L-Band (1200-1500MHz) Survey Spectrum Notes

The L-Band 1200-1500MHz spectrum shows a number of features, which can act as sources of interference to radioastronomy observations. The 2 most dominant sources are the licensed transmissions associated with the Digital Radio Concentrator Services (DRCS) at 1438.5MHz, and 1499MHz. These transmissions are point to point links, requiring around 2MHz of spectrum. The DRCS signal at 1438.5MHz is at it's strongest from the north east (Wellington), and the DRCS signal at 1499MHz is at it's strongest from the south south west (Grenfell). There were some other very minor DRCS type transmissions (ie 2MHz BW), from the north west, with centre frequencies of 1473.12MHz, 1475.32MHz, 1478.12MHz, & 1480.44MHz, as well as another DRCS type signal, again from the north west, and from the south at 1490.88MHz.
There were a number of instances of transmissions from the Glonass beacon at 1246.43MHz, which occupies around 1MHz of spectrum.
There were a number of CW type signals measured (being very weak), when the RFI monitoring antenna was pointed to the west, and hence with a view to the main observatory tower. These signals are attributed to the radiotelescope, being:
1200MHz, 1208MHz, 1240MHz, 1250MHz, 1280MHz, 1313MHz, 1320MHz, 1375MHz, 1400MHz, 1408MHz, 1479.81MHz, & 1491.68MHz
Some of these CW signals can be attributed to the various clocks, reference frequencies used on site for the radioastronomy backend instrumentation. Identifiable ones being 1408MHz, 1280MHz being harmonics of the multibeam/DAS sampler clocks, and 1400MHz from the hydrogen maser. A number of the CW signals are exact frequencies, and are more than likely to be reference frequency related harmonics.