JPS59151541A - Radio signal receiving system - Google Patents

Abstract

PURPOSE:To detect the presence of an electromagnetic wave such as an X band radar signal or K band radar signal by inserting a key signal like a pilot signal to an antenna output, and using only a signal including the key signal as the detecting signal. CONSTITUTION:A signal of the X band antenna 10 is coupled to a mixer 14 and heterodyned with a signal from a local oscillator 16 and frequency-modulated by the pilot signal. The output of the mixer 14 is fed to a common amplifier 20 via an IF amplifier 18. A K band antenna 12, mixer 22, local oscillator 24, and an IF amplifier 26 are constituted similarly. The output of the common amplifier 20 is connected to a mixer 28 receiving a signal from a local oscillator 36. The output of a band pass filter 34 is amplified by a tuning amplifier 36 and fed to a discriminator 38. The intermittent pilot signal demodulated by the discriminator 38 passes through a narrow band pass filter 40 and is given to a PLL42 via the amplifier 41.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wireless signal receiving method that can be applied to a device that detects the presence of electromagnetic waves. In particular, the present invention relates to a radio signal reception method using pilot signals.

The U.S. FCC (Federal Communications Commission) defines the X-band radar signal Y as 0.525 GHz±0.025 GHz, and K/(y t(7,,) radar signal Y 24.1
50 GHz±0.100 GHz. It is necessary to suppress the presence of signals in these bands, often in the form of CW or pulse waves, and various schemes have been developed in the past. however.

Detection of these weak signals using low-cost equipment is still unsatisfactory.

According to the present invention, when a first mixer output of, for example, 1.033 GHz is extracted, if a signal that is seven times as strong as a radio wave of an amateur frequency band of, for example, 1.0 MHz is generated in this mixer output, this is a signal from an antenna. Since it is not possible to distinguish between waves and interference waves, a key signal such as a pilot signal is inserted into the antenna output at 1%, and only the signal containing this key signal is used as a detection signal. The target pilot signal is frequency modulated and inserted into the first local oscillator signal input to the first mixer. This intermediate frequency amplified heterodyne signal is further heterodyned with a frequency swept second local oscillation signal in a second mixer.

This second mixer output is applied to a first bandpass filter. Depending on the frequency sweep signal (the second
When the mixer output falls within the pass frequency range of the first BPF, it is output from the first BPF, and these intermittent outputs are then demodulated by a frequency discriminator.

A tone burst of the pilot signal is detected.

These tone burst signals are provided to the second BPF. Narrowband BP with passband of pilot signal frequency
The output from F is phase-compared with the continuous pilot signal in phase-lock-loose.

The locked state of the phase-locked loop is detected by the reception instruction means.

The figure is a block diagram of a microwave receiving system incorporating the present invention. In this method, C of X band and C band
W or pulsed electromagnetic radiation signal respectively from the first antenna 1
0 and a second antenna 12. X band is 10.500-10.550
Covers the frequency of G (giga) Hertz, and
'! It is regulated to cover 24.050 to 24.250 GHz. X-band antenna 10 is coupled to a mixing circuit 14 where the signal from antenna 10 is heterodyned with a local oscillator signal from local oscillator 16. This local oscillator signal from the oscillator 16 is in the form of a 9,492 GHz signal that is frequency modulated with a 19 KHz pilot signal, as will be described later. The output from mixer 14 is connected to an IF amplifier SIC, which is tuned to amplify the (1,033±0.025) GHz signal. The amplified signals from the IP amplifiers 18 and the like are applied to the inputs between the common amplifiers.

The first mixed signal η connected to the X-band antenna, the first
The circuit consisting of a local oscillator and an IF amplifier multiplexer whose output is connected to the other input between the common amplifiers is substantially the same as the circuit described above for the X-band antenna IO, but with a second The output of each local oscillator is 23.117 GH frequency modulated with the 19 KHz pilot signal mentioned above.
z signal and the heterotine output from the first mixer η is of a frequency of (1,033±0.100) GHz.

The output between the common amplifiers is read directly into the second mixer path. Therefore, this second mixer is for X-band microwave (
1033 Sat 0.025 ) Band microwave related to IP multiplied signal of GHz (1.033±o, xoo; G
It is designed to receive an IP times signal t of Hz. Furthermore, what is received by the second mixer 4 is the M2 local oscillator signal from the second local oscillator (source). The frequency of this oscillator signal may vary continuously between 0.983 and 1.083 GHz. The roughness of sweeping such a frequency range is determined by a 30 Hz sawtooth wave from sweep generator β. In order to sweep the frequency of the second local oscillator signal, a triangular wave or the like may be used instead of the above-mentioned sawtooth wave. Second
Mixer path is 1.033 GHz IF multiplied signal, 30Hz
Heterodyne with this variable frequency local oscillator swept by a sweep signal of
According to the frequency range of the center frequency of Hz.

Let it pass. This frequency range is required due to the role of the phase-locked loop (PLL) described below. The output of the first BPF 34 is amplified by a 10.7 MHz tuned amplifier, and is applied to a discriminator 38.

This discriminator 38 detects an intermittent 10.7 MHz pilot tone signal so as to detect an intermittent 19 kHz pilot signal when the microwave receiving system is receiving an X or band wave. ! - It's starting to demodulate. The period of occurrence of these 19 KHz pilot tones depends on the frequency of the sweeping sawtooth wave generated by sweep generator 32.

The demodulated intermittent pilot signal is 19 KHz narrow range B.
PF Shunka passes. BPF 40 has a passband of 19 KHz±100H2 in the preferred embodiment.

The output of this second BPF is amplified by an amplifier 41,
A phase-locked loop (PI, I, ) 42 is provided. The illustrated PLL 42 is a voltage controlled oscillator (VCO)
44. It consists of a phase comparator section and a low pass filter 48. V
The CO 44 provides a 19 KHz continuous pilot signal on the line, which is amplified by an amplifier 52 and then provided to the X-band and 2-band first local oscillators 16 and 24 for frequency modulation. .

When an X-band or 2-band signal is received by the illustrated receiving scheme, an intermittent 19 KHz demodulated pilot signal of the form 17) is produced in the PLI, a human-powered line. In this intermittent demodulated pilot signal & phase comparator 46, the phase is compared with the continuous vCO output from the VCO 44, which is the same as the continuous pilot signal to be modulated with 11 frequencies. The result of this comparison activates a switch 56 connected to the PLL output, which in turn activates both the buzzer drive circuit and the lamp drive circuit to provide an audible and visual indication of the reception of the X-band and 2-band signals. P.L.
The low pass filter of the L block 42 is configured to provide a continuous pilot signal to be frequency modulated, even though there is some phase difference between the continuous pilot signal and the intermittent demodulated pilot signal, and also a small number of burst Q-pulses for each demodulated pilot burst. Even if only PL and L42' are included, it operates to bring the locked state to PL and L42'. 10,7MHz B P
The wider the F34 band, the more bursts can be included in each pilot tone burst. Shikajinaga1), BPF34 bandwidth? Making it wider will reduce the sensitivity of the pilot SL servo loop. In a preferred embodiment,
It has been found that PLL 42 will lock stably as long as there are only a few pulses in each burst. This provides a narrow passband for the first BPF 34 and provides a large pilot signal servo gain.

By using narrowband 19 KHz BPF4U'&.

A high S/N ratio is provided. In the reception method of the present invention for detecting tone signal signals, it is possible to minimize the reception frequency bandwidth and provide highly sensitive performance. Yet again. Since only the signals passing through the first mixers 14 and 22 are frequency modulated with the pilot signal, the system of the present invention does not react to spurious or noise that enters after these first mixers.

[Brief explanation of drawings]

The figure shows a block diagram of an embodiment of the present invention, in which 10 is an X-band antenna, 12 is a second antenna, 14.
22 is a first mixer, and 16.24 is a first local oscillator. 18. 26 is an intermediate frequency amplifier, 28 is a second mixer, 30
is a second local oscillator, 32 is a sweep signal generator, vane is a first bandpass filter, 38 is a discriminator, phrase is a second bandpass filter, and 42 is a phase-locked loop. % indicates lamp drive circuit χ. =205 Procedural amendment (method/December 1999/2007) Commissioner of the Japan Patent Office Kazuo Wakasugi 1, Indication of the case Showa offense 2013 Patent application No. 0 YuCme/2 No. 2 Reception of #signal without title of invention Power formula 3 Relationship with the case of the person making the amendment Patent applicant Address Name: General Research of Electro-X Co., Ltd. 4, Agent Address: 105 Address Shiba 3-chome Building, 3-2-14 Shiba, Minato-ku, Tokyo Description" insert.

Claims (1)

[Claims] antenna means for receiving a radio frequency signal within one frequency range; and a first local oscillator signal connected to the antenna means and frequency modulated with a continuous pilot signal to heterotine the random frequency signal to provide an intermediate frequency signal. a first mixer, a tuned amplifier for amplifying the intermediate frequency signal, and a second local oscillator signal which is swept with a frequency sweep signal at a predetermined sweep rate in response to the output of the tuned amplifier; The second mixer for the tuning amplifier has a hetero gain, and the output receiver of the second mixer has a passband in a predetermined frequency range, and the output of the second mixer falls within the frequency range of the passband. a first band-pass filter that passes this part when the first band-pass filter is detected; a discriminator that receives the output of the first band-pass filter and demodulates the tones/bursts of the pilot signal at seven frequencies; a second bandpass filter for receiving and passing the tone-burst signal and having a narrow passband characteristic; a voltage controlled oscillator for generating said continuous pilot signal; A phase comparator that compares the phase of the signal tone burster, and a low-pass filter that controls the voltage controlled oscillator based on the result of the comparison, and , means for giving an instruction indicating reception of the radio frequency signal.