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Status of KVN Instrumental Phase Calibration System Development

Status of KVN Instrumental Phase Calibration System Development.

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Status of KVN Instrumental Phase Calibration System Development

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  1. Status of KVN Instrumental Phase Calibration System Development Do-Heung Je1, Moon-Hee Chung1, Ji-Man Kang1, Seung-Rae Kim1, Min-Kyu Song1, Sung-Mo Lee1, Taehyun Jung1, Seog-Tae Han1, Do-Young Byun1, Seog-Oh Wi1, Bong-Won Son1, Soo-Yeon Kim2, and Won-Kyu Lee3 1Korea Astronomy and Space Science Institute 2Korea University 3Korea Research Institute of Standards and Science 2013. Oct. 12. 2nd IVTW

  2. Contents • KVN Round Trip System • Specification • Development progress • System configuration • Test results (old & new) • KVN Wide-band phase calibration • Specification : power vsfreq, reference frequency • P-cal System Configuration • Component’s design and fabrication • Timeline

  3. KVN System Configuration RTS (3 sets installed in 2012) 1.4 GHz H- maser Reference Generator RTS Antenna Module RTS Control Room Module 1.4 GHz P-cal (under development) 10 MHz 100 MHz 1 pps 5 MHz 100 MHz Distributor 10 MHz Distributor 1 pps Distributor 1 pps Distributor Station Clock x2 DigitalE/O Digital O/E QO 22 GHz FE Digital Filters Down Converter IF Selector Mk5B Sampler Down Converter 43 GHz FE Sampler WDM Optical MUX WDM Optical DMUX Down Converter 86 GHz FE Sampler Down Converter Sampler 129 GHz FE Antenna Receiver Room Control Room

  4. KVN RTS(Round Trip System) Specification • RTS is needed for compensating the cable length change due to temperature variations & movement • H-maser frequency stability : ~ 2E-15@1000s • RTS transmission stability : ~ 2E-16@1000s (10 times better than H-maser stability)

  5. KVN RTS Development • KASI developed KVN RTS through research cooperation with KRISS (Korea Research Institute of Standards and Science) in 2011. • KASI installed RTS system in 3 KVN sites in 2012. • Fiber-optic reference signal transmission method (from NICT, Dr. Fujieda, 2009) • The measured stability satisfied the stability specification, 2E-16@1,000s. • Real-time remote signal monitoring functionwas added.

  6. KVN RTS Configuration , , , . Remote signal phase cannot be measured directly. We need any method to check remote signal phase for diagnosis of the system performance.

  7. Expectation of remote signal phase . () , . Remote signal phase can be expected from vco signal phase and round-trip signal phase.

  8. KVN RTS Test setup Observation Building MZM laser VCO Photo Diode Antenna Vertex Room Phase Compensation Circuit H-maser MZM laser Photo Diode Controller Vector Voltmeter

  9. Test results I (2011. June)

  10. Test results II (2012. Jan.)

  11. Test results III (after temperature stabilization)

  12. Test results IV (after temperature stabilization)

  13. Comparison of Allan deviations before and after temperature stabilization Before stabilization After stabilization

  14. Contents • Round Trip System • Specification • Development progress • System configuration • Test results (old & new) • Wide-band phase calibration • Specification : power vsfreq, reference frequency • System Configuration • Component’s design and fabrication • Timeline

  15. KVN 4 ch Receiver (Front End) 45 degree mirror

  16. KVN Wide-band Pcal Specification • Quasi-optic injection is needed for calibrate path delays in 4 bands receivers • Frequency band : 20 – 130 GHz • Covers KVN 4 ch receiver full bandwidth • Reference frequency : 200 MHz • 2 tone signals are positioned in 500 MHz IF bw • Power : ~ - 100 dBm (in front of each receiver’s horn antenna)

  17. KVN P-cal Configuration 20-130 GHz 200 MHz 100 MHz Quasi-Optic Injection Feeder Reference Generator Comb Generator Attenuator Double-ridged feedhorn < 50 GHz doubler Power Amp

  18. Quasi Optic Injection • KVN is comprised of 3 LPF, several mirrors. • Quasi optic P-cal injection is needed. • Double ridged feedhorn, ellipsoidal mirror, Mylar sheet are used for quasi optic P-cal injection. To subreflector Ellipsoidal mirror Mylar Film Transmission Loss Double-ridged horn 125 um 50 um 25 um Mylar Film 45 degree mirror

  19. Comb Generator • Signal Generation • Step Recovery Diode: ~ 20 GHz • Tunnel Diode : ~ 40 GHz • NLTL (Nonlinear Transmission Line) Comb generator : > 100 GHz • PSPL : -30 dBm @ 50 GHz (200 MHz reference) • Agilent : -85 dBm@ 67 GHz (10 MHz reference)

  20. Wideband Feed Horn Development (Dr. Moon-Hee Chung) • Double-ridged waveguide horn was designed and fabricated as a ultra-wide band feeder • VSWR : < 2 @ 20-130 GHz • Aperture size : 24 mm x 28 mm • Lower return loss measured above 80 GHz

  21. Timeline for KVN wideband P-cal • P-cal system using commercialcomb generator(< 50 GHz or 86 GHz), widebandfeeder, Quasi-optic injection system • 1st injection test : 2013. Dec. • 2nd injection test : 2013. March. • 3 sets installation : 2014. July (TBD) • Further Works for full-band Phase calibration • NLTL MMIC Chip development needed. • MMIC Module loaded feeder development.

  22. Summary • KVN RTS development • 2E-16 @ 1000s • O(E-17) @ 1000s (after temperature stabilization) • Real time remote signal phase expectation method was suggested. • KVN wide-band Pcal system is under development • Ultra wide-band feed is developed. • Quasi-optic injection • Custom designed high frequency comb generator is needed.

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