29 May 13 Webcast Slides
-
Upload
bilal-ahmed -
Category
Documents
-
view
217 -
download
0
Transcript of 29 May 13 Webcast Slides
-
8/10/2019 29 May 13 Webcast Slides
1/41
2013 Agilent Technologies
Aerospace & Defense Symposium
2013
Mult i -antenna Array Measu rementsUsing Digi t izers
Presented by: Alexander Dickson, Agilent Technologies
-
8/10/2019 29 May 13 Webcast Slides
2/41
-
8/10/2019 29 May 13 Webcast Slides
3/41
2013 Agilent Technologies
Aerospace & Defense Symposium
3 2013 Agilent Technologies
Aerospace & Defense Symposium
Multi-antenna Array Measurements
3
Agenda (cont.)
Configuring a Test System (10 min)
Phase coherence
Digitizer features
Conversion loss / NF, power levels Occupied dynamic range
System-level calibration
Realized Solution (10 min)
M9703A digitizer DDC and segmented memory
Measurement example
-
8/10/2019 29 May 13 Webcast Slides
4/41
2013 Agilent Technologies
Aerospace & Defense Symposium
4 2013 Agilent Technologies
Aerospace & Defense Symposium
Parabolic Dish
Antenna
Mechanically
Steered Array
Passive
ElectronicallyScanned Array
Active
ElectronicallyScanned Array
Antenna Architectures
APARMarconi Martello S-723 AEGIS AN/SPY1D(V)
1940 - Cavity Magnetron
6-bit Digital Phase Shifter
4-bit Digital Phase Shifter
RADAR Dish Antenna
T/R ModuleIntegrated Phase Shifters
T/R Modules
http://en.wikipedia.org/wiki/File:Radar-hatzerim-1-1.jpghttp://en.wikipedia.org/wiki/File:APAR.jpghttp://www.radartutorial.eu/19.kartei/pic/img1121.jpg -
8/10/2019 29 May 13 Webcast Slides
5/41
2013 Agilent Technologies
Aerospace & Defense Symposium
5 2013 Agilent Technologies
Aerospace & Defense Symposium
Modern Active Electronically Scanned
Phased Array (AESA)
Key Benefits
Fixed position antenna
Ability to form multiple agile beams
Fast scan rates with hard to predict, irregular scan patterns
Independent transmit/receive modules per element
Reduced power loss from integration of RF source on each T/R
Graceful degradationsingle source failure will not cripple system
AESA Installed on First US Air Force F15Chttp://www.aviationnews.eu/
-
8/10/2019 29 May 13 Webcast Slides
6/41
2013 Agilent Technologies
Aerospace & Defense Symposium
6 2013 Agilent Technologies
Aerospace & Defense Symposium
Historical Phased Array Test Challenges
Aligning Radiating Elements for Optimum Performance
Phase and amplitude errors lead to an increase in side lobe levels (SLL)
Large side lobes indicate a waste of beam forming power and causeinterference
Average side lobe level due to phase and amplitude errors (normalized to
isotropic level and using /2 element spacing) [1]:
+
Where is the phase error variance (radians) and is the fractionalamplitude error variance
SLL
-3dBHP BW
[1]: J. Ruze, Pattern degradation
of space fed phased arrays, MIT
Lincoln Laboratory, Project Rept.
SBR-1, Dec. 1979.
-
8/10/2019 29 May 13 Webcast Slides
7/41 2013 Agilent Technologies
Aerospace & Defense Symposium
7 2013 Agilent Technologies
Aerospace & Defense Symposium
New, or growing Challenges
Array Element Counts Increasing(need speed without loss of accuracy)
Digital Moving Closer to the Antenna(may not have access to stimulus in analog form)
Broadband Modulated Signals (not just pulsed)(need to generate and capture full-bandwidth signals)
Multi-Function(need flexible measurement system, other typesof signal analysis such as modulation accuracy)
Search, SAR, etc.
Communications
-
8/10/2019 29 May 13 Webcast Slides
8/41 2013 Agilent Technologies
Aerospace & Defense Symposium
8 2013 Agilent Technologies
Aerospace & Defense Symposium
Multi-antenna Array Measurements
8
Agenda
Phased Array Applications Overview (10 min)
Antenna architectures and enabling technology
Benefits of modern phased array antennas
Test challenges of phased arrays Testing Multi-Element Array Antennas(15 min)
Phase and gain measurements
Using complex signals
Sensitivity to match BWAccelerate your measurements
-
8/10/2019 29 May 13 Webcast Slides
9/41 2013 Agilent Technologies
Aerospace & Defense Symposium
9 2013 Agilent Technologies
Aerospace & Defense Symposium
Two Approaches
Narrow Band Approach
Swept or stepped tone
Narrowband receiver
Measure one freq at a time
Cross-channel computations in timedomain
Lower variance by integratinglonger (narrower RBW)
Broadband Approach
Broadband stimulus
Wideband receiver
Measure all frequenciessimultaneously
Compute cross-channel spectrum
Lower variance by averaging
Measuring Relative Phase and Gain
DUT RX +DIGITIZER
Signal
Generator
AWG
Network Analyzers are limited tonarrowband measurements
Digitizers and VSAs with DDCs have
adjustable bandwidths
-
8/10/2019 29 May 13 Webcast Slides
10/41
2013 Agilent Technologies
Aerospace & Defense Symposium
10 2013 Agilent Technologies
Aerospace & Defense Symposium
Digital Down-conversion (DDC)
What is a digital down-converter?
Its a flexible processing block that allows an ADC to run at full rate while the
output sample rate and bandwidth are optimized to match the current signal.
Digital signal processing
Produces complex I&Q samples from real ADC samples
Frequency translation (tune)
Filter and decimation (zoom)
-
8/10/2019 29 May 13 Webcast Slides
11/41
2013 Agilent Technologies
Aerospace & Defense Symposium
What a DDC Does For You:
Isolate the signal of interest
Improve the analog performance
and dynamic range (SNR, ENOB),
by reducing the amount of
integrated noise
Extend the amount of capture
memory (in seconds), or reduce the
amount of data that need to be
transferred for a given duration.
Reduce the workload on post-
processing algorithms less data
to analyze
11
DDC Benefits
Noise & other signals in the full ADC
BW are eliminated with DDC
Analyzed
bandwidth
-
8/10/2019 29 May 13 Webcast Slides
12/41
2013 Agilent Technologies
Aerospace & Defense Symposium
12 2013 Agilent Technologies
Aerospace & Defense Symposium
DDC - Tune Result
12
-
8/10/2019 29 May 13 Webcast Slides
13/41
2013 Agilent Technologies
Aerospace & Defense Symposium
13 2013 Agilent Technologies
Aerospace & Defense Symposium
DDC - Zoom Result
13
For a proper analytic signal,
the negative frequencies
need to be removed by the
decimation filters
-
8/10/2019 29 May 13 Webcast Slides
14/41
2013 Agilent Technologies
Aerospace & Defense Symposium
14 2013 Agilent Technologies
Aerospace & Defense Symposium
DDC - Real vs. Complex
14
0 Hz f1-f1
Bandwidth that determines sample rate
Real-Only signals are
conjugate symmetric about DC
Minimum sample rate: 2*f1
0 Hz
Complex signals can be
asymmetrical about DC
Minimum sample rate: B
Bandwidth that determines sample rate
B
B
2 Step Process
Tune (shift)
Zoom (filter and decimate)
-
8/10/2019 29 May 13 Webcast Slides
15/41
2013 Agilent Technologies
Aerospace & Defense Symposium
DDCProcess Gain for Measurements
15
DDC Bandwidth
-
8/10/2019 29 May 13 Webcast Slides
16/41
2013 Agilent Technologies
Aerospace & Defense Symposium
16 2013 Agilent Technologies
Aerospace & Defense Symposium
DDCNoise Reduction in Time Domain
T0System2
T0System1
Phase measured
from reference
channel to other
channels
16
Decimation Ratio = 2
Decimation Ratio = 4
Decimation Ratio = 8
-
8/10/2019 29 May 13 Webcast Slides
17/41
2013 Agilent Technologies
Aerospace & Defense Symposium
17 2013 Agilent Technologies
Aerospace & Defense Symposium
Narrow-BandComputing Cross-Channel Time
Let r(t) be the reference channel and x(t) be the signal on one of the receive
channels. The test signal is positioned away from spurs and does not have to be at
the center of the IF.
Let X = [x0x1x2 xn-1] be N complex samples of x(t)
Let R = [r0 r1 r2 rn-1] be N complex samples of r(t)
In Matrix Form the complex number the can be converted to amplitude and phase is:
where R is the conjugate transpose of R
In Summation Form the computation is:
= =
This calculation is unbiased as the expected value ofthe noise and off-frequency spurious is zero
Use N=1 when the DDC bandwidth provides sufficient isolation from system spurs and integrated noise power.
Use N > 1, i.e. 10 or 100 samples, to reduce the phase variance due to noise and spurious.
17
G1 = Complex ch-ch ratio (I&Q) Use this
to compute relative mag and phase
using:
Mag = (1)^2 + (1)^2
Phase = tan()
()
-
8/10/2019 29 May 13 Webcast Slides
18/41
2013 Agilent Technologies
Aerospace & Defense Symposium
Frequency Domain Approach (wideband)
SX
SN
H(f) SY = HSX+ SN
S xf( )
tx t( ) e j 2 f t
d
+
H(f) is DUT transfer function
x(t) is a broadband signal with energy at all frequencies of interest
(noise, chirp, etc.)
Sx is the vector input spectrum of x(t) computed as the FFT(x(t))
Sy is the vector output spectrum
Sn is noise
-
8/10/2019 29 May 13 Webcast Slides
19/41
2013 Agilent Technologies
Aerospace & Defense Symposium
Frequency Domain Approach (wideband)
SX
SN
H(f) SY = HSX+ SN
S xf( )
tx t( ) e j 2 f t
d
Hest = GYX /GXX
GYX= SYSX*
GXX= SXSX*
* conjugate operation
+
Hest = SY /SX
Average operation
-
8/10/2019 29 May 13 Webcast Slides
20/41
2013 Agilent Technologies
Aerospace & Defense Symposium
20 2013 Agilent Technologies
Aerospace & Defense Symposium
Comparing Wide- and Narrow-Band
Response Methods
Narrowband is familiar (traditional network analysis, classic RADAR signal)
Tones used in narrowband have a 0dB peak/avg, with all of the source powerat one frequency. May have better dynamic range.
Narrow RBWs may have long settling times which slow measurements ordegrade accuracy
Wideband signals can be almost anything provided theres energy at the
frequencies of interest. May even be DUT generated. Can use chirps for0dB pk/avg. Lower spectral power density than a tone.
Wideband signals that mimic DUT signals may be more DUT friendly, orprovide a more realistic answer in the presence of nonlinearities. Pulseshaping, if present, doesnt need to be gated.
For narrow RBWs wideband measurements may be faster as all frequenciesare captured in parallel. However, there are many variables such as datatransfer time and number of averages that also need to be considered
-
8/10/2019 29 May 13 Webcast Slides
21/41
2013 Agilent Technologies
Aerospace & Defense Symposium
21 2013 Agilent Technologies
Aerospace & Defense Symposium
Agenda (cont.)
Configuring a Test System (10 min)
Phase coherence
Digitizer features
Conversion loss / NF, power levels Occupied dynamic range
System-level calibration
Realized Solution (10 min)
M9703A digitizer
DDC and segmented memory
Measurement example
Multi-antenna Array Measurements
21
-
8/10/2019 29 May 13 Webcast Slides
22/41
-
8/10/2019 29 May 13 Webcast Slides
23/41
2013 Agilent Technologies
Aerospace & Defense Symposium
23 2013 Agilent Technologies
Aerospace & Defense Symposium
Requirements for a Digitizer
Feature List:
Multi-channel (n inputs), where n >= antennas in a group
Sufficient 3dB analog BW
Digital down converter (DDC)
Phase coherent inputs (< 1 degree phase diff) Scalable platform
-
8/10/2019 29 May 13 Webcast Slides
24/41
-
8/10/2019 29 May 13 Webcast Slides
25/41
2013 Agilent Technologies
Aerospace & Defense Symposium
Two Methods Used:
Sine-fit
Mathematic sine fit to single tonesamples
Based on IEEE basic test
methods for digitizers Relatively slow as compared to
DDC
DDC (software)
Uses complex samples
Complex conjugate ratio methodcancels common mode phasemodulation
Measuring Digitizer Ch-Ch Phase Coherence
Signal Generator (CW)
-
8/10/2019 29 May 13 Webcast Slides
26/41
2013 Agilent Technologies
Aerospace & Defense Symposium
26 2013 Agilent Technologies
Aerospace & Defense Symposium
Measuring Digitizer Ch-Ch Phase Coherence
-
8/10/2019 29 May 13 Webcast Slides
27/41
2013 Agilent Technologies
Aerospace & Defense Symposium
27 2013 Agilent Technologies
Aerospace & Defense Symposium
System Level Calibration
Considerations:
How accurate is good enough?
At what is your IF center frequency and IF BW?
Using the DDC?
Using one or more digitizers?
What software environment are you using?
Do you have data on complex frequency response for all signal path
blocks out to the calibration reference plane?
-
8/10/2019 29 May 13 Webcast Slides
28/41
2013 Agilent Technologies
Aerospace & Defense Symposium
28 2013 Agilent Technologies
Aerospace & Defense Symposium
System Level Calibration (cont.)
Signal Source (StepGenerator, Comb
Generator) with
Known Complex
Frequency
Response
IF Magnitude and Phase Calibration with Channel Matching
Signal
Path
NF and Gain
Known (SP)
Digitizer
(ADC 1)Signal
Path
NF and Gain
Known (SP)
Digitizer
(ADC 1)Signal
Path
NF and Gain
Known (SP)
Digitizer
(ADC 1)Signal
PathNF and Gain
Known (SP)
Digitizer
(ADC 1)
Signal
Path
NF and Gain
Known (SP)
Digitizer
(ADC 1)SignalPath
NF and Gain
Known (SP)
Digitizer(ADC 1)
Signal
Path
NF and Gain
Known (SP)
Digitizer
(ADC 1)Signal
Path
Response
Known (SP1)
Digitizer
(ADC 1)
Sp
litter
Convolution of response for source, signal path and digitizer is represented indigitized waveform FFT (divide out source and signal path):
* W1 = Source * SP1* Digitizer Response1
* Note: Need to account for splitter impact on ch-ch phase. Possibly using differential 2-step cal.
Digitized W1
Source
CH 1CH 2
CH 3CH 4
CH 5
CH N
Cal Ref
Plane
-
8/10/2019 29 May 13 Webcast Slides
29/41
2013 Agilent Technologies
Aerospace & Defense Symposium
29 2013 Agilent Technologies
Aerospace & Defense Symposium
System Level Calibration (cont.)
Magnitude Phase
-
8/10/2019 29 May 13 Webcast Slides
30/41
2013 Agilent TechnologiesAerospace & Defense Symposium
30 2013 Agilent Technologies
Aerospace & Defense Symposium
Agenda (cont.)
Configuring a Test System (10 min)
Phase coherence
Digitizer features
Conversion loss / NF, power levels
Occupied dynamic range
System-level calibration
Realized Solution (10 min)
M9703A digitizer
DDC and segmented memory
Measurement example
Multi-antenna Array Measurements
30
-
8/10/2019 29 May 13 Webcast Slides
31/41
2013 Agilent TechnologiesAerospace & Defense Symposium
31 2013 Agilent Technologies
Aerospace & Defense Symposium
Agilent M9703A High-Speed Digitizer
Key Features 12 bit Resolution
8 channels @ 1.6 GS/s
Interleaving option to get 4 ch @ 3.2 GS/s
DC to 2 GHz analog 3dB bandwidth
Optional real-time digital downconversion
(DDC) on 8 phase-coherent channels Up to 256 MS/ch memory and segmented
acquisition
> 650 MB/s data transfer
Agilent 89600 Software support
Reduce the test t ime o f you r DUT with the new M9703A!
Higher number of sync hron ous acqu is i t ion channels, wider signal capture with the
best accuracy and f lex ib i l ity , and opt im ized thro ugh put
M9703A OS support
Windows XP (32-bit)
Vista (32/64-bit)
7 (32/64-bit)
Linux
DriversMD1 software
IVI-C, IVI-COM
LabVIEW MATLAB (through IVI-COM)
OTS application software
MD1 soft front panel
AcqirisMAQS U1092A-S01/S02/S03
89600 VSA software
31
-
8/10/2019 29 May 13 Webcast Slides
32/41
2013 Agilent TechnologiesAerospace & Defense Symposium
32 2013 Agilent Technologies
Aerospace & Defense Symposium
x8
M9703A - DDC Features and Benefits
Reduce the bandwidth to match the signal
Reduce noise (including quantization noise) and interference,
Allows lower sample rate without aliasing Reduce sample rate to the appropriate values for the signal being analyzed.
More efficient use of memory allows longer duration captures
Or, allows less data to transfer for the same duration
Baseband (0 Hz, real-only) or use LO (complex) to tune
32
Full Sample Rate
(1.6 GSa/sec)
Frequency
Shift
Decimation
Filter
Sample
Rate
Analysis
Bandwidth1.6 GS/s 1 GHz
400 Ms/s 300 MHz
200 Ms/s 160 MHz
100 Ms/s 80 MHz
50 Ms/s 40 MHz
50/2NMs/s 40/2NMHz
-
8/10/2019 29 May 13 Webcast Slides
33/41
2013 Agilent TechnologiesAerospace & Defense Symposium
Optimum Memory Utilization
Accelerate test time with fewer samples
Reduced acquisition cycle time
Longer duration acquisitions
M9703As Segment Memory Mode
Event 1 Event 21 2
3
Segmented memory optimizes capture time by
dividing the digitizers available acquisition memory
into smaller segments.
-
8/10/2019 29 May 13 Webcast Slides
34/41
2013 Agilent TechnologiesAerospace & Defense Symposium
AWG
Demo Setup
AWG Configured to Generate 100MHz Wide LFM Chirp
Digitizer Configured as a Multi-channel Tuned Receiver
Trigger
Signals here have bandwidth
And because they have BW, we can compute FRF at multiple frequencies.
Splitt
er
RX +
DIGITIZER
PC w/89600
VSA SWPCIe
-
8/10/2019 29 May 13 Webcast Slides
35/41
2013 Agilent TechnologiesAerospace & Defense Symposium
The Hardware
-
8/10/2019 29 May 13 Webcast Slides
36/41
2013 Agilent TechnologiesAerospace & Defense Symposium
36 2013 Agilent Technologies
Aerospace & Defense Symposium
Broadband Stimulus Signals
Chirped Pulse (e.g. Radar)
Spectrum
PvT
FRF Mag
FRF Phase
Pulse Width: 4usec
BW 100 MHz
Uniform Window
Trigger Delay
250 avgs/secSpectrum
PvT
FRF Mag
FRF Phase
9 03 C C
-
8/10/2019 29 May 13 Webcast Slides
37/41
2013 Agilent TechnologiesAerospace & Defense Symposium
Customer Requirement:
Multi-antenna array measurements
Element to element phase alignment for narrowbandand wideband signals
Obtain down-converted IQ data for further analysis
Hardware/Software:
N6171A MATLAB software
Agilent M9703A High Speed Digitizer
Agilent M8190A Arbitrary Waveform Generator
Demonstration:
Configure M9703A and acquire baseband IQ signals
Calculate and visualize: Signal phase of each of the first four channels of M9703A
Narrowband Signal: Cross Channel phase correlation
Wideband Signal: Frequency Response Function (FRF) magnitude
and phase of channels 2x1, 3x1, and 4x1
MATLAB Demo: M9703A Cross Channel Phase
-
8/10/2019 29 May 13 Webcast Slides
38/41
2013 Agilent TechnologiesAerospace & Defense Symposium
Measurement Throughput
Segment #1 Rearm
(DUT dependent switching
time80us)
Segment #2 Offload
Segment Intervals Rearm Time DUT
Time
Acquisition
Cycle
Time/Interval Speed
500 us 100 160 us
(1.56 MSa/s)
80 us 660 us 6.6 us 152k int/sec/ch or
1.2M meas/sec
500 us 100 80 us(3.125 MSa/s)
80 us 580 us 5.8 us 172k int/sec/ch or1.4M meas/sec
500 us 10 40 usec (6.25
MSa/s)
80 us 580 us 58 us 17.2k int/sec/ch or
138k meas/sec
Acquire: 100
intervals (tones) or
10 intervals
(broadband)
Acquire: 100
intervals (tones) or
10 intervals
(broadband)
PCIe
trig trig
Idle
E ti ti C Ch l Ph V i
-
8/10/2019 29 May 13 Webcast Slides
39/41
2013 Agilent TechnologiesAerospace & Defense Symposium
39 2013 Agilent Technologies
Aerospace & Defense Symposium
Estimating Cross Channel Phase Variance
Variance and Power are closely related. For small angles we can use the relationship
sin()and we also recognize that not all of the noise power goes to changing angle, italso changes amplitude. For a single channel we can show that the angle variance is
Noise is complex: NR+jNI
Noise Power: NR2+ NI
2
For a nominal angle of zero degrees, only
the imaginary element of the noise
contributes to the angular variance hence
the angular variance in radians is half the
normalized noise variance
NR
NI
180
10
_
2+
10_
2
Noise on each channel is uncorrelated so we can simply add the variances to get:
EXAMPLE ( i l th di iti i )
-
8/10/2019 29 May 13 Webcast Slides
40/41
2013 Agilent TechnologiesAerospace & Defense Symposium
40 2013 Agilent Technologies
Aerospace & Defense Symposium
EXAMPLE (using only the digitizer noise)
DUT
SNR = SigLevel(Noise Density + 10 log10 (ENBW)) where ENBW ~= 1/T
M9703
Noise Figure ~30dB (1V range)
Ch1 (stim) chN (resp)
-10dBm -50dBm
180
10
_
2+
10_
2
Assume T= 100 usec
SNR_STIM = -10(-174 + 30 + 10log10(1.0/100usec)) = 94 dB
SNR_RESP = -50(-174 + 30 + 10log10(1.0/100usec)) = 54 dB
Angle Variance = 6.5 mDeg2or equivalently a standard deviation of 0.08 degrees
S d C l i
-
8/10/2019 29 May 13 Webcast Slides
41/41
A & D f S iA & D f S i
Summary and Conclusion
Using an Agilent M9703A digitizer with DDC in a solution for multi-
antenna array measurements provides the following benefits:
1) Multi-channel coherent measurement solution (< 1 deg)
2) Fast, adjustable BW measurements producing complex samples withjust enough sample rate (reduced variance)
3) Integrated 89600 VSA control (w/ hardware DDC acceleration) toleverage wealth of existing, industry standardized measurements
For more information:
www.agilent.com/find/axie-antennatest
http://www.agilent.com/find/axie-antennatesthttp://www.agilent.com/find/axie-antennatesthttp://www.agilent.com/find/axie-antennatesthttp://www.agilent.com/find/axie-antennatest