LO Subsystem Terry Cotter LOIF Group Leader 3122021
LO Subsystem Terry Cotter LO/IF Group Leader 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 1
Introduction • The LO system – Overview – Module Specifications and Performance 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 2
Master LO System 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 3
Antenna Reference System 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 4
L 350 Central Reference Generator • Takes Maser 5 MHz and generates the references required at the backend. • Phase Noise of 512 MHz d. Bc/Hz Specification 3/12/2021 Terry Cotter Measured 10 Hz -74 -80 100 Hz -104 -110 1 K Hz -134 -142 100 KHz -159 -162 EVLA LO/IF 19 -21 May 2004 5
L 350 Phase Noise 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 6
L 350 Performance Frequency Harmonics (Spec/Meas) Spurs (Spec/Meas) 128 MHz 25 d. Bc /41 d. Bc 40 d. Bc / 56 d. Bc 512 MHz 25 d. Bc /54 d. Bc 40 d. Bc / 55 d. Bc 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 7
L 351 Offset Generator 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 8
L 351 LO Offset Generator • Phase Noise required for Round Trip measurements • Phase Noise measurements are still pending • Total Phase Noise needs to be <500 fs for times under 1 sec 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 9
L 352 Round Trip Measurement • To be Covered Later in another talk 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 10
L 353 • L 353 Functions Summary • Hardware, Mechanical, and Software Status • Testing 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 11
L 353 Functions • • Provides 512 MHz LO to Antenna via Fiber Optics On-Off Keying (OOK) used to sync 19. 2 Hz Heartbeat Remote Monitor + Control Software Phase Noise Alarm and Returns 512 MHz for RTP 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 12
L 353 Block Diagram 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 13
Pulse Blanking 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 14
Mechanical Drawings 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 15
L 353 Summary Completed Work – – – Unfinished Work ICD Mechanical Drawings Part Lists Software/Firmware RF Shielding Tests 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 – Last PCB Revisions – Testing of new phase board 16
L 304 Antenna Reference Receiver • Receives 512 MHz reference with the. 1 pps reset pulse • Returns 512 MHz back to central antenna for roundtrip phase measurement • Uses Anacom receiver 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 17
L 304 Reference Receiver 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 18
L 305 Antenna Ref Generator • Receives 512 MHz plus reset pulse from L 304 • Strips reset pulse off • Cleans up 512 MHz • Generates references needed by antenna • Synchronizes timing with reset pulse. 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 19
L 305 Timing Board 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 20
3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 21
3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 22
L 305 Harmonics Frequency Spec Measured 128 MHz 25 d. Bc None 512 MHz 25 d. Bc 42 d. Bc 1024 MHz 25 d. Bc 49 d. Bc 2048 MHz 25 d. Bc 34 d. Bc 4096 Mhz 25 d. Bc None 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 23
L 305 Spurs Frequency Spec Measured 128 MHz 40 d. Bc > 47 d. Bc 512 MHz 40 d. Bc > 59 d. Bc 1024 MHz 40 d. Bc > 62 d. Bc 2048 MHz 40 d. Bc > 55 d. Bc 4096 MHz 40 d. Bc > 53 d. Bc 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 24
L 305 Antenna Reference Generator • Phase Noise of 512 MHz d. Bc/Hz Specification 3/12/2021 Terry Cotter Measured 10 Hz -74 -80 100 Hz -101 -105 1 K Hz -129 -140 100 KHz -149 -142 EVLA LO/IF 19 -21 May 2004 25
L 305 Phase Noise 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 26
Questions? 3/12/2021 Terry Cotter EVLA LO/IF 19 -21 May 2004 27
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