JP2000180483A - Selection level-measuring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a selection level-measuring system capable of preventing the mixing of CPU noise in a low-noise amplifier and highly accurate and highly sensitive measurement. SOLUTION: A preamplifier part 1 constituted by embedding a low-noise amplifier 6 in an electromagnetically shielded case is arranged outside a case 4 in which a section level measuring module 2 and a CPU 3 are embedded. By this constitution, it is possible to prevent CPU noise from mixing in the low-noise amplifier 6 and to perform highly accurate and highly sensitive measurement. In addition, by embedding the preamplifier part 1 in the separate case connected to the outside of the case 4, mode conversion between highly sensitive measurement mode and normal level measurement mode becomes easy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a selective level measuring system mainly used for analyzing a frequency component of a signal and measuring a signal level, and more particularly to improving accuracy with a simple configuration.

[0002]

2. Description of the Related Art Conventionally, as shown in JP-A-8-212488 and JP-A-10-19613, a measurement module built in a personal computer (PC) or a dedicated measurement frame is known. This measurement module can be designed to be small and low-cost by limiting it to a specific measurement function, and by combining measurement modules with the required functions from various measurement modules, the optimum It has the feature that a simple measurement system can be constructed.

[0003] Conventionally, as an apparatus for measuring the level of a high-frequency signal for each frequency, for example, Japanese Patent Laid-Open No. 10-160 is disclosed.
No. 771 discloses a selection level measuring device, which is also generally used as a measurement module (selection level measurement module). This selection level measurement module is used, for example, for electric field level measurement and unnecessary radiation measurement, and measures a signal level included in a specific bandwidth of a signal component.

In general, in order to improve the measurement sensitivity of this selection level measurement module, it is necessary to improve the overall gain and noise figure by adding a low-noise amplifier to a high-frequency amplification stage of the measurement apparatus. Sensitivity type selection level measurement module).

In general, such a selection level measurement module has a measurement frequency range of about 1000 MHz (for example, 1 to 1000 MHz, 1000 to 200 MHz).
0 MHz) in many cases. Therefore, when it is necessary to simultaneously (or at a high speed) measure signals over a wider frequency range (for example, 1 to 2000 MHz), prepare a plurality of selection level measurement modules corresponding to different measurement frequency ranges, and input signals. It had to be distributed by a distributor to a plurality of selection level measurement modules (broadband selection level measurement system).

On the other hand, in a receiver and a receiving system,
An example in which a low-noise amplifier is installed at a position directly below an antenna or the like away from a measuring device in order to prevent noise contamination is disclosed in Japanese Unexamined Patent Publication No.
No. 27168, JP-A-6-350471 and JP-A-10-75191. As means for separating signals in a plurality of relatively narrow frequency bands, for example, JP-A-8-237166 and JP-A-9-8885 use an antenna duplexer configured by combining band-pass filters. It has been proposed.

[0007]

However, in the conventional high-sensitivity selection level measurement module, a high-gain high-frequency amplification stage is built in the housing of a PC or a dedicated measurement frame. There has been a problem that an interfering electromagnetic wave (noise) generated by an internal CPU or a power supply is mixed into a low-noise amplifier, thereby deteriorating the measurement accuracy during high-sensitivity measurement.

A system for measuring only a relatively high signal level (normal level measurement system) does not require the high-gain high-frequency amplification stage. This high gain, high frequency amplification stage is generally expensive. Therefore, in order to realize a normal level measurement system with an inexpensive and optimal configuration, it is necessary to separately prepare different types of selected level measurement modules (normal level selection level measurement modules) having low-gain and inexpensive high-frequency amplification stages. was there.

There is another problem that the measurement level range cannot be switched at a high speed.

In the conventional wideband selection level measurement system, a resistance divider is generally used as a divider in order to divide a broadband measurement frequency range. However, a distribution loss is large (6 dB in two distributions). There is a problem that the measurement sensitivity is deteriorated by the loss.

In addition, when high sensitivity measurement is performed simultaneously using a plurality of selection level measurement modules, there is a problem that the measurement level accuracy is degraded due to the frequency deviation of the total gain of the low noise amplifier (preamplifier unit) and individual differences. .

The present invention solves the above-mentioned conventional problems, and enables high-accuracy, high-sensitivity measurement, high-speed switching of the measurement level range, and simultaneous or high-speed measurement of wide-band signals. The purpose of the present invention is to provide a selection level measurement system capable of performing the measurement with a minimum necessary configuration.

[0013]

Therefore, in the selection level measurement system of the present invention, an electromagnetically shielded preamplifier is selected to prevent CPU noise from being mixed into the preamplifier and to enable high-sensitivity measurement. The level measurement module and the CPU are arranged outside a housing containing the CPU.

In order to simultaneously measure a plurality of measurement frequency ranges with high sensitivity, one low-noise amplifier corresponding to the measurement frequency ranges of the plurality of selected level measurement modules is built in the preamplifier unit.

Further, in order to switch the measurement level range at a high speed, the preamplifier has a through function for passing the measurement signal without passing through the low noise amplifier.

Further, in order to realize high-accuracy level measurement, a memory device is incorporated in the preamplifier unit and a correction table is provided.

Therefore, a highly accurate selection level measurement system can be realized with a simple configuration.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 of the present invention relates to a measurement system including a selection level measurement module having a selection level measurement function and a CPU. A preamplifier section for amplifying the measurement signal is provided outside the body, thereby preventing CPU noise from being mixed into the preamplifier section and enabling high-sensitivity measurement. Further, by separating the preamplifier unit, the preamplifier unit can be removed in the normal level measurement mode, and the mode transition between the high sensitivity measurement mode and the normal level measurement mode can be easily performed.

According to a second aspect of the present invention, the preamplifier is electromagnetically shielded.
The effects of PU noise can be completely eliminated.

According to a third aspect of the present invention, a plurality of selection level measurement modules corresponding to a plurality of different measurement frequency ranges are provided as selection level measurement modules, and a preamplifier section is provided for a plurality of different measurement frequency ranges. It is provided with two preamplifiers, and it is possible to simultaneously measure a plurality of frequency ranges with high sensitivity.

According to a fourth aspect of the present invention, the preamplifier is provided with a low noise amplifier for amplifying the measurement signal and a distribution means for distributing the output of the low noise amplifier to a plurality of select level modules. By supplying the output of the distribution means to each of the selected level measurement modules, it becomes possible to simultaneously measure a plurality of frequency ranges with high sensitivity.

According to a fifth aspect of the present invention, an antenna duplexer is provided as a distributing means, so that a plurality of frequency ranges can be measured simultaneously with high sensitivity.

According to a sixth aspect of the present invention, in the preamplifier, an antenna duplexer for dividing a measurement signal into a plurality of measurement signals in different measurement frequency ranges, and a plurality of amplifying each measurement signal divided by the antenna duplexer are provided. And a high-sensitivity measurement in a plurality of frequency ranges simultaneously.

According to a seventh aspect of the present invention, the preamplifier has a function of passing a measurement signal without passing through a low-noise amplifier, so that the high-sensitivity measurement mode and the normal level measurement mode can be switched at high speed. Can be switched.

According to an eighth aspect of the present invention, a plurality of levels corresponding to both a first mode in which a measurement signal is amplified by a low-noise amplifier and a second mode in which a measurement signal passes without passing through a low-noise amplifier are provided in a preamplifier section. A correction table is provided, and the level measurement result is corrected by the plurality of level correction tables, so that a highly accurate measurement result can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) As shown in FIG. 1, a selection level measuring system according to a first embodiment has an input terminal
A preamplifier 1 for amplifying an input signal from the module with low noise and outputting the signal, a selected level measuring module 2 for measuring a level of a signal input from a module input terminal 12, an internal control of the selected level measuring module 2, and a processing of output data And a selection level measurement module 2 and C
A housing 4 with a built-in PU 3 and a display unit for displaying measurement results
11 and are provided.

The measurement frequency range of this selection level measurement system will be described as, for example, 1 to 1000 MHz.

The preamplifier unit 1 has a low noise amplifier 6 built in an electromagnetically shielded housing, amplifies the input signal from the input terminal 5 with low noise, and outputs the amplified signal to the module input terminal 12. The low noise amplifier 6 is, for example, an MMI
The gain (G1) is set to about 13 dB and the noise figure (NF1) is set to about 4 dB in a frequency range of 1 to 1000 MHz. The preamplifier unit 1 is disposed outside a housing 4 containing a selection level measurement module 2 and a CPU 3.

The selection level measuring module 2 includes a CPU 3
And a local oscillator 7, a frequency converter 8 and a level detector 9. The local oscillator 7
It is composed of a PLL synthesizer and a voltage controlled oscillator,
The oscillation frequency can be swept by the control signal 10 from the CPU 3. Further, the frequency conversion unit 8 mixes the input signal input from the module input terminal 12 with the local oscillation signal input from the local oscillation unit 7 and converts it to an intermediate frequency. The level detector 9 detects the output level of the frequency converter 8.

The CPU 3 controls the local oscillation frequency output from the local oscillator 7 and processes the output data of the level detector 9.

The display section 11 displays the frequency controlled by the CPU 3 and the detection result of the intermediate frequency level detection section 9.

As described above, the selection level measurement module 2
Operates to measure the level of a signal in the measurement frequency range (1 to 1000 MHz) input from the module input terminal 12.

In this selection level measurement system, the detection level range of the selection level measurement module 2 is, for example, -100 to -30 dBm, the minimum detection level (sensitivity: S2) is -100 dBm, and the selection level measurement is performed. The total noise figure (NF2) of module 2 is 11
Let it be dB. This is the level detection performance in the normal level measurement mode.

In the high sensitivity measurement mode, by connecting the preamplifier 1 to the outside, the level detection performance of the entire selected level measurement system is improved. From the noise figure (NF1 = 4 dB) and the gain (G1 = 13 dB) of the low-noise amplifier 6 of the preamplifier unit 1, the noise figure (NFtotal) of the overall selected level measurement system is NFtotal = NF1 + (NF2-1) / G1 = 5 dB (1).

Here, assuming that the bandwidth (BW) of the selected level measurement system is 15 kHz and the carrier-to-signal ratio (C / N) required for level detection is 10 dB, the input-converted noise level (Pn) is Pn = 10Log [KT BW] + C / N + NFtotal = −117 dBm (2) (K: Boltzmann constant, T: absolute temperature, [KT BW
] Indicates the product of K, T, and BW.) The detection level range in the high sensitivity measurement mode is the low noise amplifier 6
Is -113 to -43 dBm
Becomes Since this is a level higher than the input-converted noise level shown in Expression (2), the minimum detection level (sensitivity:
S1) becomes -113 dBm. That is, the selection level measurement module 2 connects the preamplifier 1 to
A highly sensitive measurement in dB can be performed.

In general, the CPU 3 radiates an interfering electromagnetic wave (noise) having a frequency of several tens to several hundreds of MHz to cause interference to other circuits inside the housing 4, and the degree of the interference depends on the signal level handled by the circuit to be interrupted. The lower the is, the more serious the problem. For example, the minimum signal level handled by the selected level measurement module 2 in the normal level measurement mode is -100 dBm as described above, and the electromagnetic interference (noise) generated by the CPU 3 does not matter. However, in the high sensitivity measurement mode, the minimum signal level handled is-
113 dBm, which often causes a problem when interfering electromagnetic waves (noise) generated by the CPU 3 are mixed.

However, in the selection level measurement system shown in FIG. 1, the preamplifier 1 is disposed outside the housing 4 as an electromagnetically shielded structure, so that the interfering electromagnetic wave (noise) generated from the CPU 3 is prevented from being mixed. can do.

Further, by providing the preamplifier unit 1 as a separate case connected to the outside of the case 4, the preamplifier unit 1 can be easily removed, and the transition from the high sensitivity measurement mode to the normal level measurement mode and vice versa. Migration is easy.

As described above, in the selection level measurement system according to the first embodiment, it is possible to prevent the CPU noise from being mixed into the preamplifier unit and to perform the high sensitivity measurement with high accuracy. Mode transition between the mode and the normal level measurement mode can be easily performed.

(Second Embodiment) A selection level measurement system according to a second embodiment includes two selection level measurement modules 2-1 and 2-2 in a housing 4 as shown in FIG. ,
Further, a distributor for distributing the output of the low-noise amplifier 6 to two selected level measurement modules 2-1 and 2-2 in the preamplifier unit 1.
13 built-in. In FIG. 2, components denoted by the same reference numerals as those in FIG. 1 perform the same operations.

In this selection level measurement system, for example, the measurement frequency range of the selection level measurement module 2-1 is 1 to 1000 MHz, and the selection level measurement module 2-
The measurement frequency range of 2 is 1000 to 2000 MHz.

The distributor 13 is housed in an electromagnetically shielded housing together with the low-noise amplifier 6, and converts the input signal, which has been low-noise amplified by the low-noise amplifier 6, into selection level measurement modules 2-1 and 2-2.
Distribute to The distributor 13 generally causes a distribution loss. For example, the distribution loss (Ld) is set to 6 dB. Further, the low-noise amplifier 6 is formed of, for example, an MMIC, and generally shows a flat frequency characteristic with a flat gain and noise figure in a relatively narrow bandwidth (about 1000 MHz). However, a wide bandwidth (2
(About 000 MHz), it is difficult to obtain a flat frequency characteristic, and the gain and the noise figure generally tend to deteriorate in a high frequency region.

Here, the characteristic of the low noise amplifier 6 is, for example, a gain (G3) in a frequency range of 1 to 1000 MHz.
13 dB, noise figure (NF3) of about 4 dB, and gain (G
4) Assume 12 dB and noise figure (NF4) 5 dB.

In this selection level measurement system, the detection level range of the selection level measurement modules 2-1 and 2-2 is, for example, -100 to -30 dBm, the minimum detection level is -100 dBm, and the selection level is The total noise figure (NF2) of the measurement modules 2-1 and 2-2 is 1
It is assumed that it is 1 dB. This is the level detection performance in the normal level measurement mode.

In the high sensitivity measurement mode, the level detection performance of the entire selected level measurement system is improved by connecting the preamplifier 1 to the outside. Therefore,
The total noise figure (NFtotal2) of the selected level measurement system in the frequency range of 1 to 1000 MHz is NFtotal2 = NF3 + (NFLd-1) / G3 + (NF2-1) / (G3 · Ld) = 7 dB (3) (NFLd: Noise figure of the distributor).

The frequency range is 1000 to 2000M.
The total noise figure (NFtotal3) of the selected level measurement system in Hz is NFtotal3 = NF4 + (NFLd-1) / G4 + (NF2-1) / (G4.Ld) = 8 dB (4)

Here, assuming that the bandwidth (BW) of the selected level measurement system is 15 KHz and the carrier-to-signal ratio (C / N) required for level detection is 10 dB, the input converted noise level (Pn) in the frequency range of 1 to 1000 MHz.
2) and the input conversion noise level (Pn3) in the frequency range of 1000 to 2000 MHz is: Pn2 = 10Log [KTBW] + C / N + NFtotal2 = -115dBm (5) Pn3 = 10Log [KTBW] + C / N + NFtotal3 = -114dBm (6) Becomes

The detection level range in the high-sensitivity measurement mode is as follows. In the frequency range of 1 to 1000 MHz, the total gain of the pudding amplifier unit 1 is 7 dB (= 13−6).
In the frequency range of 107 to -37 dBm and the frequency range of 1000 to 2000 MHz, the total gain of the pudding amplifier unit 1 is 6 dB (= 12-6), so
36 dBm. Therefore, the frequency range 1 to 10
The minimum detection level at 00 MHz is -107 dBm,
The minimum detection level in the frequency range of 1000 to 2000 MHz is -106 dBm.

As described above, the selection level measurement module 2-
1 and 2-2 are 7 to 6 by connecting the preamplifier unit 1.
A highly sensitive measurement in dB can be performed. In addition, the input signal is supplied from the distributor 13 to the selected level measurement modules 2-1 and 2
-2, the input signal is selected using the selected level measurement modules 2-1 and 2-2, and the frequency range is 1 to 1000M.
Hz signal and a signal in the frequency range of 1000 to 2000 MHz can be measured simultaneously.

As described above, in the selection level measurement system according to the second embodiment, by incorporating the distributor in the preamplifier section, it is possible to simultaneously measure a plurality of frequency ranges with high sensitivity.

In this embodiment, the number of selection level measurement modules is two. However, the present invention is not limited to this, and the same effect can be obtained if the number of selection level measurement modules is three or more.

(Third Embodiment) In a selection level measuring system according to a third embodiment, as shown in FIG. 3, the output of the low noise amplifier 6 is distributed in the preamplifier 1 by dividing the frequency band. An antenna duplexer 14 is provided. In FIG. 3, components denoted by the same reference numerals as those in FIG. 2 perform the same operations.

In this selection level measurement system, for example, the measurement frequency range of the selection level measurement module 2-1 is 1 to 1000 MHz, and the selection level measurement module 2-
The measurement frequency range of 2 is 1400 to 2400 MHz.

This selection level measurement system is obtained by replacing the distributor 13 in the selection level measurement system shown in FIG. Antenna duplexer 14
Is configured by combining a band-pass filter, transmits a signal in a frequency range of 1 to 1000 MHz to the selection level measurement module 2-1, and outputs a signal in a frequency range of 1400 to 240 MHz.
It operates to transmit the 0 MHz signal to the selected level measurement module 2-2. The antenna duplexer 14 generally has a small transmission loss of about 1 dB or less. Here, for the sake of explanation, this transmission loss will be ignored.

In this selection level measurement system, as in FIG. 2, when the noise figure (NF3) of the low noise amplifier 6 is 4 dB and the gain (G3) is 13 dB in the frequency range of 1 to 1000 MHz, the frequency range is 1 to 100.
The total noise figure (NFtotal4) of the selected level measurement system at 0 MHz is NFtotal4 = NF3 + (NF2-1) / G3 = 5 dB (7) In addition, a frequency range of 1400 to 2400 MHz
The noise figure (NF5) of the low noise amplifier 6 is 5d
B, if the gain (G5) is 12 dB, the frequency range 14
The total noise figure (NFtotal5) of the selected level measurement system at 00 to 2400 MHz is NFtotal5 = NF5 + (NF2-1) / G5 = 6 dB (8). Here, the bandwidth of the selected level measurement system (B
If W) is 15 KHz and the carrier-to-signal ratio (C / N) required for level detection is 10 dB, the frequency range is 1 to 1.
The input converted noise level (Pn4) at 000 MHz and the input converted noise level (Pn5) in the frequency range of 1400 to 2400 MHz are as follows: Pn4 = 10Log [KTBW] + C / N + NFtotal4 = -117dBm (9) Pn5 = 10Log [KTBW] + C / N + NFtotal5 = -116 dBm (10)

Therefore, the detection level range in the high sensitivity measurement mode is -113 to -113 since the total gain of the preamplifier 1 is 13 dB in the frequency range of 1 to 1000 MHz.
43 dBm. This is a level higher than the input-converted noise level shown in the equation (9), so that the frequency range 1
The minimum detection level from -1000 MHz is -113 dBm
It is. In addition, a frequency range of 1400 to 2400 MHz
Since the total gain of the preamplifier is 12 dB, the detection level range is -112 to -42 dBm. This is a level higher than the input-converted noise level shown in Expression (10), so that the frequency range is 1400 to 2400.
The minimum detection level at 400 MHz is -112 dBm.

Therefore, the selection level measurement module 2-
For 1 and 2-2, by connecting the preamplifier unit 1, measurement with high sensitivity of 13 to 12 dB can be performed. Further, since the input signal is distributed to the selection level measurement modules 2-1 and 2-2 by the antenna duplexer 14, the input signal is divided into frequency ranges of 1 to 1000 MHz using the selection level measurement modules 2-1 and 2-2. Signal and frequency range 1400 to 24
A signal of 00 MHz can be measured simultaneously.

As described above, in the selection level measuring system according to the third embodiment, by incorporating the antenna duplexer in the preamplifier section, it is possible to simultaneously measure a plurality of frequency ranges with high sensitivity.

In this embodiment, the number of selection level measurement modules is two. However, the present invention is not limited to this, and the same effect can be obtained if three or more selection level measurement modules are used.

(Fourth Embodiment) As shown in FIG. 4, a selection level measuring system according to a fourth embodiment is an antenna duplexer for distributing an input signal in a frequency band in a preamplifier 1. 14 and two low-noise amplifiers 6-1 and 6-2 for amplifying the output of the antenna duplexer 14. In FIG. 4, components denoted by the same reference numerals as those in FIG. 3 perform the same operations.

In this selection level measurement system, the measurement frequency range of the selection level measurement module 2-1 is 1 to 1000 MHz, as in FIG.
The measurement frequency range of 2-2 is set to 1400 to 2400 MHz.

The low noise amplifiers 6-1 and 6-2 are connected to the antenna duplexer 14 at 1 to 1000 MHz and 1400 to 2400 MHz.
It operates to amplify the input signal distributed to the frequency band of Hz with low noise and to input the amplified signal to the selected level measurement modules 2-1 and 2-2. The operating frequency range of the low noise amplifier 6-1 is 1
To 1000 MHz, and the operating frequency range of the low noise amplifier 6-2 is set to 1400 to 2400 MHz.

The low noise amplifiers 6-1 and 6-2 are, for example, MMI
C and generally has a relatively narrow bandwidth (1000 MH
z), the gain and the noise figure show flat frequency characteristics. The characteristic of the low noise amplifier 6-1 is, for example, a frequency range 1
The gain (G6) is 13 dB from to 1000 MHz,
The noise figure (NF6) is about 4 dB, and the characteristics of the low noise amplifier 6-2 are, for example, in a frequency range of 1400 to 2400.
At 400 MHz, the gain (G7) is 13 dB and the noise figure (NF7) is 4 dB.

In this selection level measurement system, as in FIG. 3, the total noise figure (NFtotal) of the selection level measurement system in the frequency range of 1 to 1000 MHz.
6) is NFtotal6 = NF6 + (NF2-1) / G6 = 5 dB (11), and the frequency range is 1400 to 2400 MHz.
Noise figure (NF)
total7) is NFtotal7 = NF7 + (NF2-1) / G7 = 5 dB (12) Similarly, the input conversion noise level (Pn6) in the frequency range 1 to 1000 MHz and the frequency range 14
The input conversion noise level (Pn7) at 00 to 2400 MHz is as follows: Pn6 = 10Log [KTBW] + C / N + NFtotal6 = -119dBm (13) Pn7 = 10Log [KTBW] + C / N + NFtotal7 = -119dBm (14)

The minimum detection level in the frequency range 1 to 1000 MHz is -113 dBm, and the frequency range 1
The minimum detection level at 400 to 2400 MHz is-
113 dBm, which is equal.

As described above, in the selection level measurement system according to the fourth embodiment, a measurement signal is input to a plurality of low-noise amplifiers via an antenna duplexer, so that a plurality of frequency ranges can be simultaneously measured with high sensitivity. Becomes possible.

In this embodiment, the number of selection level measurement modules is two, but the present invention is not limited to this, and the same effect can be obtained if three or more are used.

(Fifth Embodiment) In the selection level measurement system according to the fifth embodiment, as shown in FIG. 5, whether the input signal is passed through the low noise amplifier 6 to the preamplifier unit 1 (high sensitivity measurement mode). Two high-frequency switches 15 and 16 for selecting whether or not to pass (normal level measurement mode) are provided. The housing 4 includes a selection level measurement module 2 and a CPU 3 for controlling selection of the high-frequency switches 15 and 16. Is built-in. In FIG. 5, components denoted by the same reference numerals as those in FIG. 1 perform the same operations.

The high frequency switches 15 and 16 are, for example, GaAs
It is composed of sMMIC or PIN diode. The input signal is selected by the high frequency switch 15 and transmitted to either the low noise amplifier 6 or the high frequency switch 16. The high-frequency switch 16 operates to select the output of the low-noise amplifier 6 or the output of the high-frequency switch 15 and input the selected output to the selected level measurement module 2.

The high frequency switches 15 and 16 are controlled by a control signal 17 from the CPU 3 and set to a high sensitivity measurement mode or a normal level measurement mode.

Here, in the high sensitivity measurement mode, the input signal is transmitted through the low noise amplifier 6 to the selected level measurement module 2.
Is input to In the normal level measurement mode, the input signal is input to the selected level measurement module 2 without passing through the low noise amplifier 6. Generally, when a high-frequency switch is inserted, an insertion loss occurs. For example, the operation will be described below with an insertion loss (IL) of 1 dB.

In this selected level measurement system, the total noise figure (NFtotal 8) of the selected level measurement system when the high frequency switches 15 and 16 are switched to the high sensitivity measurement mode is the gain of the low noise amplifier 6 as in FIG. (G
8) is 13 dB, noise figure (NFtotal8 since NF8) is 4dB = NFIL + (NF8-1) / IL + (NFIL-1) / (G8 · IL) + (NF2-1) / (G8 · IL 2) = 6 dB (15) (NFIL is the noise figure of the high-frequency switch). When the high-frequency switches 15 and 16 are switched to the normal level measurement mode, the total noise figure (NF
Total9) becomes NFtotal9 = NFIL + (NFIL-1 ) / IL + (NF2-1) / IL 2 = 13dB (16). Similarly, the input-converted noise level (Pn8) when switching to the high-sensitivity measurement mode and the input-converted noise level (Pn9) when switching to the normal level measurement mode are: Pn8 = 10Log [KTBW] + C / N + NFtotal8 = -116dBm (17) Pn9 = 10Log [KT BW] + C / N + NFtotal9 = -109dBm (18) Here, when the high frequency switches 15 and 16 are switched to the high sensitivity measurement mode, the total gain of the preamplifier 1 is 11dB.
(= 13-2), the measurable detection level range is from -111 to -41 dBm. This is given by equation (1)
Since the level is higher than the input-converted noise level shown in 7), the minimum detection level when switching to the high-sensitivity measurement mode is -111 dBm. In addition, the high-frequency switch 15 and
When 16 is switched to the normal level measurement mode, since the total loss of the preamplifier 1 is 2 dB (= 1 + 1), the measurable detection level range is -98 to -28 dBm. Since this is a level higher than the input conversion noise level shown in Expression (18), the minimum detection level when switching to the normal level measurement mode is -98 dBm.

Therefore, by switching the high-frequency switch by the control signal 17 from the CPU 3, the measurement level range can be quickly switched from the normal level measurement mode of -98 to -28 dBm to the high sensitivity measurement mode of -111 to -41 dBm. . In addition, the high-speed switching from the high-sensitivity measurement mode to the normal level measurement mode is also possible.

As described above, in the selection level measurement system according to the fifth embodiment, the preamplifier section has a through function for passing the measurement signal without passing through the low noise amplifier, so that the measurement level range can be switched at high speed. Will be possible.

In this embodiment, the number of selection level measurement modules is one. However, the present invention is not limited to this, and the same effect can be obtained if two or more are selected. (Sixth Embodiment) Sixth Embodiment As shown in FIG. 6, in the selected level measurement system of the embodiment, the preamplifier 1 stores a correction table 19 for storing the frequency characteristics of the total gain in the high sensitivity measurement mode and the frequency characteristics of the total gain in the normal level measurement mode. And a memory device 18 having a correction table 20 to be used. In FIG. 6, components denoted by the same reference numerals as those in FIG. 5 perform the same operations.

The memory device 18 is generally composed of a rewritable semiconductor memory such as an EEPROM, and the correction tables 19 and 20 written in the memory device 18 are
It is read by the signal 21 from U3.

In this selection level measuring system, the preamplifier unit 1 comprises a low noise amplifier 6 and high frequency switches 15 and 16. Generally, the low-noise amplifier 6 and the high-frequency switches 15 and 16 have a frequency characteristic of gain having a deviation of about 1 to 3 dB, and the total gain of the preamplifier 1 also has a deviation. In addition, there is an individual difference in the total gain among a plurality of preamplifier units 1 designed in the same manner.

Here, for example, the frequency characteristic of the total gain in the high-sensitivity measurement mode of the preamplifier 1 is corrected by a correction table.
19 and the frequency characteristic of the total gain of the preamplifier 1 in the normal level measurement mode is stored in the correction table 20. For example, when the high-frequency switch is switched to the high-sensitivity measurement mode and measurement is being performed, the CPU 3 operates to read the correction table 19 via the signal 21 and correct the level measurement result. Similarly, even when level measurement is performed in the normal level measurement mode, C
The PU 3 operates to read the correction table 20 and correct the level measurement result.

With the above configuration, the frequency characteristics of the measurement level can be flattened and the measurement accuracy can be improved. Further, individual differences in the total gain of the plurality of preamplifiers 1 can be absorbed, and the measurement accuracy can be improved.

As described above, in the selected level measurement system according to the sixth embodiment, the memory device is built in the preamplifier and the correction table is provided, so that highly accurate level measurement can be performed.

[0082]

As is apparent from the above description, in the selection level measurement system of the present invention, the preamplifier for amplifying the measurement signal is provided outside the housing containing the selection level measurement module and the CPU. Thus, high sensitivity measurement can be performed while preventing CPU noise from being mixed into the preamplifier section. Further, by doing so, it is possible to realize a selection level measurement system with a simple configuration in which the mode transition between the high sensitivity measurement mode and the normal level measurement mode is easy.

Further, by incorporating a distributor in the preamplifier section, it is possible to realize a selection level measurement system capable of simultaneously measuring a plurality of frequency ranges with high sensitivity with a simple configuration.

Further, by incorporating a duplexer in the preamplifier, a selective level measurement system capable of simultaneously measuring a plurality of frequency ranges with high sensitivity can be realized with a simple configuration.

Further, by inputting a measurement signal to a plurality of low noise amplifiers via an antenna duplexer, a selection level measurement system capable of simultaneously measuring a plurality of frequency ranges with high sensitivity can be realized.

Further, by providing the preamplifier with a through function for passing the measurement signal without passing through the low noise amplifier, a selection level measurement system capable of switching the measurement level range at high speed can be realized with a simple configuration. .

In addition, by providing a memory device in the preamplifier unit and providing a correction table, it is possible to realize a selection level measurement system capable of performing highly accurate level measurement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a selection level measurement system according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a selection level measurement system according to a second embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a selection level measurement system according to a third embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of a selection level measurement system according to a fourth embodiment of the present invention;

FIG. 5 is a block diagram showing a configuration of a selection level measurement system according to a fifth embodiment of the present invention;

FIG. 6 is a block diagram illustrating a configuration of a selection level measurement system according to a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Preamplifier part 2 Selection level measurement module 3 CPU 4 Housing 5 Input terminal 6 Low noise amplifier 7 Local oscillation part 8 Frequency conversion part 9 Level detection part 10 Control signal 11 Display part 12 Module input terminal 13 Distributor 14 Antenna duplexer 17 Control signal 15, 16 High frequency switch 18 Memory device 19, 20 Correction table

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tohru Okada 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture Inside Matsushita Communication Industrial Co., Ltd. No.3-1, Matsushita Communication Industrial Co., Ltd. F-term (reference) 2G035 AA08 AB10 AB13 AC20 AD00 AD28 AD51 AD53

Claims (8)

[Claims] 1. A measurement system comprising a selection level measurement module having a selection level measurement function and a CPU, wherein a preamplifier unit for amplifying a measurement signal is provided outside a housing containing the selection level measurement module and the CPU. A selection level measurement system, comprising: 2. The selection level measurement system according to claim 1, wherein said preamplifier is electromagnetically shielded. 3. As the selection level measurement module,
It comprises a plurality of selection level measurement modules corresponding to a plurality of different measurement frequency ranges, and as the preamplifier section,
3. The apparatus according to claim 1, further comprising one preamplifier unit corresponding to the plurality of different measurement frequency ranges.
Selection level measurement system according to. 4. The preamplifier unit according to claim 3, further comprising: a low noise amplifier for amplifying a measurement signal; and a distribution unit for distributing an output of the low noise amplifier to a plurality of selected level modules. The selected level measurement system described. 5. The selection level measurement system according to claim 4, wherein an antenna duplexer is provided as said distribution means. 6. An antenna duplexer for dividing a measurement signal into a plurality of measurement signals in different measurement frequency ranges, and a plurality of low-noise amplifiers for amplifying each of the measurement signals divided by the antenna duplexer. The selection level measurement system according to claim 3, comprising: 7. The selection level measurement system according to claim 1, wherein the preamplifier has a function of passing a measurement signal without passing through a low noise amplifier. 8. The preamplifier section includes a plurality of level correction tables corresponding to both a first mode in which a measurement signal is amplified by a low-noise amplifier and a second mode in which the measurement signal passes without passing through a low-noise amplifier. 9. The selected level measurement system according to claim 7, wherein a level measurement result is corrected using the plurality of level correction tables.