Radar detectors warn drivers of the use of police radar, and the potential for traffic citations if the driver exceeds the speed limit. The FCC has allocated several regions of the electromagnetic spectrum for police radar use. The bands used by police radar are generally known as the X, K and Ka bands. Each relates to a different part of the spectrum. The X and K bands are relatively narrow frequency ranges, whereas the Ka band is a relatively wide range of frequencies. Within each of the bands, the spectrum is typically subdivided into a number of smaller range frequency blocks or sub-bands.
Radar detectors typically comprise a microwave receiver and detection circuitry that is typically realized with a microprocessor or digital signal processor (DSP). Microwave receivers are generally capable of detecting microwave components in the X, K, and very broad Ka band. In various solutions, either a microprocessor or DSP is used to make decisions about the signal content from the microwave receiver. Systems including a DSP have been shown to provide superior performance over solutions based on conventional microprocessors due to the DSP's ability to find and distinguish signals that are buried in noise. Police use of laser has also been countered with laser detectors, and products are now available that combine laser detection into a single product with a microwave receiver to provide comprehensive protection.
Methods of conditioning detector response are gaining importance, due to an increasing number of signals present in the X, K and Ka bands from products that are completely unrelated to police radar. These products share the same regions of the spectrum and are also licensed by the FCC. The growing number of such signals is rapidly undermining the credibility of radar detector performance. Radar detectors cannot tell the difference between emissions from many of these devices and true police radar systems. As a result, radar detectors are increasingly generating false alerts, reducing the significance of warnings from radar detectors. Commonly-assigned U.S. Pat. No. 8,525,723, which is incorporated herein by reference, provides a description of a number of stationary, unrelated microwave sources, which are also referred to herein as false sources or unknown sources.
Commonly-assigned U.S. Pat. No. 6,670,905 (“the '905 patent”) and U.S. Pat. No. 9,279,881—both of which are incorporated herein by reference—describe systems and methods that aid in the management of unrelated sources, and permit a detector to dynamically improve its handling of unrelated sources. The '905 patent discloses a Global Positioning Satellite System (GPS) enabled radar detector that uses GPS to aid in the management of non-police-related or otherwise irrelevant sources of radar signals, permitting the detector to dynamically improve its handling of such sources and reduce false alerts. The detector references previously-stored geographically-referenced information on such sources, and compares the detector's current location to locations of known stationary false alert sources, to improve the handling of signals from those sources. When the detector is within a threshold distance of a stored false alert source, the detector suppresses alerts for frequency bands or sub-bands that correlate to the frequency of the known false alert source. False sources may be manually identified and “locked out” by the user, or may be automatically identified based upon multiple repeated encounters of the detector with the source at a particular geographic location. Thus, the GPS-enabled detector offers an electronic method for establishing current physical coordinates and using those coordinates to ignore false sources.
Systems embodying the '905 patent have been successfully commercialized by the assignee of this application, but these systems continue to face certain challenges. For instance, the detection and suppression of false sources relies primarily upon location data obtained by and stored in a single detector. This may be adequate when a vehicle repeatedly travels a similar path, such as during a daily commute to/from work or school. However, when following a new route, such as on a road trip or vacation, the detector lacks a store of stationary false alert source locations and, thus, may produce numerous false alerts. The '905 patent, notes the possibility that signal information can be obtained from outside sources, such as internet sites or other radar detectors, to address this problem. However, even in this solution the location of a stationary false source is identified based on data which only provides a rough estimate of the false source location. More accurate identification and lockout of false alerts requires more precise positioning data regarding the geographic location of non-police radar sources.
To respond to these challenges, the assignee and others have developed social networks through which drivers can share radar events and sightings of police into a social network, so that a warning can be delivered to other drivers approaching the area. Unfortunately, users of social networks often report police activities that are not actually speed traps, for example, social network users may warn of a police car that is driving with traffic, waiting at a traffic light on a cross street, or involved in other activities that are not characteristic of a fixed location speed trap. As recognized by the present inventors, alerts that can be confirmed, e.g., via radar detection, are more reliable.
Additionally, due to the increased number of false alert sources, the present inventors recognized that it is desirable to know the band of a detected signal. Knowing the band enables a driver to decide whether to discount an alert as likely emanating from a false source, as may be the case with many X-band signals; or to heed the alert and reduce speed, if the signal is in the Ka-band or a laser signal, which more commonly originate from a police radar source. Additionally, when receiving an alert, the present inventors recognize that it is desirable to know not only the signal band, but also the direction that the signal came from, since multiple signals may be received at the same time and accorded different levels of importance. For example, it may be much more significant to know that there is a Ka-band signal, particularly one originating from the direction of travel of the vehicle, rather than to know that there is an X-band signal originating behind the vehicle. Furthermore, when driving at a high rate of speed, such as on a highway, a driver needs to receive this information in as clear and concise a manner as possible, in order to be able to make a quick decision on how to respond. Accordingly, as recognized by the present inventors, it is desirable to have a radar detector with a display that conveys both signal band and direction simultaneously for one or more detected signals, and it may be desirable to have a display that provides multiple types of information through illumination of a single indicator.
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