1. Future LBO Developments
Steven Durand & Jonathan Romney

2. US-China workshop July 2017

3. Samplers in the Vertex room
US-China workshop July 2017

4. RF over Fiber
US-China workshop July 2017

5. Attributes of RF over Fiber
Positive
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 room
US-China workshop July 2017

7. Attributes of Vertex Room Samplers
Negative
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 capability
Supports 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 Correlator
Mark 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 Dichroic
Ka-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 System
Instrumentation 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 Upgrade
Replaces 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 Radiometers
Many 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 Compressors
US-China workshop July 2017

17. RFI Generator
US-China workshop July 2017

18. RFI shielded Rack 60-80dB of shielding .2 – 20 GHz
Honey 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 Shielding
US-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 RFI
Module 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