch l h d f h h i d h f i between users Frequency Division Multiplex and Time Division Multiplex are most common techniques In general, Frequency Division Multiplex signals do not cause power measurement issues Time Division Multiplex signals may cause unstable power measurements
What About Channel Access Methods? • • • • •
GSM TDMA Frame Structure is shown below GS S i h b l 8 Time slots per frame – 577 µS per slot If all time slots in the frame are active‐ Power Measurement is Easy If only one slot is active, this means that there is one burst every 4.6 mS In this case, a Burst Average Power or Peak Power Measurements are best
Burst Average Power
Peak / Pulse Power Measurement • • • •
Pulse Width (τ), Pulse Repetition Frequency, and Duty Cycle must be l id h ( ) l ii d C l b considered Choose Power Meter Type Based Upon These Parameters Low PRF waveforms may result in unstable readings In many cases, stability may be improved through averaging
Peak / Pulse Power Measurement •
4314B Is fastest peak power meter (400nS Minimum Pulse Width) 3 f k ( 00 S i i l id h)
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5012A / 5016 / 5017 Provide peak power measurements (500 nS minimum pulse width) with added benefit of variable measurement averaging when used with 5000XT or VPM2
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4391A Also provides peak power readings (800 nS minimum pulse width)
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5010B Provides peak power measurements when used with conventional 5010B Provides peak power measurements when used with conventional elements
Multiple Carrier Applications •
Multiple Carriers Always Add as Voltages (Vectors) in the System li l C i l dd l ( )i h S
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Worst Case Analysis Yields Peak / Average Ratio of Signal Increases by 3 dB Each Time Number of Carriers is Doubled
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Exact Analysis is Possible if Phase Relationships Between Carriers is Known Exact Analysis is Possible if Phase Relationships Between Carriers is Known
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Multiple Carrier Contribution Must Be Added to Modulation Effects
Model 43 and Family
Model 43 and Family •
Si l Simple, Reliable way to get VSWR performance and RF power in watts li bl S f d i
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May Be Used with Constant Envelope Modulation (CW, FM)
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Will Measure Peak Envelope Power When Equipped with 4300‐400 Peak Detector Kit Detector Kit
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May NOT Be Used with Non Constant Envelope Digital Modulation
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Accuracy is specified as a percentage of Full Scale – No Temperature compensation works in‐line with coax 50Ω impedance device
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Coaxial Cable Impedance • FFeed lines are designed for a specific d li d i df ifi impedance. – Impedance Impedance is a measurement of the total passive is a measurement of the total passive opposition to the signal – Impedance in transmission line is a function of the p diameters of the center conductor to the outer conductor
Zo = 138/√ε 138/√ log l 10(D/d) Where Zo = 50 Ω ε = the dielectric constant of the insulating material the dielectric constant of the insulating material D = outer conductor diameter d = inner conductor diameter
Coaxial Cable Impedance • Understanding what causes impedance d di h i d changes is half way to solving feed system problems Inner Conductor Inner Conductor t di t outer diameter
d Outer Conductor Outer Conductor i inner diameter di t
• Changes in any of these dimensions will change the impedance of the feed line
Maximum Power Transfer • One of the fundamental laws of physics states when the load resistance or impendence is equal to the source's internal resistance or impedance maximum power will internal resistance or impedance, maximum power will be developed in the load. If the diameter ratio changes, the impedance of the • If the diameter ratio changes, the impedance of the cable will change and the power transfer changes also • Such as from a dent, kink, deformation, too sharp , , , p of a bend radius, etc.
Signal Reflections • If If the transmission line (coax) and load (antenna) h i i li ( ) dl d( ) impedances are not the same, power is reflected from the load in the form of a wave traveling back from the load in the form of a wave traveling back to the source. Waves moving in the other direction (i.e., towards the load) interact, resulting in a series of standing waves along the length of the transmission line. • A short or open causes 100% of the power to be A h 100% f h b reflected • Measured in VSWR or Return Loss (in dB) Measured in VSWR or Return Loss (in dB)
Signal Reflections? • Any point where there is an impedance mismatch – 75 coax connected to a 50 antenna – 50 coax connected to an antenna with an impedance of something other than 50 (bad antenna or wrong frequency range)
• Any point in the system that has an impedance g of something other than 50 – Incorrect system component – Damaged or defective component
Impedance Mismatch Causes • Cable problems C bl bl – Open, shorted, dented, kinked, crimped, deformed, bullet hole, over tightened ground kit, over tightened bullet hole, over tightened ground kit, over tightened clamp, water intrusion, improper bend radius
• Connector problems – Poor quality, improperly installed, improper center pin depth, corroded, water intrusion
• Antenna – Defective, improperly mounted, UV damage, damage from icing, lightning damaged, wrong frequency range
Mismatch Terms • Reflection Coefficient • VSWR • Return Loss Return Loss
Reflection Coefficient () Reflected power is always proportional to the p mismatch that is present. Forward Power = Pf
Mismatch
Power Reflected = Pr
Reflection Coefficient = Γ = √(Pr/Pf)
Voltage Standing Wave Ratio (VSWR) • •
VSWR = (1 + (p r/p f )/(1 ‐ (p r/p f ) VSWR = (1 + )/(1 VSWR (1 + )/(1 ‐ ) – = (VSWR –1)/(VSWR +1)
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Expressed as X:1 – Such as 1.5:1 or 2.0:1
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1 is the mathematical lowest number possible and is the highest possible, and is the highest The lower the value of X, the better
Return Loss (dB) • Similar to VSWR • Expressed in dB (always negative) – Referenced to the input signal
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RL = 10 * log Pr/Pi RL = 20 * log ( = pr/pi) RL = 20 * log [(VSWR RL = 20 log [(VSWR – 1)/(VSWR +1)] 1)/(VSWR +1)] 0 is mathematically highest number possible The higher the absolute number, the better h h h h b l b h b – Absolute value equals the number without the negative sign
Power Output
Accuracy 5% of Full Scale
Note that the meter scale is compressed at the top‐ follows di d diode non‐linear characteristic li h i i
4410A
Model 4410A •
Patented detector scheme provides extremely wide dynamic range dd h id l id d i
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Seven power ranges with a single element‐ example: A 1 kW element will also provide 300W, 100W, 30W, 10W, 3W, 1W full scale ranges
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Accuracy is +/‐5% Accuracy is +/ 5% of Reading of Reading
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Inherently accurate over wide temperature range
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Does not perform well in cases of non‐constant envelope modulation
4391A
Model 4391A •
Uses Conventional Model 43 Type Elements in Pairs In Order to Provide C i l d l 3 l i i Od id Automatic VSWR and Return Loss Measurements
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Provides Peak Power Measurements ( 800 nS Minimum Pulse Width)
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Accuracy is +/‐5% Accuracy is +/ 5% of Full Scale of Full Scale
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Provides % AM Measurement
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Requires 2 elements 10:1 dB separation
4314B
Model 4314B •
Uses Conventional Model 43 Type Elements and Peak Power Elements C i l d l 3 l d k l
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Provides Peak Power Measurements ( 400 nS Minimum Pulse Width) – Our Fastest Peak Power Measurement Instrument
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Accuracy is +/‐5% Accuracy is +/ 5% of Full Scale of Full Scale
APM16
Model APM16 •
Similar to Model 43, with added benefit of true average responding Si il d l 3 i h dd d b fi f di detectors. Square law detector
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Performs very well with non‐constant envelope complex modulation
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Accuracy is +/‐5% Accuracy is +/ 5% of Reading of Reading
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Temperature compensated
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IDMA , AMPS, CDMA, TDMA, AM, FM, CW, SSB, GSM, FSK QPSK
Diode Detector Power Meters • Operates in: Operates in:
Vo ((log)
– square‐law region – Linear region
P in (watts)
Diode Detector Power Meters • Square‐law region is where the rectified p p p q output is proportional to the square of the RF signal input regardless of signal content. • When the diode is biased in the linear When the diode is biased in the linear region, the rectified voltage output is a f function of the voltage input. This is where f h l h h the model 43 (series) operate
5000XT / 5010B / 5012 Series Power Measurement System
5000‐XT
5014
5012A, 5016, 5017 5018
VPM 2 VPM‐2 5010B
VPM2 Analog Display
VPM2 Digital Display
VPM2 Logging
VPM2 Versatility
Multiple sensors can be connected
5000XT / VPM2/ 5010B / 5012 Series Power Measurement System • Universal Power Measurement System – Universal Power Measurement System – May Be Used With All May Be Used With All Modulation Formats USB Interface • USB Interface • Full‐ Feature , Highly Flexible User Interface Provides for Data Logging, Variable Averaging and Multiple Display Modes Logging, Variable Averaging and Multiple Display Modes • 5012A / 5016 / 5017 / 5018 Will Provide Average, Peak, and Burst Average Measurements – g No Elements Required q • 5010B / 5014 Will Provide Average and Peak Measurements‐ Uses Both Conventional and True Average Responding Elements
Power Meter Selection Matrix
Measurement of True Power
Measurement Results, CW Signal
Measurement of True Power
Measurement Results, COFDM Modulation
Military Radio Test Set Then & Now
• 4131
4132
4132 Radio Test Set
BIRD 4132
Thank You !
Lighthouse at Cleveland Harbor Entrance
Questions