Abstract: A method and apparatus for producing special motion effects such as slow or fast motion, still frame and other effects from video magnetic tape is disclosed which is particularly applicable to helical wrap recording and reproducing apparatus. The apparatus employs a transducing head that is mounted on a revolving scanning drum, with the head being movable in a line generally transverse to the recorded track. The present invention utilizes the transverse positioning of the head to accurately follow a track during reproducing or playback and, at the completion of the track, to properly position or set the head in position to either play the next adjacent successive track, replay the same track, or play yet another track so that special motion effects can be achieved without experiencing picture breakup or unwanted noise.

Abstract: A capstan servo for moving video tape with variable speed during playback controls the tape speed according to time period inputs. The input specifies the number of seconds per hour of program length, for example, that a segment of recorded video information is to be expanded or compressed compared relative to its normal real time playback length. The speed of tape transport during playback is varied by locking the reproduced control track vertical sync signal to a synthesized time adjustable reference signal.

Abstract: A synthetic control track signal is provided for a magnetic video tape recording and/or reproducing machine having a motor driven capstan and capstan servo which controls the speed of the tape during recording and reproducing. The synthetic signal enables the capstan servo to operate when the control track signal has not been recorded or has been improperly recorded. The synthetic signal is generated from vertical synchronization information extracted from the video information extracted signal.

Abstract: A method and apparatus is disclosed for recording and reproducing color television signals on a magnetic media such as magnetic tape, wherein the signals recorded on and reproduced from the magnetic media are in a digital domain. The analog color television signal is converted to digital signals in a manner whereby the horizontal blanking interval is compressed and digital synchronizing information is inserted in the compressed horizontal blanking interval for every line. Upon reproduction, the digital synchronizing information is extracted from the reproduced information and is provided to servo circuits for controlling the relative transport of the magnetic tape and operatively associated magnetic heads to effect synchronous reproduction of the recorded information relative to a reference signal.

Abstract: An improved microprocessor controlled scanning drum servo adapted for use in a recording and reproducing apparatus is disclosed. The scanner servo includes a velocity loop as well as a position loop, and by virtue of the fact that it is controlled by a microprocessor in a unique way, has extraordinary accuracy because the resolving power of the servo is essentially that of the microprocessor itself. The interrupts to the microprocessor occur in sequence with a first interrupt causing the microprocessor to cease current activity, store all required information in a stack register and thereafter wait until a subsequent interrupt occurs which enables it to immediately act to perform control operations with respect to the scanner servo. This enables the velocity loop to perform the vast majority of the work required by the servo and as a result of this, the phase closed servo loop operates as a positioning loop in the true sense.

Abstract: A method and apparatus are disclosed for performing a reduction of the data rate of a data stream for transmission through a transmission channel or recording and for subsequently reconstructing the original data stream upon receipt or during reproducing. The method and apparatus utilizes a combination of two processes, one of which eliminates or drops digital samples from the data stream to reduce the data rate for transmission and which subsequently reconstructs the original data stream using the unaltered and recovered digital samples to generate an interpolated value for each of the samples that had been dropped. The second process utilizes differential pulse code modulation for reducing the number of data bits per sample before sending the data stream through the transmission channel and for subsequently restoring the data to its original multi-bit form.

Abstract: A method and apparatus is disclosed for recording and reproducing color television signals on a magnetic media such as magnetic tape, wherein the signals recorded on and reproduced from the magnetic media are in a digital domain. The apparatus utilizes a rotating head wheel having a plurality of transducing heads spaced around its circumference which operate to record and reproduce the digital data transmitted through two separate channels at a very high data rate. The analog color television signal is converted to digital signals in a manner whereby the horizontal blanking interval is compressed and digital synchronizing information is inserted in the compressed horizontal blanking interval for every line. The portion of the real time horizontal blanking interval for which recording is not performed enables time base correction to be accomplished on an individual line by line basis.

Abstract: Apparatus is disclosed for acquiring and maintaining a generally continuous clock signal from a very high frequency encoded data stream of the type which is self-clocking and has logic state transitions occurring at two locations within each bit cell of the data stream. The apparatus is particularly useful in decoding apparatus, such as may be used in a magnetic recording and reproducing system. The apparatus effectively generates the clock signal from the encoded data stream and reclocks the data stream utilizing the generated clock signal to accurately position the logic signal transitions within the bit cells and thereby assure accurate decoding of the data. The apparatus processes two simultaneously transmitted synchronous data streams, and has the capability that permits the generated clock signal from one data stream processed in one channel to be used to maintain synchronization of the other processing channel notwithstanding a loss therefrom of the data stream for short periods of time.

Abstract: A method and apparatus is disclosed for obtaining second order velocity error correction signals for use in a time base corrector that removes instabilities in a video information signal reproduced from a magnetic medium. The apparatus utilizes the phase of the color burst component of the video information signal from successive horizontal lines to determine the change in velocity error. The change in the phase of the burst components of successive horizontal lines is first used to generate a first order or straight line approximation of the velocity error, and the difference between successive changes in burst phase, from which two successive first order error approximations are generated, is used to determine the approximate rate of change of velocity error.

Abstract: A method and apparatus for detecting errors in the accuracy of multi-bit data words, i.e., a parity method and apparatus, is disclosed. The invention is intended for use in determining the accuracy of multi-bit data words that are being transmitted through a communication channel or are being recorded and reproduced using magnetic recording or other technique.

Abstract: In an apparatus for automatically maintaining a transducing head assembly on the proper track, which is particularly adapted for a helical scan recording and/or reproducing apparatus capable of providing special motion effects, an automatically compensated movable head servo is disclosed. The apparatus is of the type which utilizes transverse positioning of the transducing head assembly to accurately follow a track during reproducing and, at the completion of the reproduction from the track, to properly position the head in position to either reproduce the next adjacent successive track, reproduce the same track or reproduce another track so that the appropriate special motion effect is achieved. Proper tracking is maintained by applying a small oscillatory motion to the head to cause it to vibrate laterally of the track, examining the resulting modulation of the reproduced signal's envelope to generate a tracking error correction signal and applying the error correction signal to the head assembly.

Abstract: Apparatus is disclosed for providing error compensation for a digital video information signal and is particularly adapted for use with a PAL format video information signal. The apparatus takes advantage of sampling being done in a precise manner, i.e., at a rate of four times the chrominance subcarrier frequency of the PAL information signal, and alternately along the U and V vector axes. The apparatus generates a substitute value for a defective sample that is the average of selected samples which are in close proximity to and which are of the same type as the defective sample. More particularly, replacement samples taken along the U vector axis (U samples) are generated by averaging the nearest in proximity U samples and the replacement V samples are obtained by averaging the nearest in proximity V samples. Switching means appropriately substitute the generated values for the defective values so that V samples replace V defective samples and U samples replace defective U samples.

Abstract: Apparatus is disclosed for providing compensation for missing, incorrect or otherwise defective data in a data stream preferably comprised of video information. The apparatus is particularly useful in a magnetic recording and reproducing system for digital video data signals. The apparatus effectively stores the digital video data that occurred 262 video lines prior to the current data at the input and continuously updates, (i.e., stores in place of) the stored data with current data unless defects occur in the current data, in which case the defective current data is not stored. The data from the store is inserted in the video data streams when the drop-outs or parity information associated with the data stream indicates that the current data is defective.

Abstract: A method of operating a signal recording and reproducing apparatus is disclosed whereby generally continuously and noise-free transfers of signal information are obtained while reproducing the information from a magnetic tape being transported at a changing speed. The apparatus is of the type which utilizes transverse positioning of the transducing head to accurately follow a track during reproducing. While the tape is transported at speeds other than the normal record and reproduce speed, transport derived signals are employed to control the tape transport servo. When the normal speed is attained, the reproduced signal is detected to determine whether synchronous reproduction conditions have been achieved. If synchronous reproduction conditions are not achieved, the transducing head is moved to a new track to effect synchronous reproduction of the signal information.

Abstract: A method and apparatus is disclosed for controlling the sampling of a composite analog color video signal so that the analog signal is sampled at precise locations relative to the phase of the color subcarrier of the color video signal in the absence of modulation. The invention thereby enables a digitized signal having a constant phase relationship relative to the unmodulated subcarrier phase to be provided which can be advantageously used in magnetic recording and reproducing apparatus. Since the constancy of the location of the samples relative to the phase of the color burst is maintained prior to recording, there is no phase error that would pose a problem during reproducing of the signal.