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Basic Equations

For the Plateau de Bure interferometer, the conversion from sky frequencies down to the IF band (100-600 MHz) is done using two local oscillators. The first frequency conversion (with the LO1 oscillator) is double sideband from sky frequency down to 1.5 GHz. The second frequency is a lower sideband conversion with a second oscillator LO2 around 1.875 GHz. In this document, I will use the following frequencies :

All frequencies are derived from Fsyn, with frequency multipliers to generate the relevant harmonic numbers, according to the following equations (with frequencies in MHz)

\begin{displaymath}
Flo2 = Fsyn - 0.5
\end{displaymath} (1)


\begin{displaymath}
Flo1 = M \times (H \times Flo2 - L \times Eps)
\end{displaymath} (2)


\begin{displaymath}
Fsky = Flo1 + S \times (Flo2-350)
\end{displaymath} (3)


\begin{displaymath}
Frest = \frac{Fsky - S \times (Fcent-350)}{Doppler}
\end{displaymath} (4)


\begin{displaymath}
Frest = \frac{ ( (M \times H+S) \times Flo2 - M \times L \times Eps )
- S \times Fcent}{Doppler}
\end{displaymath} (5)

Five parameters introduced in these equations, M, H, L, S, and Eps, depend on the phase lock and receiver system, while Doppler depends on the source:

The phase lock system nominal performances are obtained for Flo2 in the range 1.850 - 1.900 GHz.


next up previous contents
Next: Image Frequency Doppler Tracking Up: Frequency Setup IRAM Plateau Previous: Contents   Contents
Gildas manager 2018-06-22