Overview
This note provides details of the new parameter conversion types supported by the
LnT-PlotList and GRAF8 engineering unit converters. It also provides details of
changes and enhancements to older parameter conversion types. Its aim is to
provide a supplement to the information in the GRAF6 help file.
New Types
TYPE20 Single-precision IEEE floating-point value
TYPE20, digits after, eng min, eng max, units string;
A parameter that decodes a single-precision IEEE floating-point value stored in the
flight data file. This type is normally only used in an artificially created data file, for
example a flight data file created from a CSV input file. Since a single-precision
floating-point value occupies 32 bits and a recorded word is only 12 bits long, at
least 3 LOCN records will be required to specify one sample.
The Equation
Answer = assembled raw value
Data Field List
F1 digits after – integer 0-4. The number of digits after the decimal point that would
normally be useful when displaying a value of this parameter. The system will
use this value as the default when displaying values of this parameter.
F2 eng min - floating. The minimum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F3 eng max - floating. The maximum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F4 units string - string 31 char. A description of the units of the constant parameter
above.
TYPE21 Double-precision IEEE floating-point value
TYPE21, digits after, eng min, eng max, units string;
A parameter that decodes a double-precision IEEE floating-point value stored in the
flight data file. This type is normally only used in an artificially created data file, for
example a flight data file created from a CSV input file. Since a double-precision
floating-point value occupies 64 bits and a recorded word is only 12 bits long, at
least 6 LOCN records will be required to specify one sample.
The Equation
Answer = assembled raw value
Data Field List
F1 digits after – integer 0-4. The number of digits after the decimal point that would
normally be useful when displaying a value of this parameter. The system will
use this value as the default when displaying values of this parameter.
F2 eng min - floating. The minimum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F3 eng max - floating. The maximum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F4 units string - string 31 char. A description of the units of the constant parameter
above.
TYPE22 Multiple Polynomials
TYPE22, no of equations, no of parts, digits after, sign flag,
raw min, raw max, no of terms, c1, c2, c3, c4, c5, c6,
eng min, eng max, units string;
// for each equation
A parameter that can be converted using several polynomial equations. An
intermediate value is assembled from the specified raw parts; the relevant equation
is selected according to the intermediate raw value; then the result is calculated in
the same way as for a TYPE2 parameter.
The Equation
Raw = assembled raw value.
Select the constants from the relevant equation.
Answer = c1 + c2.raw + c3.raw ^ 2 + c4.raw ^ 3 + c5.raw ^ 4 + c6.raw ^ 5
Data Field List
F1 no of equations – 1-64. The number of equations specified in the parameter
definition.
F2 no of parts – 1-16. The number of LOCN records per parameter sample.
F3 digits after – integer 0-4. The number of digits after the decimal point that would
normally be useful when displaying a value of this parameter. The system will
use this value as the default when displaying values of this parameter.
F4 sign flag – integer 0-1. A value of zero indicates that the raw value is an
unsigned quantity. A non-zero value indicates that the most significant bit of the
raw value contains the sign bit.
F5 … raw min, raw max, no of terms, c1, c2, c3, c4, c5 and c6, one set for each
equation.
F6 eng min - floating. The minimum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F7 eng max - floating. The maximum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F8 units string - string 31 char. A description of the units of the constant parameter
above.
TYPE1021 Multi-part BCD with cut points
TYPE1021, BCD config, no of ranges, no of parts, digits after,
weight1, weight2, ...
// one for each digit
raw min, raw max, offset, // one set for each range
eng min, eng max, units string;
The Equation
Raw = assembled raw value.
Offset = appropriate offset for given raw value.
Data Field List
F1 BCD config. A string containing one numeric character (‘1’ to ‘4’) defining the
number of bits used by each BCD digit, in order from left to right, in the result.
F2 no of ranges.
F3 no of parts – 1-16. The number of LOCN records per parameter sample.
F4 digits after – integer 0-4. The number of digits after the decimal point that would
normally be useful when displaying a value of this parameter. The system will
use this value as the default when displaying values of this parameter.
F5 weight1, weight2, … The scaling factor to be applied to each BCD digit, most
significant digit first (that is, in the same order as the “BCD config” string).
F6 raw min, raw max, offset, … The minimum and maximum raw values for which to
apply the offset, one for each raw range.
F7 eng min - floating. The minimum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F8 eng max - floating. The maximum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F9 units string - string 31 char. A description of the units of the constant parameter
above.
TYPE1024 ARINC 542 Pneumatic Altitude
TYPE1024, digits after, eng min, eng max, units string;
A parameter that records altitude from a pneumatic transducer in a certain type of
scratch-foil replacement UFDR. Like TYPE1014, but for a different model of recorder.
The Equation
raw[1] is recorded temperature; raw[2] is recorded pneumatic altitude. The answer
is in feet.
Data Field List
F1 digits after - integer 0-4. The number of digits after the decimal point that would
normally be useful when displaying a value of this parameter in the units
generated by this equation. The system will use this value as the default when
displaying values of this parameter.
F2 min - floating. The minimum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F3 max - floating. The maximum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F4 units string - string 30 char. A description of the units generated by this
conversion equation (e.g. "kts", "ft", "DegC"). This field is used on output formats
and in the automatic documentation.
TYPE1025 ARINC 542 Pneumatic Airspeed
TYPE1025, digits after, eng min, eng max, units string;
A parameter that records airspeed from a pneumatic transducer in a certain type of
scratch-foil replacement UFDR. Like TYPE1015, but for a different model of recorder.
The Equation
The answer is in knots.
Data Field List
F1 digits after - integer 0-4. The number of digits after the decimal point that would
normally be useful when displaying a value of this parameter in the units
generated by this equation. The system will use this value as the default when
displaying values of this parameter.
F2 min - floating. The minimum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F3 max - floating. The maximum credible value of this parameter, in the units
generated by this equation. This value may be used by the system as a guide to
selecting default output formats (e.g. automatic trace scaling).
F4 units string - string 30 char. A description of the units generated by this
conversion equation (e.g. "kts", "ft", "DegC"). This field is used on output formats
and in the automatic documentation.
Enhancements to Existing Types
TYPE10
The documentation states that each raw part is multiplied by ascending powers of 2.
This is no longer the case; each part’s multiplier is deduced from the number of bits
in the previous part. Another way of looking at it would be to say that the parts are
first assembled, least significant part first, into a 32-bit word; the assembled value is
then multiplied by the slope (c2), and the offset (c1) is added.
TYPE1001 Coarse/fine parameter with adjacent bit patterns
The wrap adjustment logic has been improved. The old algorithm was effectively
"adjust if the difference is between 90% and 110% of the fine range". The new
algorithm is "adjust if the difference is between 50% and 100% of the fine range".
Sign-extend logic can be enabled by setting c6 = maximum value in engineering
units. Needed for the A340 where height can be negative but the sign is not
recorded. This option (obviously) only works if the sign bit is NOT specified.
TYPE1002 Coarse/fine with overlapping bit patterns
The documentation states that ‘c5’ contains “the range of the fine part”. In fact, the
algorithm does not use c5.
TYPE1017 Coarse/fine GMT in seconds past midnight.
The wrap adjustment logic has been improved. The old algorithm was effectively
"adjust if the difference is between 90% and 110% of the fine range". The new
algorithm is "adjust if the difference is between 50% and 100% of the fine range".
New LFD Keywords
PARAMNUM Specify the sequence number and the parameter number.
PARAMNUM, sequence number, parameter number;
This optional record specifies the sequence number (“Row pointer, continuous
number created by the map compiler”) and parameter number (“Airline parameter
number”) for Teledyne frame layouts. These items correspond to the first and second
fields of a PA11 record in a PRM file. If present, this record must appear between the
PARAM record and the TYPE record.
TITLES Specify the parameter titles to be used in the engineering listing output.
TITLES, “title text 1”, “title text 2”, “title text 3”;
This optional record specifies the titles to be used in the engineering listing output.
The three fields correspond to the first three fields of a PA50 record in a PRM file. If
present, this record must appear after the PARAM record and before the first LOCN
record.
Enhancements to Existing LFD Keywords
TIMING
It appears that this keyword, which has always been available, has never been
documented. There is now an additional timing type, “CYCLES”. This should be used
when the cycle number in which parameters are recorded is known.
TIMING, timing type, number of cycles;
Data Field List
timing type – the timing method used in the recording. This field can be either
numeric or textual. Possible values are:
0 or “POS” - timing by position. The time at which a value is recorded is determined
by its position (word number) within the subframe. This style is typically used by
older recording systems where some sort of hardware multiplexing was used to store
the data in a particular word slot.
1 or “AGE” - timing by sample number. The time at which a value is considered to
have been recorded is determined by its sample number. All samples are considered
to be distributed evenly within the subframe.
2 or “CYC” - timing by cycle number. The time at which a value is recorded is
determined by the cycle number specified in the LOCN record. When specifying
timing by cycle number, you must also specify the number of recording cycles.
number of cycles – integer. The number of recording cycles used in this data frame.
This value can be obtained from the airborne equipment documentation.
LOCN
There is now an optional additional field in which to specify the cycle number.
LOCN, superframe id, superframe value, subframe pattern, word, bit mask, cycle;
Raw data location definition. The set of LOCN commands, which follow each TYPE
command, define the location(s) of the raw value(s) within the recorded data frame.
These raw values provide the inputs into the conversion equation.
Data Field List
superframe id - integer 0-8. If this raw value is a superframe value (i.e. it is only
present when a superframe counter is set to a certain value) then this field identifies
the superframe counter associated with this raw value. A value of 0 here indicates no
dependence upon a superframe counter.
superframe value - integer 0-4095. If 'superframe id' above is set to a non-zero
value, indicating that this raw value is associated with a superframe counter, then
this is the value of that counter that corresponds to this raw value being available in
the frame.
subframe pattern - integer 1-15. A bit pattern indicating in which subframes this raw
value is available. Bit 0 (the least significant bit) corresponds to subframe 1, bit 1 is
subframe 2, bit 2 is subframe 3, and bit 3 is subframe 4. A value of 1 in each bit
indicates that the raw value is present in that subframe.
word – integer between 1 and the subframe size. The word number within the
subframe that contains the raw value.
bit mask - integer. A bit mask identifying the raw value within the word. Bits set to
1 mask the required raw value. The mask must contain a single contiguous block of
set bits. If the conversion type is greater than 0 (i.e. not a special type) then the bit
mask must be > 0, otherwise it can be 0.
cycle – integer between 1 and the number of recording cycles specified in the
TIMING record. This field is only valid when timing by cycle number.