Future LBO Developments Steven Durand & Jonathan Romney

US-China workshop July 2017

Samplers in the Vertex room US-China workshop July 2017

RF over Fiber US-China workshop July 2017

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

Samplers in the Vertex room US-China workshop July 2017

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

US-China workshop July 2017

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

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

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

Weather Station Specification (VLBA) Wind Direction : 0-360 ±3° Wind speed: 0-60 m/s ±5% Barometer: 600-1000 mbar ± 6mbar Temperature: -40 to 60°C ± 0.4°C Dew Point: -45 to 50°C ± 1°C Solar Irradiance: 0 - 1400 W/m2 ± 3 W/m2 Liquid precipitation: resolution 0.001 inches ±5% Camera (360º Sky View) Battery back-up Calibration required – annually US-China workshop July 2017

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

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

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

Interconnection of three Helium Compressors US-China workshop July 2017

RFI Generator US-China workshop July 2017

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

Equipto Rack RF Shielding US-China workshop July 2017

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

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

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

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

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

US-China workshop July 2017