JP2794973B2 - Satellite communication earth station equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication earth station apparatus, and more particularly to a reception frequency control method of a communication signal receiving apparatus in a satellite communication earth station when a communication signal is captured by changing a communication frequency to be received. .

[0002]

2. Description of the Related Art In satellite communication, a frequency variation of a communication signal transmitted by a communication partner station, a frequency deviation between a plurality of communication partner stations, a frequency variation of a transmission / reception frequency in a satellite, and a reception frequency variation of a communication signal receiving apparatus of the own station. For example, there are many factors that cause a frequency deviation of a communication signal to be received.

[0003] For this reason, when performing satellite communication, a communication signal receiving device generally uses an AFC (Auto Frequency Control: AFC) to receive and capture a communication signal transmitted by a communication partner station.
Automatic frequency control) function.

The AFC function performs control by assuming a deviation of a communication signal to be captured with a certain margin in consideration of all factors that cause a frequency deviation of a communication signal to be received. I have.

FIG. 2 is a block diagram of such a conventional satellite communication earth station apparatus. Normally, a communication signal transmitted from a partner station via a satellite is received by a communication signal demodulator 4 through an antenna 1, a low noise amplifier 2, and a reception frequency converter 3.

The reception frequency of the communication signal is the frequency switching information.
When specified by 101, the logic unit 11
2, the frequency synthesizer 13 is controlled to set a desired frequency, and the frequency deviation is corrected by an AFC function unit including a synthesis unit 14, a demodulation unit 15, and a voltage controlled crystal oscillator (VCO) 16. The captured communication signal is passed to the communication signal terminal device 5 through the data processing unit 19.

Transmission is performed through a communication signal modulator 6, a transmission frequency converter 7, a high power amplifier 8, and an antenna 1.

In this case, the correction range of the frequency deviation performed by the AFC function unit is, for example, ± 20 kHz for the frequency fluctuation in the satellite, ± 2 kHz for the transmission frequency fluctuation in the transmitting station,
When the reception frequency fluctuation of the receiving station is ± 2kHz, VCO
The frequency is set to about ± 30 kHz to ± 40 kHz in consideration of 16 modulation sensitivities and the like.

In the earth station having such a configuration, a communication signal is received only when communication is performed. Therefore, when communication is not performed, a reception frequency not used for communication is set or the power supply of the receiving device is turned off.

[0010] Since control for receiving and capturing a communication signal must take into account the frequency deviation due to satellites and the deviation between each earth station, the communication signal receiving apparatus is used for communication when communication is not performed. If the receiving frequency is not set, it takes time to acquire the receiving frequency the next time communication is performed, and if the transmission speed of the communication signal is slow, the acquisition time of the communication signal may be as long as several minutes. However, there is a disadvantage that the satellite line cannot be used effectively.

In the case where communication is performed by turning on the power of the communication signal receiving device after the power is turned off, it takes time for the frequency of the receiving device itself to stabilize. Even if the frequency of the receiving device itself is stabilized immediately, it is not possible to estimate how much the frequency deviation at the satellite is at present, so that there is a disadvantage that the frequency acquisition time becomes long.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem. It is an object of the present invention to provide a receiving apparatus for shortening a frequency acquisition time with a simple structure.

[0013]

According to the present invention, there is provided a satellite communication earth station apparatus for communicating via a satellite, comprising: receiving means for receiving a communication signal transmitted by a communication partner station; and receiving means for receiving the communication signal. Frequency deviation detecting means for detecting a frequency deviation,
Storage means for storing the detected frequency deviation, and reading the frequency deviation stored in the storage means in response to an instruction to change the frequency of the communication signal to be received, and controlling the reception frequency in accordance with the frequency deviation. a frequency control range setting means for setting a range, viewed contains a reception frequency control means for capturing the communication signal by the frequency control range, the
Receiving frequency control means starts capturing the communication signal
If acquisition cannot be performed within a certain time from
A satellite communication earth station apparatus characterized in that the range is controlled to be enlarged .

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and the same parts as those in FIG. 2 are denoted by the same reference numerals. In one embodiment of the present invention, when the communication signal demodulator 4 is receiving the signal as shown in FIG. 1, the frequency controller 17 stores the frequency deviation of the currently received signal in the memory 20 using the frequency deviation notification signal 106.
And this is stored in the nonvolatile memory 20. For example, assume that the frequency deviation at this time is +12 kHz.

The reception frequency of the communication signal is frequency switching information.
When specified by 101, the logic unit 11
2 controls the frequency synthesizer 52 to set a desired frequency.

The frequency deviation of the signal received so far is read from the memory 20 by the frequency deviation read signal 107, and the frequency deviation to be corrected by the AFC function unit is calculated.
The frequency deviation up to now + 12kHz is the satellite frequency fluctuation,
Since frequency fluctuation of the transmitting station, frequency fluctuation of the receiving station, etc. are included, if the desired frequency is f, if AFC is performed near f + 12 kHz, the frequency deviation due to the satellite will be removed. The reception frequency may be captured in consideration of only the inter-frequency deviation.

In this case, the frequency fluctuation of the transmitting station is ± 2 kHz,
Since the frequency fluctuation of the receiving station is ± 2 kHz, the frequency can be captured by correcting ± 4 kHz near f + 12 kHz. That is, the present invention requires only ± 4 kHz as compared with the conventional frequency control range of ± 30 kHz to ± 40 kHz, so that the acquisition time of the received signal is shortened.

Therefore, the logic section 11 has a frequency of f + 12 kHz ±
The frequency control range information 104 of 4 kHz is passed to the frequency control unit 17. The frequency controller 17 derives the received frequency correction information 105 in the frequency control range to the VCO 16.

In this case, the frequency control unit 17
1 for the midpoint voltage (corresponding to frequency f) of the control voltage of 6
Generates a variable range voltage equivalent to 2kHz ± 4kHz,
This is the reception frequency correction information 105. Then, when the communication signal is received, the reception frequency deviation at that time is detected (a deviation voltage with respect to the midpoint voltage of the control voltage of the VCO 16 is detected), and this is output to the nonvolatile memory 20 as the frequency deviation notification signal 106. And store it.

The time after the AFC function is activated is measured by the timer 18, and if the received signal cannot be captured within a certain time, ± 30 kHz as in the prior art.
If it is controlled to be about z to ± 40 kHz, the received signal can be captured.

[0022]

As described above, according to the satellite earth station apparatus of the present invention, when changing the frequency of the communication signal received by the satellite earth station, the communication signal is removed by excluding the frequency deviation at the satellite. Since the signal can be captured, the signal capture time is shortened. Also, if the frequency deviation at the satellite is larger than expected, a sufficient capture range is set and the communication signal is captured after a certain period of time. Is not incapable of being captured, and is not inferior to the conventional capturing time.

Furthermore, even if the power of the communication signal receiving apparatus is turned off, the previous frequency deviation is stored, so that there is an excellent effect that the signal capturing time is shortened.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a conventional satellite communication earth station device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Logic part 13 Frequency synthesizer 16 VCO 17 Frequency control part 18 Timer 20 Memory

Claims (1)

(57) [Claims] 1. A satellite communication earth station apparatus for performing communication via a satellite, comprising: a receiving means for receiving a communication signal transmitted by a communication partner station; and a frequency for detecting a frequency deviation caused by receiving the communication signal. Deviation detecting means, storing means for storing the detected frequency deviation, and reading out the frequency deviation stored in the storing means in response to an instruction to change the frequency of the communication signal to be received, in accordance with the frequency deviation. a frequency control range setting means for setting a control range of the receiving frequency Te, saw including a reception frequency control means for capturing the communication signal by the frequency control range, the reception frequency control
Within a certain time after the means starts capturing the communication signal
If the signal cannot be captured, the reception frequency range is expanded and controlled.
A satellite communication earth station device.