JPS6041902B2 - Time division multiple access carrier frequency measurement method and device - Google Patents

Description

[Detailed description of the invention] [Industrial application field] INDUSTRIAL APPLICATION This invention is utilized for a satellite communication system.

In particular, the present invention relates to a method and apparatus for measuring the frequency of a TDMA carrier wave transmitted from each earth station from a received signal in a time division multiple access (hereinafter referred to as "TDMA") communication system. [Summary] The present invention is an IT) MA communication system in which the transmission carrier frequency of the own station is measured within the own transmitting device, and the received signal that the transmit signal of the own station is relayed by a satellite and received. By measuring the control voltage of the voltage controlled oscillator for carrier wave regeneration with respect to the received signals from each earth station and other earth stations, and comparing and calculating the measurement results of the control voltages, one earth station can easily and accurately transmit signals from other earth stations. It measures the transmit carrier frequency of the earth station.

[Conventional technology]

In the TDMA communication system, a burst carrier wave is transmitted from each earth station using phase shift keying (hereinafter referred to as "PSK").

) and then relayed by a repeater installed on the satellite. Centralized monitoring and control is required to ensure that the burst signal carrier transmitted by each earth station is maintained within a predetermined deviation. Conventionally, for this purpose, a method has been used in which each earth station measures the carrier wave of its transmitted signal, and the measurement results are collected as separate information at a station that performs monitoring and control. Furthermore, in order to directly measure the carrier frequency of the transmitted signal from another earth station from the received signal, special equipment was required, such as converting the frequency shift in the satellite repeater. [Problems to be solved by the invention] However, collecting measurement results as separate information requires a measuring device at each earth station and a means to transmit the measured values, which has the disadvantage of being expensive. .

Also, what converts the frequency deviation at a satellite relay station is
The device was complicated and had the disadvantage of poor measurement accuracy. The present invention is an improvement on this, and its first object is to provide an accurate measurement method for easily measuring the carrier frequency transmitted by each earth station from a received signal in a TDMA communication system. A second object of the present invention is to provide an automatic measuring device that automatically executes this measuring method.

[Means for solving problems]

A first aspect of the present invention is a measurement method, in which one earth station in a time division multiple access communication system measures the frequency Fx of a carrier wave transmitted from another earth station. Measure the frequency FO within the local transmitter,
The control voltage of the voltage controlled oscillator for regenerating the carrier wave of the received signal is measured for the received signal from the other earth station mentioned above and the received signal received by relaying the transmitting signal of the own station (however, Vx is The above control voltage for the received signal from the earth station of
It is characterized by calculating.

The second invention of the present invention is a device that directly uses the above-mentioned method to perform automatic measurement, which is equipped in an earth station of a time division multiple access communication system and is based on the frequency F of a carrier wave transmitted from another earth station.
In a measuring device that measures and a processor that takes in the measured values of the frequency measuring means and the voltage measuring means, and the processor receives the burst signal from the other earth station and when the transmitted burst signal from the own station is relayed. means for temporarily storing the measured values X and VO of the voltage measuring means at the time of reception, respectively;
(where m is a coefficient) according to the measured value.

The above coefficient m is a value specific to each voltage controlled oscillator determined by the relationship between the oscillation frequency and the input control voltage of the voltage controlled oscillator, and is a constant in the range where the relationship between the oscillation frequency and the input control voltage of the voltage controlled oscillator is linear. becomes. [
Operation] The transmitting carrier frequency of the local station can be measured fairly accurately using a frequency meter within the transmitting device of the local station.

On the other hand, in the TDMA communication system, the satellite repeater uses the same relay system to relay the transmission signals of other earth stations and the transmission signal of the own station in chronological order, so the received carrier wave is regenerated from the received signal within the own station. The control voltage of the voltage controlled oscillator for each earth station is automatically controlled to a value corresponding to its transmit carrier frequency. Therefore, the above control voltage when transmitting burst signals from other earth stations are received is compared with the above control voltage when transmitting burst signals from the own station are relayed and received. By performing the calculation, it is possible to measure the frequency of the transmitted carrier wave of another earth station. [Embodiment] FIG. 1 is a block diagram of main parts of an apparatus according to an embodiment of the present invention.

A modulated signal given to the control section 1 is modulated by a PSK modulator 2 under the control of the control section 1, converted to a transmission frequency by a converter 3, and applied to a power amplifier 4. This output is transmitted from the antenna 6 to the satellite via the coupler 5. On the other hand, signals from the own station and other earth stations relayed by a satellite are received by an antenna 6, amplified by an amplifier 7, frequency-converted by a converter 8, and applied to a PSK demodulator 9.

The demodulated signal here is extracted by the control section 1 in a known manner. Here, the mixer 10 extracts and mixes the signal of the carrier wave oscillator of the PSK modulator 2 and the signal of the local oscillator of the converter 3, and the transmitting carrier wave frequency FO of the own station is obtained as the output.

This frequency FO is measured by a frequency meter 11. On the other hand, the PSK demodulator 9 includes a voltage controlled oscillator (not shown in FIG. 1, but will be described in detail later in FIG. 2) in order to generate a regenerated carrier wave necessary for demodulation.

), and the control voltages (20, Vx) of this voltage controlled oscillator are taken out to the sample and hold circuit 12. Since the received signal is in a burst form, the sample and hold circuit 12 samples and holds the control voltage by the control section 1 when receiving a signal from a station of interest. This held value is measured by a voltmeter 13. The measured value of this voltmeter 13 and the above-mentioned measured value of the frequency meter 11 are taken into the processor 14 and processed.

In order to measure the transmission carrier frequency of each earth station with such a device, first the transmission carrier frequency FO of the own station is measured within the transmitting device using the frequency meter 11, and this value is sent to the processor 1.
4.

Next, when the own station's transmission signal receives a burst signal relayed by a satellite, the control voltage of the voltage controlled oscillator described above
is detected by the sample hold circuit 12 and stored in the processor 14. Regarding the burst-like signal in which the transmitted signal of the earth station of interest is relayed by the satellite, the control voltage Vx of the voltage-controlled oscillator when this is received is similarly detected by the sample-and-hold circuit 12, and the result is detected by the processor 14.
to be memorized. The processor 14 performs a comparison operation on these two control voltage values VO and X as follows. That is, the transmission carrier frequency Fx of the other earth station of interest can be determined as r input=l゛υTllll(▼ υ ▼41).

Here, m is a coefficient determined from the relationship between the oscillation frequency and the control voltage of the voltage controlled oscillator. The value of this coefficient m can be set based on the characteristics of the voltage controlled oscillator used, or can be calibrated in advance by changing the transmission carrier frequency of the local station. In a practical '1DMA communication system, the transmission carrier frequencies of each earth station are extremely close to each other, so the values in parentheses in the above equation are extremely small.
Under the control of the control unit 1, the processor 14 can determine the transmission carrier frequency of each earth station by sequentially performing the above measurements and calculations on the received signals from each earth station.

This result can be displayed by any known means or used for 11) remote centralized monitoring of the MA communication system.

l As mentioned above, the means for generating a regenerated carrier wave in the PSK demodulator 9 and the means for extracting the control voltage of the voltage-controlled oscillator for that purpose can be any known means, but the method is shown in FIG. An example is shown in detail.

In Fig. 2, the input PSK modulated carrier wave is transmitted to the multiplier 2.
1 to an appropriate frequency and applied to one input of mixer 22.

The output signal of the voltage controlled oscillator 23 is multiplied by a multiplier 24 and applied to the other input of the mixer 22 .
A frequency-converted signal is obtained at the output of the mixer 22,
This signal is passed through a bandpass filter 25, has its frequency lowered by a downgrader 26, and is applied to a mixer 27. In the mixer 27, the signal is mixed with the output of the voltage controlled oscillator 23 described above, and an unmodulated carrier wave is obtained as the output. At this time, the input and output signals of the bandpass filter 25 are transmitted to the phase detector 28.
The phases are compared, and the output thereof is supplied to the voltage controlled oscillator 23 as a control voltage via a low-pass filter 29. This control loop controls the voltage controlled oscillator 23 so that the frequency of the input carrier wave of the bandpass filter 25 is always constant even when the output frequency of the multiplier 21, that is, the frequency of the input signal changes. Therefore, the control voltage of the voltage controlled oscillator 23 varies depending on the carrier frequency of the incoming signal. This control voltage is the voltage controlled oscillator 2
It is branched at the control input No. 3 and used as described above.
The above explanation describes an example in which the frequency measurements of the own station and each earth station, as well as the comparison calculations, are all automatically executed under the control of the processor. Measurements can be made even if

The present invention can also be carried out by manually performing all of these measurement procedures. [Effects of the Invention] As explained above, according to the method of the present invention, it is possible to measure the frequency of the transmitted carrier wave of each earth station from the received signal in the TDMA communication system.

This method does not require special equipment and can be easily implemented. Furthermore, since the measurement method of the present invention involves comparative measurement over a short period of time, the accuracy of the measurement is extremely high. Furthermore, according to the automatic measuring device of the present invention, a simple device that can automatically carry out the above method can be obtained.

By using this automatic measuring device, remote centralized monitoring of the TDMA communication system becomes extremely efficient.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of an apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing an example of a carrier recovery circuit included in a PSK demodulator. 1...Control unit, 2...PS
K modulator, 3... converter, 4... power amplifier, 5.
...Coupler, 6...Antenna, 7...Amplifier, 8...
・Converter, 9...PSK demodulator, 10...mixer,
DESCRIPTION OF SYMBOLS 11... Frequency meter, 12... Sample hold circuit, 13... Voltmeter, 14... Processor.

Claims (1)

[Claims] 1. In a method in which one earth station in a time division multiple access communication system measures the frequency Fx of a carrier wave transmitted from another earth station, the frequency Fo of the carrier wave transmitted by the own station is transmitted by the own station. measuring within the device a control voltage of a voltage controlled oscillator for regenerating the carrier wave of the received signal for the received signal from the other earth station and the received signal received by relaying the own station's transmitted signal; Fx = Fo + m (Vo - Vx) (where, Vx is the above control voltage for the received signal from another earth station, Vo is the above control voltage for the received signal received by relaying the transmission signal of the own station, m is a coefficient). 2 In a measuring device installed in an earth station in a time division multiple access communication system that measures the frequency Fx of a carrier wave transmitted from another earth station, the frequency used to measure the frequency Fo of the carrier wave transmitted within the transmitting device of the own station. A measuring means 11, a voltage measuring means 13 for measuring a control voltage of a voltage controlled oscillator for reproducing a carrier wave of a received signal, and a processor 14 for taking in the measured values of the frequency measuring means and the voltage measuring means. are the measured values Vx and V of the voltage measuring means at the time of receiving a burst signal from the other earth station and at the time of receiving the transmitting burst signal of the local station after being relayed, respectively.
A means for temporarily storing o and Fx according to this measured value.
=Fo+m(Vo-Vx) (where m is a coefficient).