JP3033006B2 - Communication line bit error measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bit error of a communication line when a digital signal of a digital line is converted into an analog signal by a codec (a combination of an encoding unit and a decoding unit) and transmitted by the analog line. It is about a measuring device.

[0002]

2. Description of the Related Art The principle of bit error measurement will be described with reference to FIG. FIG. 5A is an example of transmission data in which a digital signal is represented at a bit level, and "1", "0",
"1" and "0" are transmitted. FIG. 5A is an example of the received data of FIG. 5A, which is "1", "1", "1", and "0". FIG. 5C is comparison data between FIG. 5A and FIG.
The error bit "1" is measured.

Next, a configuration diagram for measuring a bit error in FIG. 5C will be described with reference to FIG. In FIG. 6, 7 is a comparator, 16 is a reference pattern, and 17 is a reception pattern. The reference pattern 16 is the same as the transmission data in FIG. 5A, and the reception pattern 17 is the reception data in FIG. Reference pattern 1
6 and the reception pattern 17 into the comparator 7,
The error bit in FIG. 5C is obtained from the output of the comparator 7.

Next, a bit error measurement system diagram of a digital line will be described with reference to FIG. In FIG. 7, 1 is a random code generator, 4A is a digital line, and 6 is a code error measuring device. In FIG. 7, a bit-level random code is sent from the random code generator 1 to the digital line 4A, and the output of the digital line 4A is input to the code error measuring device 6,
Then, the bit error is measured by comparing the reference pattern and the reception pattern.

Next, a configuration diagram of a conventional apparatus for measuring bit errors in a communication line will be described with reference to FIG. 3B of FIG.
Is a codec that performs D / A conversion, 5 is an analog line,
3C is a codec for performing A / D conversion, 4B is a digital line, and the others are the same as those in FIG. As shown in FIG. 8, when the digital lines 4A and 4B and the analog line 5 are used, the transmitted digital signal and the received digital signal are converted into an analog signal by the codec 3B and a digital signal again by the codec 3C. Are different. In addition, the random code is affected by level fluctuations due to the analog line 5 and cable loss.

Next, the conversion contents by the codec are shown in FIG.
This will be described below. FIG. 9A is a byte-level waveform obtained by encoding a sine wave, and FIG. 9A is a waveform obtained by decoding FIG. 9A. FIG. 9C is a byte-level waveform obtained by encoding FIG. 9A, and when the delay due to transmission is considered, the sampling points are different between FIG. 9A and FIG. Therefore, since the coded waveforms are different between FIG. 9A and FIG. 9C, the transmission-side digital signal and the reception-side digital signal by the codec differ at the bit level.

[0007]

According to the present invention, a first modem for modulating a random code to a frequency, a phase or an amplitude at a bit level between a random code generator 1 and a digital line 4A shown in FIG. A first codec for encoding the output of the modem at the byte level is disposed, and the output of the digital line 4B is decoded to the frequency, phase or amplitude at the byte level between the digital line 4B and the code error detector 6 in FIG. And a second modem for demodulating the output of the second codec and the output of the second codec to bit-level "0" and "1", thereby eliminating the influence of the difference in the conversion contents at the byte level by the codec. An object of the present invention is to provide a bit error measuring device for a communication line.

[0008]

According to the present invention, a digital line 4A for transmitting a digital signal, a codec 3B for D / A converting the output of the digital line 4A, and an output of the codec 3B are provided. The analog line 5 to be transmitted and the output of the analog line 5 are A /
Of a communication line having a codec 3C for D-conversion and a digital line 4B for transmitting the output of the codec 3C,
In a device for measuring a bit error, a random code generator 1 for generating random codes of "0" and "1", and a modem 2A for modulating the output of the random code generator 1 at a bit level to a frequency, a phase or an amplitude. , Digital line 4A
, A codec 3A that encodes the output of the modem 2A at the byte level, a codec 3D that receives the output of the digital line 4B as an input, and decodes the frequency, phase or amplitude at the byte level, and the frequency of the output of the codec 3D. , A modem 2B for demodulating the phase or amplitude to “0” and “1”, and a code error measuring device 6 for measuring “0” and “1” from the output of the modem 2B and measuring a bit error.

[0009]

Next, the configuration of a bit error measuring device for a communication line according to the present invention will be described with reference to FIG. 2A and 2B of FIG.
Is a modem, 3A and 3D are codecs, and the others are the same as those in FIG. That is, FIG. 1 shows the modem 2A between the random code generator 1 and the digital line 4A of FIG.
And the codec 3A, and the digital line 4 shown in FIG.
A codec 3D and a modem 2B are arranged between B and the code error measuring device 6.

The modem 2A modulates the output of the random code generator 1 at a bit level into a frequency, a phase or an amplitude. FIG. 1 illustrates an embodiment in which the modem is a frequency modulation modem and the codec is a 64K bit codec.
The modem 2A modulates the output “0” of the random code generator 1 to the frequency fa and the output “1” to the frequency fz.
The codec 3A encodes the output of the modem 2A at a byte level. In FIG. 1, the frequencies fa and fz are encoded into a code such as 8 bytes.

The codec 3D decodes the output of the digital line 4B at a byte level into a frequency, phase or amplitude. In FIG. 1, the output of the digital line 4B is decoded to frequencies fa and fz as an embodiment. The modem 2B demodulates the frequency, phase or amplitude of the output of the codec 3D to "0" and "1" at the bit level.

In FIG. 1, a random code generator 1 generates a random code, and a modem 2A modulates the random code into an analog signal. For example, if the bit “0” is changed to the frequency fa =
The frequency is modulated to 1300 Hz and the bit “1” is changed to the frequency fz =
Frequency modulated to 2100 Hz. The signal frequency-modulated by the modem 2A is converted into a byte-level digital signal by the codec 3A and sent to the digital line 4A. The output of the digital line 4A is D / A converted by the codec 3B and enters the analog line 5.

In FIG. 1, reference numeral 11 denotes a bit level "0".
A digital signal of "1", 21 is a modulated frequency fa
An fz analog signal, 12 is a byte-level coded digital signal, 22 is an analog signal, 13 is a byte-level digital signal, 14 is a decoded analog signal with a frequency fa · fz, and 15 is demodulated. These are digital signals of bit level “0” and “1”.

Next, the relationship between the modems 2A and 2B will be described with reference to FIG. The modem 2A has a digital signal 11A.
Is modulated to the frequency fa, and the bit "1" is modulated to the frequency fz. The signal of the frequency fa · fz is demodulated by the modem 2B into a digital signal 11B. Modem 2
B demodulates the frequency fa into a bit “0” and demodulates the frequency fz into a bit “1”, so that B can be converted to the original bit.

When the digital signal 11A of FIG. 2 is compared with the digital signal 11B, the digital signal 11A is correctly converted to the digital signal 11B. Therefore, when the digital signal 11A is in the PN pattern, the digital signal 11B is correctly reproduced in the PN pattern, and the bit error can be measured.

Next, the modem 2A and the codec 3 shown in FIG.
The relationship of A will be described with reference to FIG. When the digital signal 11 is input to the modem 2A, the modem 2A generates the frequency fa when the bit is "0", and generates the frequency f when the bit is "1".
generate z. Analog signal 2 of this frequency fa · fz
1 to the codec 3A, the frequency fa · fz
Analog signal 21 is a byte level digital signal 1
Converted to 2. Byte level digital signal 12
Is different from the bit-level digital signal 11 in that one bit of the digital signal 11 is converted by the modem 2A into an analog signal 21 having a frequency fa · fz,
The fz analog signal 21 is changed to the byte level digital signal 12.

Next, the relationship between the codec 3B, the analog line 5, and the codec 3C in FIG. 1 will be described with reference to FIG. When the byte-level digital signal 12 is input to the codec 3B, the codec 3B converts the digital signal into an analog signal 22 for every 8 bits and sends the analog signal 22 to the analog line 5. When the analog signal 22 transmitted through the analog line 5 is input to the codec 3C, the analog signal 22 is converted into a byte-level digital signal 13 corresponding to the analog signal 22 in units of 8 bits.

The byte-level digital signal 13 which is A / D-converted and output by the codec 3C is almost the same as the digital signal 12 in the sense of a signal for the frequencies fa and fz. According to the CCITT data communication V-series recommendation in the telephone network, errors up to ± 10 Hz are allowed. The relationship between the digital signal 12 obtained by encoding the frequency fa · fz and the frequency fa · fz obtained by decoding the byte-level digital signal 13 is ± 10H.
z. And digital line 4
The byte level digital signal 13 is input to the codec 3D via B, D / A converted, and demodulated by the modem 2B.

That is, the digital signal 11 is transmitted to the modem 2
A modulates the frequency fa · fz to A, sets the frequency fa · fz as the object of the conversion of the codecs 3A to 3D, and demodulates the frequency fa · fz to “0” and “1” by the modem 2B, so that the digital signal 11 Even if the levels of the frequencies fa and fz corresponding to "1" and "0" slightly change between the digital signals 13, if there is a bit error, the bit error can be reliably measured.

In the modems 2A and 2B shown in FIG.
Although modulation / demodulation is performed to fz, it goes without saying that modulation other than frequency modulation such as phase modulation and amplitude modulation can be used.

[0021]

According to the present invention, when a digital signal on a digital line is converted into an analog signal by a codec and transmitted on the analog line, the first modem converts the bit-level digital signal into a frequency, a phase or an amplitude. Modulation, the modulation output is transmitted by a plurality of codecs on digital and analog lines, and the frequency, phase or amplitude is demodulated by a second modem, so that errors in conversion of analog signals by the codec are eliminated. , The bit error can be reliably measured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a communication line bit error measuring device according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a modem 2A and a modem 2B in FIG. 1;

FIG. 3 is an explanatory diagram showing a relationship between a modem 2A and a codec 3A in FIG. 1;

FIG. 4 is a diagram illustrating the relationship among a codec 3B, an analog line 5, and a codec 3C in FIG. 1;

FIG. 5 is a principle diagram of bit error measurement.

6 is a configuration diagram for measuring the bit error in FIG. 5C.

FIG. 7 is a system diagram of a bit error measurement of a digital line.

FIG. 8 is a system diagram for measuring bit errors in a communication line according to the prior art.

FIG. 9 is an explanatory diagram of conversion contents by a codec.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Random code generator 2A ・ 2B Modem 3A ・ 3B ・ 3C ・ 3D Codec 4A ・ 4B Digital line 5 Analog line 6 Code error measuring device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Nishizawa 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Takahiro Nakamura 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Japan Inside Telegraph and Telephone Corporation (72) Inventor Kazunari Toshima 5- 10-27 Minamiazabu, Minato-ku, Tokyo Anritsu Corporation (72) Inventor Koji Sahara 4-7-17 Kamata, Ota-ku, Tokyo Ando Electric Co., Ltd. In-company (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 1/00

Claims (1)

(57) [Claims] A first digital line (4A) for transmitting digital signals and an output of the first digital line (4A)
A second codec (3B) for / A conversion, an analog line (5) for transmitting the output of the second codec (3B), and a third codec (A / D conversion for the output of the analog line (5)) 3C) and an apparatus for measuring bit errors in a communication line having a second digital line (4B) for transmitting the output of the third codec (3C) generates random codes of "0" and "1". A random code generator (1), a first modem (2A) that modulates the output of the random code generator (1) to frequency, phase or amplitude at a bit level, and a first digital line (4A). , The first modem (2A)
First codec that encodes the output of at the byte level
(3A), a fourth codec (3D) that receives the output of the second digital circuit (4B) as input, and decodes the frequency, phase or amplitude at the byte level, and an output of the fourth codec (3D). A second modem (2B) for demodulating the frequency, phase or amplitude to "0" and "1"; measuring "0" and "1" from the output of the second modem (2B);
A bit error measuring device for a communication line, comprising: a bit error measuring device (6) for measuring a bit error.