Table of contents
- 1. Setup for 4 Gbps
- 2. ALMA Mode 4 Gbps
- 2.1.1. DBBC2 setup
- 2.1.2. FILA10G setup
Setup for 4 Gbps
ALMA Mode 4 Gbps
For ALMA compatibilty the DBBC2 stations must observe in fullband PFB mode covering the full 512 MHz per polarisation in a single IF channel.
DBBC2 setup
It is recommended to restart the DBBC PFB control software, if it was used in another mode (SPOL or FLEX) before setting the fullband mode. Reprogramming might not be necessary. Of course reprogramming is required if the DDC mode was used before.
The only option to be commanded is
dbbcform=full
The 2bit digitalization threshold is fixed in this mode and optimization of the bit statistics is done most easily by adjusting the input counts using the IFx commands. To check the bit statistics short recordings can be analyzed with m5bstate.
All data from the last Core2Board (IFD) will be send to VSI1 and all from last-1 (IFC) to VSI2. There is no option to choose something else.
FILA10G setup
To combine the both VSI streams it is usually enough to set the Fila10G to:
splitmode off inputselect vsi1-2 vsi_samplerate 64000000 reset vdif_frame 2 2 8000 reset
However, this will join the two steams to a single 64 bit stream one after each other VSI1 bit 0-31 and VSI2 bit 32 to 61. The correlator expects to have alternating bits from channel 1 and 2. VSI1 bit 0+1, VSI2 bit2+3, ....
This can be forced with the following changes of the channel permutation matrix:
regwrite chan_perm 0 0x21200100 regwrite chan_perm 1 0x23220302 regwrite chan_perm 2 0x25240504 regwrite chan_perm 3 0x27260706 regwrite chan_perm 4 0x29280908 regwrite chan_perm 5 0x2B2A0B0A regwrite chan_perm 6 0x2D2C0D0C regwrite chan_perm 7 0x2F2E0F0E regwrite chan_perm 8 0x31301110 regwrite chan_perm 9 0x33321312 regwrite chan_perm 10 0x35341514 regwrite chan_perm 11 0x37361716 regwrite chan_perm 12 0x39381918 regwrite chan_perm 13 0x3B3A1B1A regwrite chan_perm 14 0x3D3C1D1C regwrite chan_perm 15 0x3F3E1F1E reset
The mode has been succesfully tested at Effelsberg (details).
