摘要:
An apparatus for the tape recording of a video signal, which is a signal of a bandwidth extending up to a prescribed maximum frequency, processes this signal to generate a folded-spectrum signal. The video signal is digitized and supplied to a digital band-splitting filter (90,91,92) with a cross-over frequency at one-half said prescribed maximum frequency, for separating the digitized video signal into samples of a lower-frequency-band component and into samples of a higher-frequency-band component. A balanced modulator (98,99,100) is connected for modulating a folding carrier wave of the prescribed maximum frequency. The modulation is done in accordance with the higher-frequency-band component to generate a balanced modulation signal, which is linearly combined with the lower-frequency-band component to generate the folded-spectrum video signal. Preferably, the sampling rate of the digitized video signal is exactly the Nyquist rate of the prescribed maximum frequency, thereby reducing the balanced modulation of a suitably phased folding carrier wave to multiplication of successive samples of the modulating signal alternately by plus one and by minus one.
摘要:
In a video signal processing apparatus suitable for use with a VCR of the VHS PAL system or NTSC 8 mm system, an output signal of a voltage-controlled oscillator (VCO) (31) is frequency-divided to generate a four-phase signal including four kinds of signals having a phase different by 90° from each other. The VCO has a free-running frequency substantially equal to or integer multiple of, a sum of a television color subcarrier frequency f SC and a horizontal synchronizing frequency f H multiplied by 40.125 or 47.25. Eight or four kinds of signals having the color subcarrier frequency f SC and a phase different by π/4 or π/2 from each other are generated using a crystal oscillator (30) and phase shifter (39). The eight or four kinds of signals are selected by a selector (40) in a predetermined order at each one period of the horizontal synchronizing signal f H , the sequentially selected eight or four kinds of signals each having a phase shifted by π/4 or π/2 from the previously selected relevant one. The selected signal and the corresponding four-phase signal are inputted to a delayed flip-flop (D-FF) (35) which in turn generates a difference or subtraction result between the two inputted signals. This subtraction signal is frequency-divided to the horizontal synchronizing frequency f H . The phase of the obtained frequency-divided signal is compared with the phase of the horizontal synchronizing frequency f H by a phase comparator (37). Using the phase difference therebetween, a control signal for controlling the VCO is generated. An output of the VCO is frequency-divided to generate the carrier frequency used for frequency conversion without generating unnecessary harmonics.
摘要:
Eine Vorrichtung zum Aufzeichnen von FM-Signalen in Schrägspuren eines Video-Magnetbandes weist einen zwischen FM-Modulator und Schreibkopfanordnung geschalteten Phasenschieber auf, der das FM-Signal vom FM-Modulator einer Phasenverschiebung unterzieht) für die folgendesgilt: - für eine beliebige Zeile n einer beliebigen Spur m ist die Phasenverschiebung eine beliebig festgelegte erste Phasenverschiebung P1, - für die Zeile n+1 derselben Spur m ist die Phasenverschiebung eine beliebig festgelegte zweite Phasenverschiebung P2, - für die in der folgenden Spur m+1 unter der Zeile n liegende Zeile ist die Phasenverschiebung eine beliebig festgelegte dritte Phasenverschiebung P3, - und für die in der folgenden Spur m+1 unter der Zeile n+1 liegende Zeile weist eine vierte Phasenverschiebung P4 einen durch die anderen drei Phasenverschiebungen so vorbestimmten Wert auf, daß die Differenz D zwischen der Differenz D1 der vierten und der zweiten Phasenverschiebung (D1 = P4 - P2) und der Differenz D2 der dritten und der ersten Phasenverschiebung (D2 = P3 - P1) 180° beträgt (D = D1 - D2 = 180°) beträgt. Durch einen derart ausgestalteten Phasenschieber wird erreicht) daß eine übersprechstörung, die in einer Zeile n zu einer Aufhellung gegenüber einer Originalhelligkeit führt, in der Folgezeile zu einer Abdunklung gleicher Größe führt. Diese Abweichungen von Zeile zu Zeile werden vom Auge gemittelt, falls die übersprechstörung nicht zu groß ist. Um auch bei starken Übersprechstörungen gute Bilder zu erzielen, wird vorzugsweise eine Vorrichtung verwendet, die die Hell- und Dunkelabweichungen mittelt, wie sie von Zeile zu Zeile auftreten, wenn die Aufzeichnung mit Hilfe der erfindungsgemäßen Aufzeichnungsvorrichtung erfolgte.
摘要:
A magnetic tape recording/reproducing apparatus for recording video signals on a magnetic tape without providing a guard band between each two adjacent signal tracks. The apparatus comprises a first switching circuit (4) for exchanging 2-channel component signals every nH period to obtain two combined signals each composed of the 2-channel signals which alternate every nH period, two modulators (11,12) for modulating the two combined signals, a head section (14) having two pairs of rotary magnetic heads for recording the modulated signals on the magnetic tape so that each two adjacent blocks contain a same channel component signal and for reproducing the recorded signals from the magnetic tape, two demodulators (36,37) for demodulating the reproduced signals, and a second switching circuit (40) for exchanging the demodulated signals every nH to obtain the 2-channel component signals. With this arrangement, the recording density is remarkably increased and the cross talk interference hardly occur.
摘要:
@ A carrier chrominance signal recording apparatus comprises a first circuit (12, 14) for sampling a carrier chrominance signal at a sampling frequency which is four times a chrominance subcarrier frequency, and then quantizing the sampled signal so as to produce a first digital color signal, a second circuit (15) for subjecting the first digital color signal to a phase shift process so as to produce a second digital color signal related to a carrier chrominance signal in which the phase of a chrominance subcarrier is equivalently and successively shifted by approximately 90° in a predetermined direction for every one horizontal scanning period, a third circuit (16, 17) for converting the output second digital color signal of the second circuit into a frequency converted digital color signal which is in a low-frequency range, a circuit (19) for obtaining an analog frequency converted carrier chrominance signal by subjecting the frequency converted digital color signal to a digital-to-analog conversion, and a circuit (21, 22) for recording the analog frequency converted carrier chrominance signal on a recording medium (23). A reproducing apparatus reproduces the signals recorded on the recording medium by the above recording apparatus.
摘要:
A chrominance signal processing circuit of VTR comprises a first frequency converting circuit (3) for converting a frequency of a chrominance signal in a video signal. The frequency converting circuit multiplies an inputted chrominance signal and a four-phase signal from a phase shift circuit (29). On the other hand, a second frequency converting circuit (17) generates a signal of 4 (f SC ± 40f H ) by multiplying an oscillating output of 4f SC of a first oscillation circuit and an oscillating output of 160f H which is obtained by dividing into 1/2 a frequency of an output of 320f H of VCO (26), and only a signal of 4 (f SC + 40f H ) is extracted by BPF (28) to be applied to the phase shift circuit (29). The phase shift circuit (29) divides a frequency of the signal into 1/4 and shifts the resulting signal by 90° every one horizontal period. Since an input to a phase shift circuit (29) is 4 (f SC + 40f H ), a highly precise phase shift circuit can be used.
摘要:
Die Aufgabe besteht darin, bei einem Videorecorder mit Standard- und Langzeitbetrieb das Übersprechen insbesondere für die Farbsignale zu verringern. Dies wird dadurch erreicht, daß die Wiedergabe bei Standardbetrieb mit den an sich für Langzeitbetrieb vorgesehenen Videoköpfen (K2) erfolgt. Insbesondere für Videorecorder mit wahlweisem Langzeitbetrieb nach dem VHS-System