RU2577848C1 - Radar detector - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: radar detector comprises an antenna connected to a signal receiver, the first mixer which mixes the signal from the antenna with the signal from the first heterodyne, an amplifier, the second mixer which mixes an amplified signal with the signal from at least a second heterodyne, a bandpass filter, a signature module and a central processing unit which outputs information on detected radar through an audio amplifier and a speaker. The central processing unit controls at least the second heterodyne and, through a saw-tooth voltage generator connected thereto, the first heterodyne. The device also includes a photodiode and a laser module connected thereto, the signal from which is analysed by the central processing unit.

EFFECT: high sensitivity and noise-immunity.

4 cl, 2 dwg

Description

The claimed technical solution relates to the field of detection tools designed to warn drivers and passengers of cars about speed control or other violations detected by law enforcement agencies.

All modern radar detectors (possibly with the exception of some expensive exclusive models) use almost the same principles, algorithms and circuitry, work in a similar way and have the same disadvantages.

1. Weak sensitivity to many modern police radars.

The classical scheme of the radar detector (RD) is made so that it sees well only an unmodulated signal (there are no police radars with such a signal at all), or a signal with a long pulse duration. On radars with short pulses (Robot, Mesta), the sensitivity can drop tens or hundreds of times, up to a complete loss of sensitivity.

2. Response to radiation sources other than police radars.

This is the main reason why many do not want to buy taxiways at all. He squeaks at every automatic door, at every car with blind spot sensors or active cruise control. Among dozens and hundreds of fires for all this, it is almost impossible for the user to single out one fire for a police radar. Over time, the number of such sources of interference will only grow, it is impossible to rebuild from them within the framework of the classical scheme.

3. Misses single shots of handheld radars.

Classic RD scans ranges alternately and rather slowly. He may miss a single shot because at that time he scanned another range or another part of the same range.

4. The need to select an operating mode.

The user is invited to find a compromise between sensitivity and noise immunity, using modes with reduced sensitivity, turning off some ranges and other settings. It is believed that in any conditions you can choose the optimal settings. In fact, this is not a solution to problems, but only the appearance of their solution. An ordinary user, as a rule, does not have the necessary knowledge to properly configure the detector, and noise immunity in any case is achieved due to a significant decrease in sensitivity. The user wants to have a turn-on and drive-based taxiway, from the settings he only needs the sound volume and display brightness.

The closest technical solution that eliminates a number of the above disadvantages is the radar detector described in RF patent No. 124404 of 01/20/2013. This radar detector additionally contains a signal processing circuit including serially connected: an amplifier, a comparator and a logic analyzer, while the intermediate frequency signal of the device is supplied to the amplifier, and the logical analyzer is connected to the comparator with its first output for supplying a signal for changing the comparison level its second output is an output to indicating means or a processor for processing and controlling the device, while the signal processing circuit detects a signal between the weft frequency and at least one or more of the following operations:

i. sequential comparison of the amplitude of the pulses in the detected signal with programmed levels;

ii. comparing the period of the pulses in the detected signal with a programmed period;

iii. comparing the duration of the pulses of the received signal with the programmed duration.

The disadvantage of this radar detector is the lack of sensitivity.

Using signature filtering of signals, you can eliminate all or almost all of the above disadvantages.

You can get a radar detector, which:

- will identify all known police radars with a definition of their type;

- the detection range will not depend on the type of modulation, but only on the signal strength (the robot will be visible from afar, possibly even when installed in the back);

- will not miss single shots;

- will not respond to doors, blind spots sensors, etc. (false positives may possibly be reduced to zero);

- will not have unnecessary user settings.

Modern police radars.

According to the signal features that are important for us, all modern police radars can be divided into 2 large groups.

1. Doppler radars.

These include, for example, CDIP, Binar, Vizir. Speed is measured directly by the Doppler frequency. They have a long pulse duration. According to the engineers of Simikon, the pulse cannot be shorter than 16 ms, otherwise the spectrum expands so much that it becomes difficult to isolate the Doppler frequency. They can work in single shot mode.

2. Nedopplerovsky radars.

These include Arrow, Robot, Places, Gyrfalcon, Cordon. Directly by the Doppler frequency, the speed is not measured, but it is calculated based on the measurement of other parameters (range, azimuth, etc.). Short pulses (microsecond, and Arrow even nanosecond) emit. May have several operating frequencies. They work in continuous mode, they do not have a single shot mode.

Probably, in the future, the 2nd group of radars will develop mainly, since they have more features, they can record not only speeding, but also many other violations.

The technical result of the claimed technical solution is an increase in sensitivity and noise immunity.

The technical result is achieved in that the radar detector comprises an antenna connected to a signal receiver, a first mixer mixing the antenna signal with the signal from the first local oscillator, an amplifier, a second mixer mixing the amplified signal with the signal from at least one second local oscillator a filter, a signature module, and a central processor that outputs information about detected radars by means of a sound amplifier and speaker, while the central processor controls at least one m by the second local oscillator and by means of a sawtooth voltage generator connected to it, the first local oscillator, in addition, the device contains a photodiode and a laser module connected to it, the signal from which is analyzed by the central processor.

The signature module includes an ADC, a digital bandpass filter associated with at least one digital comparator, each of which is associated with a signature analyzer, and an ADC is associated with at least one additional digital comparator, each of which is also associated with a signature analyzer , while the signature analyzer checks the signals at the output of all comparators for compliance with the known radiation parameters of the radars stored in it, and provides information on the detected radars and power to the central processor when yatogo signal.

In addition, the band-pass filter can be connected to a frequency discriminator and a comparator, the output of which is connected to the central processor.

Also, the central processor may additionally be able to display information about detected radars on the display.

The claimed technical solution is illustrated by the following figures: in FIG. 1 shows a general block diagram of a proposed radar detector.

In FIG. 2 shows a possible block diagram of a signature module.

The device shown in FIG. 1-2, works as follows. The signal received by antenna 1 is fed to the 1st mixer 2, where it is mixed with the signal of the 1st local oscillator 16 for transfer to the 1st intermediate frequency. The 1st local oscillator is a voltage controlled oscillator. Its frequency varies depending on the control voltage coming from the sawtooth voltage generator 17, so that the radar detector scans the entire frequency range in which police radars can operate. Then the signal of the 1st intermediate frequency through the amplifier 3 is fed to the 2nd mixer 4, where it is mixed with the signal of the 2nd local oscillator 15 for transfer to the 2nd intermediate frequency. To scan several frequency ranges, several 2 local oscillators can be used, which can be switched on alternately. The signal of the 2nd intermediate frequency through a band-pass filter 5 is supplied to the signature module 9, which compares the parameters of the received signal with the parameters of the signals of known police radars and, if they match, provides information on the detected type of police radar to processor 8. Information on the strength of the received signal may also be transmitted. The central processor processes the received information and notifies the user of the detected radars by outputting information to the display 10 and sound signals, through the amplifier 13 and speaker 14. The processor 8 also controls the operation of the sawtooth voltage generator 17 and the local oscillators 15, 16. The circuit, consisting of a frequency discriminator 6 and comparator 7, is used in a conventional radar detector to receive any signals in the frequency ranges of police radars, and can be stored in a signature taxiway for receiving radars with unknown stnymi signal parameters. If reception of unknown radars is not required, this circuit may be disabled by the processor or completely absent. Photodiode 12 and laser module 11 are designed to receive signals from laser speed meters.

In FIG. 2 shows a possible block diagram of a signature module. Obviously, for signature analysis, it is necessary to separate the operating frequencies that are close enough to each other. We need a narrow-band filter with steep sections of the frequency response, with deep suppression outside the passband and quite fast. In this case, it is advisable to use a digital band-pass filter 19. Several digital comparators 20 are required to measure the power level. The number of comparators 20 corresponds to the number of power levels displayed by the radar detector. The Strelka signal, due to the very wide spectrum at the output of the digital filter, is likely to be greatly attenuated, therefore, to work with the Strelka (and other nanosecond pulses, if any), one more group of comparators 20 connected in front of the filter may be required. The signature analyzer 21 checks the signals at the output of all comparators for compliance with the known parameters of radar radiation (pulse duration, pause time between pulses, pulse repetition period) and provides information on the detected radars and received signal power to the central processor 8. The digital filter and all subsequent components of the signature module should be fast enough (if you do not change the second intermediate frequency of the radar detector, then the sampling frequency of the ADC 18 should be about 40 MHz). Obviously, on the processor, which are usually used in radar detectors, such signature processing of the signal cannot be implemented. But it can be implemented for example on FPGA FPGA. Now there are fairly cheap and copy-protected FPGA chips that have enough resources to implement the entire circuit of the signature module (except for the ADC), for example, Xilinx Spartan-3AN chips.

Scanning algorithm.

There are no and probably will not be Ka range police radars in Russia. Only the Sokol radar, discontinued in 2008, operates in the X band. Therefore, if scanning different ranges creates problems for signature detection, the Ka range can be turned off altogether (included only during foreign trips), and the K and X ranges can be scanned simultaneously if the frequency of the 1st local oscillator is changed. In the Pilot 21R, Sho-Me G800 and other detectors on the same receiver, the frequency of the 1st local oscillator is selected so that the X and K bands are received simultaneously without switching the 2nd local oscillator. The main focus should be on K.

All 4 operating frequencies are below the lower limit of the range K. We have tested several Robot SD-580 radars, they are all like that. Apparently, for reliable detection of all radars, you need to scan the range 24.00-24.30 GHz.

Signature analysis of a signal is possible if one of the following conditions is met:

Ts <min (Ton, Toff)

Tw> Ton + Toff,

where Ton is the radar pulse duration,

Toff - the duration of the pause between pulses,

Ts is the scanning period of the entire range,

Tw is the time spent by the received radar signal in the passband of the filter during scanning.

Therefore, we have 2 scanning methods.

Fast scan when the scan period is shorter than the shortest pulse and shortest pause of all known radars. The duration of a radar pulse or the pause between pulses is measured by counting the number of scan periods in which a signal is present or absent at a specific frequency.

Slow scanning when the time spent in the signal bandwidth is longer than the longest pulse repetition period of all known radars. The duration of a radar pulse or the pause between pulses is measured directly.

Obviously, slow scanning is not suitable for Doppler radars, because they can work with single shots, and they will almost certainly be skipped. A quick scan for nedopplerovskih radars is almost impossible because of the small pulse durations. An attempt to find a scanning period such that for Doppler radars is fast and slow for Nedoppler radars also does not lead to a positive result. It remains to take advantage of the fact that all non-Doppler radars operate continuously, at each scanning period to search for such radars in a small part of the range and alternate these parts. That is, the control voltage of the 1st local oscillator should change approximately sawtooth.

The claimed technical solution can be implemented using means and components known in the art and meets the condition of "industrial applicability".

Claims (4)

1. A radar detector comprising a central processor, characterized in that it further comprises a series-connected antenna, a first mixer, the second input of which is connected to the first local oscillator; amplifier; a second mixer that mixes the amplified signal with the signal from the at least one second local oscillator, a bandpass filter, a signature module and a central processor that outputs information about the detected radars by means of an audio amplifier and speaker, while the central processor controls by means of the associated one the sawtooth voltage generator, the first local oscillator, also controls at least one second local oscillator, in addition, the radar detector contains a photodiode and associated with m laser module, which analyzes the signal from the CPU. 2. The radar detector according to claim 1, characterized in that the signature module includes an ADC, a digital bandpass filter associated with at least one digital comparator, each of which is associated with a signature analyzer, and the ADC can be associated with, at least one additional digital comparator, each of which is also associated with a signature analyzer, while the signature analyzer checks the signals at the output of all comparators for compliance with the known parameters of the radar radiation stored in it, and gives it to the central percentage quarrels information about detected radar and received signal power. 3. The radar detector according to claim 1, characterized in that the band-pass filter is connected to a frequency discriminator and a comparator, the output of which is connected to a central processor. 4. The radar detector according to claim 1, characterized in that the central processor further has the ability to display information about the detected radars on the display.
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