JPS58147288A - Differential encoding system - Google Patents

Abstract

PURPOSE:To use a low speed differential encoding circuit, by differentially encoding a color signal A/D-converted by a frequency having n-times the subcarrier frequency at every (n-1) sets of the said color signal. CONSTITUTION:The color signal is sampled with a frequency n.fsc (in this case, n=3) having n-times the subcarrier frequency fsc of the said color signal and converted into a digital signal at an A/D conversion circuit 1. This signal is converted into a parallel signal at a series/ parallel conversion circuit 2. This parallel signal is inputted to the 1st, the 2nd, and the 3rd differential encoding circuits 3, 4 and 5 corresponding to the combination for differential operation. The signal differential-encoded and outputted sequentially are outputted to a transmission line 10 via a P/S conversion circuit 8 and a transmission line encoder 9.

Description

[Detailed description of the invention] (1) Technical field of the invention Regarding the encoding method.

(bJ iE US technology and problems When transmitting a weak signal with band compression to y-v!, the color vlkiIl! signal (hereinafter referred to as color signal) is transmitted at a frequency that is more than twice that of the main carrier. The color signal is sampled and A/D converted, and the A/D converted color signal is differentially encoded to perform band compression of the power 2 signal.

However, when the color signal has a bird's resolution l1iIiJX, the color signal is not a wideband television signal, and if the band compression of such a wideband television signal is performed using a conventional differential encoding circuit, the sampling frequency will be high. 9. It becomes technically difficult to calculate the difference between each of the force 2-signals that match each other.

(C) Object of the Invention In order to solve the above-mentioned problems, the present invention performs A/D conversion at the nXfcO frequency of the subcarrier fc and performs differential encoding on every (n-1) color signal. The purpose of this study is to provide a new differential encoding method.

(dJ Structure of the Invention For this purpose, the present invention has a means for sampling and A/D converting the force 2-image signal at a frequency n times the subcarrier frequency of the force 2-image signal, It has a means for differentially encoding every (n-1) A/D-converted color video signal, and converts the armpit differentially encoded color video signal into (
This is achieved by decoding every n-1) pieces.

- Embodiments of the Invention The present invention will be described below with reference to the drawings. Figure 1 shows the arrangement of digital color signals in a device used in the differential encoding method according to the present invention. The sampling frequency is 69 with a frequency nXfsc (n: integer) that is twice the carrier frequency facon, and the tempering frequency fs
Digital signal when color signal is A/D converted with c
Showing the signal (hereinafter referred to as digital signal)・#11Figure ia
) indicates the relationship to be noted when performing a differential calculation on the digital signal using H-a 3. In Figure (a), the difference between the signal ``■'' and the signal ``■'' is sequentially calculated by a difference calculation circuit.

FIG. 1(b) shows the case of 0n-5. In FIG. 1(b), the difference between the ■ signal and the ■ signal is calculated, and the difference between the ■ signal and the ■ signal is calculated.

or 115 cycles, and each can be converted into a differential signal. The above difference calculation is performed as follows.

That is, if a difference calculation is performed on every (n-1) digital signal, the difference calculation will be performed on the color signals divided into 1/n groups. In this way, the calculation of the differential encoding circuit can be facilitated.

For this purpose, by converting the color signal in the form of a serial signal into n columns of parallel signals and performing a difference calculation between the parallel signals, it is possible to perform a difference calculation for every n color signals. Based on the above principle, the embodiment shown in FIG. 2 will be described. In the same figure, the subcarrier frequency f of the color signal
Frequency n・fsc, which is n times ac (n-3 as an example)
That is, the force 2 signal is sampled by 3 fac and converted into a digital signal by the A/D conversion circuit 1. The digital signals are arranged as shown in No. 111(a). When this signal is converted into a parallel signal by a serial/parallel conversion circuit (hereinafter referred to as an S/P conversion circuit) 2, an arrangement as shown in FIG. 3 is obtained.

This parallel signal (■, ■, @), (■, ■, ■), (■■
, ■)・-・・・・・・・・・・・・The first corresponding combination of ■ and ■, ■ and ■, and ■ and ■. Second. Third
Differential encoding circuit 3. 4. The subtracter 6 calculates the difference, and the quantizer 7 quantizes and shapes the band compressed signal ■r. The quantization characteristics of the quantization circuit 3 will be described later in FIG. 6. The band compressed signal is inputted to a parallel-to-serial conversion circuit (hereinafter referred to as a P/S conversion circuit) 8, and outputted to a transmission line 10 via a transmission line code 11I9.

Further, a part of the band compressed signal ``■'' is added to the value of the previous signal in the adder 8611, delayed by one signal interval in the delayer 13, and inputted to the inverter 6 and the adder ill.

Next, every third parallel signal ■ is input to the subtracter 6, and a difference operation is performed with the signal ■′ held in the delay device 12, and a difference signal ■−■I is output, and the difference signal ■−■ (2) I is quantized by the quantization circuit 7 as shown in FIG.

Thereafter, differential calculations are sequentially performed with every third signal, and the signal is output as a band compression signal from the quantization circuit 7, passes through the P/S conversion circuit 8, the transmission line encoder 9, and then goes to the transmission line 10 on the receiving side. transmitted.

Next, the difference calculations for the respective sets of parallel signals ■ and ■ and ■ and ■ are performed in the second and #! 3 differential encoding circuits 4 and 5, namely, subtracter 13 - quantization circuit 14 - adder 15 - delay unit 16 and subtractor 17 - ft childization circuit 18 - adder 19 - delay unit 2
0, differential encoding is performed in the same manner as in the first differential encoding (b) path 3, and the respective doji conversion circuits 15, 16 and 4
The signals are sequentially output as differentially encoded signals as shown in the figure. The output is sent to the transmission line 1 via the &$ conversion circuit 8 and the transmission line encoder 9.
0 and transmitted to the receiving terminal station 21.

Figure 5 shows the addition of the digital signal transmitted to the receiving terminal station.
The decoding circuit is shown. In the same figure, a transmission line encoder 22 of a receiving terminal station 21 converts a transmission line code signal into a digital signal before transmission, which has been band-shifted.
The signal is converted into a parallel signal by the conversion circuit 23, and becomes the differentially encoded signal. The leading value ■' of the parallel signal is sent to the adder 25. of the first addition/decoding circuit 24. The signal is converted into a color signal by the D/A converter circuit 27 via the P/S converter circuit 26, and a portion of the signal is delayed by one signal interval by the x' signal delayer 28 and held. Next, the three differential encoding circuits ``--'' are inputted to the adder 25, and the output ``■'' of the delay device 28 is added and decoded into the original parallel signal ``■''.

Also, in the second addition/decoding circuit 31 consisting of the addition tI 29 and the delay device 30, and the third addition/decoding circuit 34 consisting of the adder 32 and the delay device 33, other sets of parallel signals are processed using the same method as described above. The band-compressed digital signal is demodulated into the original digital signal. The demodulated parallel signal is converted into a serial signal by the FiP/8 conversion circuit 26, and returned to the original power 2-signal by the D/A conversion circuit 27.

The characteristics of the aforementioned Doji conversion circuit 7.14.18 are shown in Fig. fg6. In the figure, the horizontal axis shows the input signal, and the vertical axis shows the quantized output signal. The numbers in the figure are shown in decimal notation. The input signal is quantized by 4 for input levels 2 to 5.

(fJ Effects of the Invention According to the present invention, differential encoding is performed by dividing the digital color coefficient by 1/n, so a low-speed differential encoding circuit can be used and the cost of the circuit can be reduced. has advantages.

[Brief explanation of drawings]

FIG. 1 is a diagram showing n frequency division of a digital signal for explaining the present invention, FIG. 2 is a differential encoding circuit according to an embodiment of the present invention, FIG. 3 is a diagram of parallel arrangement of digital signals, and FIG. FIG. 5 shows the differentially encoded signal according to the present invention, FIG. 5 shows the differential decoding circuit of the non-inventive embodiment, and FIG. 6 shows the human output % of the doji conversion circuit. In the figure, 1 is an A/DR conversion circuit, 2 and 23 are S/P conversion circuits, 3 and 4.5 are differential encoding circuits, b, 13° and 17 are subtractors, and 7 and 14.18 are quantization circuits. Round trip, 8°26 is P/S
conversion circuit, 9Fi transmission line encoder, 10 transmission line, 11,
15, 19, 25, 29.32 are adders, 12, 16,
20, 28, 30.33 are delay devices, 21 is a receiving terminal station, 2
2#'J: Transmission line decoder, 24, 31゜34 is addition decoding circuit, 27Fi D/A conversion circuit is shown.

Claims (1)

[Claims] Power 2 - A for digital band compression transmission method
A differential encoding method having means for converting the A/D-converted color movie signal into a differential code every (D-1)@.