JPH1010168A - Spectrum analyzer for measuring tdma wave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a spectrum analyzer for measuring TDMA wave having a wide frequency band and a robust gated sweep function by passing a trigger signal or a gate signal through a circuit for passing or delaying the signal by a specified time and the delivering the signal to a ramp voltage generator through a switch. SOLUTION: A down converter 30 comprises a mixer 31, a local oscillator 33 for trigger, and a BPF 32. An arbitrary burst wave taken out from the BPF 32 is fed to a trigger signal generation circuit 28 in order to generate a trigger at the edge of the burst wave. A variable delay circuit 36 can switch a path for passing a signal as it is and a path for delaying a signal by integer times of the burst width. A trigger signal or a gate signal p2 is fed to a ramp voltage generator 21 through a switch S1 for switching a continuous wave measurement and a TDMA (time division multiple path) wave measurement. This arrangement realizes a robust spectrum analyzer in which only 1 frequency can be selected among a wide band frequencies and can be processed at high sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TDMA (Time Division Multipl
The present invention relates to a spectrum analyzer used for analyzing and testing a burst wave (hereinafter, referred to as a “TDMA wave”) of the e Access (time division multiple access) system.

[0002]

2. Description of the Related Art In wireless telephone communication, digital mobile communication has recently been expanded, and TDMA wireless telephones, for example, automobile / mobile telephones and cordless telephones have been developed. Here, the TDMA system is a multiplex transmission communication system time-divided into the same carrier. For example, 800 MH as a carrier wave
PHS (Personal Haas) modulated and multiplexed with a digital audio signal using one frequency in the z band or the 1.9 GHz band.
ndyhorn System) and PDC (Personal Digital Cellul
ar). In these communication systems, the carrier frequency and the system system may be changed in the future.

[0003] First, referring to FIGS. 2A and 2B, T
A description will be given of a DMA wave. A transmission signal from each wireless telephone, that is, a transmission signal from the mobile device A is a burst wave a as shown in FIG. At the base station, for example, 800 MHz
1 carrier F ₁ to four mobile stations A band, B, C, D, 4 single modulation wave a from, b, c, multiplexed in a time division d, modulated wave a, b, c, d is It is transmitted alternately in chronological order.
A radio wave as shown in FIG.

Since the frequency deviation of radio waves, spurious emission intensity, occupied frequency band, adjacent channel leakage power, and the like are determined by the radio law according to the Radio Law and the enforcement regulations, it is necessary to measure and inspect them. Conventionally, spectrum analyzers have been used for spectrum analysis and tests of radio waves radiated from communication devices and the like. A spectrum analyzer can also be used for TDMA wave analysis.

As described above, the radio waves from the individual mobile units are burst waves modulated by the modulated wave a as shown in FIG. 2B. When this is observed by a normal sweep of the spectrum analyzer, the spectrum spreads at the rising and falling edges of the burst signal, so that the carrier wave F
_It is difficult to measure near ₂ spurious and noise components.
Therefore, the measurement is performed by using a spectrum analyzer to which a burst wave analysis function, that is, a gated sweep function is added, excluding the spread of the spectrum.

FIG. 2 shows the gated sweep function.
A gate signal as shown in FIG. 2C is applied to the burst wave of FIG. 2B to a ramp voltage generator of a spectrum analyzer to be described later, and a sweep is performed during a time period during which the burst wave signal is generated. The same measurement is performed as for the continuous wave. That is, as shown in FIG. 2C, only when the gate signal is turned on, the ramp voltage is increased to perform the frequency sweep.
As shown in (D), when the gate signal is off, the sweep is stopped. Overall, the frequency is swept as shown in FIG. 2 (E), and it is displayed as if it were a continuous wave signal. Is clearly displayed.

In the case of a continuous wave, the frequency deviation is usually measured using a frequency counter.
In the case of the MA wave, the output from the base station becomes a multiplex wave, and the output from the mobile station becomes a burst wave, so that it becomes difficult to measure with a frequency counter. Therefore, measurement can be easily performed by using a spectrum analyzer having a gated sweep function and a built-in frequency counter. Also in the modulation accuracy measurement, in the case of a TDMA wave, it can be easily measured by using a spectrum analyzer having a gated sweep function.

FIG. 3 shows a configuration diagram of an example of a conventional spectrum analyzer having a gated sweep function.
First, the configuration of the spectrum analyzer will be described with reference to FIG. The signal is input to the burst wave f7 input terminal 10 from the mobile device. The input signal f7 is an attenuator (ATT) 11
And attenuates it to an appropriate value of 0 _dbm or less, and _supplies it to the first mixer 12 for down-conversion. The other input terminal of the first mixer 12 receives a sweep signal f71 from a sweep oscillator 22 composed of a YTO (YIG oscillator), and outputs a first intermediate signal f72, which is a difference signal therebetween.

The first intermediate signal f72 is extracted by a band-pass filter or (BPF) 13, mixed with the signal f73 from the local oscillator 23 by the second mixer 14, and converted into a second intermediate frequency f74 of the difference signal. The second intermediate frequency f74 is mixed with a signal from the local oscillator 24 by the third mixer 15 and down-converted to a third intermediate frequency f76 that can perform signal processing. This third intermediate frequency f76 is
F16, logarithmically converts the amplitude of the signal by a log amplifier 17, amplifies the signal, converts the signal into a DC signal by a detector 18, and performs A / D conversion.
The data is converted into a digital value by the converter 19 and given to the display 20 as a Y-axis signal. The ramp voltage applied to the display 20 as an X-axis signal and to the sweep oscillator 22 is a ramp voltage generator 2
Generated by 1. The lamp voltage generator 21 is constituted by a D / A converter. The above is the configuration of the general spectrum analyzer.

The gated sweep function is to provide a third intermediate frequency f76 to the trigger signal generation circuit 28, generate a trigger signal at the time of rising and falling of the burst signal, and provide the same to the ramp voltage generator 21. This is to generate a lamp voltage. Alternatively, it can be set so that a gate signal is generated only in a section of a known burst wave from a trigger signal at the time of rising to generate a ramp voltage. This function includes at least a detector, a trigger circuit such as a Schmitt circuit, and a fixed-time pulse generator, and amplifies the burst wave with a linear amplifier if necessary. Although a trigger signal may be generated from the output signal of the detector 18, the sensitivity is degraded because the input signal is log-compressed by the log amplifier 17 at the preceding stage. The switch S1 is a switch for switching between continuous wave measurement and burst wave measurement.

[0011]

The above-described gated sweep function is very effective for a burst wave related to a frequency to be measured which is currently undergoing signal processing. However, the trigger signal generation circuit 28 is effective only for the same burst wave of the frequency to be measured. That is, the frequency band of the signal generating the trigger is very narrow. To extend this frequency band, although not shown, the input terminal 10
It is also conceivable to generate a trigger signal with a wide-band burst signal by directly using the wide-band detection circuit for the input signal f70 from. However, this is vulnerable to extraneous noise,
It is often not possible to predict when a trigger signal will or will not occur at another unintended frequency signal. Particularly in digital mobile communication, this possibility is high because other channels are also burst signals.

According to the present invention, a trigger signal or a gate to be applied to the ramp voltage generator is separately generated, a trigger signal is generated in synchronization with a predetermined burst wave, and is synchronized with a burst signal of a predetermined carrier frequency. It is intended to achieve a gated sweep function. Of course,
It synchronizes with the conventional burst signal of the frequency to be measured and also synchronizes with any other predetermined burst signal. This is because if the uplink frequency from the mobile station to the base station is different from the downlink frequency from the base station to the mobile station in the future, one T
The EMA wave measurement spectrum analyzer measures and inspects all TDMA waves.

[0013]

In order to achieve the above object, the present invention provides an input signal f70 which is appropriately attenuated by an ATT 11 and branches an input signal f70 input to a first mixer 12 to downconvert the input signal f70. A variable delay that extracts an arbitrary burst signal scheduled at the above at a reduced frequency capable of signal processing, generates a trigger signal with this burst signal, or generates a gate signal, and passes this trigger signal or gate signal or delays it for a fixed time The configuration is such that the voltage is applied to the lamp voltage generator through the circuit and the switch S1.

The down converter does not need to display a precise spectrum, but only needs to be able to detect only the edge of the burst signal. Therefore, only one mixer may be used. Several stages may be provided. The local oscillator may be a YTO or a simple synthesizer. Although a fixed frequency is oscillated, an arbitrary predetermined frequency is oscillated, so that a device capable of changing the frequency is required. The down-converted burst signal is extracted by a band-pass filter.

A trigger signal is generated at the edge of the burst wave by a trigger signal generation circuit for a burst signal having a frequency that facilitates signal processing. This trigger signal generation circuit may be a conventional one. That is, it is composed of a detector and a trigger circuit such as a Schmitt circuit, and generates a trigger at rising and falling edges. Alternatively, a rectangular wave in a certain period, that is, a burst section may be generated by a rising trigger signal. Rather, it is more convenient to generate two types of signals.

The generated trigger signal is supplied to a ramp voltage generator via a variable delay circuit. The variable delay circuit only needs to be able to switch between the case of direct communication and the time of an integral multiple of the burst section. As in the prior art, a direct pass signal is used when triggering on a frequency signal to be measured, and a direct or fixed delay is applied when triggering on another frequency signal. The adjustment is performed when the frequency of the uplink signal and the frequency of the downlink signal between the mobile station and the base station are different, and the timing of the burst wave is shifted by an integral multiple of the burst section.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention and the following examples will be described in detail.

The first invention is a basic circuit configuration.
A downconverter for splitting an input signal of a first mixer of a spectrum analyzer to reduce a burst signal of an arbitrary frequency to a frequency at which signal processing is easy, and a trigger signal generating circuit for generating a trigger signal from the reduced burst signal And a variable delay circuit for directly passing the trigger signal or delaying the trigger signal for a predetermined time, and a changeover switch.

The second invention is an appropriate configuration of the down converter of the first invention. Since the circuit does not require precise spectrum measurement, it is directly down-converted to the required frequency. Therefore, one mixer may be used. The local oscillator oscillates at a constant frequency and needs to oscillate at an arbitrary frequency. It may be a YTO, a simple synthesizer, or a multiplying oscillator provided with several types of crystal oscillators. It is preferable to use the cheapest circuit configuration. The beat wave that has been beaten down is supplied to a trigger signal generation circuit at the next stage.

[0020]

FIG. 1 is a block diagram showing an embodiment of the present invention. The TDMA wave f7 input to the input terminal 10 is attenuated by the ATT11 to have an appropriate value of 0 _dbm or less, and is branched to the first mixer 12 and the downconverter 30 as described above to give an input signal f70 to each. The path of the spectrum analyzer drives the sweep oscillator 22 with the ramp voltage from the ramp voltage generator 21 and mixes it with the first mixer 12.
The difference frequency is extracted by the BPF 13, and the operation is performed in the conventional manner.

The down converter 30 includes a mixer 31, a local oscillator 33 for trigger, and a BPF (bandpass filter).
32. Since a predetermined frequency signal is extracted from the BPF 32, the trigger local oscillator 33 must oscillate at an arbitrary fixed frequency.
Therefore, it is most convenient to use YTO and D / A, but a synthesizer may be used. It may be composed of a crystal oscillator and a multiplier. The beat down may be performed in only one stage, but may be performed in two stages or three stages as necessary.

An arbitrary burst wave extracted from the BPF 32 is generated by a trigger signal generation circuit 28 at the edge of the burst wave. The trigger signal generation circuit 28 may use a conventional circuit. Since the section and timing of the burst wave are known in advance, a gate signal for a predetermined time, that is, a rectangular wave may be generated here. This gate signal may be generated by the ramp voltage generator 21.

The variable delay circuit 36 is a variable delay circuit 36 that can be switched between a path that passes through the path as it is and a path that delays an integer multiple of the burst width. In the case of the frequency to be measured or another frequency, in the case of a burst wave of the same timing, it is passed as it is. If the burst wave timing is delayed by one burst width at another frequency, a delay of one burst width is given, and if the burst wave is delayed by two burst widths, a delay of two burst widths is taken to take the ramp voltage sweep timing. . The variable delay circuit 36 is desirably provided at the subsequent stage of the trigger signal generation circuit 28, but may be provided at the preceding stage.

The trigger signal or the gate signal p2 is supplied to the lamp voltage generator 21 via the switch S1 for switching between continuous wave measurement and TDMA wave measurement.

[0025]

As described above in detail, according to the present invention, in a spectrum analyzer having a gated sweep function for measuring a TDMA wave, a circuit for generating a trigger signal generated at the edge of a burst wave is provided. It was provided separately from the processing circuit. Therefore, it is possible to generate a gate signal with a burst wave of a predetermined arbitrary frequency and generate a ramp voltage.

Therefore, only one frequency can be selected from the broadband frequencies, processing can be performed with high sensitivity, and noise is strong. TDM with different uplink and downlink frequencies in the future
Since the A wave can be easily measured with one measuring instrument, the technical effect is great.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram related to a TDMA wave. (A) is a TDMA wave radiated from a base station, (B) is a burst wave radiated from a mobile station, (C) is a gate signal of a ramp voltage of a gated sweep function,
(D) is a ramp voltage waveform based on the gate signal,
(E) is the entire lamp voltage waveform.

FIG. 3 is a configuration diagram of a conventional example.

[Explanation of symbols]

 Reference Signs List 10 input terminal 11 attenuator (ATT) 12 first mixer 13 bandpass filter (BPF) 14 second mixer 15 third mixer 16 bandpass filter (BPF) 17 log amplifier (logarithmic amplifier) 18 detector 19 analog / digital converter (A / D) 20 Display 21 Lamp voltage generator 22 Sweep oscillator 23, 24 Local oscillator 28 Trigger signal generation circuit 30 Down converter 31 Trigger mixer 32 Bandpass filter (BPF) 33 Local oscillator 34 Detector 35 Trigger circuit 36 Variable delay circuit

Claims (2)

[Claims] In a spectrum analyzer having a gated sweep function, an input signal (f70) of a first mixer (12) of the spectrum analyzer is branched, and a burst signal of a predetermined arbitrary frequency is reduced to a frequency at which signal processing is easy. A downconverter (30) for reducing the frequency; and a trigger signal generating circuit (28) for generating a trigger signal or a gate signal (p2) from the reduced burst signal.
A variable delay circuit (36) for passing or delaying the trigger signal or the gate signal (p2) for a predetermined time; and turning on / off providing the trigger signal or the gate signal (p2) to the ramp voltage generator (21). And a switch (S1) for performing TDMA wave measurement. 2. The down converter (30) comprises a trigger mixer (31), a local oscillator (33) that oscillates at a constant frequency with variable frequency, and a band-pass filter (32). The TD according to claim 1,
Spectrum analyzer for MA wave measurement.