JP3361629B2 - Comb-like spectrum signal generator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal generator for generating a comb-shaped spectrum, and more particularly to a comb-shaped spectrum signal generator for generating a multi-channel signal for measuring carrier sense of a mobile communication device. .

[0002]

[Prior art]

(Explanation of Mobile Communication) In the field of mobile communication such as automobiles, mobile phones and cordless phones, frequency division multiplexing (FDM) is used as a means of multiplexing.
Ivision Multiplex) and Time Division Multiplex (TDM)
iplex).

For example, PHS (Personal Ha)
In the ndyphone System), frequency division multiplexing uses frequency band 1.9 GHz (24 MHz width), channel separation 300 KHz, number of channels 77 CHs.
Has become. In addition, time division multiplexing has four uplink slots,
It has 4 slots downstream. When the PHS communicates, it must detect a free frequency channel and use that channel. One of the PHS quality tests,
It is necessary to test whether the carrier sense function is satisfied. FIG. 9 is a block diagram of the carrier sense test apparatus.

The carrier sense function means that the test equipment 10 transmits at the test frequency when the test frequency is idle, and the test equipment 10 does not transmit when the test frequency is not available. Therefore, the multi-channel signal generator used for the test needs to continuously generate one carrier of the control frequency and all carriers other than the test frequency without modulation.

(Conventional Test Apparatus) In the conventional test apparatus,
The signals from a plurality of oscillators were combined to generate a multi-frequency comb-shaped signal, which was used as a multi-channel signal generator. Then, the carrier sense is tested by the signal excluding the output of the oscillator of the channel.

[0006]

That is, in the conventional technology, as many oscillators as necessary are required. Furthermore, because it is controlled by a computer (personal computer),
The circuit scale becomes large. Moreover, in order to change the frequency or the frequency interval, the oscillation frequencies of all the oscillators must be changed. The present invention has been made in view of the above circumstances, and provides a comb-shaped spectrum signal generator and a carrier sense test apparatus capable of downsizing, increasing the number of channels, and setting an arbitrary frequency. This is an issue.

[0007]

[Means for Solving the Problem] 406 of "Spread spectrum communication system" (written by Mitsuo Yokoyama, published by Science and Technology Publishing Company)
According to the page, PN (Pseudorandom No.
The power spectrum of the “ise: pseudo random” waveform is composed of a line spectrum, and the frequency interval is 1 / T (one period of the PN waveform). The power at f = 0 is 1 / n
^{Is 2} . As shown in FIG. 8, the power spectrum of the PN waveform when n = 15 is described as an example.

According to the present invention, in order to solve the conventional problems, in the comb-shaped spectrum signal generator according to claim 1, a PN that spreads a spectrum with a spreading sequence which is a pseudo-random code.
We paid attention to the fact that the signal generator can be used as a comb generator. Furthermore, a means for reducing the power at f = 0 by using a quadrature modulator has been realized. Further, in the carrier sense test apparatus of the second aspect, the output signal of the comb-shaped spectrum signal generator is further processed to be a multi-channel signal generator for carrier sense test.

Specifically, in claim 1, a PN signal generator for generating a line spectrum at a predetermined frequency interval;
A waveform shaping circuit for shaping the output waveform of the signal generator, a capacitor for cutting a direct current component of the output of the <br/> waveform shaping circuit, an oscillator for outputting a signal of any frequency, alternating binding difference the balanced Two multipliers each including a moving stage are connected to each of the multipliers, and a bias circuit that adjusts an in-phase component (I component) to remove a carrier leak by applying a bias current and a quadrature component are adjusted. By having a bias circuit, a signal of an arbitrary frequency output from the oscillator is input, and the center frequency of the plurality of line spectra output from the waveform shaping circuit input via the capacitor is set to the arbitrary frequency. Set to.

According to a second aspect of the present invention, there is provided a carrier sense test apparatus for testing a transmission / reception function of a predetermined channel of an EUT, wherein a tester connected to the EUT by a line and a center frequency are set for a channel to be tested. A comb-shaped spectrum signal generator according to claim 1,
When the output of the comb-shaped spectrum signal generator and the signal of the center device are mixed and output to the equipment under test, the frame signal detector that receives the signal from the tester and detects the frame signal, and when the frame signal is detected And a switching unit for disconnecting the device under test from the comb-shaped spectrum signal generator.

[0011]

According to the comb-shaped spectrum signal generator of the present invention having the above-mentioned structure, the center frequency of the plurality of line spectra generated by the PN signal generator can be set to the oscillation frequency of the oscillator. The level of the output signal thus generated can be further reduced. Further, the center frequency of the output signal can be set to an arbitrary frequency by changing the oscillation frequency of the oscillator.

Further, in the carrier sense test apparatus of the second aspect, by using the comb spectrum signal generator of the first aspect, the center frequency at which the output level becomes low can be set arbitrarily. That is, it becomes possible to test carrier sense in an arbitrary channel.

[0013]

[First Embodiment]

(Structure) FIG. 1 is a block diagram of a comb-shaped spectrum signal generator. The PN signal generator 1 generates a line spectrum at a predetermined frequency interval (300 KHz in the first embodiment). The waveform of the line spectrum is clamped by the waveform shaping circuit 2. The capacitor 3 cuts the DC component of the output of the waveform shaping circuit 2. The quadrature modulator 4 sets the output of the waveform shaping circuit 2 to an arbitrary frequency. The arbitrary frequency (160 MHz in the first embodiment) is generated by the oscillator 5 and output to the quadrature modulator 4. The output signal of the quadrature modulator 4 is input to the multiplier 7 via the attenuator 6 and the frequency of the oscillation circuit 9 (1.74 GHz in the first embodiment).
And the center frequency is a signal in the use band of 1.9 GHz. The signal is band-limited by the bandpass filter 8 and output.

(Explanation of Operation) FIG. 2 shows waveforms at points of and in the comb-shaped spectrum signal generator of FIG. Is the output waveform eyepan (left side) and spectrum (right side) of the PN signal generator 1, and is the output waveform eyepan (left side) and spectrum (right side) of the waveform shaping circuit 2.
Since the output stage of the PN signal generator 1 is not ideal, waveform distortion occurs. By inputting it into the waveform shaping circuit 2, an ideal waveform is obtained. Is an output waveform of the output waveform of the quadrature modulator 4, and CENTER (center frequency) = 160.
000MHz, SPAN (screen frequency width) = 3.00
It is set to MHz. That is, a spectrum signal is generated at 300 KHz intervals, and the center frequency is 160.000M.
It can be seen that the output level of Hz is low.

FIG. 3 shows a block diagram of the PN signal generator 1. The spectral interval of the comb generator is determined by the clock F _ck to the shift register 1a. The shift register 1a of the present embodiment is composed of 7-stage PN and its clock is 38.1 MHz. Therefore, the spectrum interval is 38.1 MHz / 127 = 300 KHz. Also, a 38.1 MHz clock generator is used for the PLL (Ph
Since it is composed of an as Locked Loop (phase locked loop) circuit, frequency stability can be achieved.

One input of the phase comparator 1b of the PLL circuit is a 300 KHz signal obtained by dividing the output of the oscillator 1c having a frequency of 9.6 MHz by the frequency divider 1d. The other input has a period of n = 2 ^k −1 for the M sequence, so that all of them become 1 once in 127 times. Therefore, the frequency of the output of the one detector 1e is 38.1 MHz / 127 = 300 KHz. The phase difference signal of the 300 KHz signal is passed through the low-pass filter 1f and the voltage controlled oscillator (VCO) 1g.
To enter. The output waveform of the VCO 1g is shaped by the waveform shaper 1h and used as the clock F _ck to the shift register 1a.

If all the outputs of the shift register 1a become zero, they are held as they are,
It will malfunction. Therefore, the zero detector 1i detects all zeros and forcibly resets the shift register 1a.

(Description of Quadrature Modulator) Further, the quadrature modulator 4
Since the input to is AC coupled, there is no influence of the DC component. The quadrature modulator 4 separates the I component and the Q component.
Therefore, the carrier leak can be removed by controlling the I component and the Q component independently. This multiplier 4a, 4b
Is normally composed of a balanced cross-coupled differential stage, and acts to suppress carriers when each element is balanced. However, since there are variations in each element, a bias current is applied by the bias circuits 4c and 4d to remove carrier leak. This principle will be described with reference to FIG. If only the I component is controlled, + b will remain. However, the A vector can be made zero by controlling the I and Q components independently. That is, the A vector becomes zero by controlling the I and Q components and creating the -a and -b components.

(Effect of First Embodiment) PN signal generator 1
Since the PLL circuit constitutes a PLL circuit, the frequency is stabilized. Since the input to the quadrature modulator 4 is AC coupled, there is no influence of the DC component. Further, since the I component and the Q component are separated by the quadrature modulator 4, the carrier leak can be removed by controlling the I component and the Q component independently. Also, by changing the frequency of the oscillator 5,
The center frequency can be set to any frequency. Further, the frequency interval can be changed by changing the number of stages of the shift register 1a in the PN signal generator 1 or the frequency F _{ck of the} PLL circuit.

The PN signal generator 1 may be an LC oscillating circuit, an RC oscillating circuit, or a crystal oscillating circuit as long as it is stable according to the characteristics of the device using the comb-shaped spectrum signal generator.

[Application to Testing Device] FIG. 5 is a conceptual diagram showing a carrier sense testing device for testing the transmitting / receiving function of a predetermined channel of the device under test 10 utilizing the invention of claim 1. The communication format of TDM for mobile communication is shown in FIG. One frame is made up of 5 msec, and one frame is divided into four downlink slots and four uplink slots. The control slot is assigned to the first downlink slot. A means for not outputting the output of the comb-shaped spectrum signal generator to the device under test 10 is required in the control slot.

One slot (625 μsec) shown in FIG. 6B is synchronized with the frame signal from the tester 11.
During this period, the input end of the device under test 10 is separated from the output end of the comb-shaped spectrum signal generator 12 and connected to the tester 11 side.
By detecting the frame signal, the control frequency of 1
You can remove the waves. Further, the output of the comb-shaped spectrum signal generator 12 can be used for the carrier sense test because the test frequency is removed.

FIG. 7 is a block diagram in which the invention of claim 2 is incorporated into a multi-channel signal generator of a conventional carrier sense test apparatus. A tester 11 for line-connecting with the device under test 10, a comb-shaped spectrum signal generator 12 according to claim 1, wherein a center frequency is set for a channel to be tested.
Output of the comb-shaped spectrum signal generator 12 and tester 11
A mixer 13 that mixes the signals of and outputs to the test device 10,
A frame signal detection unit 14 that receives a signal from the tester 11 and detects a frame signal, and a switching unit 15 that disconnects the device under test 10 from the comb-shaped spectrum signal generator 12 when the frame signal is detected are provided. .

The measurement operation procedure will be described with reference to FIG. (1) The device under test 10 is connected to the tester 11 by a line and put in a receiving state. (2) The output of the multi-channel signal generator 16 is set to about 200 μV as the input voltage of the device under test 10 so that radio waves cannot be emitted at frequencies other than one control frequency and the test frequency. To do. (3) Minimize the output of the standard signal generator 17, which transmits the standard encoded test signal of π / 4 shift QPSK modulation at the test frequency. (4) Connect a line between the device under test 10 and the tester 11,
It is confirmed by the spectrum analyzer 18 that radio waves of the test frequency are emitted. In this case, the peak search function of the spectrum analyzer 18 confirms that the frequency of the emitted radio wave is the test frequency. (5) Put the device under test 10 in the receiving state. (6) The output of the standard signal generator 17 is set to 110 μV as the input voltage of the device under test 10 and the spectrum analyzer 18 confirms that no radio wave is emitted from the device under test 10.

[0026]

As described above, according to the comb spectrum signal generator of the first aspect, the line spectrum generated by the PN signal generator 1 is input to the quadrature modulator 4. Therefore, the center frequency can be set to the frequency of the oscillator 5, and the level of the set frequency can be further reduced.
Further, the center frequency of the output signal can be set to an arbitrary frequency by changing the frequency of the oscillator 5.

According to the carrier sense test apparatus of the second aspect, by using the comb spectrum signal generator of the first aspect, the center frequency at which the output level becomes low can be arbitrarily set. That is, it becomes possible to test carrier sense in an arbitrary channel.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of claim 1. FIG.

FIG. 2 is a waveform diagram of each output signal of the block diagram showing the first embodiment.

FIG. 3 is a block diagram showing details of the PN signal generator of the first embodiment.

FIG. 4 is a diagram illustrating an operation for reducing carrier leak in the quadrature modulator according to the first embodiment.

FIG. 5 is a conceptual diagram for explaining control means of the carrier sense test apparatus of claim 2 excluding the control frequency.

FIG. 6 is a communication format diagram of TDM for mobile communication.

FIG. 7 is a block diagram of the carrier sense test apparatus of claim 2;

FIG. 8 is a diagram showing a power spectrum of a PN waveform.

FIG. 9 is a block diagram of a conventional carrier sense test apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... PN signal generator, 2 ... Waveform shaping circuit, 4 ... Quadrature modulator, 4c ... Bias circuit, 4d ... Bias circuit, 5 ... Oscillator, 10 ... Test equipment, 11 ... Tester, 12 ... Comb spectrum signal generation Container, 13 ... Mixer, 14 ... Frame signal detection unit, 15 ... Switching unit.

Claims (2)

(57) [Claims] 1. A PN signal generator (1) for generating a line spectrum at a predetermined frequency interval, a waveform shaping circuit (2) for shaping an output waveform of the PN signal generator, and an output of the waveform shaping circuit . Condenser that cuts DC component
(3), an oscillator (5) for outputting a signal of an arbitrary frequency, and two multipliers (4) composed of a balanced type alternating coupling differential stage.
a, 4b) and their multipliers, respectively, and bias
And a bias circuit for adjusting the bias circuit for adjusting the phase component (I component) in order to remove the carrier leak (4c) and quadrature component (Q component) (4d) over the current, and the output of said oscillator Input signal of any frequency
Force and the waveform shaping input through the capacitor
The center frequencies of the multiple line spectra output by the circuit are
And a quadrature modulator (4) for setting an arbitrary frequency
Comb spectrum signal generator. Wherein examination apparatus (10) of a carrier sense test apparatus for testing a transmission and receiving function in a given channel, the examination device and tester for line connection (11)
A comb-shaped spectrum signal generator (12) according to claim 1, wherein a center frequency is set for the channel to be tested,
Mixer for output to the examination device by mixing a signal output to the tester of the comb-shaped spectrum signal generator (13),
Frame signal detector for detecting a frame signal to receive a signal from the tester (14) and, the said examination device when detecting the frame signal comb spectrum signal generator from cut away form the switching unit (15) And a carrier sense test device provided with.