-
Notifications
You must be signed in to change notification settings - Fork 6
/
Copy pathDBBCnotes.txt
143 lines (100 loc) · 4.76 KB
/
DBBCnotes.txt
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
Last Update: 2013-04-05, Cormac Reynolds
The following is an ad hoc list of features and constraints for the DBBC, which
I deem relevant to SCHED. These have been distilled from various email
exchanges with Jon Quick, Jim Lovell, Ed Himwich and Gino Tuccari. Their
accuracy is not guaranteed. There is a dearth of formal documentation, but this
should suffice for the DDC personality for SCHED's purposes. I don't yet have
much information on the PFB personality.
DBBC Description:
-----------------
The DBBC consists of a number of Conditioning Modules (CoMo, referred to as ifX
in the Field System, where X is a, b, c or d) which each consist of a 4-way IF
(or L-band RF) input selector switch followed by a switchable set of Nyquist
zone analogue filters, an IF amplifier, a computer-controlled variable
attenuator and a total power detector. There are two variants (Unica3 and
Unica4) which differ in the number of Nyquist filters (4 vs 8).
Each IF is fed to an A-to-D board (of which there are two variants). ADB1 and
ADB2 boards can sample at 1024 Msps. The ADB2 can in principle also sample at
2048 Msps but the current firmware does not support that.
Currently there is only a 1024 Msps firmware version. The 2048 Msps firmware
will enable new modes only on the Unica4/ADB2 implementations. Due date for
this is unknown.
The arrangement of A-to-D and FPGA 'Core2' boards (each of which mimics 4
BBCs) inside the DBBC currently defines which 'ifX' is feeding which bbcNN.
This is planned to be flexibly switchable but currently is not.
Although the DBBC design is quite modular, there appear to be 3 basic varieties
in the field which I refer to as 'ASTRO', 'GEO' and 'Hybrid'.
Known DBBC Constraints
----------------------
*) number of IF inputs allowed.
ASTRO = 4
GEO = 2
HYBRID = 3
There may be some ASTRO versions with just 2 IFs (CoMos).
*) Accessible IF frequency range.
The following filters are possible:
1: 512-1024 MHz,
2: 10- 512 MHz,
3: 1536-2048 MHz,
4: 1024-1536 MHz,
5: 0-1024 MHz,
6: 1200-1800 MHz (L Band, RF)
Filters 3 and 4 are optional and not available in all DBBCs.
Filters 5 and 6 require an ADB2/Unica4 version of the DBBC and await a
future 2048 Msps firmware upgrade to enable them.
For the immediate future we probably only need to consider filters 1 and 2.
Known Constraints on the DBBC DDC Personality.
-----------------------------------------------
*) Constraints on mapping a given IF to a particular BBC.
This was planned to be fully flexible but that is not implemented yet. Current
mappings are:
ASTRO:
ifa -> bbc01, bbc02, bbc03, bbc04
ifb -> bbc05, bbc06, bbc07, bbc08
( ifc -> bbc09, bbc10, bbc11, bbc12
ifd -> bbc13, bbc14, bbc15, bbc16 )
(ifc and ifd may not be available in all implementations).
GEO:
ifa -> bbc01, bbc02, bbc03, bbc04, bbc05, bbc06, bbc07, bbc08
ifb -> bbc09, bbc10, bbc11, bbc12, bbc13, bbc14, bbc15, bbc16
HYBRID:
ifa -> bbc01, bbc02, bbc03, bbc04
ifb -> bbc05, bbc06, bbc07, bbc08
ifc -> bbc09, bbc10, bbc11, bbc12, bbc13, bbc14, bbc15, bbc16
*) Output channel order.
BBCs map to Mk5B bitstreams in the conventional way. The USB channels come
first in BBC order, followed by the LSB channels in BBC order.
http://auscope.phys.utas.edu.au/opswiki/lib/exe/fetch.php?media=hardware:mapping-2-mk5b.pdf
*) Available BBC filters.
Presently 1, 2, 4, 8 or 16MHz. The 32 MHz filter awaits the 2048Msps firmware
version.
*) Maximum output data rate.
1024 Mbps (or 2048Mbps with a future 2048 Msps firmware).
*) Resolution for setting the BBC frequencies.
The DBBC has both a binary and a decimal tuning mode. The decimal mode has
10KHz resolution and is the one normally used. The binary mode can set the
frequency with resolution 1024MHz/2^31=0.476 Hz.
*) Allowed values for number of bits per sample.
Fixed at 2-bits per sample (though 1-bit is possible by channel selection on
the Mark5B).
*) Allowed sampling rates.
Nyquist only.
Known Constraints on the DBBC PFB Personality.
-----------------------------------------------
The following from Gino Tuccari:
The PFB mode in the DBBC can be applied to any Nyquist zone
between 1 and 4. Corresponding side bands are:
1st Nyq all the contiguous 15 channels are USB
2nd Nyq all the contiguous 15 channels are LSB
3rd Nyq all the contiguous 15 channels are USB
4th Nyq all the contiguous 15 channels are LSB
A set of PFB channels is produced for each IF available
(normally between 1 and 4), and any channel produced
by any IF can be routed on the 2 VSI-H output in
a flexible fashion.
In the DBBC2010 configuration (8 IFs) all the channels
from all the IFs are available in the output.
Two input bandwidth are permitted depending on the
hardware ADB board available, 512MHz and 1024 MHz.
In the first case the output PFB bands are wide 32 MHz,
in the second 64 MHz.