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• Space and Atmospheric Sciences •
Arecibo Observatory – HF Facility and diagnosticsSAS Director: Christiano Brum Ph.D., Head Radar Science: Mike Sulzer Ph.D.
HF Team: Eliana Nossa Ph.D., Eng. Alfredo Santoni, SwS. Phil Perillat, Carlos Perez, Victor Iguina. Other SAS team: Nestor Aponte Ph.D., Jonathan Friedman Ph.D., Jean Lautenbach Ph.D., Shikha Raizada Ph.D., Pedrina Santos Ph.D., Edvier Cabassa, Eframir Franco, Raul García, Eva Robles
HF Facility To artificially modify the ionosphere
Other diagnostics Neutral density, airglow, scintillations, echoes,…
State of the art facility with flexible design and multiple diagnostics to modify the ionosphere
Lidars Measure neutral density and
temperatures using resonance and Rayleigh techniques
• K• Na• Ca ion/Rayleigh
Contact: Shikha Raizada ([email protected]) Jean Lautenbach ([email protected])
Passive Optics Onsite
and Culebra island
• Imagers• Spectrometers• Fabry Perots• Lightening cameras
Contact: Pedrina Santos ([email protected])
Other RF systems • Ionosondes• SDR
Contact: Alfredo Santoni ([email protected])
User’s instrumentation
Support user’s equipment at AO sites and around the
island • Satellites (dedicated) • GPS networks • Other radars • VLF receivers • Dedicated cameras • and more
Contact: Christiano Brum ([email protected])
DiagnosticsFrequency 5.1MHz 8.175MHzGain 22dB 25.5dBBeam width 13 deg. 8.5 deg. Max Power 600kW
CW
RF
5.1MHz 8.175MHz
1 MW 1 MW 1 MW 1 MW
Tx 100kW
Tx 100kW
Tx 100KW
Tx 100kW
Tx 100kW
Tx 100kW
PS PS PS PS PS PS
Contacts: Science: Eliana Nossa ([email protected])
Engineer: Alfredo Santoni ([email protected])
19 Jun 2015
23 24 25 26 27 28Time (LT)
75
80
85
90
95
100
105
110
Alti
tude
(km
)
Na atoms (/cc)
1.00 2500.75 5000.50 7500.25 10000.00
Commercial Power or generator
Power Supply • 4160V → >100kV DC
Modulation Tank (2.MW) • 2 amplifiers (klystrons) of 1.25MW each• Duty cycle between 1-6%
Wave Guide (WR2100)
• 1300 ft length to platform• Signal loss < 1dB
Platform Host the two transmitter systems
for the 430MHz system Gregorian dome and Line feed antenna: Host: 6 receivers at different freq.
4 transmitters (S-band, 46MHz, and two at 430MHz)
• 0 - 720deg. – azimuth angle / 30 min • 0 - 19.6deg. - zenith angle • Suspended at 525ft altitude by 3 towers • Weight ~900 tons
430MHz antennas• Dual beam/ Single beam • Dual polarization
Dual beam split the power.
Dish • Spherical dish - diameter = 305 m • Works for a bandwidths between
47MHz-10GHz
TxPicture by Ismael Cabrera
Picture by Frankie Lucena, Camara: John Mathews at Cabo Rojo
Culebra Island site
Artificial airglow
Generators Cumming / Automatic • 4160V → 13200V
Tx signal generator Transmit CW + RF signal
• Broadband amplifier • 3 amplifier tubes • Filters between stages
Coaxial lines • One per frequency • Multiple of lambda/2, Diameter 3 1/8’’ • Losses <0.5dB • Max velocity / air dielectric
(UVF =0.93 or ~3ns)
Antennas • Two set of arrays of antennas (one per
frequency) • The array is triangular concentric
formed by three cross dipoles • Transmit: Linear, O and X mode
Sub-reflector (mesh) • Mesh of 4x4m that reflect frequencies < 20MHz • It is transparent for higher frequencies. • Protects sensitive equipment in the platform.
Dish Use the same dish as the ISR system
Tx
Transmitters Continental Electronics
• 6 Transmitters/100 KW each • 6 possible frequencies
(only two used) • 5.1 and 8.175 MHz
Power Supply Continental Electronics
• DC (1320V, 750V, 2002V) • AC (480V, 208V, 120V)
• A 25 MHz bandwidth. • Flexible LO/IF system (part
of the astronomy system for all Gregorian feeds)
• 430 MHz +/- 5MHz (+/- 9MHz with loss in sensitivity).
• 30MHz IF from the carriage house to the control room.
• Mixes and filters allow all part of this bandwidth to be selected and/or shifted to baseband
Linefeed Gregorian
RxRx
Data sampling and storage Same radar pulses are used for both ion and plasma line
Plasma line (electron density profiles): • High speed digital receivers and disk arrays are used for recording • Echotek card allows two 5MHz sampled bandwidths to be written • A USRP digital receiver/recorder allows a single 25 MHz bandwidth to be
sampled and written.
Ion line (power, temperature, composition profiles): • A radar interface samples data • Averaged spectra or acfs are
computed and monitored • Web based monitor (acfs, and
temperature and composition for some experiments)
• Voltage samples and computed results are stored indefinitely.
ISR - 430 MHz system Measure/estimate: Electron density, ion/electron temperature, ion composition, ion drifts, electric fields, neutral winds,
…
• Synchronization to the radar pulses occurs later in software
• We store the computed spectra, not store the raw data (not indefinitely).
Contacts: Mike Sulzer([email protected]) Nestor Aponte ([email protected])
Ran
ge K
m
240
220
200
180
160
140
4.0 4.5 5.0 5.5Frequency in MHz from 430MHz
6.0
Artificial layerDensity increase from 4.6MHz to 5.1MHz
Plasma Line 20170315 tm:08:32:14 pos(az.zgr,zacn):(348.0,1.1,11.0)
FoF2 > fh FoF2 > fh
8.175 MHz 5.1 MHz
