FIELD OF THE INVENTION
The present invention relates generally to CPRU (Critical Parameter Recorder Unit) with
parallel acquisition of digital data on ARINC‐717 and ARINC‐429 interface ports along with
audio data. The invention facilitates parallel recording of digital data on two buses,
formatting and storing them in the fixed frame format with configurable recording rate
256/512/1024 words per second and allowing retrieval of these stored data from crash
protected memory through data downloading equipment.
BACKGROUND OF THE INVENTION
The critical flight parameters are derived from continuous recording during operational flight
of an aircraft and include a minimum number of functional parameters considered essential
for reconstructing the aircraft flight profile in post‐ accident investigation proceedings.
The recorder unit typically employs one digital bus transmitter and receiver for
communication with other aircraft subsystems. The current generation FDRs generally
consist of computer program running on main processor which first initializes all the
associated hardware modules, then performs various Built In Tests on the associated
hardware modules, in order to monitor the health of the various sub units of the system and
acquires formatted aircraft parameters sent via the ARINC 717 Harvard Bi‐phase interface
digital data, acquires compressed audio data sent by the Digital Signal Processor via the
shared memory. The same data is then formatted as per the defined data and voice frame
format and stored in CPMM. This stored data can be downloaded for further analysis of
parameters.
Flight Data Recorder System that has increased as well as fast acquiring and storing capacity
of critical digital data would be more advantageous.
SUMMARY OF PRESENT INVENTION
In accordance with one aspect of the present invention is to provide a critical parameter
recorder system that acquires digital data on two buses (ARINC‐717 and ARINC‐429) and
provides fast formatting and storing of these parameters on crash protected environment
for safe retrieval of thee critical parameters after crash.
In accordance with yet another aspect of the present invention, the desired functionality has
been realized by computer program residing in the CPRU and is executed by the main
processor ‐ PowerPC.
Annexure‐II
According to one embodiment, the parameter acquisition and storing process consists of
following steps‐
 Initialization of all the associated hardware modules,
 Performing various Built In Tests on the associated hardware modules, in order to monitor
the health of the various sub units of the system
 Acquisition of formatted aircraft parameters sent by the aircraft subsystems via the ARINC
717 Harvard Bi‐phase interface and ARINC‐429 interface.
 The acquired ARINC‐429 parameters will be placed at the specified location in the data
frame of 512 words as described by the ARINC‐717 protocol.
 Acquisition of compressed audio data sent by the ADSP21060 via the DPRAM.
 The Fault Indication report the status of the hardware tested during the different BITs.
 Formatting of acquired compressed audio data into data frames as per the Voice Data
Records format (Ref. figure‐4) and storing these frames along with the previously
formatted aircraft parameters in the crash protected memory module (CPMM).
 Downloading the flight and audio data stored in the CPMM to the Ground support
equipment.
 Performing Initiated Built in test on command from Ground Support Equipment/ Test
Equipment and also one discrete signal assertion from control unit or Glass Cockpit
Computer.
 Uploading the application software (Computer Program) from the Personal Computer
Based Memory Programmer/ Test Equipment to the FLASH memory.
In accordance with yet another aspect of the present invention, format and writing of
aircraft parameters and audio data to CPMM happens within 250 milliseconds. It also stores
the internal parameters like built in test error words in the CPMM.
In accordance with yet another aspect of the present invention, this capability shall be
repeated periodically as long as the system is in recording mode.
In accordance with yet another aspect of the present invention, the CPRU will record and
store ARINC‐429 parameters even in absence of ARINC‐717 parameters.
Annexure‐II
In accordance with yet another aspect of the present invention, the CPRU will record and
store ARINC‐429 parameters by encoding them in 12 bit words encoded in frames.
The advantage of present invention is increased parameter recording and storing capability
of CPRU, which facilitates the investigation crew post‐accident investigation. As more critical
parameters were stored which on retrieval helps to diagnose the problem.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the present invention will become more apparent and
descriptive in the description when considered together with figures/flow charts presented:
Fig. 1 is a Block Diagram ofthe CPRU.
Fig. 3is a Flow Chart of computer program of CPRU.
Fig. 4 is a Voice Data Format
DETAILED DESCRIPTION
With reference to figure 1 there is shown a block diagram for CPRU system according to one
embodiment of the invention. In essence the CPRU system utilizes one or more digital data
buses for quick access and retrieval of flight critical data parameters. Specifically, a digital
communication bus and local area network bus are provided within the CPRU system for data
access and storage capabilities herein described.
The present invention provides a critical parameter recorder unit that is capable of recording
and storing digital data on ARINC‐717 and ARINC‐429 buses along with audio data. CPRU will
operate in different modes of operation.
1. Recording mode.
2. S/w download mode.
3. Data download mode.
4. Calibration and test mode
These modes are described below‐
1) Record Mode‐
This mode shows whether CPRU is recording or not recording.
Annexure‐II
2) S/W Download Mode‐
In this mode, Application S/w (Computer Program) will be downloaded to processor card
flash memory using RS‐232 line.
3) Calibration and Test Mode‐
The function of this mode is to perform IBIT. Test Equipment is used to provide test function
and stimulus in order to check the functionality of CPRU.
4) Data Download Mode‐
In this mode data stored in CPMM of CPRU will be downloaded to ground support
equipment through Ethernet 10/100 Mbps.
With reference to figure 2 the application software (computer program) running on main
processor performs following functions in a sequence‐
1) Initialization ‐ It initializes the resource hardware, determines the reset and mode status of
the unit and maintains redundant sortie tablein CPMM for retrieval of Sortie table in case of
sortie table corruption in NVRAM. The latest sortie information will be made available.
2) Power On Built‐In‐Test‐ It performs tests on various hardware modules. This BIT is
associated with the power‐on event.
3) Continuous Built‐In‐Test‐It continually performs tests on hardware modules, in the record
mode, without interfering with the process of recording.
4) Initiated Built‐In‐Test‐It performs tests on hardware modules, on receiving command from
the user. This BIT is a part of the Maintenance activities.
5) Fault Indication‐It obtains the audio Error word and merges the obtained audio Error word
with the main processor error word of the currently completed BIT then sends FAULT
indication signals (discrete) to the control unit after the completion of each BIT.
6) Acquisition of Formatted A/C parameters‐It acquires the formatted aircraft parameters sent
via the ARINC 717 and ARINC 429 interfaces while in record mode.
7) Acquisition of compressed audio‐It acquires the compressed audio data while in record
mode.
8) Format and write to CPMM‐It stores the acquired formatted aircraft parameters in the
CPMM while in record mode then formats the acquired compressed audio in Voice Data
Records Format (Ref figure 3) and store them in the CPMM along with CBIT and PBIT error
words in the CPMM.
9) Data Download‐It downloads the entire content of the CPMM (aircraft parameters and
audio data) or a selected portion corresponding to a valid Sortie number entry by the user
after establishing communication with the ground support equipment. Essentially in
accordance to the request issued by the user the CPMM data milked out.
10) Software Upload‐ It uploads the application software (computer program) to defined
locations of the FLASH memory (of CPRU) after establishing communication with the
Annexure‐II
Personal Computer Based Memory Programmer. This gets executed in software upload
mode.
11) Calibration and Test‐ It establishes communication with the ground support equipment or
Test Equipment via an Ethernet interface in the Calibrate and Test mode and performs IBIT
on receiving command for the same.
12) Send data for Telemetry‐It sends the formatted Aircraft data through the Ethernet port for
telemetry.
While the invention has been described with respect to specific preferred embodiments,
variations and modifications will become apparent to those skilled in the art upon reference
to this specification. It is therefore intended that the appended claims be interpreted as
broadly as possible in view of prior art to include all such variations and modification.

WE CLAIMS:-
Accordingly, the description of the present invention is to be considered as illustrative only and is for the purpose of teaching those skilled in the art of the best mode of carrying out the invention. The details may be varied substantially without departing from the spirit of the invention, and exclusive use of all modifications which are within the scope of the appended claims is reserved.I Claim

1. The CPRU (Critical Parameter Recording System) comprising of recording unit carrying CPU module (POWER PC processor) and audio module (DSP processor) and Control Unit intended to record 25 hours of aircraft data on two digital buses and 2 hours of audio data for each four channel is unique.

2. The application software (computer program) running on the CPRU according to claim 1 includes a module (small part of program) allowing recording and storage of ARINC-429 data along with ARINC-717 data and audio data is novel.

3. The CPRU acquires ARINC-429 digital bus data even in absence of ARINC-717 data.

4. The non-transitory computer readable medium having embodied thereon a computer program configured to cause the processor to perform the desired function as per claim 2.

5. The application software (computer program) runs on CPRU POWER PC according to claim 2 without any compatibility issues.

6. The CPRU according to claim 2 acquires digital data on both ARINC-717 and ARINC-429 interfaces simultaneously.

7. The non-transitory computer readable medium having embodied thereon a computer program configured to cause the processor to perform the desired function as per claim 3.

8. The CPRU stores the data which is unambiguous, continuously updated per second in CPMM. ,TagSPECI:As per Annexure-II