JPS60199246A - Reception power measurement device - Google Patents

Abstract

PURPOSE:To prevent mis-decision by providing a memory storing the relation among reception wave levels of a desired reception channel and adjacent channel, the output of an out-band noise measuring section and the output of an envelope detector in advance and referencing the memory to decide whether the received wave is on the desired channel or the adjacent channel. CONSTITUTION:A computer 12 obtains a received wave level Bd when the received wave is a desired channel wave and the received wave level Bu when the wave is the adjacent channel wave from the level of an out-band noise output 6 and obtains the received wavelevel Dd when the wave is the desired channel wave and the received wave level Du when the wave is the adjacent channel wave from the received envelope level of the received envelope output 9. Then the Bd and the Dd, and the Bu and the Du are compared respectively, and when Bd=Dd, it is decided that the input wave is the desired channel wave and when Bu=Du, it is decided that the received wave is the adjacent channel wave. The result of decision is outputted to the decision output terminal 14. Then the received wave level is outputted to a received electric field level output terminal 15 at the same time.

Description

TECHNICAL FIELD The present invention relates to a received power measuring device for measuring the electric field strength of received waves for a desired channel and an adjacent channel in mobile communication.

BACKGROUND ART FIG. 1 is a block diagram showing an example of a conventional received power measuring device of this type. That is, the received wave is converted into an intermediate frequency band signal (IF signal) and inputted to the IF signal input terminal l, the IF signal is amplified by the IF amplifier 2, and the signal detected and demodulated by the discriminator 3 is output as an audio signal. The signal is input to the envelope detector 5 through a bypass filter 4 for signal removal. The output of the bypass filter 4 is out-of-band noise suppressed according to the input electric field strength, which is sent to the envelope detector 5.
The smoothed signal is output as an out-of-band noise output 6, and the electric field strength of the received wave is measured based on the level of the out-of-band noise output 6. The relationship between the level of the m-band noise output 6 and the electric field strength of the received wave varies depending on whether the received wave is the desired channel or the adjacent channel. The curve ■ shows the relationship between the electric field strength of the received wave for the adjacent channel and the noise output. The horizontal axis of the figure shows the electric field strength of the received wave (diIL), and the vertical axis , shows the level (dBs+) of the out-of-band noise output 6.

According to FIG. 2, for example, when the noise output is -38 dBm, the received wave level of the desired channel is determined to be O dB#L from point A on the curve ψ. However, even when the received wave of the desired channel has not arrived, if the received wave level of the adjacent channel is high, the noise level is suppressed according to the characteristic shown by the curve ψ.For example, if the received wave of the adjacent channel is? If it is about 1 dB, the noise output will be -38 dB at point B on the curve ψ. This is because the noise of the synthesizer used for local oscillation of the receiver is converted to an intermediate frequency by the adjacent channel wave, thereby suppressing demodulation noise. Therefore, the conventional device described above may not be able to determine whether the received wave is a desired channel wave or an adjacent channel wave.

An electric field measuring device as shown in FIG. 3 is also commonly used. In this case, the received wave is converted to an intermediate frequency and inputted to the logarithmic amplifier 7 from the IF signal input terminal l,
The envelope of the carrier wave is logarithmically compressed. Then, the envelope detector 8 detects the envelope of the output of the logarithmic amplifier 7,
It is output as a reception envelope connection output 9. The level of the received envelope output 9 naturally corresponds to the received wave level. Figure 4 is.

It is a diagram showing the level relationship between the electric field strength of the received wave and the received envelope output 9, where the horizontal axis represents the electric field strength (di#L) of the received wave, and the vertical axis represents the envelope output level (di#L) of the received envelope output 9. V)
The curve ■ in the same figure shows the relationship between the received signal field strength of the desired wave and the envelope line output, and the curve [share] shows the relationship between the received wave electric field strength and the envelope line output for the adjacent channel.From the same figure, For example, when the envelope output is 1.3 V, the received wave level is OdB at point 0 on curve ■, and 72 dBIL at point D on curve 1, so the received input is the desired wave. It is not possible to separate whether it is a wave or an adjacent wave,
This is also because, as described above, the synthesizer noise converted to the intermediate frequency is subjected to envelope detection.

In mobile communications, many radio channels are repeatedly used in different regions, and when a mobile device changes zones,
The so-called channel that switches the wireless channel to the destination wireless channel! 1lJfiF is performed. When switching channels or starting a call, it is necessary to measure the electric field level of the desired channel and determine that there is no radio wave in that channel and that it can be used. For this reason, the reception level of the desired channel wave is measured, but with the conventional device described above, it is not possible to separate the local channel wave and the adjacent channel wave and measure the reception level, so the measurement accuracy of the reception power is poor. For example, in the above-mentioned example, when the adjacent channel wave is at a high level, it is incorrectly determined that the aW channel wave is unusable even if it does not exist.

An object of the present invention is to solve the above-mentioned conventional drawbacks, and to provide a received power measuring device that can accurately measure received power by separating desired channel waves and adjacent channel waves. It's about doing.

Structure of the Invention The received power measuring device of the present invention includes a discriminator that demodulates a received signal, an out-of-band noise measuring section that measures high-frequency out-of-band noise of the output of the discriminator, and a received power measuring device that demodulates a received signal. An envelope detector for measuring the level, a relationship between the received wave level of the desired reception channel, the output of the out-of-band noise measurement unit, and the output of the envelope detector, and the relationship between the received wave level of the adjacent channel and the out-of-band A memory is provided in which the relationship between the output of the noise measuring section and the output of the envelope detector is stored in advance, and the received wave is determined by referring to the memory from the output of the envelope detector and the out-of-band noise measuring section. It is characterized by determining whether it is a desired channel or an adjacent channel.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

FIG. 5 is a block diagram showing an embodiment of the present invention.

That is, the intermediate frequency band signal (IF signal) input from the IF signal input terminal l is amplified by the IF amplifier 2, and the IF
The output of the amplifier 2 is detected and demodulated by a discriminator 3, the output of the discriminator 3 is extracted by a bypass filter 4 (cutoff frequency: 20 kHz), high frequency noise outside the band is extracted, and the envelope detector 5 extracts high frequency noise from the bypass filter 4. In this embodiment, the bypass filter 4 and the envelope detector 5 constitute an "out-of-band noise measurement unit that measures high-frequency out-of-band noise". ”. On the other hand, the IF multiplied signal of the IF signal input terminal 1 is inputted to the envelope detector 8 through the logarithmic amplifier 7, the envelope detector 8 performs envelope detection, and the signal is output as a reception envelope output 9. The out-of-band noise output 6 is converted into a digital signal by an analog-to-digital converter lO and input to the computer 12;
The reception envelope output 9 is converted into a digital signal by an analog-to-digital converter II and input to the computer 12. A memory 13 is connected to the computer 12, and in the memory 13, the relationship between the received electric field level, noise output, and received wave envelope output for the desired channel wave and the adjacent channel wave is measured in advance and stored in a table format, for example. has been done. Then, the computer 12 refers to the memory 13 based on the noise output level input from the analog-to-digital converter IO and the received wave envelope output level input from the analog-to-digital converter 11, and determines whether the received wave is the desired channel. However, it determines whether it is a desired channel wave or an adjacent channel wave, and outputs the received electric field strength of the desired channel wave or the adjacent channel wave as a determination output 14 and a received electric field level output 15.

Figure 6 is a characteristic diagram showing the relationship between the electric field strength of the received wave, the out-of-band noise output level, and the reception envelope output level.The horizontal axis shows the electric field strength (dB#L) of the received wave, and the left end The vertical axis shown corresponds to the out-of-band noise output level (dB), and the vertical axis shown at the right end corresponds to the receiving envelope output level (V). The curves ■ and ■ shown by solid lines in the same figure are
This shows the level relationship between the received wave and noise output for the desired channel and the adjacent channel, respectively, and the characteristics are the same as those shown in FIG. In addition, the curves ■ and [
4 shows the relationship between the received wave level and the received envelope output level, respectively, and has the same characteristics as shown in FIG. The memory 13 stores in a table format the levels of the noise output and reception envelope output corresponding to the reception electric field levels of the desired channel wave and the adjacent channel wave, respectively.

Next, the operation of this embodiment will be explained with reference to FIG. Now, for example, the level of out-of-band noise output 6 is -44,
5 dBm (indicated by point E), and the level of the reception envelope output 9 is 1.53 V, indicated by point H. First, the computer 12 assumes that the received wave is a desired channel wave and calculates the received electric field by referring to the memory 13. The received electric field combined with the curve ■ in Figure 6 is 8 dBp, which is indicated by one point F.
The received electric field from one curve ■ is also 8 dBp, which is shown by point F.
Therefore, there is no contradiction. If we assume that the received wave is an adjacent channel and the received electric field from the memory 13 is added to the 0th order, we get a curve ■
From the point G, 93 dB IL is obtained, and from the song -0, 79.5 dJt, shown at the point I, is obtained, giving contradictory results. Therefore, the computer 12 determines that the received wave is the desired channel, outputs a signal indicating the determination result to the determination output terminal 14, and outputs the received wave level to the received electric field level output terminal 15 as 8 dBp.

Generally, the computer 12 calculates the received wave level Bd when the received wave is the desired channel wave and the received wave level Bu when the received wave is the adjacent channel wave from the level of the out-of-band noise output 6, From the reception envelope level of the reception envelope output 9, determine the reception wave level Dd when it is a desired channel wave and the reception wave level Du when it is an adjacent channel wave, and then calculate the above Bd and Dd. Compare Bu and Du respectively, and if Bd=Dd, it is determined that the input wave is the desired channel wave, and if Bu=Du, it is determined that the received wave is the adjacent channel wave.The 0 determination result is the determination output terminal. Output to 14. At the same time, the received wave level is output to the received electric field level output terminal 15.

However, if the noise output and envelope output for the input wave have similar characteristics for the desired channel wave and the adjacent channel wave, the determination accuracy decreases and the dynamic range in which the received input can be measured becomes narrower.

FIG. 7 is a diagram showing the characteristics of another embodiment of the present invention that improves this point. This is because the cutoff frequency of the bypass filter 4 shown in Fig. 5 is set to a low frequency (for example, about 6 kHz) that can remove signals in the audio band.In this case, the received wave level for the desired channel wave is set to The relationship between the level and the level of the out-of-band fiber sound output 6 is shown by a curve ``■'' in the same figure, and the noise output characteristic for adjacent channel waves is shown by a curve ``black'' in the same figure. In the above embodiment,
Since the cutoff of the bypass filter 4 is as high as 20kHz, the amount of noise suppression is large when the input level of the adjacent channel wave is high.

This is because by lowering the cutoff of the bypass filter 4, the amount of noise suppression is reduced even when the level of adjacent channel waves is high. When the input wave is the desired channel wave, lowering the cutoff frequency of the bypass filter 4 has little effect, and the relationship between the received electric field level and the received envelope output level is similar to the desired channel wave and the adjacent channel wave. , respectively, as shown by curves ■ and [stock] in the same figure, which are almost the same as the characteristics shown by curves ■ and curves in FIG. 6.

Now, suppose that the noise output is -39 dB as shown by the dot in Fig. 7, and the envelope output is 1.28 V as shown by the point M.
Assuming that the received input is an adjacent channel wave, the received electric field level is 72 dBp as indicated by point N from the curve.
The received electric field level cannot be estimated from the curve 1, so the above assumption is rejected. Then, the input wave is determined to be the desired channel wave, and the curve and ■
From this, it can be seen that the received electric field is 0 dBIL. That is, there is an advantage that the accuracy of determining whether a received wave is a desired channel wave or an adjacent channel wave is improved. Furthermore, the amount of noise suppression differs greatly depending on whether the received wave is a desired channel wave or an adjacent channel wave, and in the range where the noise output is below P, the received electric field level is uniquely determined from the noise output. There are advantages. In the above characteristic example, if the received electric field is 110 dBx or more, it is possible to uniquely and accurately determine the received electric field level from the noise output.

this is.

Covers a sufficient range for practical use.

As described above, in the present invention, the level relationship between the received electric field, noise output, and received envelope output for the desired channel wave and the adjacent channel wave is stored in memory, and the received The noise output level and reception envelope output level for the wave are measured, and the received electric field level as the desired channel wave or adjacent channel wave is calculated by referring to the memory from the above two measured values. This has the advantage that it is possible to accurately determine whether a wave is a desired channel wave or an adjacent channel wave, and to measure the received electric field level with high accuracy.

If the present invention is applied to mobile communications and used to measure the received electric field to confirm that the desired channel is empty during so-called channel switching, when a mobile device switches to a new wireless channel when changing zones, The effects of interference from adjacent channels can be removed, and the tolerance for co-channel interference (interference from radio channels in other zones that use the same frequency) and the tolerance for adjacent channel interference are set separately. There is also the advantage of being able to

Furthermore, unlike in the prior art, when a desired channel is not in use, it is possible to prevent an erroneous determination that the desired channel is in use due to a received wave of a high-level adjacent channel.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a conventional received electric field measuring device, Fig. 2 is a diagram showing the noise output characteristics of the above conventional example, and Fig. 3 is a block diagram showing an example of a conventional received electric field measuring device.
FIG. 4 is a block diagram showing an example of a conventional electric field measuring device, FIG. 4 is a diagram showing envelope line output characteristics of the conventional example, FIG. 5 is a block diagram showing an embodiment of the present invention, and FIG. 6 is a block diagram showing an example of the conventional electric field measuring device. FIG. 7 is a diagram showing the noise output characteristic and reception envelope output characteristic of the above embodiment, and FIG. 7 is a diagram showing the noise output characteristic and reception envelope output characteristic in another embodiment of the present invention. In the figure, l: IF signal input terminal, 2: IF amplifier,
3: Discriminator, 4: Bypass filter, 5:
Enveloping line detector, 6: Out-of-band noise output, 7: Logarithmic amplifier,
8: Envelope detector, 9: Reception envelope output, 10, 11:
Analog-digital converter, 12: Computer, 1
3: Memo Ic 14=judgment output terminal, 15: Received electric field level output terminal. Applicant: Nippon Telegraph and Telephone Public Corporation Agent: Patent Attorney: Toshimune Sumita

Claims (1)

[Claims] a discriminator that demodulates a received signal, an out-of-band noise measurement unit that measures high-frequency out-of-band noise of the output of the discriminator, an envelope detector that measures the power level of the received wave, and The relationship between the received wave level of a receiving channel, the output of the out-of-band noise measurement unit, and the output of the envelope detector; and the relationship between the received wave level of an adjacent channel, the output of the out-of-band noise measurement unit, and the output of the envelope detector. and a memory in which the relationship between the signals and the signals is stored in advance, and determines whether the received wave is a desired channel or an adjacent channel by referring to the memory from the outputs of the envelope detector and the out-of-band noise measuring section. A received power measuring device characterized by: