1 Future LBO DevelopmentsSteven Durand & Jonathan Romney

2 US-China workshop July 2017

3 Samplers in the Vertex roomUS-China workshop July 2017

4 RF over Fiber US-China workshop July 2017

5 Attributes of RF over FiberPositive Only Analog hardware is in the antenna Samplers in the control building are easier to cool Bandwidth is determined by Fiber and RF over Fiber equipment Negative LO signals are required in the vertex room. Analog and LO Fiber wraps require effort Bandwidth is determined by Fiber and RF-over-Fiber equipment US-China workshop July 2017

6 Samplers in the Vertex roomUS-China workshop July 2017

7 Attributes of Vertex Room SamplersNegative LO signals are required in the vertex room. LO Fiber wraps require effort Samplers in the vertex room can generate RFI Many digital fiber transmitters Cooling Digital Electronics in the Vertex is required Positive Samplers are close to the receivers - less noise Bandwidth is determined by samplers Digital fiber wraps easier Possible to have multiple colors on a single fiber NRAO is familiar with this technique. US-China workshop July 2017

8 US-China workshop July 2017

9 MARK 6 Four 10GigE input ports 16Gbps sustained record capabilitySupports up to four 8-disk modules for recording/playback Based on high-performance COTS hardware Easily upgradeable hardware on Moore's Law curve Linux OS (6.0.3) Supports all VLBI data formats US-China workshop July 2017

10 Data Transmission to the CorrelatorMark 6 disk recorders for the VLBA. We are installing units at one VLBA site. A corresponding complement of Mark 6 unit to replay the recorded bits into the correlator We are also investigating a real-time data transmission scheme, using long-range optical fiber networks US-China workshop July 2017

11 VLBA X/Ka Band DichroicKa-band 26.5 to 40.0 GHz X-band 7.9 to 8.9 GHz Maintaining the existing S/X system US-China workshop July 2017

12 Weather Station Specification (VLBA)Wind Direction : ±3° Wind speed: 0-60 m/s ±5% Barometer: mbar ± 6mbar Temperature: -40 to 60°C ± 0.4°C Dew Point: -45 to 50°C ± 1°C Solar Irradiance: W/m2 ± 3 W/m2 Liquid precipitation: resolution inches ±5% Camera (360º Sky View) Battery back-up Calibration required – annually US-China workshop July 2017

13 Monitor and Control SystemInstrumentation installed at VLBA stations, as part of the 2013 upgrade, required new monitor-and-control capabilities, Monitor Interface Board (MIB) were installed by adapting the EVLA’s Ethernet based system. VLBA-oriented “executor” program was developed, to support the new MIBs and has already replaced many functions of the original VLBA monitor-and-control system. All the features with the MIB based system are available, search engine, plotting, and archiving US-China workshop July 2017

14 VLBA ACU/Servo UpgradeReplaces the functionality of current ACU and FRM electronics COTS PC-104+ based CPU board stack running Real Time Linux Ethernet interfaces to both VLBA M&C system & a dedicated Maintenance/ Engineering GUI (Linux based PC) Fully in-house supportable software system We have all source code and rights to modify it for our use Fully compatible with the New VLBA Monitor & Control system Appears to the system as another MIB Additional built-in test, evaluation and engineering capability using the supplied GUI Supports all current safety requirements US-China workshop July 2017

15 Water-Vapor RadiometersMany VLBA observations require accurate corrections for fluctuations in interferometer phase and delay The prototype NRAO Water-vapor radiometer (WVR) is designed to make simultaneous measurements of the water-vapor content using the 22-GHz emission lines of H2O molecules. Successfully demonstrated a 3-channel WVR system An improved 5-channel design is being developed US-China workshop July 2017

16 Interconnection of three Helium CompressorsUS-China workshop July 2017

17 RFI Generator US-China workshop July 2017

18 RFI shielded Rack 60-80dB of shielding .2 – 20 GHzHoney comb air filters Cooling air flow - Bottom to Top RFI absorbing foam lined AC power filters Filtered data connectors RFI tight fiber connectors US-China workshop July 2017

19 Equipto Rack RF ShieldingUS-China workshop July 2017

20 RFI tight Modules Moto: Too many screws>60 dB of shielding from 0.2 – 18 GHz Many styles: double wide, Triple wide, with heat sink, Honey comb filters or wave guides enable forced air cooling. US-China workshop July 2017

21 Module RF Shielding 60 dB 18 GHz I US-China workshop July 2017

22 Working to Reduce the RFIModule plus Rack > 120 dB of shielding Sometimes challenging to retrofit commercial enclosures Best to design using RFI tight enclosures at start Consider cooling AC power filters Fiber connections Filtered data connectors US-China workshop July 2017

23 Conclusion Existing suite of hardware is mature yet still scientifically interesting LBO has well-designed enhancement projects ready to install 2 Gbit samplers Mark 6 recording X/Ka receiver system Upgraded Weather station Replacement ACUs Compatibility - Data rates, Tunability, Channel band passes LBO is interested in data quality and system compatibility US-China workshop July 2017

24 Shanghai SOHM-4A Maser US-China workshop July 2017

25 US-China workshop July 2017