1. Field of the Invention
The present invention relates generally to video recording equipment with playback capability. More specifically, the present invention relates to a digital format video cassette recorder with playback capabilities and a recording format which is compatible with electronic systems on board and aircraft.
2. Description of the Prior Art
Airborne video cassette recorders in use by the military are generally analog units which is a dated technology. Analog data may be lost and copied analog data is not as reliable as the data recorded on a cassette from which the copy is made.
Currently, the only digital format video cassette recorders in use are specialty recorders such as DCT (Discrete Cosine Transform) format recorders used in the Advanced Tactical Reconnaissance Airborne System. This type of digital video cassette recorder is very expensive, is not sized to fit in an aircraft cockpit and not easily adapted for use with the aircraft electronics and sensor systems such as an aircraft's FLIR (forward looking infrared) devices.
Additional problems associated with video cassette recorders currently in use on military aircraft include lack of time code capability, lack of machine control for multi-tape review, and image quality is often sub-standard.
Further, the quality of video cassette recordings is between 3 MHz and 4 MHz and is analog which overtime will degrade significantly when copied or archived. There is also an effort by the video recording industry to convert from an analog format to a digital format for recording video data and is expected that analog technology will be obsolete within the next three to five years.
Accordingly, there is a need for a digital video cassette recorder which is compact, lightweight, easily adapted for aircraft cockpit use and is fully compatable with the electronics on board the aircraft.
The present invention comprises a relatively simple in design, yet highly effective, compact, lightweight and low cost digital video cassette recorder for use in an aircraft to record aircraft flight and other data. The present invention is adapted for use on an aircraft to record video data in a digital format as opposed to an analog format.
Data to be recorded is provided by video sources on board the aircraft including the aircraft's FLIR system and other video sensors on board the aircraft. A frame sync card stabilizes the video signal and adds color burst to the video signal when the aircraft's FLIR system generates a video signal which is black and white. The video signal from frame sync card is supplied to a GPS to SMPTE converter which passes the video signal through the converter and also uses the video signal to encode time and date and TSPI (Time, and Space, Position Information) data onto a SMPTE (Society of Motion Picture and Television Engineers) time code for each frame of video data. The video signal and the SMPTE time code are then supplied to a digital video cassette recorder which records the data in an 8-bit digital format. When a digital format is used to record the video information, the video data will not degrade overtime when the data is backup data or when the data is archived.
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The frame sync device/card 14 receives a video signal from external video source 12, which processes the signal and adjust the timing of all incoming video signals to the NTSC (National Television System Committee) RS-170 color video standard format. The frame sync card 12 stabilizes the video signal and adds color burst to the video signal when necessary. For example, the aircraft's FLIR system generates a video signal which is black and white, which requires processing of the signal by the frame sync card 12 before supplying the signal to converter 16. This is necessary because the SMPTE (Society of Motion Picture and Television Engineers) time code does not operate correctly (timing is not correct for the SMPTE time code) when a video signal does not have a color burst in the signal.
At this time it should be noted that SMPTE time code is a digital signal whose ones and zeros assign a number to every frame of video representing hours minutes, seconds, frames and additional user specified information such as tape number. For example a time code number 01:12:59:16 represents a picture 1 hour, 12 minutes, 59 seconds and 16 frames into the tape.
The video signal from frame sync card 14 is supplied to GPS to SMPTE converter 16 which passes the video signal through converter 16 and also uses the video signal to time encode time and date data and TSPI (Time, and Space, Position Information) data onto a SMPTE time code for each frame of video data. Converter 16 also assigns a number and data bit to each frame of video data received by converter 16.
Converter 16 receives TSPI data from an external GPS or INS (Inertial Navigation System) unit 22. For example unit 22 may be a commercially available, high accuracy GPS Time and Space Position Information System of the type manufactured by NAVSYS Corporation of Colorado Springs, Colo. has which is designed for military and civilian aircraft use and provides reliable TSPI data.
There are a pair of signal lines/cables 24 and 26 which connect the GPS to SMPTE converter to Digital VCR 18. Signal line 24 sends the video signal to a composite video input for Digital VCR 18. Signal line 26 sends the SMPTE time code with the user bit data for each frame data to the TC/UB (User Bit) input for Digital VCR 18. The actual time may be written into the user bit area.
The power supply 20 connected to digital VCR 18 is a MIL-SPEC-704D 28 to 12 volt step down power supply module which supplies power to the Digital VCR 18 and its internal components. The power supply 20 also has an additional 12 volt output for a GPS receiver.
The digital video cassette recorder used in the preferred embodiment is a Sony model DSR-50 digital cassette recorder which employs a DVCAM tape format which is a digital format. The Sony DVCAM format uses an 8-bit digital component recording format with a 5:1 compression ratio and a sampling rate of 4:1:1 for the NTSC (National Television System Committee) standard. The recorder is capable of recording and playing back DV format tapes. The recorder is also capable of reproducing video at a 6.3 MHz bandwidth which allows for reproduction of video at up to 550 lines of horizontal resolution. The DVCAM format allows for recording of up to 184 minutes with a standard size tape cassette and a 40 minute recording time with a mini-size tape cassette. Other features of the Sony DSR-50 digital cassette recorder include four 32 KHz/12 bit audio tracks which allow a user to record various types of audio including radio, sonar, etc. along with 12 bit audio data. When a digital format is used to record the video information, the video data will not degrade overtime when the data is backup data or when the data is archived.
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Converter 16 provides SMPTE Time code (block 34 of
Recording GPS TSPI data on digital tape cassettes allows military and civilian aircraft pilots to review position information during playback. The GPS to SMPTE converter 16 translates NMEA ASCII Serial GPS data into user bit data that is inserted into the SMPTE time code on the digital video tape.
Sony's DVCAM format is an in expensive format (under $10,000) which allows for a continuous upgrade of information recorded in the user bit portion of the SMPTE time code. User bit playback capability offers several advantages including the display of GPS TSPI data at various speeds of playback and display of the TSPI data during a still frame. The DVCAM format also allows digital cassette tapes to be labeled with information such as the pilot's name and aircraft number on a data code track that be displayed at a later date on a playback VCR.
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From the foregoing, it may readily be seen that the present invention comprises a new unique and exceedingly useful digital airborne video cassette recorder and player for recording aircraft video information which constitutes a considerable improvement over the known prior art. Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims that the invention may be practiced otherwise than specifically described.