Table of contents
- 1. Systems Check
- 1.1. R2DBE setup
- 1.2. Control computer setup
- 1.2.1. /etc/dnsmasq.conf
- 1.2.2. /etc/ntp.conf
Temporary page for filling in details on the NOEMA April 2019 setup.
Systems Check
RF-over-Fiber to R2DBE
The RFoF receiver and IF processor unit currently receives Antenna 4, 2 polarizations x~4 GHz.
Internal dual-LO chain (9.0 GHz +5.4 dBm, 4.0 GHz +16.9 dBm) splits this into 2 pol x 2 sideband x 2 GHz.
R2DBE receives lower 2 GHz from boths pols into if0, if1.
R2DBE power levels checked to be within +-1 dBm of ideal.
R2DBE 2048 MHz clocking and the dual-LO clocking is somewhat adventurous. Timetech freq dist amp (in: H-maser 5 MHz) in the correlator room, one output sent to a stack of three synthesizers (R&S SMA 100B for 9 GHz, SMA 100A for 4 GHz and 2.048 GHz) with ext.ref. from this 5 MHz line shared by BNC-T. Oscilloscope shows distortion of sine. Spectrum analyzer shows still good phase noise.
R2DBE setup
Clock 2048 MHz clk, 0 +- 3 dBm 50 ohm
Driven by 5 MHz H-maser locked R&S SMB 100A
HB input from GPS 1PPS
1PPS ref input from Maser 1PPS, to utilize internal counter-comparator in addition to separate external 1PPS GPS-MASER unit
Control computer setup
Enabled ip4 NAT/masquerade to allow Mark6's to use further NTP, and access the internet for installing DiFX for zero baseline tests
Added jwagner as publickey-only auth (/etc/ssh/sshd_config section like "Match User daan").
Reverted back to the R2DBE scripts from SAO-EHT https://github.com/sao-eht rather than Radbout written-from-scratch "vlbicontrol" (we have not tested it, especially not for GMVA, and no earlier experience since neither NOEMA nor APEX were in the EHT dress rehersal)
