Table of contents
- 1. Description
- 2. Notes
- 3. Results
Description
Test of DBBC2 fullband mode to be used when co-observing with ALMA.
Participating stations:
| Log | Prc | |
|---|---|---|
| Ef | t162aef.log | t162aef.prc |
| On | t162aon.log | t162aon.prc |
| Yb | t162ays.log | t162ays.prc |
| Mh | t162amh.log | t162amh.prc |
Notes
- Ys had trouble with flexbuf recording in the beginning of the test. Data was recorded for scans 7-9 only. Inspection of the transferred files with vsum and other VDIF tools revealed problems in decoding the data. Reason needs to be investigated. So far no valid data from Ys.
- Mh had very bad weather during the whole test.
- Efffesberg did parallel recording with RDBE system (Eb). VDIF data is stored on module MPI+1621. RDBE was configured for DDC mode (2nd Nyquist zone).
Results
Effelsberg zero-baseline correlation
Some test data was taken using the t162a setting prior to the observations. Test data was named full_ef_no006 (DBBC full band mode) and full_eb_no0006 (RDBE 4x128 MHz). The channel settings are:
$FREQ;
*
def 86140.00MHz4x128MHz;
* mode = 1 stations =Eb
sample_rate = 256.000 Ms/sec; * (2bits/sample)
chan_def = : 86140.00 MHz : U : 128.00 MHz : &CH01 : &BBC01 : &U1Cal; *Rcp
chan_def = : 86140.00 MHz : U : 128.00 MHz : &CH02 : &BBC02 : &U1Cal; *Lcp
chan_def = : 86268.00 MHz : U : 128.00 MHz : &CH03 : &BBC03 : &U2Cal; *Rcp
chan_def = : 86268.00 MHz : U : 128.00 MHz : &CH04 : &BBC04 : &U2Cal; *Lcp
enddef;
*
def 86524.00MHz2x512MHz;
* mode = 1 stations =Ef:On:Ys:Mh
sample_rate = 1024.000 Ms/sec; * (2bits/sample)
chan_def = : 86524.00 MHz : L : 512.00 MHz : &CH01 : &BBC01 : &NoCal; *Rcp
chan_def = : 86524.00 MHz : L : 512.00 MHz : &CH02 : &BBC02 : &NoCal; *Lcp
enddef;
The data from the DBBC was recorded on the Mark6 combining both VSI data streams are combined and written as interleaved single threaded VDIF data with 8000 bytes packages. VDIF_8000-4096-2-2.
The data from the RDBE was recorded on the Mark5C in multi-threaded VDIF data with 5032 bytes per frame. Below an example how to convert this with vmux to single threaed data VDIF_20000-1024-4-2.
oper@eff-mark5c-1:~$ vdifbstate full_eb_no0006.m5a 5032 1024 0,1,2,3 500
Executing: vmux full_eb_no0006.m5a 5032 6400 0,1,2,3 - 0 | m5bstate - VDIF_20000-1024-4-2 500
Mark5 stream: 0x92960c0
stream = File-1/1=<stdin>
format = VDIF_20000-1024-4-2 = 3
start mjd/sec = 57660 29686.000000000
frame duration = 156250.00 ns
framenum = 0
sample rate = 128000000 Hz
offset = 0
framebytes = 20032 bytes
datasize = 20000 bytes
sample granularity = 1
frame granularity = 1
gframens = 156250
payload offset = 32
read position = 0
data window size = 524288 bytes
10000000 / 10000000 samples unpacked
Ch -- - + ++ -- - + ++ gfact
0 1698169 3306628 3311096 1684107 17.0 33.1 33.1 16.8 1.05
1 1694346 3311571 3311592 1682491 16.9 33.1 33.1 16.8 1.05
2 1698207 3309868 3304658 1687267 17.0 33.1 33.0 16.9 1.05
3 1693271 3305839 3319599 1681291 16.9 33.1 33.2 16.8 1.05
The convereted single threaded data can then be correlated with zerocorr in zoom band mode. Below some plots and the zerocorr parameter files to process the data.
Fig. 1 DBBC auto correlation
Fig. 2 RDBE auto correlation
Fig. 3 RDBE and DBBC autocorrelation combined
Fig. 4 DBBC and RDBE BBCs zoom band cross correlations
