Cosmic Microwave Technology, Inc. A Wideband Receiver for FAST Stephen Smith Cosmic Microwave Technology, Inc. Sandy Weinreb, Ahmed Akgiray, Andrew Janzen, Ahmed Soliman from Caltech Jin Chengin, Liu Hongfei, Cao Yang from BAO

Outline of Talk Wideband Receiver for FAST Cryogenics Cryogenic LNA’s Cryogenic Noise Sources Warm Electronics Design RF Performance Fiber Optic Links Motherboard Control Software

Receiver for the FAST Telescope Frequency range .27 to 1.62 GHZ Dual-linear polarization QRFH feed-uncooled Front end Receiver Cooled to 11K Integrated Cryogenic Noise Sources for Stable Calibration High pass filter for RFI mitigation Warm Back end electronics 2 Bands-Full Band .27 to 1.62 GHZ-Reduced Band 1.3-1.62 GHZ Linear/Circular Polarization Selected by Switched Hybrid 2 GHZ Fiber Optic Transmitters RF Power Monitors 5 bit Attenuators-1 dB/Step 31 dB total Spectrum Analyzer-Rigol DSA1030 Warm Electronics Thermal Electric Cooler Software control over Ethernet

Block Diagram of the FAST Receiver

Overall View of the FAST Receiver Power Supply Box Warm Electronics Box Cryogenic Dewar Mounting Plate, 10mm Thick Feed Horn 2mm Thick Walls Feed Support Rods, 51mm Diameter Round mounting plate has diameter of 1.5m Feed is 1.453m square at the bottom Total height is 1.706m All boxes are RFI sealed and water sealed Weight estimate is 189 kg

Another View Showing Access Panels Warm Electronics Access Door Removable Panels AC Input & Output

Cryogenic Dewar CTI 350 2 stage Cryogenic Cooler 50K 1st Stage, 11K 2nd Stage Removable access panels on 3 sides of the Dewar for easy access Direction Couplers, High Pass Filters, LNAs on 2nd Stage Noise Sources, Directional Couplers on 1st Stage N Connector Input (2) from Feed SMA Connector Outputs (2) to Warm Electronics SMA Comb Generator Calibration Input (1)

Measured Cryogenic Performance of the LNA’s Gain Noise

Measured Noise Performance

Measured Performance of a Cryogenic Noise Source 133K @RM 392K @10 mA 273K @18 mA 14.3K @13K

Warm Electronics Replaceable, Off-the shelf Components Components are field replaceable without a Soldering Iron Thermal Electric Cooler keeps component temperature @ 40C Outside temperature variation > 30 degrees 2 GHz Fiber optic TX for IF Output Fiber optic to Ethernet converters for control and Spectrum Analyzer Rigol Spectrum Analyzer for RFI monitoring Voltage, Current Monitors Total power Detectors. One for each polarization 5 Bit Digital step attenuators 4 total signal paths 2 Wide Band Channels, 2 Narrow Band Channels Water tight, RFI tight box

Warm Electronics

Warm Electronics Warm Electronics Box RF Inputs DC Power

Warm Electronics Floating Plate Fiber Optic RF Components Spectrum Analyzer

Warm Electronics Mother Board LabJack Fiber Optic Digital Modules

Warm Electronics Thermal Electric Cooler

Measured System Performance

Measured System Performance

Measured System Performance

Measured System Performance

Measured System Performance

Measured System Performance

Measured System Performance

Measured System Performance 1/f Plot 250 mHz to 60 KHz 200 uV/Div Wide Band Noise Plot

Fiber Optic Links 2 GHZ Fiber Optic Transmitter 2 GHZ Fiber Optic Receiver

Fiber Optic Links 10 MHz – 5 GHz

Motherboard Voltage regulation for Receiver 16 Voltage and 13 Current monitors 96 bits of digital I/O 4 RF Power Monitor Inputs-16 Bit ATD 12 General Purpose 16 Bit ATD, +/-10V 3 Warm Electronic Temperature sensors 2 Cryogenic Temperature sensors Vacuum gauge 2 Noise Diode current sources Control Receiver with Ethernet Connection using Labjack T7

Control Software Python Language Controls Receiver State Monitors health of receiver GUI display Software sub-routeen for each function Ability to record data over time Spectrum Analyzer

Control Software

Status of Receiver Wideband Receiver has been delivered to the Beijing Currently undergoing Testing First light end of August

Summary and Conclusions A stable wide band receiver design has been presented Receiver provides: 2 Polarizations 2 bandpass outputs for each polarization Temperature controlled warm electronics box Monitor and control hardware Fiber optic TX Soon to provide Galactic Disoveries