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28-476: It can handle signal frequencies of up to 500 MHz and local oscillator frequencies of up to 200 MHz. The mixer is a “ Gilbert cell ” multiplier configuration which provides both a gain of 14 dB and a noise figure of 5 dB at 45 MHz. The IC belongs to a family of the following ICs: NE602, SA602, NE612 and SA612. It is widely used in amateur radio applications, e.g. in the commercial Elecraft products, and others. This electronics-related article

56-415: A point of interest database of known speed trapping locations, into a single device to improve their chances of success. The superheterodyne receiver in radar detectors has a local oscillator that radiates slightly, so it is possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz). The VG-2 Interceptor

84-432: A superheterodyne receiver to detect these electromagnetic emissions from the gun, and raise an alarm to notify the motorist when a transmission is detected. False alarms can occur however due to the large number of devices, such as automatic door openers (such as the ones at supermarkets and drug stores), speed signs, blind spot monitoring systems, poorly designed radar detectors and adaptive cruise control , that operate in

112-402: A variable-frequency oscillator which leads to a compromise between stability and tunability. With the advent of high-speed digital microelectronics, modern systems can use frequency synthesizers to obtain a stable tunable local oscillator, but care must still be taken to maintain adequate noise characteristics in the result. Detection of local oscillator radiation may disclose the presence of

140-412: A different type of device called a LIDAR detector is required. However, LIDAR detection is not nearly as effective as radar detection because the output beam is very focused. While radar's radio waves can expand to 85 feet (26 m) across at 1,000 feet (300 m) from their source, LIDAR's light beam diffuses to only about 6 feet (1.8 m). A police officer targeting a car will most likely aim for

168-513: A form of civilian electronic "warfare" . For example, as new frequencies have been introduced, radar detectors have initially been "blind" to them until their technology, too, has been updated. Similarly, the length of time and strength of the transmissions have been lowered to reduce the chance of detection, which in turn has resulted in more sensitive receivers and more sophisticated software counter technology. Lastly, radar detectors may combine other technologies, such as GPS -based technology with

196-531: A frequency licensed by the Federal Communications Commission (FCC) without a licence is a violation of FCC regulations, which may be punishable by fines up to $ 10,000 and/or up to one year imprisonment. Newer speed detection devices use pulsed laser light, commonly referred to as LIDAR , rather than radio waves . Radar detectors, which detect radio transmissions, are unable to detect the infrared light emitted by LIDAR guns, so

224-778: A signal at a fixed frequency gives a radio receiver improved performance. In many receivers, the function of local oscillator and mixer is combined in one stage called a " converter " - this reduces the space, cost, and power consumption by combining both functions into one active device. Local oscillators are used in the superheterodyne receiver , the most common type of radio receiver circuit. They are also used in many other communications circuits such as modems , cable television set top boxes , frequency division multiplexing systems used in telephone trunklines , microwave relay systems, telemetry systems, atomic clocks , radio telescopes , and military electronic countermeasure (antijamming) systems. In satellite television reception,

252-619: A simple improvised radio receiver which has no local oscillator. Radar detector A radar detector is an electronic device used by motorists to detect if their speed is being monitored by police or law enforcement using a radar gun . Most radar detectors are used so the driver can reduce the car's speed before being ticketed for speeding . In general sense, only emitting technologies, like doppler RADAR , or LIDAR can be detected. Visual speed estimating techniques, like ANPR or VASCAR can not be detected in daytime, but technically vulnerable to detection at night, when IR spotlight

280-646: A technique known as "kill the equipment", referred to as "JTK" or "Jam to Kill." Officers can often detect this by observing that their LIDAR equipment is unable to lock in a speed properly, along with visual indication of sudden deceleration of the targeted vehicle. They will then pull the offending vehicle over and look for LIDAR jammers on the front of the vehicle, potentially ticketing the motorist with an obstruction of justice charge. Some states also have laws against jamming of police radar or LIDAR: California, Colorado, Illinois, Iowa, Minnesota, Oklahoma, South Carolina, Tennessee, Texas, Utah and Virginia. In these states,

308-411: Is a stub . You can help Misplaced Pages by expanding it . Local oscillator In electronics , a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal. This frequency conversion process, also called heterodyning , produces the sum and difference frequencies from the frequency of the local oscillator and frequency of the input signal. Processing

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336-582: Is near the RF frequency). This resulted in detector manufacturers responding by changing their local oscillator frequency. The VG-2 is no longer in production and radar detectors immune to the Spectre Elite are available. It is illegal in many countries to sell or possess any products that actively transmit radar signals intended to jam radar equipment. In the United States, actively transmitting on

364-494: Is sensed, thus preventing detection by such equipment. This technique borrows from ELINT surveillance countermeasures. In the early 1990s, BEL-Tronics, Inc. of Ontario , Canada (where radar detector use is prohibited in most provinces) found that the local oscillator frequency of the detector could be altered to be out of the range of the VG-2 Interceptor (probably by using two local oscillator stages such that neither

392-442: Is used. There are no reports that piezo sensors can be detected. LIDAR devices require an optical-band sensor, although many modern detectors include LIDAR sensors. Most of today's radar detectors detect signals across a variety of wavelength bands: usually X , K , and K a . In Europe the K u band is common as well. The past success of radar detectors was based on the fact that radio-wave beams can not be narrow-enough, so

420-716: The Wireless Telegraphy Act 1949 . Use of illegal radar detector is prosecuted €1500 fine & 6 points on driver's license. Laser The Portuguese Tax and Customs Authority can seize any imported radar detectors. Radar jammers are also illegal. Radar detectors fine up to 3 points from the driving license and €200. Radar jammers are banned under federal rule, but laser jammers are not specifically banned. Eleven states specifically ban laser jammers : California , Colorado , Illinois , Iowa , Minnesota , Oklahoma , South Carolina , Tennessee , Texas , Utah , and Virginia . Radar detectors are not banned in

448-399: The microwave frequencies used from the satellite down to the receiving antenna are converted to lower frequencies by a local oscillator and mixer mounted at the antenna. This allows the received signals to be sent over a length of cable that would otherwise have unacceptable signal loss at the original reception frequency. In this application, the local oscillator is of a fixed frequency and

476-588: The FCC. These jammers attempt to confuse police LIDAR into showing no speed on the display. They are often successful, and therefore many LIDAR manufacturers produce LIDAR guns that have "jam codes" that show when they are being jammed. They will work against some LIDAR jammers, but not all. In spite of this, police can often tell when they are being jammed when they see no reading on their LIDAR gun. Many jammer-equipped motorists try to counter this by reducing their speed to legal limits before turning off their jammer equipment,

504-446: The center mass or headlight of the vehicle and, because radar detectors are mounted on the windshield away from the beam's aim, they may not alert at all. With such a focused beam, an officer using a LIDAR gun can target a single car in close proximity to others at ranges of up to 3,000 feet (910 m). This has resulted in some manufacturers producing LIDAR jammers. Unlike those of radar, LIDAR's frequencies and use are not controlled by

532-608: The coordinates of sites of frequent false alarms, which the GPS enabled detector will then ignore. The detector can also be programmed to mute alerts when traveling below a preset speed, limiting unnecessary alerts. Some GPS enabled detectors can download the GPS coordinates of speed monitoring cameras and red-light cameras from the Internet, alerting the driver that they are approaching the camera. Radar guns and detectors have evolved alternately over time to counter each other's technology in

560-651: The detector usually senses stray and scattered radiation, giving the driver time to slow down. Based on a focused laser-beam, LIDAR technology does not suffer this shortcoming; however it requires precise aiming. Modern police radars incorporate formidable computing power, producing a minimum number of ultra-short pulses, reusing wide beams for multi-target measurement, which renders most detectors useless. But, mobile Internet allows GPS navigation devices to map police radar locations in real-time. These devices are also often called "radar detectors", while not necessary carrying an RF sensor. One device law enforcement use to measure

588-480: The device, or both. These prohibitions generally are introduced under the premise that a driver who uses a radar detector will pose a greater risk of accident than a driver who does not. The table below provides information about laws regarding radar detectors in particular nations. In 1967 devices to warn drivers of radar speed traps were being manufactured in the United Kingdom; they were deemed illegal under

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616-680: The down-converted signal frequency is variable. Application of local oscillators in a receiver design requires care to ensure no spurious signals are radiated. Such signals can cause interference in the operation of other receivers. The performance of a signal processing system depends on the characteristics of the local oscillator. The local oscillator must produce a stable frequency with low harmonics. Stability must take into account temperature, voltage, and mechanical drift as factors. The oscillator must produce enough output power to effectively drive subsequent stages of circuitry, such as mixers or frequency multipliers. It must have low phase noise where

644-508: The expected speed of a moving vehicle is Doppler radar , which uses the Doppler effect to measure the relative speed of a vehicle. Doppler radar works by beaming a radio wave at a vehicle to then measure the expected change in frequency of the reflected wave (that bounces off the vehicle). Law enforcement often employs Doppler radar via hand-held radar guns , from vehicles, or from fixed objects such as traffic signals . Radar detectors use

672-431: The penalties can be severe. Despite the advent of LIDAR speed detection, radar remains more prevalent because of its lower price and the amount of radar equipment already in service. In addition, proper use of LIDAR equipment requires the officer to remain stationary in order to beam a very precise signal. Using or possessing a radar detector or jammer is illegal in certain countries, and it may result in fines, seizure of

700-452: The receiver, such as in detection of automotive radar detectors , or detection of unlicensed television broadcast receivers in some countries. During World War II , Allied soldiers were not allowed to have superheterodyne receivers because the Axis soldiers had equipment which could detect the local oscillator emissions. This led to soldiers creating what is now known as a foxhole radio ,

728-446: The same part of the electromagnetic spectrum as radar guns. In recent years , some radar detectors have added GPS technology. This allows users to manually store the locations where police frequently monitor traffic, with the detector sounding an alarm when approaching that location in the future (this is accomplished by pushing a button and does not require coordinates to be entered). These detectors also allow users to manually store

756-452: The timing of the signal is critical. In a channelized receiver system, the precision of tuning of the frequency synthesizer must be compatible with the channel spacing of the desired signals. A crystal oscillator is one common type of local oscillator that provides good stability and performance at relatively low cost, but its frequency is fixed, so changing frequencies requires changing the crystal. Tuning to different frequencies requires

784-471: Was the first device developed for this purpose, but has since been eclipsed by the Spectre III and Spectre Elite. This form of " electronic warfare " cuts both ways - since detector-detectors use a similar superheterodyne receiver, many early "stealth" radar detectors were equipped with a radar-detector-detector-detector circuit, which shuts down the main radar receiver when the detector-detector's signal

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