In the following the IFs referred to are those in the Mk3 unit and VCs are the Video Converters (synonymous with BaseBand Converters or BBCs).
There are two IFs in our Mk3 rack, but some observatories have three. The setup below describes the standard case of two IFs.
IF1 connects to odd numbered VCs
IF2 connects to even numbered VCs
group 1 is tracks 1,3,5,7,9,11,13
group 2 is tracks 2,4,6,8,10,12,14
group 3 is tracks 15,17,19,21,23,25,27
group 4 is tracks 16,18,20,22,24,26,28
mode A; all tracks (and both IFs used in all passes)
VC# 1 2 3 4 5 6 7 8 9 10 11 12 13 14
usb 1 2 3 4 5 6 7 8 9 10 11 12 13 14
lsb 15 16 17 18 19 20 21 22 23 24 25 26 27 28
mode B; only half the tracks and one IF (both sidebands) used
VC# 1 3 5 7 9 11 13
pass1 (groups 1 and 3)
usb 1 3 5 7 9 11 13
lsb 15 17 19 21 23 25 27
pass 2 (groups 2 and 4)
usb 2 4 6 8 10 12 14
lsb 16 18 20 22 24 26 28
mode C; only half the tracks and both IFs (upper sideband) used
VC# 1 2 3 4 5 6 7 8 9 10 11 12 13 14
pass 1 (groups 1 and 3)
usb 15 1 17 3 19 5 21 7 23 9 25 11 27 13
pass 2 (groups 2 and 4)
usb 16 2 18 4 20 6 22 8 24 10 26 12 28 14
mode D; only one track recorded per pass, from VC1 usb.
mode E; only a quater of the tracks and one IF (upper sideband) used
VC# 1 3 5 7 9 11 13
pass 1 (group 1) formatter in mode B
usb 1 3 5 7 9 11 13
pass 2 (group 3) formatter in mode C
usb 15 17 19 21 23 25 27
pass 3 (group 2) formatter in mode B
usb 2 4 6 8 10 12 14
pass 4 (group 4) formatter in mode C
usb 16 18 20 22 24 26 28
Polarization
Polarization setup is defined:
LCP=IF1 normal and IF2 alternate
RCP=IF2 normal and IF1 alternate
If only one of the two IFs is used it is conventionally IF1.
By convention astronomical (except S/X band, 3.6/13cm dual frequency observing) VLBI is done with LCP as the single polarization. so IF1=NOR IF2=ALT. Geodesists use RCP for S/X band, so that has also become the VLBI standard there.
If dual polarization is observed the convention is that LCP is fed into IF1 and RCP into IF2, so both IFs (even and odd VCs) are needed with IF1=NOR IF2=NOR.
These are more flexible than the other parameters. Frequencies quoted below are for the Sky frequency that comes out at video zero of the Mk3 video converter. Mode C single polarization is not quoted because it has the same bandwidth as mode B, which is used for preference (it is more compatible with VLBA systems). All frequencies are in MHz.
mode B A A dual C dual E
Fsky
1638.99 VC02
1642.99 VC04
1646.99 VC06
1650.99 VC08
1654.99 VC01 VC01 VC01,VC02 VC01,VC02 VC01
1656.99 VC03,VC04 VC03
1658.99 VC03 VC03 VC03,VC04 VC05,VC06 VC05
1660.99 VC07,VC08 VC07
1662.99 VC05 VC05 VC05,VC06 VC09,VC10 VC09
1664.99 VC11,VC12 VC11
1666.99 VC07 VC07 VC07,VC08 VC13,VC14 VC13
1670.99 VC09 VC09 VC09,VC10
1674.99 VC11 VC11 VC11,VC12
1678.99 VC13 VC13 VC13,VC14
1682.99 VC10
1686.99 VC12
1690.99 VC14
mode B A A dual* C dual E
Fsky
4958.99 VC02
4962.99 VC04
4966.99 VC06
4970.99 VC08
4974.99 VC01 VC01 VC01,VC02 VC01,VC02 VC01
4976.99 VC03,VC04 VC03
4978.99 VC03 VC03 VC03,VC04 VC05,VC06 VC05
4980.99 VC07,VC08 VC07
4982.99 VC05 VC05 VC05,VC06 VC09,VC10 VC09
4984.99 VC11,VC12 VC11
4986.99 VC07 VC07 VC07,VC08 VC13,VC14 VC13
4990.99 VC09 VC09 VC09,VC10
4994.99 VC11 VC11 VC11,VC12
4998.99 VC13 VC13 VC13,VC14
5002.99 VC10
5006.99 VC12
5010.99 VC14
* note: the Brandeis VLBI group have used a different dual pol setup with different frequencies.
There is no agreement with VLBA
mode B A A dual C dual E
Fsky
1376.99 VC02
1380.99 VC04
1384.99 VC06
1388.99 VC08
1392.99 VC01 VC01 VC01,VC02 VC01,VC02 VC01
1394.99 VC03,VC04 VC03
1396.99 VC03 VC03 VC03,VC04 VC05,VC06 VC05
1398.99 VC07,VC08 VC07
1400.99 VC05 VC05 VC05,VC06 VC09,VC10 VC09
1402.99 VC11,VC12 VC11
1404.99 VC07 VC07 VC07,VC08 VC13,VC14 VC13
1408.99 VC09 VC09 VC09,VC10
1412.99 VC11 VC11 VC11,VC12
1416.99 VC13 VC13 VC13,VC14
1420.99 VC10
1424.99 VC12
1428.99 VC14
This is a setup that was used in May 1994
mode B A A dual C dual E
Fsky
322.99 VC01,VC02 VC01
324.99 VC03,VC04 VC03
326.99 VC05,VC06 VC05
328.99 VC07,VC08 VC07
330.99 VC09,VC10 VC09
332.99 VC11,VC12 VC11
334.99 VC13,VC14 VC13
92cm standard
First used Feb 1995
mode B A A dual C dual E
Fsky
319.99 VC01,VC02 VC01
321.99 VC03,VC04 VC03
323.99 VC05,VC06 VC05
325.99 VC07,VC08 VC07
327.99 VC09,VC10 VC09
329.99 VC11,VC12 VC11
331.99 VC13,VC14 VC13
There is no agreement with VLBA. Only the frequencies 609.0 to 613.0MHz can be used with the VLBA. However the EVN standard is 607.99 to 609.99MHz
mode B A A dual C dual E
Fsky
599.99 VC01
601.99 VC03
603.99 VC05
605.99 VC07
607.99 VC09
609.99 VC11
611.99 VC13
RCP is used for compatibility with geodesy.
mode A
Fsky
2274.99 VC02
2278.99 VC04
2282.99 VC06
2286.99 VC08
2290.99 VC10
2294.99 VC12
2298.99 VC14
8404.99 VC01
8408.99 VC03
8412.99 VC05
8416.99 VC07
8420.99 VC09
8424.99 VC11
8428.99 VC13