JPH0728242B2 - Frequency signal generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention mainly relates to a method for constructing a communication device mounted on an artificial satellite, in particular, a repeater, in which the frequency of a local oscillator of a transmitter / receiver constituting this repeater is increased. The present invention relates to a frequency signal generator that can be stably and arbitrarily changed.

[Conventional technology]

Conventionally, a satellite-mounted repeater has a frequency synthesizer as a frequency signal generation source. This frequency synthesizer uses the output of the voltage controlled oscillator (VCO) in the phase locked loop (PLL) of the pilot receiver as a reference signal source and multiplies this VCO output to the required local oscillator signal. Was there.

[Problems to be Solved by the Invention]

 The frequency signal generating method described above has the following drawbacks.

(1) The phase noise of the VCO output is at least 2 of the multiplication order (n)
Degraded by 0logn decibels in the multiplier output.

(2) The frequency of the VCO output is variable within a range of about 1 / m of the receivable frequency range of the pilot receiver (m: ratio of the frequency of the first station of the pilot receiver to the frequency of the VCO output). However, it is difficult to obtain a large frequency change range beyond this range.

[Means for Solving the Problems]

The present invention, in a phase-locked loop (PLL) type receiver for receiving a pilot signal with high frequency stability transmitted from a ground station, is based on the output of the VCO that constitutes the PLL of this receiver. A digital control type frequency synthesizer group input as a signal is provided, and an output of one system of this frequency synthesizer group is connected as a reference signal of a first station signal source of the pilot receiver.

〔Example〕

FIG. 1 is a functional system diagram of an embodiment of the present invention. The pilot receiver 1 has a phase comparator 11 and a multiplier 12, and a Ka band pilot signal transmitted from a ground station is transmitted to the multiplier 12
Convert to the intermediate frequency of the S band by the local signal of the Ka band obtained in. Also, the pilot receiver 2 is a phase comparator.
It has 21 to 23, multipliers 24 to 26, and VCXO27, and these have a function of phase-locking to the S band signal by forming a PLL circuit configuration. The output of the VCXO 27 in the PLL circuit is connected to the frequency divider 31 as a reference signal of the synthesizer section 3.

The synthesizer unit 3 is composed of a frequency divider 31, a phase comparator 32, a loop filter 33, a VCO 34 and a prince scaler 35. The output of the VCO 34 serves as a local oscillator signal source of the pilot receiver 1 and a multiplier.
Connected to 12 inputs.

It should be noted that in FIG. 1, the numbers attached to the multipliers and the frequency dividers respectively represent the multiplication number and the frequency division number, and the numerical values representing the frequency are also examples, and the present invention is not limited thereto. .

Further, in the figure, only one synthesizer unit 3 is shown as a means for obtaining the local oscillator signal of the pilot receiver 1, but a plurality of synthesizer units 3 are provided so as to receive the output of the VCXO27 in parallel, and other parts are provided. Are used as various frequency signal sources.

The frequency signal obtained by the present invention is a local oscillation source obtained by dividing / multiplying a pilot signal by a signal source in which all phase relationships are in a synchronous state (coherent), and has the following characteristics.

(1) Since the local oscillation system of the pilot receiver 1 and pilot receiver 2 is synchronized with the frequency stability and phase noise level of the pilot signal, the frequency stability and phase noise level of the VCXO27 output are at least the synthesizer section 3, and It is improved by the total multiplication order of the multiplier 12. Therefore, a very stable signal can be obtained from the output of the synthesizer section 3.

(2) By changing the division ratio of the prescaler 35, the frequency of the highly stable signal source can be changed significantly. (For example, about ± 10 MHz) (3) By moving the frequency of the pilot signal, the output of the synthesizer unit 3 can be continuously moved.

〔The invention's effect〕

As described above, according to the present invention, it is possible to improve the phase noise and obtain a frequency signal with high frequency stability, and moreover, the variable width of the frequency can be largely taken as compared with the conventional one. .

[Brief description of drawings]

FIG. 1 is a functional system diagram of an embodiment of the present invention. 1,2 …… Pilot receiver, 3 …… Synthesizer section, 31 ……
Frequency divider, 32 …… Phase comparator, 33 …… Loop filter, 34…
… VCO, 35 …… Prescaler.

Claims (1)

[Claims] 1. A phase locked loop type receiver for receiving a pilot signal transmitted from a ground station, wherein the output of a voltage controlled oscillator constituting a phase locked loop of the receiver is supplied as a reference signal. A frequency signal generator comprising a digital control type frequency synthesizer group, and an output of one system of the frequency synthesizer group is connected as a reference signal of a first station signal source of the pilot receiver.