Required Parameter list (last updated 2012/03/07) - RAL

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Required Parameter list (last updated 2012/03/07) - RAL

NCAR In-situ Algorithm Needed Parameters

Gregory Meymaris ∗

March 7, 2012

Abstract

This document gives the listing of the needed aircraft parameters for recording in order to

perform both off-line verification and real-time implementation of the NCAR in-situ turbulence

algorithm.

1 List for Recording (To Run Verification off-line)

A requirement of the algorithm is that data parameters need to be equally spaced temporally. For

example, if the algorithm is being run at 8 Hz, then there should be approximately 0.125 seconds

between samples (plus or minus a small amount). Additionally, parameters need to be synchronized

so that the values input into the algorithm at the same time, should have been collected at

approximately the same time. Finally, the parameters required for the real-time implementation

all need to be available at the same sampling frequency. Upsampling for most parameters is not

acceptable, therefore, the algorithm should be run at the maximum common frequency of these

parameters. ALT and MASS are exceptions. Also it is nessecary to know the type of aircraft. This

is needed to calculate the AOAB as well as to tailor the quality control algorithm.

Table 1 lists the parameters needed in order to test, verify, and run the algorithm. The second

column requires some explanation. If, for example, the AOAB is not available on the bus, then

AOA and PTHR are required. If AOAB is available and satisfies frequency and quality requirements,

then AOA and PTHR are not required for running in real-time. The fourth column specifies

whether the parameter is needed for running in real-time and the fifth specifies the required sampling

frequency of the parameter. Note that if higher sampling frequencies or smaller precisions

are available, better turbulence EDR measurements may be obtained. In general, the recommended

sampling frequency range is between 8 and 20 Hz, and the precision of the data should be

as small as possible.

∗ NCAR/RAL meymaris at ucar dot edu (303)497-2828

c○1991-2012 UCAR RAL All Rights Reserved 1


Name in Spec

Needed if

← not

available

Parameter

Name

Needed for

Real Time

Needed for

Current C

Code

Minimum

Sampling

Frequency

(Hz)

Minimum

Precision

UTC

UTC date and TBD N 8 0.125 sec

time

ACTYPE

Aircraft type Y Y 1 N/A

(b757-200)

CGA

Vertical N N 8 0.003 g

Acceleration

Mass

Current N N 8 2 100 lbs

Weight

TAS True Airspeed Y Y 8 0.07 knots

↩→ ALT Barometric Y Y 8 2 1 ft

Altitude

↩→ CAS Calibrated Y N 8 0.07 knots

Airspeed

↩→ SAT Static Air Y N 8 TBD

Temperature

AP

Auto-pilot N N 1 NA

(on/off)

AOAB

Body-axis Y N 8 0.05 deg

Angle of

Attack

↩→ AOA Angle of Y Y 8 0.05 deg

Attack 1& 2

↩→ PTHR Pitch Rate Y Y 8 0.02

deg/sec

↩→ FLAP Flap Angle Y Y 8 2 1 deg

PTCH Pitch Y Y 8 0.02 deg

ROLL Roll Y Y 8 0.02 deg

IVV

Inertial Y Y 8 1 ft/min

Vertical

Velocity

LAT Latitude N N 1 0.0002 deg

LON Longitude N N 1 0.0002 deg

Wind Speed Wind Speed N N 1 1 knot

Wind Direction

Wind

Direction

N N 1 1 deg

Table 1: Parameters needed for in situ turbulence algorithm. Note that if higher sampling frequencies

or smaller precisions are available, better turbulence EDR measurements can be

obtained. In general, the recommended sampling frequency range is between 8 and 20 Hz, and

the precision should be as small as possible. The current C code requires 8 Hz. Downsampling is

OK.

1 Not currently a direct input but some of the initialization parameters are based on the a/c type.

2 Upsampling is OK.

c○1991-2012 UCAR RAL All Rights Reserved 2

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