JPS59151540A - Identifying device of receiving frequency band in radio signal receiving system - Google Patents

Abstract

PURPOSE:To display the receiving band by driving such as a buzzer driving circuit in receiving at an X band and a K band, respectively. CONSTITUTION:An X band antenna 10 is coupled to a mixer 14 and an output from the mixer 14 is connected to an IF amplifier 18. The output of a K band antenna 12 is connected similarly to a mixer 22 and an IF amplifier 18. An output of a common amplifier 20 is connected to the 2nd mixer 28. The frequency of the 2nd local oscillator 30 is swept. A discriminator 38 detects an intermittent pilot signal, which passes through a BPF 40-1 and is given to a PLL 42-1. The phase of this signal is compared with the continuous VCO output fed from a VCO 44-1 at a phase comparator 46-1. The result of comparison operates a switch 56-1 to make a buzzer driving circuit 58-1 and a lamp driving circuit 60-1 operate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reception frequency identification device used in a wireless signal reception system that can be applied to a device that detects the presence of electromagnetic waves such as X- and K-band radar signals. In particular, the present invention can be used in radio signal reception systems that use pilot signals.

The U.S. FCC (Federal Communications Commission) defines X-band radar signals as 0.525 GHz ± 0.0 2 5 GHz, and K-band radar signals as 24.150 GHz ± 0.1.
．． 0 0 GHz. It is often necessary to detect the presence of signals in these bands in the form of CW or pulsed waves, and various schemes have been developed in the past. However, it is still unsatisfactory to detect these weak signals using low-cost equipment.

The reception method to which the present invention is applied is, for example, 1.033GH
When taking out the first mixer output of z, for example, if a signal that is 7 times as large as the radio wave of the amateur frequency band of 1 4 4 MHz is generated in this mixer output, is this a signal wave from the antenna or an interference wave? Since they cannot be distinguished, a key signal such as a pilot signal is inserted into the antenna output, and
Only signals containing this key signal are used as detection signals. For this purpose, the pilot signal is frequency modulated and inserted into the first local signal input to the first mixer. This intermediate frequency amplified heterodyne signal is
It is further heterodyned with the frequency-swept second local oscillator signal in the mixer. This second mixer output is applied to a first bandpass filter. When the second mixer output whose frequency is varied by the frequency sweep signal enters the pass frequency range of the first IBPF, it is output from the first IBPF, and these intermittent outputs are then demodulated by a frequency discriminator to detect the tone burst of the pilot signal. be done. These tone burst signals are provided to the second BPF. The output signal of the narrow range BPF, which has a passband at the pilot signal frequency, is phase compared with the continuous pilot signal in a phase lock loop. The locked state of the phase lock loop is detected by the reception instruction means.

An object of the present invention is to provide a device for identifying signals in a plurality of frequency bands in the above-described receiving system. In the example described below, two
Although the description will be made regarding an apparatus for identifying signals of one frequency band, it is of course possible to identify signals of a plurality of other bands.

The figure is a block diagram of a microwave reception system incorporating the present invention. In this method, C of X band and K 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
It covers the G (giga) Hertz frequency, and the K band is regulated to cover 24.0 50 to 24.2 50 GHz. X-band antenna 10 is coupled to a mixing circuit 14 where the signal from antenna IO is heterodyned with a local oscillator signal from local blunt oscillator 16. This local oscillator signal from the oscillator l6 is frequency-modulated with a pilot signal of frequency fx (17 icHz) as described later.9. 4 9 2 GH
It is in the form of a z signal. The output from the mixer 14 is connected to an IF amplifier l8, which has a ratio of (1.033±0.
025) It is tuned to amplify GHz signals. The amplified signal from IF amplifier 18 is provided to the input of a common amplifier add.

a first mixer 22 connected to the K-band antenna 12;
The circuit consisting of the first local oscillator 24 and the IF amplifier 26 whose output is connected to the other input of the common amplifier 20 is of substantially the same construction as the circuit described above with respect to the X-band antenna lO, but 1 The output of the local oscillator 24 has a frequency fk (
23 KHz) pilot signal and frequency modulated 2
3, 1 1 7 GHz signal, and the first mixer 22
The heterodyne output from is (1.033±0.1 0
0) GHz frequency.

The output of the common amplifier 20 is connected to a second mixer 28 .

Therefore, this second mixer has an IF signal of (1.033±0.0 2 5 ) GHz for the X-band microwave and (1.033±0.25 ) for the K-band microwave.
100) GHz IP signals. Also, what is received by the second mixer 28 is the second local oscillator signal from the second local oscillator 30 .

The frequency of this oscillator signal is 0.983~1.083
It can vary continuously between GHz. The speed at which such frequency ranges are swept is 30% from the sweep generator 32.
Determined by the Hz sawtooth condition. In order to sweep the frequency of the second local oscillation signal, a triangular wave or the like may be used instead of the above-mentioned sawtooth wave. The second mixer 28 is 1. 0 3
3 GHz IF signal. Heterodyne with this variable frequency local oscillator swept with a 30 Hz sweep signal.

A 1 0.7 MHz first bandpass filter (BPF) 34 coupled to the second mixer outputs a 1 0.7 MHz
In response to the frequency range of the center frequency of MHz,
Let it pass. This frequency range is required for the operation of the phase lock loop (PI,L), which will be described later. The output of the IBPF 34 is amplified by a 10.7 MHz tuned amplifier, and is applied to a discriminator 38. This discriminator 38 is designed to demodulate an intermittent 10.7 MHz pilot tone signal so as to detect an intermittent pilot signal when the microwave receiving system is receiving an X or K band wave. The period of occurrence of these intermittent pilot tones depends on the frequency of the sweeping sawtooth wave generated by sweep generator 32.

The demodulated intermittent pilot signal of frequency fx is 17KH
Pass through BPF40-1 in the z-narrow area. BPF 40-1 has a passband of 17 KHz±100 Hz in the preferred embodiment. The output of this second BPF is the amplifier 41-
1, phase lock loop (PLL)
42-1. The illustrated PLL 42-1 includes a voltage controlled oscillator (VCO) 44-1 and a phase comparator 46-1.
and a low-pass filter 48-1. VC044-1 provides a 17 KHz continuous pilot signal on line /50-1, which is amplified by amplifier 52-1 and then provided to X-band first local oscillator 16 for frequency modulation. When an X-band signal is received by the illustrated receiving scheme, an intermittent 17 KHz demodulated pilot signal in the form of a sequence of 17 KHz tone bursts is applied to the PLL input line 5.
Occurs in 4-1.

This intermittent demodulated pilot signal is phase-compared in phase comparator 46-1 with the continuous CO output from VCO 44-1, which is the same as the continuous pilot signal to be frequency modulated. The results of this comparison actuate switch 56-1 connected to the PLL output to activate both buzzer drive circuit 58-1 and lamp drive circuit 60-1 to provide audible and visible reception of the X-band and K-band signals. give instructions.

The low-pass filter 48-1 of the PLL block 42-1 also provides a small number of bursts for each demodulated pilot burst, even if there is some phase difference between the continuous pilot signal to be frequency modulated and the intermittent demodulated pilot signal. Even if only a pulse is included, it will operate to bring PLL 42/-1 into its locked state. lO. 7MHzBPF3
The wider the bandwidth of 4, the more burst pulses can be included in each pilot burst. However, increasing the bandwidth of BPF 34 will reduce the sensitivity of the pilot signal servo loop. In the preferred embodiment, it has been found that PLL 42-1 can lock stably with only a few pulses in each burst. This gives the first BPF 34 a narrow passband and a large pilot signal servo gain narrowband 17 KH.
By using BPF 40-1 of z, a high S/N ratio is provided. In the reception method of the present invention for detecting tone signals, it is possible to make the reception frequency bandwidth as small as possible and provide highly sensitive performance. Furthermore, since only the signals passing through the first mixers 14 and 22 are frequency modulated with the pilot signal, this system does not respond to spurious or noise that enters after these first mixers.

The discriminator 38 outputs an intermittent pilot tone signal of -j k (Z3 K'Hz) when a K band signal is being received. This is received by and passed through a 23 KHz narrowband bandpass filter 40-2. The above-mentioned 17 KHz narrow band pass filter 40-
1 provides a shunt for the fk pilot signal, and a 23 KHz narrow bandpass filter 40-2 provides a shunt for the fk pilot signal. Therefore, the fx pilot signal system and the fk pilot signal system have substantially the same circuit configuration.

With the circuit configuration of the present invention, when receiving X-band radio waves, the pilot signal system operates to operate the buzzer drive circuit 58-1 and lamp drive circuit 60-1, while the K-band frequency Upon signal reception, the fk pilot signal system is activated to activate the buzzer drive circuit 58-2 and lamp drive circuit 60-2.

Therefore, by knowing which drive circuit has been activated, it is possible to know which band of signals has been received.

[Brief explanation of drawings]

The figure is a block diagram of one embodiment of the present invention. lO is an X-band antenna, 12 is a K-band antenna, 14.2
2 is the first mixer. 16.24 is the first local oscillator, 18.
26 is an intermediate frequency amplifier, 28 is a second mixer, and 30 is a second
Local oscillator, 32 is a sweep signal generator. 34 is the l-th band-pass filter, 38 is the discriminator, and 40-1.40-2 is the second band-pass filter. 42-1.42-2 is an air lock loop, 58-1.58-2 is a buzzer drive circuit, and 60-1.60-2 is a lamp drive circuit.

Claims (1)

[Claims] antenna means corresponding to each frequency band for receiving radio frequency signals within a plurality of frequency bands; and a first local oscillator signal connected to each antenna means and frequency-modulated with a unique continuous pilot signal, respectively. a first mixer that heterodynes the frequency signal and provides an intermediate frequency signal; a tuned amplifier that amplifies the intermediate frequency signal;
a second mixer that receives the output of the tuned amplifier and heterodynes the output of the tuned amplifier with a second local oscillator signal swept with a frequency sweep signal of a predetermined sweep speed; and an output of the second mixer. a first band-pass filter which has a pass band in a predetermined frequency range and passes this portion when the output of the second mixer falls within the frequency range of this pass band; a discriminator that receives the output and frequency-demodulates it to extract the tone burst of the pilot signal, and a discriminator that receives the tone burst of the pilot signal by distinguishing it based on the difference in frequency of each pilot signal and passes it through the discriminator and a narrow pass band. a second bandpass filter having characteristics of: a voltage controlled oscillator for generating the respective continuous pilot signals; and comparing the phases of the continuous pilot signal and the corresponding pilot signal tone burst from the second bandpass filter. a phase comparator; a low-pass filter that receives the output of the phase comparator and controls the voltage controlled oscillator based on the result of the comparison;
A radio signal receiving system comprising: means for giving an instruction indicating reception of the radio frequency signal in accordance with the output of the phase comparator, wherein the reception instruction related to each pilot signal is separately given. Received frequency identification device.