JP4153938B2 - Adjacent channel leakage power ratio measuring apparatus and measuring method - Google Patents

Description

  The present invention relates to a measurement apparatus and a measurement method related to adjacent channel leakage power ratio measurement.

  In recent years, with rapid development of technologies related to mobile communication, FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), and CDMA (Code Division Multiple Access) Various communication methods such as the division multiple access method have been used. One of the important standards for this digital communication system transmitter is the measurement of adjacent channel leakage power ratio (hereinafter referred to as ACLR).

  FIG. 8 is an explanatory diagram for explaining the flow of processing in a reference configuration which is a reference for understanding the present invention, and shows a frequency spectrum in a transmission channel of horizontal axis frequency and vertical axis power. Usually, the frequency spectrum of the transmission wave of the transmitter spreads like a skirt as shown in FIG. 8 due to distortion and noise components, and becomes leakage power to adjacent channels separated by Δf. This leakage power becomes an interference power component for a receiver that receives an adjacent channel. ACLR measurement is one of the standards defined to reduce interference with adjacent channels. Further, the ACLR measurement is to measure the ratio between the power of the transmission channel (f = Fc) and the leakage power of each adjacent channel (f = Fc ± Δf). In particular, in W-CDMA, the power ratio of Fc ± 2Δf is measured. Also measure.

  In order to accurately measure the ACLR measurement as the respective leakage power ratio in the upper and lower measurement bands in accordance with the standard, a measuring instrument having various filter functions capable of removing image frequency components, such as a spectrum analyzer, etc. Need to use.

  For example, Patent Document 1 discloses a measuring apparatus and measuring method for adjacent channel leakage power of a transmitter using a digital signal processing technique. According to Patent Document 1, the ACLR measurement processing method multiplies the signal under measurement by the frequency of the local oscillator by a frequency converter, and converts it into an IF signal as a sum signal or a difference signal.

  Next, the converted IF signal is passed through a band limiting filter, and only the signal of interest is extracted. The A / D converter converts the signal from an analog signal to a digital signal. Further, it is shown that the power of the main wave and the power of the adjacent channel are calculated by the DSP from the converted digital signal to calculate the ACLR.

JP-A-8-15353

  However, when the above-described frequency conversion unit is realized, parts such as a multi-stage local oscillator, a frequency converter, and a filter are required to remove the image frequency component, and the circuit configuration and the frequency configuration become complicated. There is a problem that becomes larger.

  Conventionally, when measuring ACLR in manufacturing or maintenance of a mobile radio communication device, an expensive measuring instrument such as a spectrum analyzer has to be prepared even if it can be determined whether the standard is OK or NG. It was.

In order to solve the above problems, the adjacent channel leakage power ratio measuring apparatus according to the present invention calculates the power ratio between the transmission channel signal output from the transmitter and the signal mixed in the adjacent channel of the transmission channel. In an adjacent channel leakage power ratio measurement device that measures and measures the performance of a transmitter, a frequency converter that down-converts an RF band signal output from the transmitter into an IF band signal , and removes unnecessary frequency components A low-pass filter, an A / D converter that converts an analog signal from the low-pass filter into a digital signal, and a digital signal converted by the A / D converter, the power of the transmission channel and the power of the adjacent channel are measured and transmitted. The leakage between the channel power and the adjacent channel power, which is the combined power of the upper and lower transmission bands of the transmission channel frequency. It includes a calculator for calculating a power ratio, a frequency converter, in order to detect the power of the transmission channel, with respect to the frequency of the signal output from the transmitter, at least 2 of the modulation frequency band of the measurement signal Transmission channel frequency conversion means that sets the local oscillator and downconverts after adding a frequency that is lower or higher by a frequency more than double, and the same frequency as the signal output from the transmitter to detect the power of the adjacent channel And an adjacent channel frequency converting means for down-converting by setting the local oscillator as a local oscillator.

Here, a simple ACLR measurement that is an adjacent channel leakage power ratio measurement according to the present invention is referred to as an ACLR DSB (Double Side Band) measurement in contrast to the conventional ACLR measurement. In this simple ACLR measurement , it is possible to easily measure the average power value of the upper measurement zone and the lower measurement zone by halving the combined measurement value.

Furthermore, in the simple adjacent channel leakage power ratio measuring apparatus according to the present invention, the calculation unit calculates a combined power average value of the upper measurement zone and the lower measurement zone by averaging the synthesized power values. It is characterized by. Here, the combined power average value is referred to as (ACLR DSB) / 2 measurement value.

The adjacent channel leakage power ratio measuring method according to the present invention measures the power ratio between the transmission channel signal output from the transmitter and the signal mixed in the adjacent channel of the transmission channel, and measures the performance of the transmitter. In the channel leakage power ratio measurement method, a frequency conversion step of down-converting an RF band signal output from a transmitter into an IF band signal , a low-pass filter step for removing unnecessary frequency components, and an analog from the low-pass filter step From the A / D conversion process for converting the signal into a digital signal and the digital signal converted in the A / D conversion process, the power of the transmission channel and the power of the adjacent channel are measured, and the power of the transmission channel and the frequency of the transmission channel are measured. Calculate the leakage power ratio between the adjacent channel power, which is the combined power of the upper and lower survey zones. It includes a calculation step, a frequency conversion process, in order to detect the power of the transmission channel, with respect to the frequency of the signal output from the transmitter, by at least 2-fold or more the frequency of the modulation frequency band of the measurement signal Set the local oscillator to the same frequency as the signal output from the transmitter in order to detect the power of the adjacent channel, and the transmission channel frequency conversion process to set the local oscillator and downconvert after adding low or high frequency And an adjacent channel frequency conversion step for down-conversion.

  Further, in the adjacent channel leakage power ratio measuring method according to the present invention, the calculating step calculates a combined power average value of the upper measurement zone and the lower measurement zone by averaging the synthesized power values. To do.

  Furthermore, the adjacent channel leakage power ratio measuring method according to the present invention simplifies the measurement of the adjacent channel leakage power measurement as the combined power ratio of the upper measurement band and the lower measurement band, thereby reducing the circuit scale required for the measurement. In a greatly simplified form, it is possible to accurately measure the ACLR measurement that combines the upper and lower measurement zones.

  When the present invention is used, the circuit configuration and frequency configuration of the analog circuit section are facilitated, and the circuit design is simplified. In addition, since the number of components such as a frequency converter and a filter can be reduced, the circuit can be physically reduced and the cost can be significantly reduced.

  In addition, the frequency band required for measurement of the IF signal to be measured is limited to a single measurement band (hereinafter referred to as both the measurement band and the single measurement band for both measurement bands). By using the set frequency band, the frequency band can be narrowed to ½ or less of the conventional frequency band. For this reason, since the digital signal processing speed can be lowered accordingly, it is easy to design the digital signal processing unit, and it is possible to reduce the cost of the digital unit.

  Hereinafter, a configuration (hereinafter referred to as a “reference configuration”) for reference in understanding the present invention and an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

1. Reference Configuration FIG. 5 is a configuration diagram showing the configuration of the measurement apparatus in the reference configuration. The reference configuration includes a frequency conversion unit 120 connected to a DUT 111 serving as an object to be measured such as a transmitter, an A / D conversion unit 131, a calculation unit 132 having a DSP, and a control unit 133 that controls them. ing. Furthermore, the frequency conversion unit 120 includes an image removal filter, a mixer, a local oscillator, and a filter, and the reference configuration is, for example, a three-stage frequency conversion unit.

  FIG. 6 is a flowchart showing the flow of processing in the reference configuration, and FIG. 7 is an explanatory diagram for explaining the flow of processing in the reference configuration. The processing flow will be described below with reference to FIGS. 5 and 7 based on the processing flow of FIG. In order to facilitate understanding, for example, a 2 GHz signal is used as an RF signal to be measured, and an IF signal is 20 MHz.

  The measured RF signal output from the DUT 111 is input to the frequency converter 120 of the adjacent channel leakage power ratio measuring apparatus 101 (step S30). First, unnecessary frequency components are removed from the signal by the image removal filter # 1 (115) and output to the mixer 121 (step S32). See S1 in FIG.

  Next, the IF1 local oscillator 112 having a frequency (for example, 2500 MHz) shifted from the measured RF signal (for example, 2000 MHz) and the frequency IF1 (for example, 500 MHz) outputs a sine wave to the mixer 121 (step S36). Frequency conversion by multiplication is performed (step S34), and a down-converted signal is output from the mixer 121 (step S38). See S2 and Conversion 1 in FIG.

  Next, in step S40, it is determined whether or not down-conversion has been achieved up to the IF frequency to be measured. If not reached, the process proceeds to step S38 to perform further down-conversion and returns to step S32 to perform similar processing.

  The converted IF signal 1 (for example, 500 MHz) passes through the image removal filter # 2 (116), and the IF2 local oscillator 113 having a frequency (for example, 800 MHz) shifted from the IF signal 1 (for example, 500 MHz) by a frequency IF2 (for example, 300 MHz). Is multiplied by the mixer 122 and converted to the IF signal 2 and output (steps S34 to S38). See S3, S4 and Transformation 2 in FIG.

  If it is determined in step S40 that the IF frequency to be measured is not down-converted, the processes in steps S32 to S38 are repeated again.

  The converted IF signal 2 (for example, 300 MHz) passes through the image removal filter # 3 (117), and the IF3 local oscillator 114 having a frequency (for example, 320 MHz) shifted from the IF signal 2 (for example, 300 MHz) by a frequency IF3 (for example, 20 MHz). Is multiplied by the mixer 123 to be converted into the IF signal 3 and output (steps S34 to S38). See S5, S6 and transformation 3 in FIG.

  The converted IF signal 3 (for example, 20 MHz) passes through a filter 124 that removes unnecessary frequency components, and is converted from an analog signal to a digital signal by the A / D converter 131.

  FIG. 8 is an explanatory diagram for explaining the flow of processing in the reference configuration, and shows the frequency spectrum of the IF signal 3 output from the frequency converter. The computing unit 132 calculates an ACLR measurement value from the obtained digital signal. In the ACLR calculation method, a digital filter (BPF) that extracts a transmission channel band from the obtained data is multiplied, and an average power calculation (square mean) of the obtained data is performed. Similarly, a band pass digital filter (BPF) that extracts data of the adjacent channel band to be measured is applied, and the average power of the obtained data is calculated, and this value is set to P1. P1-P (dB) is the ACLR measurement value of the adjacent channel in the upper measurement zone measured. Similar measurement is performed for other adjacent channels.

2. First Embodiment FIG. 1 is a configuration diagram showing a configuration of an adjacent channel leakage power ratio measuring apparatus 1 according to an embodiment of the present invention. In the present embodiment, a frequency conversion unit 20, an A / D conversion unit 31, a calculation unit 32 having a DSP, and a control unit 33 that controls these components are connected to the DUT 11 serving as an object to be measured such as a transmitter. I have. Further, the frequency converter 20 includes a mixer 22, a local oscillator 12, a frequency setting unit 13 for measuring a transmission channel, a frequency setting unit 14 for measuring an adjacent channel, and a filter 24. In addition, the circuit configuration of the frequency conversion unit is simplified compared to the reference configuration.

  The structure of the frequency converter 20 is such that a measured RF signal from the DUT 11 and a signal having the same frequency as the measured RF signal generated by the local oscillator 12 are added to the mixer 22. This makes it possible to directly extract the IF signal to be measured. Unnecessary frequency components are removed from the signal taken out using the filter 24 and converted from an analog signal to a digital signal by an A / D converter.

  FIG. 4 is an explanatory diagram illustrating the processing flow of the adjacent channel leakage power ratio measurement according to the embodiment of the present invention, and is an overview of the frequency spectrum obtained by the calculation unit. As shown in FIG. 4, when frequency conversion is performed with the frequency of the RF signal to be measured and the frequency of the local oscillator being the same, the upper measurement band and the lower measurement band are in the image frequency band. It becomes unnecessary. As a result, the combined power of the upper measurement zone and the lower measurement zone required for the ACLR DSB can be obtained by only one stage of frequency conversion.

  FIG. 2 is a flowchart showing a process flow of the adjacent channel leakage power ratio measurement according to the embodiment of the present invention. A specific ACLR DSB calculation process will be described with reference to FIG.

  First, in step S10, the measured RF signal (for example, 2000 MHz) input from the DUT 11 is acquired. Steps S12 and S24 are an iterative loop, and the power measurement of the transmission channel and the power measurement of the adjacent channel are performed by loop processing.

  First, the power of the transmission channel is measured. As shown in FIG. 4, since the power of the transmission channel is observed at DC (0 Hz), it is necessary to remove the influence of the DC offset. The IF signal is converted into an AC signal (for example, 7.8 MHz) in order to remove the influence of the DC offset most simply. As a result, noise components in the image frequency band are added, but since the power of the normal transmission channel is sufficiently larger than this noise component, in most cases there is no problem.

FIG. 3 is an explanatory diagram illustrating the processing flow of the adjacent channel leakage power ratio measurement according to the embodiment of the present invention, and is an overview of the frequency spectrum obtained by the calculation unit. As shown in FIG. 3, the transmission channel measurement oscillation frequency (for example, 2000 MHz + 7.8 MHz) is output to the mixer 22 with respect to the measured RF signal (step S16).

  In steps S14 and S18, the IF signal to be measured is acquired and band limiting processing is executed using the filter 24. In step S22, A / D conversion processing is performed, converted into a digital signal, and output to the arithmetic unit 32. . The computing unit 32 applies a band pass digital filter (BPF) that extracts the transmission channel signal, calculates the average power of the obtained data, and stores this value as P '(step S24).

Next, the process returns from the step S26 to the loop 12, and the combined power of the two measurement zones that are adjacent channel bands is obtained. The RF signal to be measured is output to the mixer 22 using the adjacent channel measurement oscillation frequency (for example, 2000 MHz) so as to convert the IF signal into a DC signal (step S16).

  Further, in steps S14 and 18, the IF signal to be measured is acquired and band limiting processing is executed using the filter 24. In step S22, A / D conversion processing is performed, converted into a digital signal, and the calculation unit 32 Output. The arithmetic unit 32 applies a band pass digital filter (BPF) that extracts the adjacent channel signal, calculates the average power of the obtained data, and stores this value as P1 '.

In step S24, P1′−P ′ (dB), which is the ACLR DSB of the adjacent channel, is calculated, and the average value of the upper measurement zone and the lower measurement zone (ACLR DSB) / 2 is half of the ACLR DSB measurement value. The obtained value (−3.01 dB) can be obtained. The process ends here. It intends row to the same measurements at the other adjacent channel.

  Hereinafter, as an example, measurement results of normal ACLR measurement, ACLR DSB measurement, and (ACLR DSB) / 2 measurement of this embodiment are shown in the W-CDMA standard format. According to the obtained results, it can be seen that simple measurement values of ACLR measurement are shown at detuning frequencies of 5 MHz and 10 MHz.

  As described above, by using this embodiment, the circuit configuration of the measuring apparatus can be greatly simplified, and the circuit design can be facilitated accordingly. Further, the circuit scale can be reduced, and the cost can be greatly reduced.

  Due to the simplification of the measurement method, it becomes the income of the measurement value as a guideline different from the format of the measurement value defined in the standard. However, in the normal production line and maintenance of mobile radio equipment, the standard is OK or NG It may be sufficient if it can be determined. In such a case, there is an effect that OK / NG can be determined without using an expensive spectrum analyzer.

  In the reference configuration and the present embodiment, specific numerical values are used for description, but the numerical values are not limited to these. It is obvious to those skilled in the art that these numerical values can take various values depending on circuit design and element characteristics to be used.

  In addition, although description has been made centering on W-CDMA from 800 MHz band to 2 GHz band related to cellular phones and the like, it is needless to say that the present invention is not limited to this and can be applied to other communication systems and frequency bands.

It is a block diagram which shows the structure of the adjacent channel leakage power ratio measuring apparatus which concerns on embodiment of this invention. It is the flowchart figure which showed the flow of the process of the adjacent channel leakage power ratio measurement which concerns on embodiment of this invention. It is explanatory drawing explaining the flow of the process of the adjacent channel leakage power ratio measurement which concerns on embodiment of this invention. It is explanatory drawing explaining the flow of the process of the adjacent channel leakage power ratio measurement which concerns on embodiment of this invention. It is a block diagram which shows the structure of the measuring apparatus in a reference structure. It is the flowchart figure which showed the flow of the process in a reference structure. It is explanatory drawing explaining the flow of the process in a reference structure. It is explanatory drawing explaining the flow of the process in a reference structure.

Explanation of symbols

  1,101 Adjacent channel leakage power ratio measuring device, 11,111 DUT, 12,112,113,114 Local oscillator, 13,14 Frequency setter, 20,120 Frequency converter, 22,121,122,123 Mixer, 24 , 124 filter, 31, 131 A / D conversion unit, 32, 132 calculation unit, 33, 133 control unit, 115, 116, 117 image removal filter #N.

Claims (4)

In the adjacent channel leakage power ratio measuring device that measures the power ratio between the transmission channel signal output from the transmitter and the signal mixed in the adjacent channel of the transmission channel, and measures the performance of the transmitter,
A frequency converter that down-converts an RF band signal output from the transmitter into an IF band signal ;
A low-pass filter that removes unnecessary frequency components;
An A / D converter that converts an analog signal from the low-pass filter into a digital signal;
The power of the transmission channel and the power of the adjacent channel are measured from the digital signal converted by the A / D conversion unit, and the adjacent power which is the combined power of the transmission channel power and the transmission channel frequency in the upper and lower measurement bands. A calculation unit for calculating the leakage power ratio of the channel power,
With
The frequency converter
In order to detect the power of the transmission channel, the frequency of the signal output from the transmitter is added with a frequency that is lower or higher by at least twice the modulation frequency band of the signal to be measured, and then applied to the local oscillator. A transmission channel frequency converting means for setting and down-converting;
In order to detect the power of the adjacent channel, and adjacent channel frequency converting means for down-converting the same frequency as the signal output from the transmitter is set to the local oscillator,
An adjacent channel leakage power ratio measuring apparatus comprising: In the adjacent channel leakage power ratio measuring apparatus according to claim 1,
The arithmetic unit calculates the combined power average value of the upper measurement band and the lower measurement band by averaging the combined power values, and the adjacent channel leakage power ratio measurement device. In the adjacent channel leakage power ratio measurement method for measuring the power ratio between the transmission channel signal output from the transmitter and the signal mixed in the adjacent channel of the transmission channel, and measuring the performance of the transmitter,
A frequency conversion step of down-converting an RF band signal output from the transmitter into an IF band signal ;
A low-pass filter process for removing unnecessary frequency components;
An A / D conversion step for converting an analog signal from the low-pass filter step into a digital signal;
From the digital signal converted in the A / D conversion process, the power of the transmission channel and the power of the adjacent channel are measured, and the power of the transmission channel and the power combined in the upper and lower measurement bands of the transmission channel frequency. A calculation step of calculating a leakage power ratio between adjacent channel power and
Including
The frequency conversion process
In order to detect the power of the transmission channel, the frequency of the signal output from the transmitter is added with a frequency that is lower or higher by at least twice the modulation frequency band of the signal to be measured, and then applied to the local oscillator. Transmission channel frequency conversion process to set and down-convert,
In order to detect the power of the adjacent channel, and adjacent channel frequency conversion process for down-converting the same frequency as the signal output from the transmitter is set to the local oscillator,
An adjacent channel leakage power ratio measurement method comprising: In the adjacent channel leakage power ratio measurement method according to claim 3,
The calculation step calculates the combined power average value of the upper measurement zone and the lower measurement zone by averaging the combined power values, and measures the adjacent channel leakage power ratio.

Images