- Current Projects
- eMERLIN
- Planck
- FARADAY
- Methanol Multibeam
- HTS Filters
- OCRA-p
- Remote Diagnostics
- SAMBA-d
- PHAROS
- Recent Publications
- Remote diagnostics systems for the MERLIN Array
- Radiometers at 30 and 44 GHz for the Planck mission
- Recent Visits
- ESTEC-EASOC-ASTRON visit
Remote Diagnostic System for MERLIN
Radio signals detected by any of the remote MERLIN telescopes are relayed to JBO via microwave radio links along with limited monitor and diagnostic information. However, in the event of a receiver fault it is necessary for engineers and/or technicians to visit the remote site (the furthest being 160 miles away by road) in order to determine the cause. It is common to require a second visit to repair the problem.
Recently, National Facility engineers have developed a comprehensive remote diagnostic system for the MERLIN receivers, based on National Instruments LabVIEW software. A prototype system has been installed at the most distant site at Cambridge. This allows engineers and technicians to perform a range of investigations and measurements on the telescope receivers from JBO, or any location with a telephone line, simply using a PC and a modem.
Figure 1: (a) Photograph of the mechanical absorber arm mounted on the 5 GHz feed at Cambridge. This is used for noise temperature measurements and is rotated out of the way when not in use. (b) Example front panel of a LabVIEW program. Once the user has chosen from various options on the panel, the program calculates and displays the diagnostic results
Screen shot of the programme used to measure Noise temperature.
The system provides a number of measurement facilities, which were previously only available to engineers and technicians visiting the remote sites. These are spectrum analysis, system noise temperature measurement, system sensitivity measurement, antenna gain measurement and system power stability measurement.
There are substantial benefits of this scheme; causes of faults can be determined remotely, allowing repairs to be carried out more efficiently, and reducing the number of costly site visits. Routine testing of receivers is made very easy, allowing faults to be picked up early and facilitating the detection of degraded receiver performance.
A recent publication is available from the menu.
Current Activities May 2005
A temperature stabilized noise diode for calibration of MERLIN telescopes is being developed. The noise diode circuit will be housed in a temperature controlled box, so that the output doesn’t drift with temperature. Various diodes are being tested.