PB8 calibration using geostationary satellites

We know that pb8 is not pointing exactly in the right position (see EME experiment at 5GHZ, October 11)

We started this week signal measurements at 5GHz using geostationary satellite.

The protocol is as follows:

  • Lock (manually) pb8 on the maximum of the received signal (beacon / channel).
  • Keep track of the position given by the system (including the offsets) and the position from the ephemeris.
  • Estimate the difference between both positions (ephemeris vs signal).  Without any errors, this difference should be 0.

Lucien and Sylvain collected measures using the following satellites: AMAZONAS-3,IS-21,IS-805,IS-23,IS-1R,NSS-806,NSS-806,IS-14,IS-11,SES 6,TELSTAR-11N,NNS-10,IS-903,Intelsat 25,IS-907,IS-905,SES 4,NSS 7,Express A4,Eutelsat 12 W,Express AM44,Eutelsat 5,Intelsat 10-02,Eutelsat 3B,Eutelsat 10 A,Amos 5,Arabsat 5C,Badr 4/5/6,Arabsat 5A,Paksat 1R,Aficasat 1A,Yamal 202,NSS 5,NSS 12,Intelsat 904,Intelsat 902.

Next two figures shows offset errors on AZ and EL respectively:

pb8-az-errors pb8-el-errors
These figures are a surprise, we didn’t expect so much variations on the offsets. Some of them could be explained by an experimental error. But for half of them we also collected two different measures without significative differences.