Preliminary Results from the AFRL-NASA W/V-BandTerrestrial Link Experiment in Albuquerque, NM

www.nasa.govNational Aeronautics and Space Administration

Michael Zemba, James Nessel, Jacquelynne Houts, Nicholas Tarasenko, Steven Lane, David Murrell

Presented by Michael ZembaNASA Glenn Research CenterAdvanced High Frequency Branch

+1.216.433.5357michael.j.zemba@nasa.gov

Wave Propagation in Terrestrial, Oceanic and Atmospheric Environments

2016 IEEE International Symposium on Antennas and Propagation • Fajardo, Puerto Rico • June 29th, 2016

Presentation Overview

2

1. Motivation & Experiment Goals

2. Site of Study

3. Receiver Site (COSMIAC)

4. Transmitter Site (Sandia Crest)

5. Instrumentation

6. Preliminary Results

7. Solar Influence

8. Concluding Remarks

Wireframe schematic of the WTLE receiver front end electronics.

Motivation & Goals

Experiment Motivation & Goals

• To assess the impact of atmospheric effects on links operating in the V and W-band (rain attenuation, scintillation, depolarization, etc.).

• To develop physical models to improve predictions of atmospheric attenuationwithin the V/W-band.

• To provide a testbed for RF propagation measurement instruments & techniques.

• To assess optical link performance with a side-by-side link in tandem with theexisting RF link.

3

WTLE transmitter front end electronicsand lens antennas.

Site of Study

4Sandia Crest(Photo: Google Earth)

COSMIAC (University of New Mexico)(Photo: Google Earth)

N

Receiver

Site UNM / COSMIAC (Roof)

Latitude 35.054031° N

Longitude 106.619443° W

Altitude 1.596 km

Installation Date September 2015

Transmitter

Site Sandia Crest

Latitude 35.215128° N

Longitude 106.451245° W

Altitude 3.239 km

Beacon Freqs.72 GHz84 GHz

Installation Date September 2015

Path

Azimuth 40.444°

Elevation 3.984°

Path Length 23.55 km

Rx Tx

AlbuquerqueN e w M e x i c o

R e c e i v e r T r a n s m i t t e r

Receiver Site (COSMIAC)

Transmitter Site (Sandia Crest)

Weather Instrumentation

Pressure Sensor: Young BPV3000

Temperature/Humidity Sensor: Young 41382VC

Tipping Bucket: Young 52203

Anemometer: Young 05178A

Beacon Receivers

Instrumentation

Antenna Gain 45.6 dBi (V / W-band)

Dynamic Range 70 dB (V) /68 dB (W)

Co/Cross-Polarization Isolation 13 dB (V) / 20 dB (W)

Polarization LHCP

Sampling Period 0.1 sec (10 Hz) 7

Laser DisdrometerThies Clima 5.4110

Block Diagram

17 18 19 20 21

-90

-80

-70

-60

-50

-40

-30

-20

-10

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V Co

V X

W Co

W X

17 18 19 20 211499

1499.2

1499.4

1499.6

1499.8

1500

1500.2

1500.4

1500.6

1500.8

1501

Beaco

n F

req

uen

cy (

kH

z)

Time (UTC)

9

Under normal operating conditions, the Vand W-band receivers track theirrespective beacon signals using amodified Quinn-Fernandes frequencyestimation algorithm. The cross-polarization signal is tracked from thecurrent co-polarization frequency

When attenuation approaches the noisefloor (below a given power threshold),the frequency estimate is replaced by anaverage of the frequency estimate priorto the fade. This allows for a slightimprovement in dynamic range duringthe beginning and end of deep fades.

Signal lock is immediately regained whenthe signal reappears above the noisefloor.

System Performance

Tracking Threshold

Beacon tracked from frequency estimate prior to rain fade.

Loss of Lock

Clear Sky Day (2015-09-30)

06 07 08 09 10 11 12 13 14 15 16 17 18 19-40

-35

-30

-25

-20

-15

-10

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V Co

V X

W Co

W X

06 07 08 09 10 11 12 13 14 15 16 17 18 191.5

2

2.5

3

3.5

4

4.5

5

5.5

AG

A (

dB

)

Time (UTC)

Meteorologically Derived AGA

V

W

Diurnal variations in atmosphericgaseous absorption (AGA) observedin timeseries attenuation on clear-skydays.

Photo Credit: NASA

18 19 20 210

2

4

6

8

10

12

14

Rain

Rate

(L

iqu

id)

(mm

/ h

r)

Time (UTC)

Deep Rain Fade (2015-11-04)

18 19 20 21-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V Co

V X

W Co

W X

Strong rain event exceeds dynamicrange of receiver on all channels.

Liquid Precipitation

Photo Credit: Albuquerque Journal

Rain on Path (2015-10-03)

15 16 17 18 19 20 21-80

-70

-60

-50

-40

-30

-20

-10

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V Co

V X

W Co

W X

15 16 17 18 19 20 210

5

10

15

20

25

Rain

Rate

(L

iqu

id)

(mm

/ h

r)

Time (UTC)

Rain at receiver subsides while rainfade continues, indicating continuedrain along the path.

Liquid Precipitation

Photo Credit: NOAA

Snow / Depolarization (2015-12-26)

18 19 20 21 22 23 00-40

-35

-30

-25

-20

-15

-10

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V Co

V X

W Co

W X

18 19 20 21-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V Co

V X

W Co

W X

18 19 20 21 22 23 000

0.2

0.4

0.6

0.8

1

1.2

1.4

Rain

Rate

(S

oli

d)

(mm

/ h

r)

Time (UTC)

Strong depolarizing effectsobserved on both V and W-bandchannels during solid precipitation(snow) event.

Solid Precipitation

Photo Credit: Albuquerque Journal

Cloud Event (2016-01-09)

06 07 08 09 10 11 12 13 14-50

-45

-40

-35

-30

-25

-20

-15

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V Co

V X

W Co

W X

06 07 08 09 10 11 12 13 140

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Rain

Rate

(L

iqu

id)

(mm

/ h

r)

Time (UTC)

Strong fluctuations on both V andW-band channels with noprecipitation while clouds obscurethe peak of Sandia Crest.

No Precipitation

Photo Credit: NASA

18 19-70

-60

-50

-40

-30

-20

-10

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V

W

16 17 18 19-18

-17

-16

-15

-14

-13

-12

-11

-10

-9

Ch

an

nel

Po

wer

(dB

m)

Time (UTC)

V

W

10-3

10-2

10-1

100

101

10-4

10-2

100

102

104

Frequency (Hz)

Pow

er

spectr

al density (

dB

2/H

z)

V

W

Attenuation (-20 dB/dec)

Scintillation (-80/3 dB/dec)

10-3

10-2

10-1

100

101

10-4

10-2

100

102

104

Frequency (Hz)

Pow

er

spectr

al density (

dB

2/H

z)

V

W

Attenuation (-20 dB/dec)

Scintillation (-80/3 dB/dec)

Measurement Spectral Density

15

1 hr

3 hrs

Atten.

Scint.

0 10 20 30 40 50 60 70 800.1

1

10

100

October

November

December

January

February

March

April

May

Total

WTLE V-Band Attenuation CDFs (2015 - 2016)

V-Band Co-Pol Attenuat ion [dB]

Per

cen

t o

f T

ime

Val

ue

is E

xce

eded

0 10 20 30 40 50 60 70 800.1

1

10

100

October

November

December

January

February

March

April

May

Total

WTLE W-Band Attenuation CDFs (2015 - 2016)

W-Band Co-Pol Attenuat ion [dB]

Per

cent

of

Tim

e V

alue

is E

xce

eded

Attenuation Statistics

16

Oct. Nov. Dec. Jan. Feb. Mar. Apr. May. Total

V 36.533 dB 31.983 dB 18.722 dB 11.457 dB 1.379 dB 0.763 dB 10.247 dB 5.971 dB 16.845 dB

W 36.967 dB 41.500 dB 24.953 dB 14.614 dB 3.249 dB 1.686 dB 17.278 dB 11.264 dB 22.065 dB

Perc

en

t o

f Ti

me

Val

ue

is E

xce

ede

d

Perc

en

t o

f Ti

me

Val

ue

is E

xce

ede

d

Attenuation

V-Band W-Band

Attenuation [dB] Attenuation [dB]

Attenuation

99% Attenuation(Exceeded 1% of the Time)

Large month-to-month variability, upto 35.8 dB (V) and 39.8 dB (W)between the best and worst months.

* Worst Month* Best Month

99% 99%

0 2.5 5 7.5 10 12.5 15 17.5 200.01

0.1

1

10

100

October

November

December

January

February

March

April

May

Total

WTLE V-Band Attenuation CDFs (2015 - 2016)

V-Band Co-Pol Attenuation [dB]

Per

cen

t o

f T

ime

Val

ue

is E

xce

eded

Rain Rate Statistics

17

Oct. Nov. Dec. Jan. Feb. Mar. Apr. May. Total

2.14% 1.31% 0.79% 1.08% 0.07% 0.05% 2.19% 3.22% 1.05%

5.656 mm/hr 4.106 mm/hr 3.399 mm/hr 1.112 mm/hr 0.000 mm/hr 0.000 mm/hr 5.179 mm/hr 0.197 mm/hr 3.513 mm/hr

Perc

en

t o

f Ti

me

Val

ue

is E

xce

ede

d

Measured Rain Rate (Liquid Precipitation)

Rain Rate [mm / hr]

In total, rain was observed 1.05% ofthe time over the 7 month period(approx. 61.48 hours).

99.9% of the 7 month period, the rainrate was less than 3.513 mm / hr.

In other words, the rain rate was lessthan 3.513 mm/hr for 90.48% of timeswhen rain was measured.

99.9%

99.9% Rain Rate(Exceeded 0.1% of the Time)

Occurrence of Rain

* Worst Month* Best Month(s)

Radome Warming (2015-10-12)

Rx

Tx

Ch

ann

el P

ow

er (

dB

m)

W-Band

Daily co/x power disturbances were observed, particularly on the W-band,and correlated with solar position. This was remedied by replacing thetransmitter radome with a more suitable εr=1 dielectric.

Concluding Remarks & Future Work

Conclusions

• The WTLE terminal has been operational since October 2015, collecting attenuation, scintillation, and depolarization data across a 26 km link in Albuquerque, NM. As of this presentation, nearly nine months of data have been collected.

• For 99% of the time, the observed attenuation was less than 16.845 dB (V) and 22.065 dB (W). The worst months in terms of the attenuation were October (V) and November (W), while the best month for both was March (V and W).

• Large monthly variability was observed, with a difference of up to 35.8 dB (V) and 39.8 dB (W) month-to-month.• Rain was observed 1.05% of the time over the analyzed 7 months (61.5 hrs). The rain rate only exceeded 3.5 mm/hr for 5.8 hrs

over the 7 months.

Future Work

• Weather station along the path is currently being installed to assess weather conditions along the link.• Tandem optical link is planned for the near future to characterize optical propagation with concurrent RF data. 19

Thank You!

Appendix Charts

21

Contact Information

James Nessel

Principal Investigator, RF Propagation Task

216.433.2546

james.a.nessel@nasa.gov

Michael Zemba

Research Engineer

216.433.5357

michael.j.zemba@nasa.gov

Jacquelynne Morse

Research Engineer

216.433.5468

jacquelynne.r.morse@nasa.gov

22

NASA Glenn Research Center

21000 Brookpark Rd. MS 54-1

Cleveland, Ohio 44135, USA

0 10 20 30 40 50 60 70 800.1

1

10

100

V-Band

W-Band

WTLE Isolation (2015 - 2016)

V-Band X-Pol Attenuation [dB]

Per

cen

t o

f T

ime

Val

ue

is E

xce

eded

Tx Air & Plate Temperatures and PWM Output

09/27 09/28 09/29 09/30 10/014

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

Air

Co

ntr

ol

Ou

tpu

t (V

)

Time (UTC)

09/27 09/28 09/29 09/30 10/0131.4

31.6

31.8

32

32.2

32.4

32.6

Air

Tem

p.

(Co

ntr

ol)

(°C

)

Time (UTC)

09/27 09/28 09/29 09/30 10/0137.97

37.98

37.99

38

38.01

38.02

38.03

38.04

Pla

te T

em

p.

(°C

)

Time (UTC)

09/27 09/28 09/29 09/30 10/018

10

12

14

16

18

20

Pla

te C

on

tro

l O

utp

ut

(%)

Time (UTC)

Power Detector Variance & PWM Outputs

09/27 09/28 09/29 09/30 10/0135.7

35.75

35.8

35.85

35.9

35.95

36

36.05

36.1

36.15

36.2

Air

Tem

p.

(RF

Co

ver)

(°C

)

Time (UTC)

09/27 09/28 09/29 09/30 10/01330

340

350

360

370

380

390

400

410

420

430

W-B

an

d D

ete

cto

r (m

V)

Time (UTC)

09/27 09/28 09/29 09/30 10/014

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

Air

Co

ntr

ol

Ou

tpu

t (V

)

Time (UTC)

09/27 09/28 09/29 09/30 10/018

10

12

14

16

18

20

Pla

te C

on

tro

l O

utp

ut

(%)

Time (UTC)

Receiver Software

6 7 8 9 10 11 1210

11

12

13

14

15

16

TLE Transmitter Power Detectors

2015-09-29

Time (Hours UTC)

Pow

er

Dete

cto

r (d

B)

V

W

6 7 8 9 10 11 12-50

-45

-40

-35

-30

-25

-20

-15

-10

TLE W-Band Receiver Power (1Hz)

2015-09-29

Time (Hours UTC)

Am

plit

ude (

dB

)

Co

X

Tx Power vs. Rx Power (2015-09-29 0600 - 1200)

11 11.5 12 12.5 13 13.5 14-45

-40

-35

-30

-25

-20

-15

-10

-5

Tx

= 0.7896 dB

Rx

= 1.815 dBy

Co = 1.1894x + -32.8114

Tx

= 0.7896 dB

Rx

= 1.446 dBy

X = 0.44256x + -39.1026

TLE Transmitter Power Detectors

2015-09-29

Receiv

er

Pow

er

(dB

)

Transmitter Power Detector (dBm)

W Co

W X