JPS6048630A - Repeating installation provided with internal switching function - Google Patents

Abstract

PURPOSE:To attain tracking of a demodulation by applying a signal from an oscillator common to a reception section and converting the signal into the same 2nd intermediate frequency after being converted into the 1st intermediate frequency so as to decrease the frequency error of each intermediate frequency. CONSTITUTION:The signal from the common oscillator 26 is applied to plural reception sections 23-25, where each reception frequency is converted into the 1st intermediate frequency close to the 2nd intermediate frquency. The 1st intermediate frequency is converted into the same 2nd intermediate frequency by mixing the 1st intermediate frequency with a signal from the independent 2nd local oscillators 27-29 having different frequencies. Thus, the variation in the 2nd intermediate frequency is reduced sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a repeater used in a digital satellite communication system, and is particularly effective in a multi-beam satellite communication system that switches, rearranges, and relays and amplifies burst signals of multiple carrier waves. This relates to a relay device.

Conventionally, the communication method most often used in satellite communication systems has been the FDM-F←FDMA method. However, in order to cope with the increase in the number of earth stations participating in the system and the increase in communication demand, the introduction of digital satellite communication systems with even higher efficiency, larger capacity, and the ability to flexibly follow traffic fluctuations is being investigated. . One such method, called 88/TDMA, has been put into practical use by combining a multi-beam satellite with TDM technology, installing a dynamic latch inside the satellite, and switching beam connections at high speed in synchronization with the TDMA frame. .

In recent years, in order to cope with the further increase in communication demand, the use of i-Luna Beam satellite repeaters that use frequencies in the high-frequency sub-millimeter wave band as carrier waves has been considered. FIG. 1 shows an example of the configuration of an 88/TDMA repeater using sub-millimeter wave band carrier waves. In the figure, 1 to 4 are receiving beam elements, and frequencies fx, ft...
...fn is assigned. 5 to 7 are receivers assigned to each receiving beam, 8 to 10 are independent local excavators placed in each receiver, and 11 is for switching the burst signal on the carrier wave. Switching circuit, 12-14
are transmitting units 15 to 18 that convert into the required frequency band and transmit it;
is the transmit beam element.

As shown above, the plurality of reception units 1 to 4 are fI, f...
...fn, but the input frequency of the switching circuit 11 that switches the burst signal on the carrier wave must be the same. In order to obtain a common intermediate frequency with the configuration shown in FIG. 1, it is necessary to set the oscillation frequencies of the local oscillators 8 to 10 in the plurality of receiving sections to the difference or sum of the receiving frequency and the intermediate frequency.

In addition, local excavators with different oscillation frequencies provided in a plurality of receivers have different frequency initial setting errors or frequency temperature changes. As a result, each intermediate frequency obtained by mixing with the received signal becomes approximately the same frequency, but the frequency dispersion between each intermediate frequency becomes considerably large.

For example, the reception input frequency of multiple receivers is 30.0GH.
z, 30.2G (z, 30.4GIiz--
--, and the oscillation frequency of the local excavator in the receiving section is 28.0 GHz and 28.2 GHz, respectively.

28.4 GIIz..., each intermediate frequency is 2.0 GHz. At this time, the maximum deviation of the frequency initial setting error in each local oscillator is +2×11,
If there is a local oscillator with a minimum deviation of +2×10, and the frequency deviation between the oscillator with the maximum and minimum frequency temperature change is 6×1o 8 degrees, the intermediate frequency will be approximately 2°OG.
Hz, but the variation in each intermediate frequency is about 280
It also becomes K11z.

In this way, when a burst signal is applied to the switching circuit 11 with each intermediate frequency widely varying, the burst signal of each channel is cut and reorganized by 4% in the switching circuit 11, and then the five required frequency bands are However, the carrier frequency of this reorganized transmission (!carrier wave) changes greatly for each burst signal.

At the receiving station that receives such a carrier wave burst signal,
The carrier wave burst signal is demodulated, but since the carrier frequency changes greatly for each burst signal, the demodulator cannot follow it, making communication impossible.

The present invention has been made in order to eliminate the above-mentioned drawbacks inherent in the conventional technology. Therefore, an object of the present invention is to supply a signal from a common oscillator to a plurality of receivers corresponding to a plurality of reception frequencies. converts each received same wave number to a first intermediate frequency close to the second intermediate frequency, and converts each received same wave number to a first intermediate frequency close to the second intermediate frequency,
The objective is to reduce the frequency error between the respective intermediate frequencies by converting the intermediate frequency into the same second intermediate frequency by mixing the intermediate frequency with a signal from an independent second local oscillator having a different frequency.

In order to achieve all of the above objects, the repeater according to the present invention includes a plurality of receiving sections provided for a plurality of receiving frequencies, and rearranges each output signal of the plurality of receiving sections into a plurality of designated signals. In the FRS dyne repeater, it has a switching circuit that converts the signal into the required frequency band and transmits it.
a plurality of receiving sections each having an independent first mixer, a first local oscillator common to the plurality of receiving sections, and a plurality of first local oscillators provided independently corresponding to the plurality of receiving sections. 2
The device is configured to include a mixer and a plurality of second local excavators each independently provided corresponding to the second mixer.

A preferred embodiment of the present invention will be described in detail below with reference to the drawings.

Figure 2 shows an 88 waveform using a carrier wave in the sub-millimeter wave band according to the present invention.
/A configuration example of a TDMA type repeater is shown. In the figure, reference numerals 19 to 22 are receiving beam elements, to which frequencies f+, ft, . 23 to 25 are receiving sections assigned to each receiving frequency, and this receiving section is configured of a first mixer and an amplifier. 26 is a first local oscillator that commonly supplies a signal with a frequency of ftoz to a plurality of receiving sections; 27 to 29 are second mixers that convert the first intermediate frequency to a second intermediate frequency; 30 to 31; are second local oscillators each having an independent frequency, 33 is a switching circuit that switches and reorganizes the burst signal on the carrier wave, and 34 to 36 are switching circuits that convert the signal into a required frequency band and transmit it (H). Transmitter with function, 37
˜40 is a transmitting beam element.

! ! The frequencies received by the receivers 23 to 25 are assigned different frequencies fl, fn, ...fn so that the frequencies on the transmitting station side do not combine, but normally this frequency assignment is done so that the frequency intervals are equal. interval or an integer multiple of a certain frequency.

Transmission fiJM using 88/TDMA communication system
Each station on the side uses a highly stable and highly accurate signal source such as an atomic oscillator such as a cesium frequency standard or a crystal oscillator with a constant temperature oven as a reference signal source, and sends signals fl, f, ... fn. Since the input terminals of the receiving sections 23 to 25 receive input frequencies f+, fmin, the error in fn is only a very slight frequency change due to the frequency setting error on the transmitting station side and the Doppler effect. Therefore, the variation in the frequency interval between each frequency is extremely small. Each signal f+%ft...fn received by a plurality of receivers has a frequency f(,
oz, respectively from the first local oscillator 26, frpz, frys, fty
It is converted to a first intermediate frequency n. At this time, the frequency 1'to1 of the first local oscillator 26 is set so that the first intermediate frequency is close to the second intermediate frequency.

A first local oscillator 26 for a plurality of receivers 23 to 25
is common, so frequency errors such as frequency initial setting error or frequency Iu degree change of the p41 local oscillator 26 appear in common at each first intermediate frequency, and therefore do not affect the frequency interval of each first intermediate frequency. I won't give it. TsutL
The frequency interval of the ml intermediate frequency is maintained at the frequency interval at the receiving input end.

The first intermediate frequency of each frequency is combined with the signals from the second local oscillators 30 to 32, each having a different frequency corresponding to the difference between the first intermediate frequency and the second intermediate frequency, so that they are almost identical. frequency to a second intermediate frequency.

Since the variations in frequency intervals at the first intermediate frequency are extremely small, the frequency error between the frequencies at the second intermediate frequency is mainly due to variations in the t42 local oscillators 30 to 32, which have different frequencies.

Figure 3 shows the second local oscillator whose frequency is 30.31.
．． 32 and the relationship between the output frequencies of these oscillators. In the figure, 30 to 32 are the same oscillators as shown in FIG. These are output terminals of the devices 30 to 33. The frequency temperature change of each oscillator measured at the output terminals 41 to 43 is v; The graph on the right side of FIG. In this figure, the vertical axis shows frequency, the horizontal axis shows temperature, the horizontal broken line shows the specified frequency of each oscillator, and the vertical broken line shows normal temperature. Since the second local oscillator is an independent oscillator with different frequencies, each oscillator has a different amount of frequency initial setting error and frequency temperature change, so this is the frequency error between the second intermediate frequencies. It appears.

However, since the first intermediate frequency is set close to the second intermediate frequency, the sm2rfJ section oscillation frequency is p4
Approximately 1/1 to 1 Oo of the local oscillation frequency shown in Figure 1.

Then, the influence on the second intermediate frequency due to the frequency error of the independent second local oscillator having a different frequency is about 1/'10 to 1/1000 compared to the case shown in the t4x diagram.

For example, if the reception input frequency is 30.0GHz or 30.2
GHz, 30.4GHJ......The frequency of the first local oscillator common to each receiver is 27.9.
GI-t z, the first intermediate frequency is 2.
1GHz, 2.3GHz, 2.5GHz -・
It becomes... The variations between the first intermediate frequencies are extremely small and can be ignored. Next, the oscillation frequency is 100 MHz 1300ME1z, 500MH
When the independent second local oscillator signal of z------- is mixed with the first width frequency and frequency converted, 2
．． 0GHz, 2.0GHz.

A second intermediate frequency of 2°0 GHz is obtained. On the other hand, the initial setting error for the frequency of a 100MHz oscillator is -2x10" (-2
00Hz), the frequency initial setting error of the 300MHz oscillator is +2>(10, (frequency +600)
Hz), and at the temperature where the difference in frequency temperature change of both oscillators is maximum, the frequency change of the 100 MI-1z oscillator has a deviation of -1-4X10 (+4 in frequency).
00I42), 300MH! If the frequency change of the oscillator is +6xto (+1.8KHz in frequency), the same wavenumber error appearing between the second local excavators is -
4-2,2KI(z), and this error appears as a frequency error at the second intermediate frequency.

Therefore, in the conventional repeater configuration example shown in FIG. 1, the frequency variation of the carrier wave of each burst signal at the input end of the switching circuit was approximately 280 KHz, but in the configuration example of the present invention, the frequency variation of the carrier wave was approximately 280 KHz. The variation is 1/127.

Like this, ↑5! A signal from a common oscillator is supplied to multiple receivers and converted into a first intermediate frequency close to the second intermediate frequency, and this first intermediate frequency is converted to an independent second intermediate frequency having a different frequency.
By mixing the signal with the signal from the local oscillator and converting it into the same second intermediate frequency, it is possible to reduce the frequency variation of each second intermediate frequency. The burst signal converted to the second intermediate frequency is switched and reorganized by the switching circuit 33 and transmitted, but the dispersion of the carrier wave number for each burst signal is sufficiently small for the reorganized signal. , when the receiving station side receives the signal and demodulates the burst signal, the demodulator can sufficiently follow the burst signal.
/'ll' This is extremely useful for DMA communication.

In the example above, the force (f: fr,
There may be three local oscillators, and this is not particularly specified. Also, the frequency used is the quasi-millimeter wave band, and the frequency of the second local excavator is explained as the V'HF band frequency, but! ! 2
The frequency of the local oscillator is determined to be 0M1Iz and is not particularly defined.

As explained above, according to the present invention, a signal from a common oscillator is supplied to a plurality of receiving sections, and is converted into a first intermediate frequency close to a second intermediate frequency, and this first intermediate frequency is converted into a first intermediate frequency whose frequency is By converting the signal from each independent second local oscillator and mixing E7 to the same second intermediate frequency,
Variations in each second intermediate frequency can be made sufficiently small.

For this reason, by using the system according to the present invention in an 88/TDMA communication system, the demodulator can sufficiently follow even when general transmission waves in the quasi-millimeter wave band are used, and in practical use f1
It's a benefit.

[Brief explanation of drawings]

Figure 1 shows a conventional S8 using a carrier wave in the sub-millimeter wave band.
/i” A block diagram showing a configuration example of a DMA type repeater,
Figure 2 shows an 88 waveform using a carrier wave in the sub-millimeter wave band according to the present invention.
/Tl) A block diagram showing an embodiment of the MA repeater. Figure 3 is a diagram showing the relationship between the output frequencies of the i2 local oscillator. , the i subordinate axis shows the frequency, and the broken line shows the specified frequency and normal temperature. 1 to 4... Reception beam element, 5 to 7... Receiving section, 8
~10...Local oscillator, 11...Switching circuit, 12~
14... Transmission unit, 15-18... Transmission beam element,
19-22...Receiving beam element, 23-25...Receiving unit, 26...First local oscillator, 27-29...Mixing block, 30-31...Second local oscillator, 33. ...Switching circuit, 34-3G...Transmission section, 37-40...Transmission ([1 beam element, 41-43...Output terminal Patent applicant: Nippon Tonkei Co., Ltd. Patent attorney: Kumagai J1a Most: 0 Meeting 1 3rd Clothes (MHz) Diagram

Claims (1)

[Claims] i number of receiving sections provided for a plurality of receiving frequencies;
In the heterodyne repeater, which has a switching circuit that reorganizes each output signal of the plurality of receiving sections into a plurality of designated signals, and a function of converting the signal into a signal in a required frequency band and transmitting the signal, an independent first mixing a plurality of receivers each having a receiver;
a gt local oscillator common to the plurality of receiving sections; a plurality of second mixers provided independently corresponding to the plurality of receiving sections; and a plurality of second mixers provided independently corresponding to the second mixers. and a plurality of second local oscillators, wherein the first local oscillator converts the reception frequency of each of the receiving sections to an if intermediate frequency close to the second intermediate frequency, and converts the first intermediate frequency, each having a different frequency. A relay device with an internal switching function, characterized in that the signal from each second local oscillator having a different frequency is mixed with the plurality of second m combiners to convert the signal into a second intermediate frequency having the same frequency. .