The correlator bandpasses

sep 2002

The correlator bandpass using a noise source in the downstairs if/lo:

    Data was taken at all allowable correlator configurations using a noise source in the downstairs if/lo. The data was integrated for 1 minute. Each link holds the bandpass for the allowable configurations at the specified bandwidth. The four sub correlators for polA are on page 1 and those for polB are on page 2. The abbreviations for the configurations are: 9lvl=9level sampling, 3lvl=3level sampling, 3lvl_IL= 3 level interleaved sampling, 3lvl_DY= 3 level double nyquist sampling.
bandwidth configurations notes
50 3lvl_IL Just the analog filters(no digital filter). 4 sbc's overplotted.
DC spikes from the digitizer are present.
Filters for sbc1,2 have different roll off then sbc2,3 causing different aliasing. 
25 9lvl,3lvl,3lvl_IL  
12.5 9lvl,3lvl,3lvl_IL,3lvl_DN  
6.25 9lvl,3lvl,3lvl_IL,3lvl_DN  
3.125 9lvl,3lvl,3lvl_IL,3lvl_DN  
1.5625 9lvl,3lvl,3lvl_IL,3lvl_DN  
.78125 9lvl,3lvl,3lvl_IL,3lvl_DN  
.390625 9lvl,3lvl,3lvl_IL,3lvl_DN  
.195312 9lvl,3lvl,3lvl_DN  

    The bandpasses for 3 level interleave less than 25 Mhz have a bandpass shape that changes. It must be related to the extra interpolation stage that is done for bandwidths less than 25 Mhz (see:  comparing computed and measured bandpass shapes).

processing: x101/020905/