RFI Characterisation Page

Locations of all licensed terrestrial transmitters within 200 km of the observatory

Worst-case flux density plot of all terrestrial transmitters near the observatory

Frequency file of the Ceduna area

Flux densities are computed in one of two ways. If an effective radiated power is available, it is used as a starting point assuming, in effect, that a directional antenna has its maximum gain in the direction of the Observatory, thereby giving a "worst case" flux density. If no antenna information is listed, it is assumed that the transmitter output power is radiated by an isotropic source. In both cases, the simplest possible propagation model is used, corresponding to a flat earth with no terrain shielding effects.

For illustrative purposes, second and third harmonic radiation from licenced transmitters are also plotted. When harmonic levels are plotted, it is assumed that emission levels with respect to the carrier are at levels of -40 dB and -60 dB for second and third harmonics respectively.

**RFI Characterisations for the various Rx bands: **

(2nd harmonics are presented as **blue** data points and 3rd harmonics are presented as **yellow** data points)

70 cm (440 MHz) Flux density plot around the centre frequency

70 cm (440 MHz) Flux density plot around the centre frequency with 2nd and 3rd Harmonics present

50 cm (660 MHz) Flux density plot around the centre frequency

50 cm (660 MHz) Flux density plot around the centre frequency with 2nd and 3rd Harmonics present

20 cm (L-band) flux density plot

20 cm (L-band) flux density with 2nd and 3rd Harmonics present

13 cm (S-band) flux density plot

13 cm (S-band) flux density with 2nd and 3rd Harmonics present

6 cm (C-band) flux density plot

6 cm (C-band) flux density with 2nd and 3rd Harmonics present

3 cm (X-band) flux density plot

3 cm (X-band) flux density with 2nd and 3rd Harmonics present

**Satellite Plots**

The Worst-case satellite density plots below, are based on the minimum distance each satellite approaches the site in the current month. These plots are updated on the first of the month.

When the downlink bandwidth is known, the spectral flux density is calculated for that satellite. When the bandwidth information is not known, the power density is calculated only (hence the greater number of satellites plotted).

Many satellites operate over a range of frequencies (such as IRIDIUM), so these are plotted as horizontal lines.

Worst-case Satellite Spectral Flux Density Plot

Worst-case Satellite Power Density Plot

**Measured Plots**

**RFI Folklore**

Back to the ATNF RFI Characterisation Page

Enquiries jsarkiss@atnf.csiro.au John Sarkissian