JP2006270337A - Noise generator and device for measuring bit error rate to cn ratio - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive and long-life noise generator that does not emit unwanted noise to the outside. <P>SOLUTION: An anode of a diode 4 is grounded. A cathode of the diose 4 is connected to a contact plug 8 via a resistor 6. A DC power source is supplied to the diode 4 from the contact plug 8 via the resistor 6. The noise generated in the diode 4 is supplied to the contact plug 8 via a capacitor 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a device used for measuring a CN ratio versus bit error rate used for evaluation of a digital signal such as an OFDM, 64QAM, xPSK signal, and a noise generator used for this device.

  As a digital signal evaluation method described above, there is a bit error rate (BER) measurement. When measuring BER, there may be error-free results. In this case, the quality of the signal is unknown. In this case, there is a method in which noise is added to the digital signal, the CN ratio versus BER characteristic is measured, the equivalent CN ratio or the equivalent CN ratio deterioration amount is obtained, and the digital signal is evaluated. In order to obtain the CN ratio vs. BER characteristic, it is necessary to add noise to the digital signal, and a noise generation source is required. As a noise source, it was necessary to use an expensive commercial product.

  As an inexpensive noise generating device, for example, there is one disclosed in Patent Document 1. The noise generator disclosed in Patent Document 1 includes a relay switch, a relay coil, and a power switch connected in series to a DC power source. The relay switch is closed when no current flows through the relay coil, and is opened when a current flows through the relay coil. By closing the power switch, a current flows through the relay coil and the relay switch is closed. This cuts off the current to the relay coil and closes the relay switch. In response to this, a current flows again through the relay coil. In this way, the relay switch repeats intermittently. As a result, an arc is generated between the contacts of the relay switch, and noise is generated by the arc.

JP-A-8-204455

  However, in this noise generator, since the noise is generated by the intermittent relay switch, the life of the relay switch is short. Further, since noise is generated based on the occurrence of an arc between the contacts of the relay switch, there is a high possibility that unnecessary noise is radiated to the outside.

  An object of the present invention is to provide a noise generator that is inexpensive, has a long service life, and does not emit unnecessary noise to the outside, and a CN ratio-to-bit error rate measurement apparatus using the noise generator.

  The noise generator of one embodiment of the present invention includes a diode, and a DC power supply is supplied between an anode and a cathode of the diode. A plug is connected to the anode and cathode of this diode through direct current blocking means. The diode and the plug are preferably housed in one housing.

  In the noise generator having this configuration, by supplying a DC power source to the diode, thermal noise generated by the diode is supplied to the plug as noise. Therefore, since it is composed of only electrical parts without using mechanical parts, it can be inexpensive and have a long life. Further, since thermal noise generated in the diode is used, no noise is radiated to the outside.

  The noise generator may be configured to supply the DC power from an external power supply device through the plug. In this case, since the noise generator itself does not need to have a power source, it can be reduced in size and weight, and the noise generator can be easily moved.

  In the above noise generator, the DC power supply may be supplied by a battery built in the noise generator. If comprised in this way, the restriction | limiting of the usage place of a noise generator will be lose | eliminated.

  Furthermore, a DC power supply can also be supplied from an external DC power supply device through the plug. In this case, switching means for switching between the battery and the external DC power supply device and supplying DC power to the diode is provided. With this configuration, the noise generator can be operated by either the internal battery of the noise generator or the external power supply device, so that it can be used according to the situation.

  One of the noise generators described above, a variable gain booster that amplifies the noise supplied from the plug of the noise generator, and the output signal of the booster and the digital signal to be measured are mixed. Then, a mixing means for supplying the bit error measuring device can be provided to provide a CN ratio versus bit error rate measuring device.

  In this configuration, the noise signal from the noise generator is amplified by the booster and mixed with the digital signal to be measured in the mixing means. By appropriately adjusting the gain of the booster, the output signal from the mixing means can be supplied to the bit error rate measuring device with a desired CN ratio. CN ratio vs. bit error measurement may be performed, for example, at the antenna output terminal, head end input terminal, same output terminal, transmission line output terminal, etc. of a joint reception system. Since a desired CN ratio can be set by using this booster, there is no need to separately prepare a noise level adjusting means, and the CN can be simply connected to the bit error rate measuring device. A CN ratio / bit error rate measuring apparatus capable of measuring a ratio / bit error rate can be easily configured at a measurement site.

  In addition, if the above noise generator does not operate only with a built-in battery, if the booster has a built-in power supply, DC power can be supplied from this power supply to the plug of the noise generator. This eliminates the need for a separate power supply for the noise generator.

  As described above, in the noise generator according to the present invention, when the DC power is supplied to the diode, the noise is generated by using the thermal noise generated in the diode. be able to. Also, by providing this noise generator, booster, and mixer, an apparatus for measuring CN ratio versus bit error rate can be easily configured at the measurement site.

  The noise generator 1 according to the first embodiment of the present invention has a small case 2 as shown in FIG. The case 2 is preferably made of, for example, a conductor and has a shielding effect.

  A diode 4 is disposed in the case 2. The anode of the diode 4 is connected to a reference potential, for example, a ground potential. The cathode of the diode 4 is connected to the central conductor of the plug 8 via the current limiting resistor 6. The outer conductor of the plug is connected to the ground potential. Further, DC blocking means, for example, a capacitor 10 is connected in parallel with the resistor 6.

  Accordingly, when a DC power supply is supplied from the outside between the central conductor of the connector 8 and the outer conductor, a reverse bias voltage is applied to the diode 4 via the resistor 6, and the diode 4 generates internal thermal noise. appear. This internal thermal noise is supplied to the plug 8 via the capacitor 10. In this way, the noise generator 1 generates noise when a DC power supply is supplied from the outside.

  The noise generator 1 is entirely composed of electrical parts, and no mechanical parts are used. Therefore, it has a long life. Further, since noise is generated based on the thermal noise of the diode 4, the generation of noise does not adversely affect the outside. Moreover, since it is composed of the diode 4, the resistor 6, the plug 8, and the capacitor 10 and a few components, the size can be reduced, and the case 2 can be used in a small size, which is convenient for carrying.

  For example, as shown in FIG. 2, the plug 8 of the noise generator 1 is connected to the input terminal of the booster 12 via a transmission line, for example, a coaxial cable 14. The booster 12 can vary its gain arbitrarily. The booster 12 has a DC power supply device 16 therein, and supplies operating power to the plug 8 through the coaxial cable 14. Therefore, when the booster 12 is operated, a DC power supply is supplied to the noise generator 1, and the noise generated by the noise generator 1 is supplied to the booster 12 as described above. The booster 12 amplifies this noise and supplies it to the mixing means, for example, the mixer 18.

  The mixer 18 is supplied with a digital signal to be measured, for example, OFDM, 64QAM, xPSK signal from any of the antenna output terminal, the head end input terminal, the head end output terminal, and the transmission line output terminal of the joint reception system. Yes. Therefore, a mixed signal of the digital signal to be measured and noise is output to the output of the mixer 18. Here, when the gain of the booster 12 is appropriately adjusted, the output of the mixer 18 becomes a digital signal under measurement having a desired CN ratio. By supplying this to a bit error rate measuring device (not shown) and measuring the bit error rate, the CN ratio versus bit error rate characteristic can be measured. The CN ratio can be made different by changing the gain of the booster 12, and the bit error rate can be measured for each different CN ratio.

  Thus, by supplying the output of the mixer 18 to the bit error rate measuring device by the noise generator 1, the booster 12 and the mixer 18, the CN ratio vs. bit error rate can be measured. An apparatus for rate measurement can be configured. Since this apparatus uses a general-purpose booster 12 to adjust the CN ratio, this apparatus can be easily configured at the site where the CN ratio versus bit error rate characteristic is to be measured. Furthermore, since the DC power is supplied from the internal DC power supply 16 of the booster 12 to the noise generator 1, it is not necessary to prepare a separate power supply for the noise generator 1, and the configuration can be further simplified. .

  As shown in FIG. 3, the noise generator 1 a according to the second embodiment of the present invention includes a battery 20 in the case 2, the negative electrode thereof is connected to the ground potential, and the positive electrode is the current limiting resistor 6. Is connected to the cathode of the diode 4. The anode of the diode 4 is grounded. The cathode of the diode 4 is connected to the central conductor of the plug 8 via the capacitor 10.

  Also in this embodiment, noise is generated in the same manner as the noise generator 1 of the first embodiment. Since it is driven by the built-in battery 20, the installation location is not restricted from the viewpoint of supplying DC power.

  The noise generator 1a can be used in place of the noise generator 1 shown in FIG. 2 to constitute a CN ratio versus bit error rate measurement device. However, in this case, since the noise generator 1a incorporates the battery 20, it is not necessary to supply DC power from the DC power supply device 16 of the booster 12 to the noise generator 1a.

  A noise generator 1c of the third embodiment is shown in FIG. The noise generator 1c can be operated by either a DC power supplied from the built-in battery 20 or a DC power supplied from the outside to the plug 8.

  That is, the central conductor of the plug 8 is connected to the contact 22 a of the changeover switch 22. A contact 22 b of the changeover switch 22 is connected to the positive electrode of the battery 20. A contact 22 c of the changeover switch 22 is connected to the cathode of the diode 4. Of course, the outer conductor of the plug 8, the anode of the diode 4, and the negative electrode of the battery 20 are grounded. The cathode of the diode 4 is connected to the central conductor of the plug 8 via the capacitor 10.

  When the noise generator 1c is operated by a DC power source supplied from the outside to the plug 8, the contact 22c of the changeover switch 22 is switched so as to contact the contact 22a. When the battery 20 is operated, the contact 22c of the changeover switch 22 is switched so as to contact the contact 22b. Thus, it can be operated by both internal and external power supplies.

  The noise generator 1c can be used in place of the noise generator 1 shown in FIG. 2 to constitute a CN ratio versus bit error rate measurement device. In this case, however, the noise generator 1c can be operated by supplying DC power from the DC power supply device 16 of the booster 12 to the noise generator 1c, or can be operated by the battery 20. Alternatively, if the booster 12 is of a type that does not include a DC power supply device, the noise generator 1c is operated by the battery 20. In this way, the noise generator 1c can be operated by either a battery or an external power source depending on the situation.

  In each of the above embodiments, only one diode is used, but a plurality of diodes may be connected in series or in parallel. Further, although the internal noise is generated with the reverse bias voltage applied to the diode, the internal noise may be generated with the forward bias voltage applied to the diode.

It is a circuit diagram of the noise generator of a 1st embodiment of the present invention. FIG. 2 is a block diagram of an apparatus for measuring CN ratio versus bit error rate using the noise generator of FIG. 1. It is a circuit diagram of the noise generator of 2nd Embodiment of this invention. It is a circuit diagram of the noise generator of 3rd Embodiment of this invention.

Explanation of symbols

1 1a, 1b 1c Noise generator 2 Case 4 Diode 8 Plug 12 Booster 18 Mixer (mixing means)
20 battery

Claims (6)

A diode to which direct current power is supplied between the anode and the cathode;
A plug connected to the anode and cathode of this diode via a DC blocking means,
Noise generator provided.   The noise generator according to claim 1, wherein the DC power is supplied from an external power supply device through the plug.   The noise generator according to claim 1, wherein the noise generator is supplied by a battery built in the DC power supply.   The noise generator according to claim 3, wherein the DC power supply is configured to be able to be supplied also from an external DC power supply device through the plug, and the battery and the external DC power supply device are switched, and a DC is supplied to the diode. A noise generator provided with switching means for supplying power.   5. A noise generator according to claim 1, 2, 3 or 4, a variable gain booster for amplifying noise supplied from the plug of the noise generator, an output signal of the booster and a digital modulation signal for measurement A CN ratio to bit error rate measurement device comprising: mixing means for mixing and supplying to a bit error measurement device. A bit error measuring device comprising: a noise generator according to claim 2; a gain variable booster connected to a plug of the noise generator; and an output signal of the booster and a digital modulation signal to be measured. And a mixing means for supplying to the CN, the booster includes the external power supply device, and the DC power supply is supplied from the external power supply device to the plug.

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