Data Format Descriptions¶
TBW¶
TBW consist of a time series of real valued data sampled at fS (196 MHz) from all antennas in the array. The stand numbering is based on the input into the digital system rather than the stand number in the array. The data are divided into packets that contain either 400 samples (12-bit data) or 1200 samples (4-bit data) per stand per polarization.
Note
Fields are big endian
Byte(s) |
Name |
Description |
---|---|---|
0-3 |
Sync Word |
0xDECODE5C |
4-6 |
Frame Count |
Frame number within capture |
7 |
ID |
Always zero |
8-11 |
Second count |
Always zero |
12-13 |
TBW ID |
Packed frame source ID |
14-15 |
Unassigned |
Always zero |
16-23 |
Time tag |
Time tag [1] |
24-1223 |
Data |
|
The packing on the TBW ID
field is:
Bit(s) |
Description |
---|---|
0-13 |
Stand |
14 |
Sample Size (0 = 12-bit) |
15 |
Is TBW? (1 = Yes) |
Both the i4
and i12
versions of the data are stored as two’s complement
integers.
TBN¶
TBN data is similar to TBW data, except that the data are complex and have a variable sample rate of up to 100 kHz. The data are divided into packets with 512 samples per stand per polarization.
Note
Fields are big endian
Byte(s) |
Name |
Description |
---|---|---|
0-3 |
Sync Word |
0xDECODE5C |
4-6 |
Frame Count |
Always zero |
7 |
ID |
Always zero |
8-11 |
Tuning Word |
Tuning frequency [2] |
12-13 |
TBN ID |
Packed frame source ID |
14-15 |
Gain |
TBN gain used |
16-23 |
Time tag |
Time tag [1] |
24-1047 |
Data |
|
The packing on the TBN ID
field is:
Bit(s) |
Description |
---|---|
0-13 |
Stand |
14 |
Reserved |
15 |
Is TBW? (1 = Yes) |
ci8
is also known as “8+8-bit complex integer”.
DRX¶
DRX data consist of a time series of complex data sampled at fS / Decimation Factor
from the beamformer. The data are divided into packets of 4096 samples per beam
per tuning per polarization.
Note
Fields are big endian
Byte(s) |
Name |
Description |
---|---|---|
0-3 |
Sync Word |
0xDECODE5C |
4-6 |
Frame Count |
Always zero |
7 |
ID |
Packed frame source ID |
8-11 |
Second Count |
Always zero |
12-13 |
Decimation Factor |
Decimation factor of fS |
14-15 |
Time Offset |
Time correction to the time tag |
16-23 |
Time tag |
Time tag [1] |
24-28 |
Flags |
Always zero |
29-31 |
Tuning Word |
Tuning frequency [2] |
32-4127 |
Data |
|
The packing on the ID
field is:
Bit(s) |
Description |
---|---|
0-2 |
Beam |
3-5 |
Tuning |
6 |
Always zero |
7 |
Polarization |
The ci4
aka “4+4-bit complex integer” data are stored as two’s complement
integers with the real part stored in the first four bits of the byte.
DR Spectrometer¶
DR Spectrometer data contain DRX data that has been transformed to the Fourier domain, converted to power, and integrated on-the-fly by the data recorder. The format allows for variable integration times, channel counts, and polarization products to be stored.
Byte(s) |
Name |
Description |
---|---|---|
0-3 |
Magic Word 1 |
0xC0DEC0DE |
4-11 |
Time tag |
Time tag of first frame [1] |
12-13 |
Time offset |
Time correction to the time tag |
14-15 |
Decimation Factor |
Decimation factor of fS |
16-23 |
Tuning Word[2] |
|
24-39 |
Fills[4] |
Fill counts [4] |
40-43 |
Errors[4] |
Error flags [4] |
44 |
Beam |
Beam |
45 |
Stokes Format |
Polarization format code |
46 |
Version |
Packet format version |
47 |
Flags |
Bit flags |
48-51 |
Nfreq |
Transform length [5] |
52-53 |
Nint |
Integration count [5] |
54-67 |
Sats[4] |
Saturation counts [4] |
68-71 |
Magic Word 2 |
0xED0CED0C |
72-N |
Data |
|
The Stokes Format
is a bit field that defines what polarizations are
included in the packet data. The fields are:
Value |
Pol. Product |
---|---|
0x01 |
XX* |
0x02 |
Real(XY*) |
0x04 |
Imag(XY*) |
0x08 |
YY* |
0x10 |
I |
0x20 |
Q |
0x40 |
U |
0x80 |
V |
The data are stored as little endian float
values.
TBF¶
TBF is similar to both TBW and TBN, but is a complex frequency domain product
that contains blocks of 12 channels from all stands and polarizations. Each
channel has a bandwidth of fC (25 kHz) and there may be up to 132
different values of First Channel
within a single recording. The stand
ordering is based on the input into the digital system rather than the stand
number in the array.
Note
Fields are big endian
Byte(s) |
Name |
Description |
---|---|---|
0-3 |
Sync Word |
0xDECODE5C |
4-6 |
Frame Count |
Frame number within capture |
7 |
ADP ID |
Always one |
8-11 |
Second Count |
Always zero |
12-13 |
First Channel |
First channel in packet |
14-15 |
Unassigned |
Always zero |
16-23 |
Time tag |
Time tag [1] |
24-6167 |
Data |
|
The ci4
aka “4+4-bit complex integer” data are stored as two’s complement
integers with the real part stored in the first four bits of the byte.
COR¶
The COR format contains full polarization complex visibility data for 132
channels from a single baseline pair. Each channel has a bandwidth of
fC (25 kHz) and there may be up to six different contiguous values of
First Channel
within a single recording. The stand numbering for the
baseline pair is based on the input into the digital system rather than the
stand number in the array.
Note
Fields are big endian
Byte(s) |
Name |
Description |
---|---|---|
0-3 |
Sync Word |
0xDECODE5C |
4-6 |
Frame Count |
Server ID |
7 |
ADP ID |
Always two |
8-11 |
Second Count |
Always zero |
12-13 |
First Channel |
First channel in packet |
14-15 |
Gain |
COR gain used |
16-23 |
Time tag |
Time tag [1] |
24-27 |
Navg |
Integration time in samples |
28-29 |
Stand 1 |
First stand in baseline |
30-31 |
Stand 2 |
Second stand in baseline |
32-4255 |
Data |
|
The data are stored as little endian Complex<float>
values.