JPH09318731A - High frequency signal variable delay circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a simulation of all propagation elements of amplitude, phase and delay time by accurately delaying a high frequency in the order of μs to allow the application of a pseudo phasing or the like outputted from a high frequency phasing simulator or the like. SOLUTION: An analog signal is converted to a light signal by an E/O conversion circuit 2 while either internal optical paths 8a-8c or first - third optical cables 4-4c are selected by first to third light switch circuits 3a-3c to change the length of optical cables. Thus, the light signal to be outputted from the E/O conversion circuit 2 is guided to a O/E conversion circuit 5 and the light signal is converted to an analog signal by the O/E conversion circuit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency signal variable delay circuit for delaying an input high frequency signal by a designated delay time and outputting the delayed high frequency signal.

[0002]

2. Description of the Related Art In a device for performing an operation test or simulation of a radar device, for example, a propagation simulator device, a high frequency signal output from a transmitting circuit of the radar device is delayed by a predetermined time and input to a receiving circuit of the radar device. Thus, the propagation delay that occurs when the high-frequency signal output from the transmission circuit propagates in space is realized, and the operation check of the transmitter circuit and the operation check of the receiver circuit are performed.

[0003]

However, in such a propagation simulator device, since a high frequency signal input by using a high frequency cable, a strip line, a filter circuit or the like is delayed, it becomes a delay target. When the delay time of the analog signal (high-frequency signal) is short (for example, on the order of ns), the high-frequency signal can be efficiently delayed, but when the delay time is long (on the order of μs), the insertion loss is large. There was a problem of several hundred dB. Therefore, in such a propagation simulator device, when a long delay time is required, a low noise amplifier is inserted in the transmission path of the high frequency signal to obtain the S / N of the high frequency signal.
However, there is a problem that the circuit design and adjustment become difficult accordingly. Further, when a high frequency signal is delayed using a high frequency cable or the like, when the ambient temperature changes, the line length changes correspondingly and the delay time changes, which causes an error. . Since it is difficult to solve these problems fundamentally and the high frequency signal cannot be accurately delayed on the order of μs, when it is necessary to delay the high frequency signal on the order of μs, A propagation time delay system that uses only a digital system to perform variable delay without using a high frequency system is used, and an operation test of a radar device is performed with this propagation time delay system.

However, in such a propagation time delay system, since it is impossible to apply pseudo fading output from a high frequency fading simulator device or the like, the radio wave transmitted from the radar device or the like is actually used. There is a problem in that it is impossible to perform a propagation simulation test or the like for simulating the characteristics when propagating in space and reflecting. In view of the above circumstances, the present invention can accurately delay a high-frequency signal in the order of μs, thereby enabling application of pseudo fading output from a high-frequency fading simulator device or the like, and amplitude, phase, and delay. An object of the present invention is to provide a high frequency signal variable delay circuit capable of simulating all propagation elements of time.

[0005]

In order to achieve the above object, a high frequency signal variable delay circuit according to the present invention comprises:
Then, by switching the connection relationship between the E / O conversion circuit that takes in the electrical signal to be delayed and converts it into an optical signal, and the connection relationship of the plurality of optical cables, the propagation path length of the optical signal is switched,
Adjusting the delay time of the optical signal emitted from the conversion circuit 1
It is characterized by comprising one or a plurality of optical switch circuits and an O / E conversion circuit which takes in the optical signals delayed by each of these optical switch circuits, converts them into electric signals and outputs them. According to a second aspect of the present invention, in the high frequency signal variable delay circuit according to the first aspect, the optical switch circuit is replaced by 1
One or a plurality of optical distributors are used, and one of a plurality of optical cables forming a multipath path is selected by each of these optical distributors, and the delay time of the optical signal emitted from the E / O conversion circuit is selected. It is characterized by adjusting.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a block diagram showing an example of a form of a high frequency signal variable delay circuit according to the present invention. The high-frequency signal variable delay circuit 1 shown in this figure includes first to third optical cables 4a to 4c for propagating an optical signal incident on the input end side while delaying and propagating the optical signal from the output end side.
E / O conversion circuit 2 for converting an input high frequency analog signal (electrical signal) into an optical signal, and controlling input side switching element 6a and output side switching element 7a based on the input ON / OFF signal The optical signal output from the / O conversion circuit 2 is guided to either the internal optical path 8a or the first optical cable 4a to be delayed, and is then output based on the first optical switch circuit 3a and the input ON / OFF signal. By controlling the input side switching element 6b and the output side switching element 7b, the first
The optical signal output from the optical switch circuit 3a is transferred to the internal optical path 8
b or the second optical cable 4b to delay and then output the second optical switch circuit 4b, and controls the input side switch element 6c and the output side switch element 7c based on the input ON / OFF signal. The second optical switch circuit 3
The third optical switch circuit 3c, which guides the optical signal output from the optical fiber b to either the internal optical path 8c or the third optical cable 4c and delays the optical signal, and the third optical switch circuit 3c.
and an O / E conversion circuit 5 for converting the optical signal emitted from c into a high frequency analog signal (electrical signal).

With the above configuration, in the high frequency signal variable delay circuit 1, an ON signal or an OFF signal is applied to the first to third optical switch circuits 3a to 3c, and the first to third optical switch circuits 3a to 3c are applied.
-The input side switch elements 6a to 6c and the output side switch elements 7a to 7c of the third optical switch circuits 3a to 3c are made to select either the internal optical paths 8a to 8c or the first to third optical cables 4a to 4c. At this time, if an ON / OFF signal is applied to the first to third optical switch circuits 3a to 3c so as to select the internal optical paths 8a to 8c, the E / O conversion circuit as shown in FIG. The optical signal output from 2 is the E / O conversion circuit 2 → the input side switch element 6a of the first optical switch circuit 3a → the internal optical path 8 of the first optical switch circuit 3a.
a → output side switching element 7a of the first optical switching circuit 3a
→ Input side switch element 6b of the second optical switch circuit 3b →
Internal optical path 8b of the second optical switch circuit 3b → output side switching element 7b of the second optical switch circuit 3b → input side switching element 6c of the third optical switch circuit 3c → internal optical path 8c of the third optical switch circuit 3c → third In the path from the output side switching element 7c of the optical switching circuit 3c to the O / E conversion circuit 5, O
The signal is guided to the / E conversion circuit 5 and converted into a high frequency analog signal. As a result, the analog signal input to the E / O conversion circuit 2 is delayed by the minimum delay time and output from the O / E conversion circuit 5.

At this time, the first to third optical cables 4a are connected to the first to third optical switch circuits 3a to 3c.
If the ON / OFF signal is applied so as to select 4c to 4c, the optical signal output from the E / O conversion circuit 2 is changed from the E / O conversion circuit 2 to the first optical switch circuit 3a as shown in FIG. Input side optical switch element 6a → first optical cable 4a → first
Output side switch element 7a of the optical switch circuit 3a → input side optical switch element 6b of the second optical switch circuit 3b → second optical cable 4b → output side optical switch element 7b of the second optical switch circuit 3b → third optical switch circuit 3c Input side optical switch element 6c → third optical cable 4c → output side optical switch element 7c of third optical switch circuit 3c → O / E conversion circuit 5
Then, the signal is guided to the O / E conversion circuit 5 and is converted into a high frequency analog signal. As a result, the analog signal input to the E / O conversion circuit 2 is delayed by the maximum delay time and output from the O / E conversion circuit 5.

In order to investigate the delay time characteristic of the high frequency signal variable delay circuit 1 shown in FIG.
Was actually manufactured and the delay characteristics of the high frequency signal variable delay circuit 1 and the delay characteristics of the conventional high frequency signal variable delay circuit using the coaxial cable were compared, and the delay characteristics shown in the table of FIG. 4 were obtained. I was able to. As can be seen from this table, in the conventional high frequency signal variable delay circuit using the coaxial cable of "RG-8U" standard having the outer diameter of 10 mm, when the high frequency signal of 3 GHz is delayed, about 70% of the speed of light is reached. A high-frequency signal can be propagated at a speed of, and an insertion loss per 1 km is 590 dB, compared to the single mode optical cable formed with an outer diameter of 2.5 mm. The high-frequency signal variable delay circuit 1 can propagate a high-frequency signal at a speed of about 70% of the speed of light, and at this time, the insertion loss per 1 km can be suppressed to 1 dB.

Further, when the change in the delay time was measured by changing the ambient temperature, it was found that in the conventional high frequency signal variable delay circuit using the coaxial cable, the length of the coaxial cable was changed in accordance with the temperature change. Although the delay time has changed, the high frequency signal variable delay circuit 1 of this embodiment using an optical cable 1
Then, the length of the optical cable did not change and the delay time hardly changed. Thus, in this embodiment, E
The analog signal is converted into an optical signal by the / O conversion circuit 2, and the internal optical paths 8a to 8c or the first to third optical cables 4a to 4 are generated by the first to third optical switch circuits 3a to 3c.
Select one of c and switch the optical cable length,
Since the optical signal output from the E / O conversion circuit 2 is guided to the O / E conversion circuit 5 and the optical signal is converted into an analog signal by the O / E conversion circuit 5, the high frequency is on the order of μs. The analog signal of can be accurately delayed, which enables application of pseudo fading output from a high-frequency fading simulator device, etc., and can simulate all propagation elements of amplitude, phase, and delay time. .

At this time, in such first to third optical cables 4a to 4c, the delay time per unit length becomes almost the same value as the coaxial cable having the same length, and the attenuation amount is the same as that of the coaxial cables. Since it becomes so small as to be incomparable, the amount of attenuation of the analog signal output from the O / E conversion circuit 5 can be reduced without using a low noise amplifier or the like, and even if the ambient temperature changes. First
Since the characteristics of the third optical cables 4a to 4c hardly change, the delay time characteristics can be stabilized. Also, with coaxial cables, the smaller the diameter of the cable, the greater the loss.Therefore, when reducing the loss, the diameter of the cable must be increased. Although a space is required, the first to third optical cables 4a to 4c are very thin, so that when a large delay time is required, the first to third optical cables 4a to 4c can be wound and used. It is possible to prevent the cable installation space from becoming large.

Further, in the above-mentioned form example, E / O
The conversion circuit 2 converts a high-frequency analog signal into an optical signal, and the O / E conversion circuit 5 converts the optical signal into a high-frequency analog signal. However, the conversion circuit 2 is not limited to such an analog signal but a digital signal. May be converted into an optical signal and delayed. Moreover, in the above-described example of the form, the first to third optical switch circuits 3a to 3 are used.
Although the first to third optical cables 4a to 4c are selectively connected by c to switch the optical cable length, such first to third optical switch circuits 3a as shown in FIG.
3c, a plurality of optical distributors 10 are used, and the delay time is switched by selecting any one of the optical cables 12 to be the multipath path 11 by each of the optical distributors 10. good. The high-frequency signal variable delay circuit 9 configured in this manner can also accurately delay the high-frequency signal on the order of μs, similarly to the above-described high-frequency signal variable delay circuit 1, and thereby output from the high-frequency fading simulator device or the like. By applying pseudo fading, it is possible to simulate all propagation elements of amplitude, phase, and delay time.

[0013]

As described above, according to the present invention, μ
It is possible to accurately delay a high frequency signal in the order of s, thereby enabling application of pseudo fading output from a high frequency fading simulator device, etc., and simulating all propagation elements of amplitude, phase and delay time. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a form of a high frequency signal variable delay circuit according to the present invention.

FIG. 2 is a schematic diagram showing a connection example when obtaining the minimum delay time of the high-frequency signal variable delay circuit shown in FIG.

FIG. 3 is a schematic diagram showing a connection example when obtaining the maximum delay time of the high-frequency signal variable delay circuit shown in FIG.

FIG. 4 is a table showing a performance comparison example between the high frequency signal variable delay circuit shown in FIG. 1 and a conventional high frequency signal variable delay circuit.

FIG. 5 is a block diagram showing another embodiment of the high frequency signal variable delay circuit according to the present invention.

[Explanation of symbols]

1 ... High frequency signal variable delay circuit, 2 ... E / O conversion circuit, 3
a to 3c ... First to third optical switch circuits, 4a to 4c ... First to third optical cables, 5 ... O / E conversion circuit, 6a to 6c
Input-side switching element, 7a to 7c ... Output-side switching element, 8a to 8c ... Internal optical path, 9 ... High frequency signal variable delay circuit, 10 ... Optical distributor, 11 ... Multipath path, 12 ... Optical cable

Claims (2)

[Claims] 1. An E / O conversion circuit that captures an electrical signal to be delayed and converts it into an optical signal and a connection relationship between a plurality of optical cables to switch a propagation path length of the optical signal. One or a plurality of optical switch circuits for adjusting the delay time of the optical signal emitted from the optical output circuit, and an O / E conversion circuit for capturing the optical signal delayed by each of these optical switch circuits, converting the optical signal into an electrical signal, and outputting the electrical signal. And a high-frequency signal variable delay circuit comprising: 2. The high frequency signal variable delay circuit according to claim 1, wherein one or more optical distributors are used instead of the respective optical switch circuits, and a multipath path is formed by each of these optical distributors. A high-frequency signal variable delay circuit, characterized in that any one of a plurality of optical cables to be configured is selected to adjust a delay time of an optical signal emitted from an E / O conversion circuit.