# User manual | Project Walter ETSI Workshop

```Project Walter ETSI
Workshop
low-temperature environment
Detlef Fuehrer
JRC
Sophia Antipolis, 7th October 2009
Agenda
UWB measurement challenges
Cryogenic LNA project
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UWB mea
UWB signal levels to be detected range from -41.3 dBm
to -80 dBm
Signals to be measured must be +6dB above the noise
floor of the instrumentation
Measurement distance must satisfy antenna far-field
conditions (typically 3 meters)
o 3m free-space path loss is 52.6 dB at 3.4 GHz
)
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UWB
Maximum mean power spectral density [dBm/MHz]
-40
-50
-60
-70
-80
-90
1.6
2.7
3.1
3.4
3.8
4.2
4.8
6
8.5
9
10.6
Frequency [GHz]
Without mitigation
With mitigation
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Far-field calculation
Measurement
antenna
EUT
d1
Spectrum analyzer
LNA
d2
D=
D
d1 = 4 cm
d2 = 28 cm
f = 4 GHz
λ = 7.49 cm
D = 273 cm
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Far field
9,00
80
Far field distance [m]
Free space path loss [dB]
8,00
70
60
6,00
5,00
50
4,00
40
3,00
2,00
30
1,00
0,00
20
1
1,5
2
2,5
3
3,5
4
4,5
5
5,5
6
6,5
Frequency [GHz]
7
7,5
8
8,5
9
9,5
10
10,5
11
Free space path loss [dB]
Far field distance [m]
7,00
UWB SNR
UWB dynamic range: ~ 49 dB (-41.3 dBm to -90 dBm)
Lowest signal level to be detected: - 90 dBm
-41 dBm
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1
2
3
-114 dBm
Spectrum
Analyzer
-41 dBm
D=3m
Path loss: 53 dB
2
-94 dBm
Example: 3.5 GHz
SNR: 20 dB
o SNR at SA input: ~ 32 dB
o Min. UWB level: -80 dBm
o 13 dB of SNR must be gained
-114 dBm
-82 dBm
-94 dBm
3
Antenna gain: 12 dB
SNR: 32 dB
-114 dBm
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Path lo
30,0
9,00
8,00
20,0
10,0
6 dB
6,00
0,0
5,00
SNR [dB]
Far field distance [m]
7,00
4,00
-10,0
3,00
-20,0
2,00
-30,0
Far field distance [m]
1,00
SNR [dB]
0,00
-40,0
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1,5
2
2,5
3
3,5
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4,5
5
5,5
6
6,5
Frequency [GHz]
7
7,5
8
8,5
9
9,5
10
10,5
11
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Signal-toThere are several ways to increase the SNR
o Increase Tx signal power
• Direct = Amplify Tx signal
• Indirect = Reduce measurement distance
o Increase antenna gain
o Reduce noise
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Nois
Ambient noise
o Filtering
o Spectral subtraction
o Temperature reduction
o Use of low-loss, low-noise components
o Filtering
o Temperature reduction
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Noise
2 dB
6 dB
12 dB
P = kTB
-110
Noise reduction in relation to room temperature (290K)
-115
Noise power [dBm/MHz]
-120
-125
-130
-135
-140
-145
-150
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60
80
100
120
140
160
180
Temperature [K]
200
220
240
260
280
300
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Cooling (Cryogenic LNAs)
o There is a number of cooling options
•
•
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Helium cooling
Nitrogen cooling
CO2 cooling
Peltier cooling
~ 4K
~ 77K
~ 195K
~ 170K
First measurements carried out by CTL in 2008
o Helium-cooled astronomy microwave sensor
Second run: JRC low-cost cryogenic LNA project
o Peltier and CO2 cooling
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Measu
Configurations
Spectrum
analyzer
1
Regular LNA
Spectrum
analyzer
2
Cryogenic LNA
Spectrum
analyzer
3
Cryogenic LNA
4
Regular LNA
Spectrum
analyzer
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Conf
-41.3 dBm
NF: 21 dB
Gain: 12 dB
Spectrum
analyzer
Gain: -1.4 dB
-93.9 dBm
Overall gain:
Gain (excl. Antenna):
10.6 dB
-1.4 dB
Overall noise figure:
22.3 dB
Signal power at SA:
Noise level at SA input:
SA noise floor:
-83.3 dBm
-114 dBm
-93 dBm
SNR:
9.7 dB
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Conf
Gain: 12 dB
Gain: 40 dB
NF: 1.6 dB
NF: 21 dB
Spectrum
analyzer
-93.9 dBm
Gain: -0.1 dB
Overall gain:
Gain (excl. Antenna):
50.5 dB
38.5 dB
Overall noise figure:
1.7 dB
Signal power at SA input:
Noise level at SA input:
SA noise floor:
-43.4 dBm
-73.7 dBm
-93 dBm
SNR:
30.3 dB
Gain: -1.4 dB
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Conf
Gain: 12 dB
Gain: 30 / 32 dB
NF: 1.0 / 0.4 dB
NF: 21 dB
Spectrum
analyzer
-93.9 dBm
Gain: -0.1 dB
Gain: -1.4 dB
290 K
77 K
Overall gain:
Gain (excl. Antenna):
40.5 dB
28.5 dB
Overall gain:
Gain (excl. Antenna):
42.5 dB
30.5 dB
Overall noise figure:
1.7 dB
Overall noise figure:
0.9 dB
Signal power at SA input:
Noise level at SA input:
SA noise floor:
-53.4 dBm
-83.7 dBm
-93 dBm
Signal power at SA input:
Noise level at SA input:
SA noise floor:
-51.4 dBm
-82.5 dBm
-93 dBm
SNR:
30.3 dB
SNR:
31.1 dB
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Gain: 12 dB
Gain: 30 / 32 dB
NF: 1.0 / 0.4 dB
Gain: 40 dB
NF: 1.6 dB
NF: 21 dB
Spectrum
analyzer
-93.9 dBm
Gain: -0.1 dB
Gain: -1.4 dB
290 K
Gain: -0.1 dB
77 K
Overall gain:
Gain (excl. Antenna):
80.5 dB
68.5 dB
Overall gain:
Gain (excl. Antenna):
82.5 dB
70.5 dB
Overall noise figure:
1.1 dB
Overall noise figure:
0.5 dB
Signal power at SA input:
Noise level at SA input:
SA noise floor:
-13.4 dBm
-44.3 dBm
-93 dBm
Signal power at SA input:
Noise level at SA input:
SA noise floor:
-11.4 dBm
-42.9 dBm
-93 dBm
SNR:
30.9 dB
SNR:
31.5 dB
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Spectrum Analyzer noise floor
Noise floor: -93 dBm
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Noise floor, LNA 2 powered on
Noise floor: -74 dBm
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Noise floor, LNA 1 and LNA 2 powered on
o LNA 1 temperature: +20 °C
Noise floor: ~ -44 dBm
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Mea
LNA 1 + LNA 2, measuring distance 3 m
UWB: TFC 5, Tx Power -55 dBm
-40 dBm
Measured power: -55.1 dBm
-80 dBm
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Mea
LNA 1 + LNA 2, measuring distance 3 m
UWB: TFC 5, Tx Power -51 dBm
-40 dBm
Measured power: -52.4 dBm
-80 dBm
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Mea
LNA 1 + LNA 2, measuring distance 3 m
UWB: TFC 5, Tx Power -47 dBm
-40 dBm
Measured power: -46.6 dBm
-80 dBm
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Mea
LNA 1 + LNA 2, measuring distance 3 m
UWB: TFC 5, Tx Power -41 dBm
-40 dBm
Measured power: -42.6 dBm
-80 dBm
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Comparison: CTL vs. JRC measurements
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LNA 1 only, measuring distance 3 m
Dynamic range:
~ 34 dB
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LNA 1 only, measuring distance 1 m
Dynamic range:
~ 43 dB
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Cryo
Based on Amplitech cryogenic microwave LNA
Uses two 3-stage Peltier modules plus active cooling
Temperature control and monitoring unit for exact setting
of target temperature
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Cryo
Amplitech cryogenic microwave LNA
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Low NF (1 dB at 290K, 0.4 db at 77K)
Operates at temperatures down to 5 K
Power consumption ~640 mW
Operating frequency range: 0.1 – 6 GHz
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FerroTec 3-stage Peltier element
o Max. ∆T = 110 °C (QC = 0.1 W )
o Max. ∆T = 90 °C (QC = 0.7 W)
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Cryoge
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Cryoge
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First & second run
o Peltier cooling only: -40 °C
o Peltier + CO2 cooling: -87.8 °C
2
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Third run
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Cooling the LNA only improves SNR but not significantly
o Gain is 1.6 dB at 20K, 1.2 dB at 77K and 0.8 dB at 190K
Using higher gain antennas could improve SNR but …
Gain ~ size ~ Far field distance
Reducing measurement distance could provide
improvements in SNR but again the Far field condition
has to be observed
The simplest way would be to increase UWB Tx power
Contacts
Coordinator
Presenter
Franck Le Gall (inno)
Detlef Fuehrer
[email protected]
[email protected]
+334 923 884 18
+39 0332 783056
http://www.walter-uwb.eu
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