3.1 Capacity

The EVN correlator has 32 correlator boards, each of which can currently handle a total of 4096 lags. The number of frequency points you will see is half the number of lags used in the correlation, so there is a total number of 65536 frequency points ( $4096\cdot 32/2$). This capacity must be divided among all the individual baseline/subband/polarization interferometers that belong to your experiment. The relevant formula is:

\begin{displaymath}
\frac{\mathcal{N}_{\rm sta}^2}{2} N_{\rm pol} N_{\rm SB} N_\nu \quad \le \quad 65536.
\end{displaymath} (4)

\fbox{\usebox{\savepar}}

You can use eq.(4) to find the maximum number of frequency points you can get per baseline/subband/polarization product. However, due to the specifics of how the correlator is configured, there are some factors to keep in mind:

Table 1 summarizes some valid configurations that use the whole correlator.


Table 1: Some $N_{\rm sta}/N_{\rm SB}/N_{\rm pol}/N_\nu$ configurations that use the whole correlator.
  16sta 1SB 1Pol 512Frq (Max. $N_\nu$ for 16 stations)
  8sta 1SB 1Pol 2048Frq (Max. $N_\nu$ for 8 stations; also current max. possible $N_\nu$)
  4sta 2SB 2Pol 2048Frq (with only 4 stations, you can get more SB/Pol)
  16sta 8SB 4Pol 16Frq (opposite extremes: many SB/Pol with low $N_\nu$)
  8sta 16SB 4Pol 32Frq  




\fbox{\usebox{\savdrie}}

campbell@jive.eu