The present invention relates generally to CVFDR (Cockpit Voice Flight Data Recording
System) according to figure 1 with a method for audio data recording and storage in absence
of digital data. It is a signal feature of the invention that improved audio data acquisition and
retrieval is obtained on consistent basis for different sorties not carrying any digital data.
BACKGROUND OF THE INVENTION
The rotary wing light weight helicopter is required to maintain and provide historical
recording of certain flight parameters. The mandated flight data 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 flight data are recorded on a flight data recording system designed to withstand crash
environments. The FDR system typically employs an ARINC‐717 and ARINC‐429 digital bus
transmitter and receiver for communication with other aircraft subsystems. The current
generation FDRs generally consist of software running on main processor which first
initializes the Timers, WatchDog, different ports, digital bus transmitter and receiver,
Ethernet Port, RS232 Port and CPMM interface, then performs built in test for the system
and acquires digital data then audio data continuously while in record mode. 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.
FDR system that is capable of recording only voice data in absence of digital data would be
more advantageous.
SUMMARY OF PRESENT INVENTION
In accordance with one aspect of the present invention is to provide a cockpit voice flight
data recorder system that is capable of recording and storing voice data coming over cockpit
area microphone as per voice data format in absence of digital data.
In accordance with another aspect of the present invention is to provide a cockpit voice
flight data recorder system with improved audio data acquisition and retrieval function.
In accordance with yet another aspect of the present invention is to provide a cockpit voice
flight data recorder system which can form a dummy data frame with all words as 0x00 in
absence of digital data.
In accordance with yet another aspect of the present invention formatting and writing of
aircraft parameters and audio data to CPMM happens within 250 milliseconds.
In accordance with yet another aspect of the present invention it provides ability to record
and store the internal parameters like built in test error words results in absence of digital
data in the crash protected memory module.
In accordance with yet another aspect of the present invention the CVFDR repeats the
recording periodically as long as the system is in recording mode.
Briefly the present invention is a method of recording and storing audio data through
operational software which formats the acquired compressed audio into data frames
according to the Voice Data Format [Refer Figure‐ 4] and writes these data frames along with
the formatted A/c parameters to the CPMM.
The advantage of present invention is recording of audio data in absence of digital data
which shows the independency of audio module from the CPU module and also facilitates
the maintenance crew to diagnose the reason for not reception of digital data.
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 of the CVFDR.
Fig. 2 is a Flow Chart of operational software of previous FDRs
Fig. 3 is a Flow Chart of operational software of improved CVFDR
Fig. 4 is a Voice Data Format
DETAILED DESCRIPTION
The present invention provides a flight data recorder system that is capable of recording and
storing audio data in absence of digital data for a flight. This feature allows recording of audio
data instead of recording nothing in absence of digital data which ensures proper functioning
of audio module and its independency from the CPU module, with the recorded, formatted
and stored PBIT and CBIT error words in CPMM it helps in diagnosing the problem due to
which digital data was not available. This feature of CVFDR saves time of the maintenance
crew who used to record and download data again and again in case of not receiving any data
even with correct recording condition set.
With reference to figure 1 there is shown a block diagram for an improved FDR system
according to one embodiment of the invention. In essence the CVFDR system utilizes one or
more digital data buses for quick access and retrieval of flight data parameters. Specifically, a
digital communication bus and local area network bus are provided within the FDR system for
data access and storage capabilities herein described.
With reference to figure 2 the operational software running on main processor used to
initialize all the associated hardware modules, performs various built in tests on the associated
hardware modules in order to monitor the health of the system, then acquires formatted
aircraft parameters sent via the ARINC‐717 harvard Bi‐phase and ARINC‐429 interface,
acquires compressed audio data sent by the DSP processor via the shared RAM, it then
formats the acquired compressed audio data into data frames as per voice data record
formats (Ref figure 4) and stores these frames along with the previously formatted aircraft
parameters in the crash protected memory module. This stored data can be downloaded for
further analysis. The prerequisite condition for these FDRs to record audio data was correct
recording condition set and availability of digital data.
With reference to figure 3 the operational software running on main processor used to follow
the same steps as stated above in addition to the recording audio data in case of nonavailability
of digital data according to another aspect of the invention. As shown in the flow
chart if digital data is not available it will format the frame with dummy data comprising all
words as zero (0x00). Then the formatted audio data will be stored with these dummy data in
the crash protected memory module.
Another aspect of the invention is that the Built in Test results will be recorded and stored
along with audio data in absence of digital data. The analysis of Built in Test error words will
reveal what actually caused non‐availability of digital data, as error words contains different
bits corresponding to the health of different hardware modules.
According to one embodiment, disclosed is a flight data recording system having following
specification of the CPU module on which the operational software runs is as follows‐
Cache Memory : 4K data and 4K for instruction.
Flash memory : 2MB (Boot memory)
SDRAM : 16 MB
NvSRAM : 128 KB NvSRAM with RTC
Ethernet 10/100Mbps : 1 No.
High speed ARINC‐429 : 2‐Tx‐channels,4‐Rx‐Channel
Bi‐phase Data AR7171lines : AR717TX+/‐ and AR717RX+/‐
Serial Communication : 1Ch‐TxD, RxD
RS‐422 Communication : 1Ch‐ TX, RX, RTS, CTS
Flash programming : Through BDM port
Serial ports : One RS232
The specification of the Audio module on which the operational software for audio exits is as
follows‐
Number of Audio input Channel : 4 (Differential and Non‐isolated)
Nominal Audio input Amplitude : 400 mV RMS
Minimal Audio input Amplitude : 50 mV RMS
Max. Audio Input Amplitude : 550 mV RMS
Audio Input Frequency Range (+/‐ 3dB) : 300 Hz to 3400 Hz.
Input Impedance (line) : 5 KΩ
Wire Type : Twisted wire screened
Number of Audio Output Channel : 1 (Differential and non‐ isolated).
Shared memory (Dual Port SRAM) : 16 KB
Memory : Flash EPROM 2MB X 8‐bit
: SRAM 256K X 32‐bit
Audio CODEC : Four input / output channels
Serial Port : RS‐232 interface
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 CLIAMS:-
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 CVFDR (Cockpit Voice Data Recording System) for LUH (Light Utility Helicopter) comprising of Data retrieval Unit carrying CPU module and audio module and Control Unit intended to record 25 hours of aircraft data and 2 hours of audio data for each four channel is unique.

2. The operational software running on the CVFDR includes a module allowing storage of audio data even for those sorties in which aircraft data is missing because of digital communication bus interface failure or may be due to any other problem is novel.

3. The process of forming dummy frame with 0x00 in absence of acquired formatted aircraft data is monolithic.

4. The CVFDR according to claim 2, functions processor module along-with audio module for data processing purposes without any compatibility issues.

5. The CVFDR according to claim 2, runs a module on processor allowing storage of Built in test error words result even for those sorties in which aircraft data is not available because of some unwanted failure is first of its kind.

6. The CVFDR according to claim 2 provides improved audio data acquisition and retrieval function. ,TagSPECI:As per Annexure-II