Dundee in UK Dundee Satellite Receiving Station is based in Dundee University, Scotland, at latitude 56.5 degrees North, longitude 3 degrees West (see in Google Earth).

The station is funded by a government organisation called NERC (Natural Environment Research Council), and is part of the Space Technology Centre alongside the Space Systems Research Group. Research is performed as part of the Centre for Remote Sensing and Environmental Monitoring.

Antenna Dundee University is situated near the banks of the River Tay estuary.
Click on the small photograph for a full-size version.

Four antennae The Satellite Station has a number of antennas on the roof of the EEP building plus two on the roof of the Dental Hospital tower building and two on the roof of the University's tower building. The tower buildings are fine locations providing unobstructed views.
Click on the small photograph for a full-size version.

The station itself is spread over two floors, the lower one containing all the reception and processing hardware, plus the tape and CD archive. The upper floor contains the photographic quicklook archive, maintenance laboratory and software development team. Administration and research offices are to be found on both floors.

For directions to the laboratory please see the University's travel pages. Visitors are welcome if arranged in advance.


Photographs of the Satellite Receiving Station

Click on a photo for a full size version.
Control centre Lab From left to right can be seen two tape recorder control PCs, four antenna control PCs with receivers above and tape recorders below, a MODIS ingest PC with antenna monitors above and UPS below, and on the far right under the desk is the MODIS file server.
Archives Tape archive Part of the tape archive, recording every satellite pass received in Dundee since 1978. Quicklook archive Part of the photographic quicklook archive, going from 1978 to the present.

Antennae and Receiving Equipment

All antennae and receiving equipment has been custom built by the satellite station. Gearboxes and reflectors are standard items; other heavy mechanical parts are manufactured to our specifications by a local firm and then assembled on site. The front-ends are usually standard items although have been custom built in the past. The rest, including all electronics and software is designed and built here. Besides lower cost, the benefits include redundancy and easier, cheaper and faster maintenance.

Operational antennae include:


Computers

The satellite receiving station primarily uses Sun SPARC workstations running the Solaris operating system.

The RAID array is a new addition; it consists of a custom-built PC running Linux with IDE disks on RAID controllers exporting disk space as a network file system. Much cheaper than commercial alternatives.

Sun 450

Storage:

Use Size (GB)
AVHRR data 24
SeaWiFS data 63
MODIS data 489
Meteosat data 40
Quicklooks 102
RAID arrays 12000
Total 12 TeraBytes

Apache

Our web server is powered by Apache with PHP and Perl.


Reception of a satellite pass

The cast:

  1. Lionel, the tracking computer
  2. Bertha, the tape recorder control computer
  3. Gavin, the reception computer
  4. Mabel, the file server computer
  5. Nigel, the tape recorder
  6. Andrew, the antenna
  7. Patricia, the photo-facsimile machine
  8. Nancy, the high-resolution laser printer
  9. Bert, the GPS receiver

Act One: Preparation

  1. The satellite's approximate position is calculated from orbital elements and a mathematical orbital model.
  2. The tracking computers have their clock set precisely from a GPS receiver.
  3. The tracking computers align the antennas to point to the location at which the satellite will appear over the horizon.
  4. The reception computer calculates parameters based on the predicted orbit and prepares for reception by plotting grid overlays etc.

Act Two: Reception

  1. When the satellite comes into view the tape recorder computers start the tape recorders and the reception computer starts receiving data.
  2. As the satellite progresses the tracking computers lock onto the position of the satellite and keep the antenna pointing in the correct direction.
  3. The signal is received and decoded then ingested into the reception computer.
  4. The data is displayed in real-time and transferred to the satellite station's file server computer. The image is scaled down to generate quicklooks.
  5. Reception is terminated when the satellite disappears over the horizon, rather than when the signal is lost. This ensures that, should an object such as a tall tree momentarily block the view, the computers keep tracking the satellite ready for when it reappears.

Act Three: Post-processing

  1. The tracking computer updates the orbital model now that the exact position of the satellite is known, making prediction of the next pass more accurate. The information is also used to plot coastlines as accurately as possible.
  2. The quicklooks are put in the archive and the pass database is updated.
  3. Customers' jobs are automatically processed with the new data.
  4. Hard-copy quicklooks are printed and photographs or processed enlargements are produced for customers.


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