Frame Definition Block

The Frame Definition Block (FDB) contains the parameters that define the attributes of a single exposure. The format of the FDB is shown in the table and described in the paragraphs that follow.

Bits(r)-> Words	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	FID
1	CM			ES				TC	AMP		ED	SF	FF	TF	MX	MN
2	ECW
3	TMUL								DT	DW	TA		TAI
4	TPC
5	FCR
6	SFCR
7	FPC
8				FCO		FCB		FCOF
9	A1REF			A1O		A1B		A1OF
10	A1RB				A1RO
11	A1CB				A1CO
12	A2REF			A2O		A2B		A2OF
13	A2RB				A2RO
14	A2CB				A2CO
15	Spare

Table 1 Frame Definition Block Format

FDB Parameter Descriptions

Frame Identifier (FID)

The FID is a 16 bit identifier supplied by the user. The sequencer has access to a table of FDB's called the Frame Definition Table(FDT). When a sequence invokes a frame, it does so by the FID. The sequence locates the FDB in the table and uses it as the basis for setting up the next exposure. The sequencer uses only the upper 13 bits of the FID to look up the frame definition. The lower 13 bits are available for use as a revision code. If there are multiple definitions using the same FID, the sequencer uses the most recently loaded definition.

Camera Mode (CM)

CM is a three bit field with the following possible values:

0: Full camera read at full resolution

1: Full camera read summed 2x2

2: Full camera read summed 4x4

3: Full camera read summed 8x8

4: Partial read centered on the camera (See ES parameter)

5: Partial read using centering of previous frame

6: Partial read centered on most recent IMAX

7: Partial read centered on most recent IMIN

Extract Size (ES)

ES defines the size of the extracted area in 64 row units, i.e., 64*(ES) rows. 0 means 16 while all other value are natural. ES applies for CM > 3 only. If CR is the center row, the extracted field is from CR- (ES)*32 through CR+(ES)*32-1. From example, is ES=2 and CM=4, the camera outputs rows 448 through 575.

Telecommand Flag (TC)

If TC is set, the image was produced using the take picture telecommand; otherwise, the image was produced by the sequencer. During operations, the sequencer generates most exposures. This bit allows ground software to readily identify images produced by telecommand.

Amplifier (AMP)

AMP is a two bit field that defines which amplifier will be used for the exposure. 0 indicates amplifier A; 1 indicates amplifier B; 2 or 3 indicates no change from the current amplifier setting.

Event Detection Area (ED)

ED defines the event detection area. 0 indicates the full field read from the camera. 1 indicates DHC extracted area (area1).

Super Flare Flag (SF)

If SF is set, the DHC phase I processing includes testing for a super flare.

Flare Flag (FF)

If FF is set, the DHC phase I processing includes testing for a flare.

Transient Flag (TF)

If SF is set, the DHC phase I processing includes testing for a transient event.

Intensity Maximum (MX)

If MX is set, the DHC phase I processing includes returning the address of the pixel containing the maximum value.

Intensity Minimum (MN)

If MX is set, the DHC phase I processing includes returning the address of the pixel containing the maximum value.

Exposure Control Word (ECW)

The ECW defines parameters associated with configuring the instrumentation prior to the exposure. It defines if the exposure is a shutter exposure or a dark, AEC or specific, and the index to the Exposure Table. The ECW is a 16-bit field which is described in detail in the ECW Description.

Time Average (TA)

TA is a two bit field that defines time averaging source for the exposure. 0 indicate no time averaging. 1 indicates time average the entire camera readout field. 2 indicates use DHC extracted area 1. 3 is unused and treated the same as 0.

Time Averaging Interval (TAI)

TAI is a 4-bit field that defines the number of frames that are time averaged in the DHC. 0 means 16 while all other numbers are natural.

Dangerous Wavelength (DW)

If DW is set (1), the DHC program executes the CCD safety algorithm. Refer to CCD Safety Check Description for details.

Dark Transient (DT)

DT determines if the transient event is a dark transient (DT =1) or a bright transient (DT = 0). The following expressions defines the processing for bright and dark transients. In both cases, transient detection counts the number of elements in T that are greater than 0.

T = where (I(NEW) * 100 > I (REF) * TMUL) Bright

T = where (I(REF) * 100 > I (NEW) * TMUL) Dark.

Transient Multiplier (TMUL)

TMUL contains the transient multiplier. The transient algorithm multiplies the current time average by 100 and subtracts the product of TMUL and the previous time average, i.e., X = 100*I₁- TMUL*I₀. Any pixel that is greater than 0 is considered a transient.

Transient Pixel Count (TPC)

If the number of transient pixels is greater than TPC, a transient event has occurred.

Flare Count Rate (FCR)

The count rate must exceed FCR in a sufficient number of pixels (see FPC) for a flare event. DHC phase I processing includes this test if FF is set. FCR is in DN per CCD pixel per second. The CC adjusts this number in accordance with summing modes so one can think in terms of counts in a CCD pixel. The count rate must not include the CCD amplifier offset as this is added by the Control Computer. See paragraph 0 for details.

Super Flare Count Rate (SFCR)

The count rate must exceed SFCR in a sufficient number of pixels (see SFPC) for a super flare event. DHC phase I processing includes this test if SF is set. SFCR is in DN per CCD pixel per second. The CC adjusts this number in accordance with summing modes so one can think in terms of counts in a CCD pixel. The count rate must not include the CCD amplifier offset as this is added by the Control Computer. See paragraph 0 for details.

Flare Pixel Count (FPC)

FPC is the number of pixels that must exceed the flare count rate for a flare event. FPC is used for both the flare and super flare events. 0 means 256 while all other numbers are natural. The CC adjusts this number in accordance with summing modes so one can think in terms of CCD pixels. See paragraph 0 for details.

Full Camera Output (FCO)

FCO is a two bit field that defines the (spacecraft) mass memory destination buffer for the full camera field. 0 results in no output. 1 codes the output for the main buffer. 2 codes the output for the current flare buffer. 3 is illegal and treated as no output.

Full Camera Binning (FCB)

FCB is the binning that is applied to the full camera field. The values of this 2 bits field can be 0,1,2, or 3 defining no binning, 2x2, 4x4, or 8x8 respectively. The output from the DHC pixel binning instruction is rounded to the 12-bit average of the input.

Full Camera Output Format (FCOF)

FCOF is a nine bit field that defines the output formatting of the full camera image. This nine bit field is shown Table 3 and defined in the paragraphs that follow.

Bit
8	7	6	5	4	3	2	1	0
JPF
0	PCK				LUT
1	HT		QT		QM

Table 3 Output Formatting Field

JPEG Flag (JPF)

If JPF is not set (0), the remainder of the field defines lookup table and packing parameters. If it is set, the remainder of the field describes JPEG compression parameters.

Packing Size (PCK)

PCK is a four bit field that indicates the number of bits in each output element. DHC phase II processing packs the data into 16 bit words using this number. If PCK is 0, the data is not packed.

Lookup Table (LUT)

If LUT is greater than 0, DHC Phase II processing looks up data values in one of 15 possible lookup tables prior to packing. If LUT is 0, there is no lookup.

Huffman Table (HT)

HT is an index to one of 4 possible Huffman Tables.

Quantization Table (QT) and Quality Multiplier (QM)

QM and QT are used together to specify one of 64 possible quantization tables. In the original design, QT had been an index to one of 4 possible quantization tables, while QM indicated one of 16 possible quality multipliers. Part way through the implementation, the use of these parameters was changed to a more general case of 64 quantizations.

Area 1 Reference (A1REF)

This 3 bit field describes the reference point for area1. The possible values are as follows:

0: Extract Centered Camera Field

1: Extract As Previous

2: Extract Centered on IMAX

3: Extract Centered in IMIN

4: Slaved to the pointing table

Value 5 -7 are unused but treated the same as 0.

Note: If there is a full camera read-out, all values of A1REF are allowed. If there is a partial camera read- out, the reference for the area must match that of the camera. If they don't match the area reference will be forced to the camera reference.

Area 1 Output (A1O)

A1O is a two bit field that defines the (spacecraft) mass memory destination buffer for the area1 field. 0 results in no output. 1 codes the output for the main buffer. 2 codes the output for the current flare buffer. 3 is the current flare buffer with the alternate APID.

Area 1 Binning (A1B)

A1B is the binning that is applied to the full camera field. The values of this 2 bits field can be 0,1,2, or 3 defining no binning, 2x2, 4x4, or 8x8 respectively. The output from the DHC pixel binning instruction is rounded to the 12-bit average of the input.

Area 1 Output Format (A1OF)

A1OF is a nine bit field that defines the output formatting of the area1 field. This nine bit field is shown in Table 12 and defined in the paragraphs that follow that table.

Area 1 Row Blocks (A1RB)

A1RB is the number of 64 row blocks in area1. 0 means 16, while all other values are natural. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction. {What do we do if this exceeds the size of the input or, with the offset goes outside the limits of the input????}

Area 1 Row Offset (A1RO)

A1RO is the number of rows to offset the center of area 1 from A1REF. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction.

Area 1 Column Blocks (A1CB)

A1RB is the number of 64 column blocks in area1. 0 means 16, while all other values are natural. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction.

Area 1 Column Offset (A1CO)

A1RO is the number of columns to offset the center of area 1 from A1REF. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction.

Area 2 Reference (A2REF)

This 3 bit field describes the reference point for area2. The possible values are as follows:

0: Extract Centered Camera Field

1: Extract As Previous

2: Extract Centered on IMAX

3: Extract Centered in IMIN

4: Slaved to the pointing table

Value 5 - 7 are unused but treated the same as 0.

Note: If there is a full camera read-out, all values of A2REF are allowed. If there is a partial camera read-out, the reference for the area must match that of the camera. If they don't match the area reference will be forced to the camera reference.

Area 2 Output (A2O)

A2O is a two bit field that defines the (spacecraft) mass memory destination buffer for the area2 field. 0 results in no output. 1 codes the output for the main buffer. 2 codes the output for the current flare buffer. 3 is the current flare buffer with the alternate APID.

Area 2 Binning (A2B)

A2B is the binning that is applied to the full camera field. The values of this 2 bits field can be 0,1,2, or 3 defining no binning, 2x2, 4x4, or 8x8 respectively. The output from the DHC pixel binning instruction is rounded to the 12-bit average of the input.

Area2 Output Format (A2OF)

A2OF is a nine bit field that defines the output formatting of the area2 field. This nine bit field is shown in Table 12 and defined in the paragraphs that follow that table..

Area 2 Row Blocks (A2RB)

A2RB is the number of 64 row blocks in Area 2. 0 means 16, while all other values are natural. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction. {What do we do if this exceeds the size of the input or, with the offset goes outside the limits of the input????}

Area 2 Row Offset (A2RO)

A2RO is the number of columns to offset the center of area 1 from A2REF. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction. The offset is a 12-bit signed number, i.e., +/- 2048.

Area 2 Column Blocks (A2CB)

A2RB is the number of 64 column blocks in Area 2. 0 means 16, while all other values are natural. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction.

Area 2 Column Offset (A2CO)

A2CO is the offset in columns from A2REF to the first pixel of Area 2. The value is in CCD pixels and is adjusted by the CC for on-chip summing and extraction.

Additional Considerations

All offsets, i.e., A1RO, A1CO, etc. as well as the IMAX and IMIN row and column are treated as if they apply to image read using amplifier A. If amplifier B is used, the offsets are corrected. Equation 1 and Equation 2 define the adjustments. X is 1 or 2. CAMSZ is 1024 for full camera reads and ES*64 for partials. RL_CM is the row length for the camera mode (See Table 21). IMAX of IMIN are adjusted in a similar manner prior to their use.

AXRO_B = CAMSZ - (AXRO_A + AXRB*64)

Equation 1 Row Offset Adjustment

AXCO_B = RL_CM-16 - (AXCO_A + AXCB*64)

Equation 2 Column Offset Adjustment

Last Update: 9/18/97 CC Version 1.26

Name: Michael Levay