JPS6318376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bipolar encoding circuit.

In the case of bipolar transmission, special information, such as a return signal for a backpack test or an emergency signal, is also transmitted in the same code as the general information. Therefore, on the receiving side, considerable circuitry and constant care are required to detect and process these special pieces of information. One possible solution to this problem is to make it possible to change the form of the bipolar code as necessary. However, although many types of conventional bipolar transmission have been developed (see, for example, Chapter 4 of ``Basics and New Technologies of PCM Communication'' edited by Hiroshi Inose (published by Sanposha)), there are many types of bipolar transmission that are independent of each other. Therefore, in order to carry out the above-mentioned measure, it is necessary to provide two sets of a transmitting section and a receiving section and use them selectively. Therefore, it is not economically preferable. The starting point of the present invention was the idea that if different bipolar codes could be obtained by locally changing the circuit configuration, the above measures could be effectively implemented.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a bipolar encoding circuit in which the shape of the code can be changed by local changes in the structure.

According to the present invention, a shift register having a variable number of stages, a first AND circuit that outputs 1 when the binary information is 1 and the output of the shift register is 1, and a first AND circuit that outputs 1 when the binary information is 1 and the output of the shift register is 1; and a second AND circuit that outputs 1 when the output of the shift register is 0, and a second AND circuit that performs an exclusive OR of the binary information and the output of the shift register, and inputs the output to the input of the shift register. A bipolar encoding circuit is obtained having an exclusive OR circuit for feeding.

Next, a detailed description will be given with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a transmitting section for bipolar transmission using a bipolar encoding circuit (hereinafter abbreviated as encoding circuit). The input binary information a and the clock b sent from the information source 11 become outputs c and d of 1 or 0 in the encoding circuit 12, and are sent out to the transmission line as a bipolar pulse e from the binary to ternary conversion circuit 13. Ru. Note that this FIG. 1 shows whether the encoding circuit 12 is a conventional one or the one of the present invention, and i, j, and m shown in parentheses are symbols related to the present invention, which will be described later. be. First, a conventional encoding circuit will be explained.

FIG. 2 is a block diagram showing an example of the configuration of a conventional encoding circuit.

FIG. 3 is a waveform diagram showing waveforms at various parts when the conventional encoding circuit of FIG. 2 is used in the transmitting section of FIG. 1. The explanation will be given below with reference to FIGS. 1 to 3. D-type flip-flop 21 has input 2
This circuit creates binary information f from value information a and clock b. The AND circuit 22 consists of two gate circuits, and the outputs c and d thereof both become 0 when the binary information f is 0, and either becomes 1 when the binary information f is 1. The 2 frequency divider 23 is combined with the AND circuit 22 so that when the outputs c and d become 1, they alternately become 1, as can be seen from the waveform of FIG. The NAND circuit 24 is paired with an inverter 25, and when the binary information f is 0, the
This is a circuit that stops the movement of the frequency divider 23. The outputs c and d generated in this way are output from the binary/ternary conversion circuit 1
3, it becomes a bipolar pulse e and is sent to a transmission path (not shown).

FIG. 4 is a diagram showing an example of the circuit configuration of the binary-to-ternary conversion circuit 13 described above. Output c of the encoding circuit
and d receive the TTL level in the level conversion circuit 27 and drive the transistor switching circuit 28,
This switching circuit drives an impedance conversion transformer 29 to generate a bipolar pulse e. Needless to say, this binary and ternary circuit is also used in a transmitter using the encoding circuit of the present invention, which will be described later. Next, the present invention will be explained.

FIG. 5 is a diagram showing a state in which information is divided into N sequences and encoded, which is the object of the encoding circuit of the present invention. In FIG. 5, binary information 1000 is divided into N bits, and N sequences 1001 to 1001 are divided every N bits.
Consider 100N. Bipolar encoding is performed on each sequence independently, and they are combined into 3
Generate value transmission path code 2000. This encoding method will be called an N-division bipolar code.

FIG. 6 is a diagram showing the electronic spectrum of an N-divided bipolar code in comparison with that of a normal bipolar code. In FIG. 6, A shows the spectrum of a normal bipolar code, B shows the spectrum of a two-part bipolar code, and C shows the spectrum of a three-part bipolar code. Assuming that the code transmission rate is f ₀ band, the spectrum of an N-divided bipolar code generally has zero points at integral multiples of f ₀ /NHz. In particular, kf ₀ (k=0, ±1, ±2, . . . ) is a zero point for any N.

FIG. 7 is a diagram showing the configuration of an encoding circuit according to the present invention that generates the N-divided bipolar code. This circuit includes a D-type flip-flop 31 that generates binary information f from input binary information a and clock b, a shift register 32 consisting of N-stage flip-flops,
When the binary information f is 1, the output of the shift register 32 is 1
The first AND circuit 3 whose output g becomes 1 when
3. Second AND circuit 3 whose output h is 1 when the binary information f is 1 and the output of the shift register 32 is 0
4. Take the exclusive OR of the binary information f and the output of the shift register 32 and send the output to the shift register 3
Exclusive OR circuit (EX-
OR circuit) 35. Note that a circuit for changing the number of stages of the shift register 32 is omitted.
However, since the operation of this circuit has multiple stages of shift registers, the explanation will be long, so next time, N is 2.
This case will be explained in detail.

FIG. 8 and FIG. 9 are diagrams showing an embodiment of a two-division bipolar code encoding circuit of the present invention and waveforms at various parts of this circuit, respectively.
The configuration of the encoding circuit shown in FIG. 8 is almost the same as that in FIG. 7, with the only difference being that the shift register 3
6 is composed of two flip-flops 37 and 38. The operation of the circuit shown in FIG. 8 will be explained below with reference to FIG. 9. Current input information a
Assume that binary information as shown in f is formed using clock b. If the binary output f is 0, the outputs i and j of the AND circuits 33 and 34 are both 0. At this time, the logic of the output k of the shift register 36 is not changed by the EX-OR circuit 35, and is input to the shift register 36 as the output l without any change. Binary information f is 1
In this case, depending on whether the output k of the shift register 36 is 1 or 0, only the output i becomes 1 or only the output j becomes 1. At this time, the logical value of the output k of the shift register 36 is inverted by the EX-OR circuit 35, and the inverted binary output l becomes the input of the shift register 36.

Outputs i and j obtained by the above encoding circuit
Referring also to FIG. 1, the binary-to-ternary conversion circuit 13
sent to. The transmission code m which is the output of this circuit
is a +1 level when the output i of the AND circuit 33 is 1, a -1 level when the output j of the AND circuit 34 is 1, and a 0 level when both outputs i and j are 0. By the above operation, 1 in Fig. 9
Mutually independent bipolar encoding is performed on alternate bit sequences #1 and #2, and two-part bipolar encoding is performed. Next, if the switch circuit 39 is used to short-circuit the flip-flop 38 when necessary, such an encoding circuit will be functionally identical to the conventional encoding circuit of FIG. 2, and will be as shown in FIG. encoding is performed. Therefore, by simply operating the switch circuit 39, that is, by locally changing the circuit configuration, the encoding circuit of the present invention shown in FIG. 8 can be made equivalent to two encoding circuits with different code shapes. The following actions can be performed.

Although omitted in the explanation of FIG. 6, it is clear that the N-division bipolar encoding circuit also performs the same operation as described above. Although the switch circuit is not shown in this case, one of the flip-flops
The configuration is such that one or more are short-circuited. This allows one encoding circuit to perform up to N types of encoding. However, one of them
One corresponds to the same encoding circuit as in the conventional case.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of a transmitting section for bipolar transmission using a bipolar encoding circuit, FIG. 2 is a block diagram showing the configuration of a conventional bipolar encoding circuit, and FIG. A diagram showing the waveforms of each part when the circuit shown in the figure is used in the transmitting section of FIG. 1, FIG. 4 is a diagram showing an example of the configuration of a binary-to-ternary conversion circuit used in the transmitting section of FIG. 1, Fig. 5 is a diagram showing a state in which information is divided into N sequences and encoded, which is the object of the present invention, and Fig. 6 shows a comparison of the electronic spectrum of an N-divided bipolar code with that of a normal bipolar code. 7 is a block diagram of a bipolar encoding circuit that generates an N-division bipolar code of the present invention, and FIG. 8 is a block diagram of a bipolar encoding circuit that generates a 2-division bipolar code of the present invention. Figure 9
The figure shows waveforms at various parts of the circuit of FIG. 8. Explanation of symbols: 31 represents a D-type flip-flop circuit, 33 and 34 represent an AND circuit, 35 represents an exclusive AND circuit (EX-OR circuit), 36 represents a shift register, 37 and 38 represent a flip-flop circuit, and 39 represents a switch. There is. Also f, i,
j, k, l, and m all represent circuit outputs at each part.

Claims (1)

[Claims] 1. a shift register with a variable number of stages; a first AND circuit that outputs 1 when the binary information is 1 and the output of the shift register is 1; a second AND circuit that outputs 1 when the output is 0; and an exclusive OR that takes the exclusive OR of the binary information and the output of the shift register and sends the output to the input of the shift register. A bipolar encoding circuit having a circuit.