Radar detector

Details Radar detector Radar detector

2002-07-24

2003-09-09

Tarcza, Thomas H. (Department: 3662)

Communications: directive radio wave systems and devices (e.g.,

Radar ew

Detection of surveilance

C340S936000, C180S170000

Reexamination Certificate

active

06617995

ABSTRACT:

This application claims the benefit of Korean Patent Application Nos. 2001-59165 filed on Sep. 24, 2001, 2001-59166 filed on Sep. 24, 2001, 2001-59167 filed on Sep. 24, 2001, 2001-62528 filed on Oct. 10, 2001, and 2001-63683 filed on Oct. 16, 2001, which are hereby incorporated by reference for all purposes as if fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radar detector that detects a speed detection system.
2. Discussion of the Related Art
A speed detecting system such as a speed gun is a device that measures the velocity of a moving object by sending out a continuous radio wave and measuring the frequency of reflected wave. Recently, a radar detector, which can detect the speed detecting system, is developed. The radar detector informs a car driver of the presence of the speed gun by detecting laser beam or ultrahigh-frequency wave from the speed gun and converting it into phonetic signs, letters or acoustic signals. The radar detector, generally, utilizes microwave or laser beam.
A conventional radar detector will be described hereinafter in detail with reference to attaching figures.
FIG. 1
is a schematic diagram of showing a principle of a conventional radar detector. As shown in
FIG. 1
, laser beam or ultrahigh-frequency wave is shot at a driving car from a speed gun (not shown). The frequency of the ultrahigh-frequency wave from the speed gun may be 10.525 GHz, 24.15 GHz, or 34.7 GHz, which are frequencies in X-band (10.525 GHz±25 MHz), K-band (24.150 GHz±100 MHz), and Ka-band (34.7 GHz±1.3 GHz), respectively. The speed gun also emits a VG-2 signal, which is a signal for sensing a radar detector of cars. Then, a radar detector detects the laser beam, ultrahigh-frequency wave, or VG-2 signal, and informs a car driver of the presence of the speed gun. The radar detector also transmits jammer or an anti VG-2 signal in order to interfere with signals from the speed gun.
On the other hand, the radar detector provides a car driver with driving information by sensing signals from sensors of railway crossings, foggy regions, or deceleration regions.
FIG. 2
is a block diagram of a conventional radar detector. In
FIG. 2
, a radar detector includes an antenna
10
, a first local oscillator
20
, a first filter
30
, a first mixer
40
, an intermediate frequency amplifier
50
, a second local oscillator
60
, a second mixer
70
, a second filter
80
, a demodulator
90
, a central processing unit (CPU)
100
, a memory part
110
, and an indicator
120
.
As shown in the figure, high frequency signal from a speed gun (not shown) received by the antenna
10
, which is a born antenna, is input into the first mixer
40
. At the first mixer
40
, the received high frequency signal is mixed with the output signal of the first local oscillator
20
, which is a local voltage controlling oscillator. A radar detector using the local voltage controlling oscillator has advantages such as low power consumption and high sensitivity. At this time, in the output signal of the first local oscillator
20
, signal of a predetermined band, i.e. noise, is removed via the first filter
30
between the first local oscillator
20
and the first mixer
40
. The output signal of the first mixer
40
is amplified by the intermediate frequency amplifier
50
, and input to the second mixer
70
. At the second mixer
70
, the amplified signal is mixed with the output signal from the second local oscillator
60
, and modulated to frequency of tie output signal. Next, only the signal of a desired frequency band is taken out via the second filter
80
from the output of the second mixer
70
, and then input into the demodulator
90
. At the demodulator
90
, the input signal is converted from analog values to digital values in order to be input into the CPU
100
.
The CPU
100
controls the oscillators
20
and
60
by generating signal, and selects specific signals by comparing the demodulated signals via the demodulator
90
with the data of the memory part
110
. The data of the memory part
110
shows relations of frequencies of the ultrahigh-frequency waves received by the antenna
10
and frequencies oscillating via the first and second local oscillators
20
and
60
.
The selected result from the CPU
100
is transmitted to a user by sound or a flickering lamp of the indicator
120
.
In this radar detector, a beam-lead diode, which can be used in a broadband region, may be used as a first mixer
40
of FIG.
2
.
FIG. 3
shows the structure of the beam-lead diode of the conventional radar detector. As shown in
FIG. 3
, the beam-lead diode is made of two diodes, each of which is a Schottky diode. The Schottky diode is a device rectifying alternating currents (AC) by a Schottky barrier, which is a potential barrier between a metal and a semiconductor contacting each other. In such Schottky diode, there is Schottky effect that emission of electrons increases when electric field is applied at the metal, which is emitting thermoelectrons.
FIG. 4
is a circuit diagram of showing a part of a conventional radar detector including a beam-lead diode as a mixer. In
FIG. 4
, the beam-lead diode
45
mixes the output signal of the antenna
10
of
FIG. 2
with the output signal of the first local oscillator
20
, which is controlling 5.8 GHz waves, and transmits the mixed signal into the intermediate frequency amplifier
50
of FIG.
2
.
FIGS. 5A
,
5
B, and
5
C are graphs of output from a first mixer versus signals of X-band (10.525 GHz), K-band (24.15 GHz), and Ka-band (34.7 GHz) received by the antenna
10
of
FIG. 2
, respectively, in a conventional radar detector including a beam-lead diode. At this time, output of the first local oscillator
20
of
FIG. 2
, which is mixed with the received signal by the antenna
10
of
FIG. 2
, has frequency of 11.49 GHz, 11.665 GHz, and 11.36 GHz.
The radar detector is arranged at a distance of 5 cm from a system of generating initial signal. The system uses Agilent 8722ES Network Analyzer to generate signal of X-band frequency. The signal of X-band, for example 10.525 GHz, is received by the antenna
10
, and is mixed with output
11
of 11.49 GHz of the first local oscillator
20
at the beam-lead diode
40
of FIG.
2
. The nixed signal is measured by 8566A Spectrum Analyzer of Hewlett Packard and is illustrated in FIG.
5
A.
By the above method, signals of K-band and Ka-band are also mixed and illustrated in
FIGS. 5B and 5C
, respectively.
However, in
FIGS. 5A
,
5
B, and
5
C, the output of the beam-lead diode
40
of FIG,
2
, i.e. the mixed signal, is unstable and output of power is very small as −38.91 dBm, −39.90 dBm, and −42.98 dBm. The dBm is a unit of power, and 0 dBm is defined as 1 mW at impedance of 50 ohms.
On the other hand, the beam-lead diode as a first mixer should have small capacitance from Schottky contact in order to be used in 30 GHz to 300 GHz band region. Resistance in series from Schottky contact, also, should be small.
The beam-lead diode has to be connected to other elements of the radar detector by packaging, and thus capacitance from the packaging should be small, too. As the packaging of the beam-lead diode has a size of less than 0.5 mm, it is impossible to make the packaging by hand or by surface mount. Therefore, beam-lead of the beamn-lead diode is formed by setting lead on a substrate, and the process needs an expensive apparatus.
Moreover, in the conventional radar detector, the output from the first local oscillator
20
of
FIG. 2
has bad characteristics.
FIG. 6
is a graph of the output from a first local oscillator in a conventional radar detector. The data of
FIG. 6
is simulated by Advanced Design System program of the Hewlett Packard. In
FIG. 6
, the output of the first local oscillator is unstable in about 12.195 GHz band. That is, since the conventional radar detector does not receive signals in various bands, it is difficult to use the conventional radar detector in broadband region.
SUMMARY OF THE INVENTION

Affiliated with

Also associated with

Rating

Radar detector does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Radar detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radar detector will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3062002