1. 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

2. 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

3. 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 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

4. Block Diagram of the
FAST Receiver

5. 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

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

7. 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)

8. Measured Cryogenic Performance
of the LNA’s
Gain
Noise

9. Measured Noise Performance

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

11. 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

12. Warm Electronics

13. Warm Electronics
Warm Electronics Box
RF Inputs
DC Power

14. Warm Electronics Floating Plate Fiber Optic RF Components
Spectrum Analyzer

15. Warm Electronics
Mother Board
LabJack
Fiber Optic
Digital Modules

16. Warm Electronics
Thermal Electric Cooler

17. Measured System Performance

18. Measured System Performance

19. Measured System Performance

20. Measured System Performance

21. Measured System Performance

22. Measured System Performance

23. Measured System Performance

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

25. Fiber Optic Links 2 GHZ Fiber Optic Transmitter
2 GHZ Fiber Optic Receiver

26. Fiber Optic Links
10 MHz – 5 GHz

27. 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

28. 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

29. Control Software

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

31. 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