JPH0552920A - Electronic tracking type receiver - Google Patents

Abstract

PURPOSE:To obtain a small-sized electronic tracking type receiver for broadcast radio waves having an excellent tracking ability. CONSTITUTION:This electronic tracking type receiver is provided with a plurality of antennas 1 constituting an array antenna, down converter 2 which converts received broadcast radio waves into the first intermediate frequency, a common local oscillator 4 which supplies local signals to the converter 2, a mixer which converts the first intermediate frequency into the second intermediate frequency, and a local oscillator 6 for a phase reference antenna system. In addition, this receiver is also provided with a phase shifter 11 or voltage- controlled oscillator 5 for a phase-tracking antenna system, narrow-band filter 7, a phase comparator 8 which compares the phase of the reference system with that of the tracking system, a power synthesizer 9 which synthesizes signals of the two systems, and the output terminal 10 of the synthesizer 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic tracking type receiving device for receiving satellite broadcasting etc. on a mobile body.

[0002]

2. Description of the Related Art Accurate pointing of an antenna beam is required for mobile reception of satellite broadcasting. There are a mechanical tracking method and an electronic tracking method for automatic tracking of the antenna beam. The mechanical tracking method is a method in which the direction of arrival of a radio wave is detected by some means and the antenna is moved in that direction. The tracking speed is slow, but omnidirectional tracking can be performed easily, so it is suitable for azimuth tracking.

Among electronic tracking methods, the adaptive array antenna tracking method directs the antenna beam in the direction of arrival of radio waves by performing a self-phasing operation so that the outputs from the antennas are automatically in phase. In general, electronic tracking can increase the tracking speed without the need for moving parts, but widening the tracking range increases the number of array elements and complicates the configuration. Therefore, it is suitable when tracking in a limited angle range such as elevation tracking or high-speed tracking is required.

Since both of these methods have their respective advantages and disadvantages, both methods are often incorporated into one tracking receiving device and used adaptively. Kenji Omaru: "Mobile Satellite Receiver", Broadcasting Technology September issue, pp 119-123,
The receiving device described in 1990 is introduced. This mobile tracking receiver is a receiver that incorporates both of the above-mentioned tracking methods. It is equipped with a monopulse antenna for the mechanical tracking method and an adaptive array antenna for the electronic tracking method. One of the planar antennas is commonly used as a monopulse antenna.

The satellite broadcast waves received by the eight planar antennas are converted into the first intermediate frequency by the BS converters of the respective antennas, and then converted into the second intermediate frequency by the respective tuners to be combined. PLL so that each tuner output is combined in phase with each tuner
The circuit (phase locked loop circuit) is built in, and the oscillation phase of the VCO (local oscillator) for frequency conversion of each tuner is adjusted so that the phase difference between each output and the other seven outputs becomes zero with respect to one output. Have control. The phase comparison at this time is performed by extracting a band of one channel with a bandpass filter. Although the phase of the antenna output changes when the direction of arrival of the radio wave changes, the antenna beam tracks the radio wave because it is nevertheless controlled to perform in-phase synthesis.

On the other hand, in this apparatus, one of the eight planar antennas in the previous period was assigned as a monopulse antenna for detecting the direction of arrival of radio waves for machine tracking, and the monopulse antenna responded to the difference between the antenna direction and the arrival direction of radio waves. A voltage is output, and the servomotor is driven so as to reduce it to mechanical tracking.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an improvement in the part related to the electronic tracking system of the above-mentioned conventional example device, but in the electronic tracking part of the above-mentioned mobile tracking receiving device, the adaptive array antenna is used. When the outputs of the eight planar antennas constituting the above are converted to the first intermediate frequency by the BS converter, each of them is frequency-converted by the independent local signal of each converter and then input to the PLL type in-phase combining circuit. Therefore, in the phase comparison when combining in-phase, the signal bandwidth of 27 M
It was necessary to take a relatively wide band such as Hz (bandwidth for one satellite broadcast channel). As a result, when the gain of one of the plurality of antennas of the array antenna is small, the received CN ratio is low and good in-phase combining cannot be performed. Therefore, when it is desired to downsize the antenna, the size of the antenna is limited, and as a result, the directivity of the antenna becomes sharp and the automatic tracking range is narrowed.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks, to use a common local oscillation signal as a local oscillation signal for conversion of the plurality of antennas of the above-mentioned array antenna to the first intermediate frequency, and By narrowing the band for comparison, the reception CN ratio is improved, and an electronic tracking type mobile receiving device that can further reduce the size of one antenna is provided.

[0009]

[Means for Solving the Problems] To achieve this purpose,
The electronic tracking type receiving device of the present invention is an electronic tracking type receiving device using an array antenna for receiving transmitted waves, where n is a positive integer representing 2, 3, 4 ---- N antennas forming an antenna, n down-converters for converting a received input signal of each antenna to a first intermediate frequency, and a common local oscillator for supplying a local signal to the down-converters, N mixers for converting the output signals of the down converters to the second intermediate frequencies, a local oscillator for supplying a local signal to the phase reference antenna system mixer, and an output of each mixer. (N-1) for comparing the signal phases of the reference system and each tracking system with n narrow-band filters that are extremely narrow compared to the transmission wave bandwidth
Phase comparators, (n-1) phase control means for controlling the phase of the local signal input to the phase-following antenna mixer so that the outputs of the phase comparators become zero respectively, and the reference. An antenna system mixer and a power combiner for combining the outputs of the (n-1) tracking antenna system mixers are provided.

[0010]

The present invention will be described below with reference to the accompanying drawings. 1 and 2 are block diagrams showing the configuration of the first and second embodiments of the electronic tracking receiving apparatus according to the present invention. This is because the receiving array antenna has only one antenna in addition to the reference system. This is a typical example of an apparatus having a tracking antenna, and generally, there are a plurality of tracking antenna elements.

The apparatus shown in FIG. 1 includes an antenna (1-1, 1-2) forming an array antenna and a down converter 2 (2-1, 2-2) for frequency-converting a received broadcast wave.
, A common local oscillator 4 for supplying a local signal to the down converter 2, and a mixer 3 (3-1, 3-
2) and the local oscillator 6 for the phase reference antenna system,
Phase shifter 11 that forms a local signal for the antenna system that follows it, and narrow band filter 7 (7-1, 7-2)
, A phase comparator 8 for comparing the phases of the reference system and the tracking system, and a power combiner 9 for combining the signals of the two systems.
And its output terminal 10.

The satellite broadcast wave received by the antenna 1 is converted into a first intermediate frequency by a down converter 2 having a common local signal and then input to a mixer 3, which is a local signal of a tracking mixer 3-2. As for the signal, the output from the local oscillator 6 is supplied through the phase shifter 11. Phase shifter 11
Is controlled by the phase comparator 8 so that the phase difference between the outputs of the mixers 3 (3-1, 3-2) of the reference system and the tracking system becomes zero. Further, the phase comparison between the reference system and the follow-up system is performed by narrowing the part of a certain channel having a high spectral component level by the narrow band filter 7 (7-1, 7-2). As a result, even if the CN ratio of the antenna is low, C
Phase comparison can be performed with a high N ratio.

In the embodiment of FIG. 1, when there are a plurality of tracking systems, the output of the local oscillator 6 can be distributed and input to the phase shifters of each tracking system.

The apparatus shown in FIG. 2 includes an antenna 1 (1-1, 1-2) forming an array antenna and a down converter 2 (2-1, 2-2) for frequency-converting a received broadcast wave.
, A common local oscillator 4 for supplying a local signal to the down converter 2, and a mixer 3 (3-1, 3-
2) and the local oscillator 6 for the phase reference antenna system,
A VCO (voltage control oscillator) 5 for the antenna system that follows it, a narrow band filter 7 (7-1, 7-2), and a phase comparator 8 for comparing the phases of the reference system and the following system,
It is composed of a power combiner 9 for combining the signals of the two systems and an output terminal 10 thereof.

As in the apparatus shown in FIG. 1, the satellite broadcast wave received by the antenna 1 is first converted into a first intermediate frequency by a down converter 2 having a common local signal. Therefore, in the output of the converter 2, the phase difference of the antenna output is maintained as it is. Then, in the reference system, another local oscillator 6 converts the second intermediate frequency. In the follow-up system, the local signal from the VCO 5 is converted into the second intermediate frequency. In this VCO 5, the phase difference between the outputs of the reference system and the follow-up system mixers 3 (3-1, 3-2) is zero. Is controlled by the phase comparator 8. Further, when comparing the phases of the reference system and the tracking system, the narrow band filter 7 (7-1, 7-2) extracts a portion of a certain channel having a high spectral component level on average. As a result, even if the reception CN ratio of the antenna is low, this operation enables phase comparison in a state where the CN ratio is high. By this PLL type in-phase combining circuit, the antenna outputs of the reference system and the tracking system are input to the power combiner 9 in phase. As a result, even when the phases of the broadcast waves incident on the reference system antenna 1-1 and the tracking antenna 1-2 are different, that is, even when the broadcast waves are incident from an oblique direction, they are combined in the same phase, so that the broadcast waves are electrically converted. You can track.

The two embodiments according to the present invention have been described above with reference to the drawings. However, the present invention is not limited to these, and various modifications can be made without departing from the gist of the present invention. That would be obvious. For example, the incoming radio wave may be the UHF band or the VHF band instead of the SHF band for satellite broadcasting.

[0017]

According to the mobile receiving apparatus of the present invention, since the antenna output is frequency-converted by the down converter having a common local signal, the phase difference of each antenna output is maintained as it is. Therefore, at the time of phase comparison, it is possible to perform phase comparison after extracting a portion having a high spectral component level on average (for example, a synchronizing signal portion of video) with a narrow band filter. As a result, the antenna is small,
Even when the reception CN ratio is low, the reception CN ratio can be improved by narrowing the band, and stable in-phase combining can be performed. In addition, the antenna can be downsized and the tracking range can be widened.

Current satellite broadcasting is 27MH per channel
Video and audio are transmitted by analog signals using the z band, but digital broadcasting may be considered in the future. For example, in digital broadcasting, 27MHz is divided into 12,
PCM using about 2MHz band per channel
A total of 12 channels of music broadcasts are being considered (see "Easy-to-understand broadcast high-tech information", Kenrokukan Shuppan, pp. 73-76). In such a case, the phase comparison is 1
It suffices if the channel is 2 MHz, but in such a case, in-phase synthesis can be easily performed by extracting this channel with a 2 MHz narrow band filter, and the present invention can be effectively utilized.

The satellite broadcasting mobile receiving apparatus currently put into practical use is carried out by machine tracking only in the azimuth direction. However, it is expected that all-electron tracking will be performed in the future. In such a case, the unit antenna forming the array antenna needs to have the beam width as wide as possible, but the unit antenna becomes small and the reception CN ratio becomes low. Even in such a case, according to the mobile receiving apparatus of the present invention, after performing frequency conversion with the common local signal, the signals are extracted by the narrow band filter and the phases are compared, so that stable reception is possible.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of a device according to a first embodiment of the present invention.

FIG. 2 shows a configuration block diagram of a second embodiment device of the present invention.

[Explanation of symbols]

 1 antenna 2 down converter 3 mixer 4 common local oscillator 5 voltage controlled oscillator 6 local oscillator 7 narrow band filter 8 phase comparator 9 power combiner 10 output terminal 11 phase shifter

Claims (2)

[Claims] 1. An electronic tracking type receiver using an array antenna for receiving a transmitted wave, where n is a positive integer representing 2, 3, 4 ... n antennas, n down-converters for converting a received input signal of each antenna to a first intermediate frequency, a common local oscillator for supplying a local signal to the down-converters, and a down-converter for each down-converter. N mixers for converting the output signals to the second intermediate frequencies, one local oscillator for supplying a local signal to one phase reference antenna system mixer, and a transmission wave band connected to the output of each mixer N very narrow compared to width
Narrowband filters, (n-1) phase comparators for comparing the signal phases of the reference system and each tracking system, respectively,
The (n-1) phase control means for controlling the phase of the local signal input to the phase tracking antenna system mixer so that the outputs of these phase comparators become zero respectively, the reference antenna system mixer and (n-). 1) An electronic tracking type reception device comprising: a power combiner for combining the outputs of the individual tracking antenna mixers. 2. The electronic tracking receiver according to claim 1, wherein the local signal for the tracking antenna mixer is generated by a voltage controlled oscillator and controlled by the output of the phase comparator.