Abstract: A phase detector for digital signals, such as television sync signals, provides a signed short path output of the phase difference between the signals. It features a means for determining which of the signals is leading and lagging, which means also provides the sign signal. A window signal is generated and clock pulses are counted during the duration of this signal. A register can provide an exact phase difference measurement or a coarse/fine output signal can be provided.

Abstract: A television standards converter uses a VTR. The capstan speed is that of the video signal recorded on the tape, however, the drum speed is that of the standard to which it is desired to convert. Thus the reproduced signal has the original line rate but the new field rate. A line rate converter converts the reproduced signal to the new line rate, the signal is now totally in the new standard.

Abstract: A digital sync separator has a separator for supplying composite sync from composite video. A counter counts clock pulses and is reset by the composite sync signals and one of its outputs. The separator can comprise a pair of controlled switches, one switch being a clamp, the other supplying a signal to a low pass filter and attenuator, and a comparator to compare the composite video with the attenuated signal.

Abstract: A group delay compensation circuit for a television transmitter comprises a signal source coupled to a series resonant circuit. A means is present for changing the resonant circuit Q without changing the amplitude of an output signal derived from the resonant circuit. A difference amplifier is coupled to the resonant circuit and to the signal source. The means can be a voltage divider and a variable resistor coupled to the divider. Changing the Q varies the group delay.

Abstract: A TV camera comprises a pair of CCD imagers subject to defects. Defect detection is done by comparing signals from the imagers, thus saving the expense of a defect location memory and also detecting more kinds of defects than one would detect by just comparing one signal to a fixed reference. As a result, CCD imagers with defects can be used thus increasing production yield of such imagers.

Abstract: A tape has Y and C components of a television signal recorded in different tracks. This can lead to mistiming and hence misregistration errors. To correct this a phase error signal is generated from the horizontal sync signals in each track and used to control variable delay lines for the Y and C to correct the misregistration. Separate delay lines for the I and Q components can also be used.

Abstract: Two or more CCD imagers, which have random defects are optically coupled to form a single image. The CCD's are in registry. Because of the random nature of the location of the defects, the defective photosensors of one imager are aligned with good photosensors of another. Memories keep track of which locations of which CCD are defective. The imagers are operated synchronously and the signals from good photosensor locations are summmed for improved signal-to-noise ratio. When a location is addressed at which one imager has a defective photosensor, the respective memory decouples it from the good photosensor of the other imager. The signal level is restored for that pixel by increasing the gain of a preamp by the correct amount. If the imagers are made from the same mask, they may have almost identically corresponding defective photosensors. Then one imager is mounted upside-down relative to the other and scanned backwards so the defects do not coincide.

Abstract: An adaptive error concealment system uses either a horizontal or vertical average as a replacement pixel for an erroneous pixel. The choice is dependent upon the amount of horizontal information in at least one adjacent horizontal line. This avoids errors if certain horizontal or vertical stripe patterns are present in the video signal.

Abstract: A high speed multiplier, such as for video signals features cascaded ROMs. Each ROM is divided into pages, and each page contains different multiplying coefficients. Different significant bits of a control signal are applied to each ROM to select a page for processing the video signal.

Abstract: A dropout compensator for time spread digital television signals uses either horizontal or vertical averaging to replace a dropped out sample. The choice of direction is made in accordance with whichever direction has the least amount of change around the missing sample or pixel. The circuitry can also be used for chroma inversion when stop or slow motion is to be transmitted or recorded.

Abstract: A recording system converts standard binary signals into new binary signals that have mostly zeroes occurring in words that are physically unrealizable. Thus when NRZ-I recording is used, long strings of zeroes (which have no transitions in them for easy detection) do not actually occur. Ones do have transitions in them for easy detection, and thus a long string of ones causes no detection problem. The physically unrealizable combinations occur due to the partial correlations of signals, such as Y, B-Y, and R-Y color signals.

Abstract: A video scrambling device requires that a key signal be periodically inserted into a subscribers box, e.g. once a month. The key signal is a function of both the box number and the time, and thus once received must be inserted relatively quickly, e.g. an hour or two. If it is not inserted quickly, a new key signal must be obtained. This makes it extremely difficult for a pirate to distribute a key signal to his customers in time for it to be effective. The scrambling method can be pseudorandom line inversion and also audio scrambling.

Abstract: A sampling PLL circuit features a frequency sweep caused by an offset voltage applied to an integrator to avoid false lock ups. At one end of the frequency range the polarity of the offset signal can be reversed. The error voltage can be sampled during a television vertical or horizontal blanking period. Once proper lock up is achieved, the offset signal can be removed.

Abstract: Color signal samples generated by CCD imagers used with a color stripe filter normally exhibit hue errors owing to cross-color components in the samples arising from misalignment of the color striped imager on the imager elements. These cross-color components are suppressed in the invention, by re-sampling the color signals.

Abstract: Output signals are derived from two portions of a CCD imager. The first output signal is derived from a drain diffusion in the form of a signal current and applied to an amplifier with poor high frequency S/N due to needed high frequency peaking. The second output signal is derived from a floating diffusion (or floating gate) through an on-chip MOSFET amplifier which has a poor low frequency S/N due to 1/f noise. The first and second output signals are filtered through complementary LPF and HPF respectively and then combined together.

Abstract: A sampled color video signal is recorded in component form in a plurality of channels. The form of the signal is chosen so that if only one channel is available due to dropouts upon playback, then at least approximate separation into color components is possible, and if all channels are available, then full color separation is possible. The form is also chosen to provide a dynamic range that fits the transmission channel.

Abstract: An encoding apparatus samples the luminance component of a video signal at a rate sufficient to avoid aliasing. Wide band chroma components are sampled at one half this rate so that aliasing occurs. A decoder determines the direction of least resolution of each sample of the luminance signal and averages the chroma signals in this direction for each sample to eliminate aliases.

Abstract: A television sync signal generator adapted for ready conversion among various television standards includes a memory in which information related to the amplitude of at least one component of a composite sync signal is stored at address locations each corresponding to at least one particular time in each recurrent television frame. A clock signal generator addresses the memory to sequentially read out the information so the sync signal can be reconstructed. For reducing the number of memory addresses required, each memory address contains information relating to the instantaneous resolution or clock rate. A sample rate controller is coupled to the memory for having the instantaneous clock address rate controlled in response to the contents of the memory.

Abstract: CCD devices, such as imagers, typically have built in MOSFET output amplifiers with a large amount of l/f noise. Instead of using the baseband video output signal, the present invention uses video signal sidebands centered about the C-register clock frequency or a harmonic thereof for improved S/N. An integrator and a gate are used to still further improve the S/N.

Abstract: A digital AM broadcast transmitter features a plurality of stages that are controlled by a digital signal representing an audio modulating signal. At least some of the stages are cascade coupled together using transformers. This reduces the need for high turns ratios and allows most or all transformers to be identical.