U.S. patent application number 11/469387 was filed with the patent office on 2008-03-20 for methods and systems for distinguishing arinc 743 from arinc 743a protocols.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. Invention is credited to Kevin J. Conner, Yasuo Ishihara, Steve C. Johnson.
Application Number | 20080068259 11/469387 |
Document ID | / |
Family ID | 38721765 |
Filed Date | 2008-03-20 |
United States Patent
Application |
20080068259 |
Kind Code |
A1 |
Conner; Kevin J. ; et
al. |
March 20, 2008 |
METHODS AND SYSTEMS FOR DISTINGUISHING ARINC 743 FROM ARINC 743A
PROTOCOLS
Abstract
An apparatus and method for automatically adjusting for data
protocol discrepancies. The apparatus includes a unit that receives
a signal from GPS receiver. The signal was formatted according to a
transmission protocol. The unit includes a first component that
estimates User Equivalent Range Error (UERE) based on the received
signal and adjusting at least one value of the received signal
based on the estimated UERE and one or more predefined scale factor
and a second component that uses the adjusted at least one
value.
Inventors: |
Conner; Kevin J.; (Kent,
WA) ; Johnson; Steve C.; (Issaquah, WA) ;
Ishihara; Yasuo; (Kirkland, WA) |
Correspondence
Address: |
HONEYWELL INTERNATIONAL INC.;PATENT SERVICES AB-2B
101 COLUMBIA ROAD, P.O. BOX 2245
MORRISTOWN
NJ
07962-2245
US
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
Morristown
NJ
|
Family ID: |
38721765 |
Appl. No.: |
11/469387 |
Filed: |
August 31, 2006 |
Current U.S.
Class: |
342/357.46 ;
342/357.53 |
Current CPC
Class: |
G01S 19/23 20130101;
G01S 19/15 20130101; G01S 19/20 20130101; G01S 19/09 20130101 |
Class at
Publication: |
342/357.06 |
International
Class: |
G01S 5/14 20060101
G01S005/14 |
Claims
1. A method for automatically adjusting for data protocol
discrepancies, the method comprising: receiving a signal at a GPS
receiver; sending the received signal from the GPS receiver to a
unit based on a transmission protocol; estimating User Equivalent
Range Error (UERE) based on the received signal; adjusting at least
one value of the received signal based on the estimated UERE and
one or more predefined scale factors; and using the adjusted at
least one value at the unit.
2. The method of claim 1, wherein the at least one value includes
one of a Horizontal Figure of Merit (HFOM) and Vertical Figure of
Merit (VFOM).
3. The method of claim 2, wherein estimating comprises: computing
the estimate of UERE using the HFOM and a Horizontal Dilution of
Precision (HDOP) value; and filtering the estimated UERE.
4. The method of claim 3, wherein adjusting includes: determining
if the filtered UERE estimate is greater than or less than a
predetermined UERE range value; multiplying at least one of the
HFOM or VFOM by one of two scale factors based on transmission
protocols, if the filtered UERE estimate is determined to be less
than the predetermined UERE range value; and dividing at least one
of the HFOM or VFOM by one of the two scale factors, if the
filtered UERE estimate is determined to be greater than the
predetermined UERE range value.
5. The method of claim 4, wherein the transmission protocols
include ARINC 743 and ARINC 743A.
6. The method of claim 5, wherein the two scale factors include an
HFOM scale factor between 28 and 29 and a VFOM scale factor between
9 and 10 and wherein range of the UERE is 4 to 33.
7. The method of claim 1, wherein the unit includes an Enhanced
Ground Proximity Warning System that uses the adjusted at least one
value to determine an aircraft's position.
8. An apparatus for automatically adjusting for data protocol
discrepancies, the apparatus comprising: a unit for receiving a
signal from a GPS receiver, wherein the signal is formatted
according to a transmission protocol, the unit comprising: a first
component for estimating User Equivalent Range Error (UERE) based
on the received signal and adjusting at least one value of the
received signal based on the estimated UERE and one or more
predefined scale factors; and a second component for using the
adjusted at least one value.
9. The apparatus of claim 8, wherein the at least one value
includes a Horizontal Figure of Merit (HFOM) and Vertical Figure of
Merit (VFOM).
10. The apparatus of claim 8, wherein the first component
comprises: a component for computing the estimate of UERE using a
Horizontal Figure of Merit (HFOM) value and a Horizontal Dilution
of Precision (HDOP) value; and a component for filtering the
estimated UERE.
11. The apparatus of claim 10, wherein the first component further
comprises: a component for determining if the filtered UERE
estimate is greater than or less than a predetermined UERE range
value; a component for multiplying at least one of HFOM or VFOM by
one of two scale factors, if the filtered UERE estimate is
determined less than the predetermined UERE range value; and a
component for dividing at least one of HFOM or VFOM by one of the
two scale factors, if the filtered UERE estimate is determined
greater than the predetermined UERE range value.
12. The apparatus of claim 11, wherein the transmission protocols
include ARINC 743 and ARINC 743A.
13. The apparatus of claim 12, wherein the two scale factors
include an HFOM scale factor between 28 and 29 and a VFOM scale
factor between 9 and 10 and wherein range of the UERE is 4 to
33.
14. The apparatus of claim 8, wherein the second component includes
an Enhanced Ground Proximity Warning System that determines an
aircraft's position based on the adjusted at least one value.
Description
BACKGROUND OF THE INVENTION
[0001] Global Positioning Systems (GPS) units transmit GPS data
using the Aeronautical Radio, Inc (ARINC) 743 or 743A protocols.
These protocols are nearly identical except for the scaling of the
Figure of Merit (FOM) terms. Currently, avionics system require the
GPS installation (unit) to specify which type of ARINC protocol is
used. However, if the GPS installation has been upgraded to use the
ARINC 743A protocol, but the GPS installation is still reporting
itself as using the ARINC 743 protocol, the outputted GPS data is
improperly scaled. Improperly scaled FOM data can adversely affect
avionic devices, such as an Enhanced Ground Proximity Warning
System (EGPWS).
[0002] Therefore, there is a need to easily and cheaply determine
the protocol type of GPS data.
BRIEF SUMMARY OF THE INVENTION
[0003] The present invention provides an apparatus and method for
automatically adjusting for data protocol discrepancies. The
apparatus includes a unit that receives a signal from GPS receiver.
The signal is formatted according to a transmission protocol. The
unit includes a first component that estimates User Equivalent
Range Error (UERE) based on the received signal and adjusts at
least one value of the received signal based on the estimated UERE
and one or more predefined scale factor and a second component that
uses the adjusted at least one value.
[0004] In one aspect of the invention, the at least one value
includes a Horizontal Figure of Merit (HFOM) and Vertical Figure of
Merit (VFOM).
[0005] In another aspect of the invention, the first component
includes a component for computing the estimate of UERE using a
HFOM value and a HDOP value and a component for filtering the
estimated UERE. The first component also includes a component for
determining if the filtered UERE estimate is greater than or less
than a range of UERE, a component for multiplying at least one of
HFOM or VFOM by one of two scale factors, if the filtered UERE
estimate is determined less than the UERE range, and a component
for dividing at least one of HFOM or VFOM by one of the two scale
factors, if the filtered UERE estimate is determined greater than
the UERE range.
[0006] In still another aspect of the invention, the transmission
protocols include ARINC 743 and ARINC 743A. The two scale factors
include an HFOM scale factor between 28 and 29 and a VFOM scale
factor between 9 and 10 and wherein the range of UERE is 4 to
33.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0007] The preferred and alternative embodiments of the present
invention are described in detail below with reference to the
following drawings.
[0008] FIG. 1 illustrates a block diagram of an example environment
and aircraft formed in accordance with an embodiment of the present
invention; and
[0009] FIGS. 2 and 3 illustrate flow diagrams of an example process
performed by the auto detector of FIG. 1 in accordance with an
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0010] FIG. 1 illustrates a block diagram of an example environment
18 formed in accordance with an embodiment of the present
invention. The environment 18 includes a plurality of satellites 22
and an aircraft 20 having a Global Positioning System (GPS)
receiver 28 and a Terrain Awareness Warning System, such as an
Enhanced Ground Proximity Warning System (EGPWS) 26 or another
system that uses GPS information received by the GPS receiver 28
from the plurality of satellites 22. In one embodiment, the EGPWS
26 includes an automatic adjustor 30.
[0011] The automatic adjustor 30 analyzes the data sent from the
GPS receiver 28 and scales certain GPS data if it determines there
is a discrepancy between the expected protocol from the GPS
receiver 28 and the actual protocol used to transmit the data. More
specifically, the auto adjustor 30 uses Figure of Merit (FOM)
information and Dilution of Precision (DOP) data for the Horizontal
channel to back compute User Equivalent Range Error (UERE). A
normal UERE should fall within the range of approximately 4 to 33
meters. If the EGPWS 26 is configured to receive GPS data according
to Aeronautical Radio, Inc (ARINC) 743 and the GPS receiver 28 is
sending according to ARINC 743A protocol or vice a versa, the
computed UERE is sufficiently outside a normal UERE range. The
automatic adjustor 30 then automatically adjusts the FOMs to the
correct value (i.e. equivalent to both systems using the same
protocol).
[0012] FIGS. 2 and 3 illustrate a flow diagram of an example
process 50 performed by the automatic adjustor 30 of FIG. 1, in
accordance with an embodiment of the invention. As shown in FIG. 2,
the process 50 begins at a block 52 whereby the GPS receiver 28
receives GPS signals from one or more of the plurality of GPS
satellites 22. At a block 54, the GPS receiver 28 processes the
received GPS signals and formats the processed information
according to either the ARINC 743 or 743A protocols. Next, at a
block 56 the adjustor 30 receives the GPS signals from the GPS
receiver 28. At a block 58, the auto adjustor 30 analyzes the sent
data and adjusts the sent data if it was determined during analysis
that a protocol discrepancy exists.
[0013] FIG. 3 shows a process 70 at block 58 from FIG. 2 for
analyzing and adjusting, if necessary, GPS data received from the
GPS receiver 28. First, at a decision block 74, the process 70
determines whether Horizontal FOM (HFOM) and Horizontal DOP (HDOP)
values are greater than 0. The process 70 is complete if the
results of the decision block 74 indicate that either the HFOM or
HDOP values are equal to or less than 0. However, if both the HFOM
and HDOP values are greater than 0, the process 70 continues to
block 76 where an estimated UERE is computed. The UERE estimate is
computed with Equation (1):
UERE = HFOM 2 ( HDOP ) ( 1 ) ##EQU00001##
[0014] At a block 78, the result of the computation performed at
block 76 is sent through a low pass filter. The filtered UERE is
used to compare to the normal limits.
[0015] The horizontal scale factor from 743 to 743A (K.sub.h) is 16
nm/1024 meters or approximately 28.856. The vertical scale factor
from 743 to 743A (K.sub.v) is 32768 ft/1024 m or approximately
9.727. At a decision block 80, if the filtered UERE is greater than
an upper limit (e.g. 115 meters (i.e. 4 m*K.sub.h)), a Rescale flag
is set to HIGH at a block 82 and the FOMs for vertical and
horizontal are divided by their respective scale factor K (K.sub.h,
K.sub.v) at block 90. In this situation, the FOMs are being
transmitted via the ARINC 743 protocol, but the EGPWS 26 interprets
the FOMs are being transmitted via the ARINC 743A protocol.
[0016] If the filtered UERE is less than the upper limit and at
decision block 86 is less than a lower limit (e.g. 1.5 meters (i.e.
33 m/K.sub.h)), the Rescale flag is set to LOW at block 88 and the
vertical FOM (VFOM) and HFOM are multiplied by their respective
scale factor K (K.sub.h, K.sub.v) at block 92. In this situation,
the FOMs are being transmitted via the ARINC 743A protocol, but the
EGPWS 26 interprets the FOMs are being transmitted via the ARINC
743 protocol. If the filtered UERE is within normal UERE limits,
the Rescale flag is set to NORMAL and the FOMs remain
unchanged--the protocol understood by the EGPWS 26 is the protocol
that is being used to send the data from the GPS receiver 28. The
resultant adjusted or unadjusted FOMs are used by the EGPWS 26 or
other avionics.
[0017] The values used at the decision blocks 80 and 86 may vary
depending upon desired results. Also, in one embodiment the low
pass filter is pre-charged, which is a standard operation on
filters. It involves setting the internal state to a specific
value.
[0018] While the preferred embodiment of the invention has been
illustrated and described, as noted above, many changes can be made
without departing from the spirit and scope of the invention.
Accordingly, the scope of the invention is not limited by the
disclosure of the preferred embodiment. Instead, the invention
should be determined entirely by reference to the claims that
follow.
* * * * *