Wednesday, August 05, 2009

What Makes the Best Radar Detector, the Best?

best radar detector

What Makes the Best Radar Detector, the Best?

Updated: 23 Apr 14, By Veil Guy

With the announcement of the Escort Redline—designed to directly compete with the Valentine 1 on its own terms—I think it is prudent to discuss what design attributes contribute to making the best radar detector, the best, in terms of overall performance.

For the purposes of this analysis, we are not including a radar detector's feature-set as part of the our consideration.

Seven Key Radar Detection Performance Attributes:
  • Sensitivity
  • Selectivity
  • Alert to Brief Radar Detections
  • Quick Alert to Radar Detections
  • Dynamic Range
  • Signal Ramp
  • Metering Type
Best Radar Detector Design Attribute #1, Sensitivity: The ability of the radar detector to sniff out the weakest of radar signals.

With higher sensitivity, a radar detector has the potential to alert its owner to an impending radar encounter sooner and farther away than a radar detector possessing lower sensitivity (ie; potentially provides greater detection range but not necessarily greater alerting range subject to the other design elements like selectivity).

Sensitivity is primarily a function of the hardware design/platform.


Extremely high Sensitivity Alerting to Cross Highway Radar Usage

The following elements are more a function of the software design (ie;firmware).

Best Radar Detector Design Attribute #2, Selectivity: The ability of the radar detector to discard (not alert) to detected radar signals having been determined as not posing a threat to the driver.

Selectivity is an element that sometimes is in direct conflict with sensitivity. In other words, trying to make a radar detector highly selective may very well undermine the otherwise high levels of sensitivity. Detected Ka signals can be examined by the radar detector so that it can be determined if the detected signal is a harmonic of another proximate radar detector's LO and if so, not reported. Detection of X and K band gets trickier for selectivity because they appear as bona-fide X and K-band sources.

Best Radar Detector Design Attribute #3, Alert to Brief (and/or Weak) Radar Detections: The ability of a radar detector to alert to the detection of brief sources of radar—especially weak signals—and can be considered part of the overall design element of selectivity, but also relates to the radar detector's alerting texture/signal ramp behavior (discussed later).


Some design approaches to increasing selectivity (to make the detector quieter) may be the requiring of brief detections of radar signal to be present for a finite amount of time before alerting to them. If this time exceeds the duration of certain quick trigger instant-on radar sources, the radar detector—even if it possess very high-degrees sensitivity, may altogether fail to alert which can make the detector quiet(er) but more lethargic/slower and negatively impact the ability of the radar detector to alert well to an approaching instant-on trap including the conveyance of the texture of the approaching threat.


An Example of Extremely Quick Alerting to Brief/Weak Traffic Radar



Conveyance of Texture to Approaching Instant-on Stationery Radar Threat


Best Radar Detector Design Attribute #4, Quick Alert to Radar Detections: The ability of a radar detector to quickly alert to a detected radar signal—and can be considered part of the overall design element of selectivity, but also relates to the radar detector's alerting texture/signal ramp behavior (discussed later).

Also in terms of quickness and selectivity there is generally a finite amount of time it takes to wait before alerting to see the radar signal present. A radar detector which requires a larger finite amount of time before alerting to a radar source can also contribute to a slower (ie; sluggish) detector.

Balancing these four elements (one hardware and three software) is critical with whatever hardware platform design.

A radar detector possessing very high degrees of sensitivity with lower levels of selectivity has the potential of becoming excessively chatty around town—while potentially providing stellar performance on the open highway. The Valentine 1, in its default configuration tends to emphasize sensitivity over selectivity as its design philosophy and falls into this category.

An otherwise highly sensitive radar detector which emphasizes being quiet while still possessing high degrees of absolute sensitivity must balance the other three design elements to some degree in achieving that level of relative quietness but may sacrifice alerting performance in certain type of encounters as a consequence but be much easier to live with in and around town. Current detectors like the Escort Passport 9500ix or the Beltronics GX-65 may fall in this category.

Detectors which posses somewhat lower levels of absolute sensitivity also possess the potential ability to be quieter just by the nature of their decreased levels of sensitivity without potentially having to rely as heavily on software designs of selectivity.

In fact, it is possible that a detector which possesses a somewhat lower level of absolute sensitivity may be able to relax or tweak the other design elements contributing to selectivity to produce a very capable radar detector in its own right. Top detectors from Whistler like the Whistler XTR-695SE, Whistler XTR-690SE, Whistler Pro-78SE fall into this category.


Quick Alerting to Instant-on Radar Signal


Best Radar Detector Design Attribute #5, Dynamic Range: A detector's dynamic range relates its signal-ramp and how it alerts to varying signal strengths with whatever sensitivity it has.

Just because a radar detector has high(er) sensitivity doesn't mean that it (must) alert at a high(er) indicated signal strength than another model (with relatively lower sensitivity) which alerts at a lower signal strength at the same range. In and of itself, the signal strength level indicated at any given distance should not be considered a reflection of how sensitive it is at that distance. This is performance attribute has been repeteadly mis-characterized in certain reviews concerning radar detection performance as it relates to sensitivity at varying ranges.

A radar detector with too high a dynamic range can have a difficult time conveying the severity of an impending radar threat because its signal strength will not alert at its maximum level when it needs to. An example of a radar detector with this behavior is the Cobra XRS-9955/Cobra XRS-9960G.

A detector with too low (ie; compressed) dynamic range can also have a difficult time at conveying the severity of an impending radar threat because it may tend to alert at its maximum signal strength when the approaching radar threat isn't eminent. A radar detector with this behavior is the Escort Passport 9500ci , Escort Passport 9500i, or Escort Passport 9500ix, and the original Beltronics STi Driver.


A Contrast in Management of Dynamic Range


In either circumstance the alerting nature may compromise the ability of the driver to properly gauge an approaching (or receding threat).


An Example of a Radar Detector with Too Wide of Dynamic Range


Best Radar Detector Design Attribute #6, Signal Ramp: Relating to dynamic range is the detector's ability to alert with a alerting/alarm strength level (audible and/or visual) at any given distance from the radar source (ie; its approach and departure slope).


A Comparison of Several Different Sloping Signal Ramps


While it may be true to infer that one—of two identically built radar detector models—which alerts with a higher signal strength than the other may be more sensitive than the other, this inference would certainly not apply across two different models or brands.

In other words, radar detector A which alerts at a signal strength of say 7 at a given distance is not necessarily more sensitive than radar detector B which only alerts with a signal strength of 4 at the same distance. In fact, if the distance is sufficiently large from the radar source, detector B may be providing a more accurate gauge with its alert, as the following chart demonstrates.

Two different alert signal ramps, one easy to gauge threat level, one hard

The above chart demonstrate two different signal ramps as reported by two different sloping detectors, the first being more natural analogue-sinuous slope and the other being less natural and more digital-like a square-wave slope. I would argue that the first signal-ramp does a better job at conveying the actual threat at any given distance and time than the second one.

Several radar detectors that fall into the sinuous sloping signal ramp profile are the Valentine 1, the Escort Passport 8500/8500 X50, Beltronics Pro RX-65, and Whistler XTR-695SE/690SE/Pro-78SE.

Several radar detectors that tend towards a more square-wave-type sloping signal ramp profile are the Escort Redline(on X & K-bands), Escort Passport 9500i/9500ix, Escort Passport 9500ci, and Beltronics STi-R, and the pre-band segmented Redlines.  (Updated: 6 JUL 13).



Best Radar Detector Design Attribute #7, Metering Type: Closely related to dynamic range (and therefore signal-ramp) is quickness to alert to rapidly varying radar detection levels.

If a detector is sluggish in this performance aspect, then the rapidity of the increasing threat may not be able to be properly assessed by the driver which may adversely affect the response time of the driver. This design attribute can also have an effect on the decaying nature of a rapidly decreasing or removed radar source (ie; trigger-released).


A Demonstration of the Relative Quickness Between Different Metering Systems


To use an analogy from hifi equipment, if you ever used a cassette recorder to establish appropriate recording levels (not too low and not too high) you would have had to use its metering system. There were two types, one (VU or average-type) was generally available in lower-end mass-produced consumer products. The other metering system (peak-type) was available only on a couple (very) high-end cassette decks.

The quicker peak-type metering system (like those used on the Tandberg TD-3014A) were much more useful in establishing the correct recording level without risk of clipping (ie; over-modulation of the recorded signal onto the tape).


Example of Norwegian Made TD-3014A Peak (ie; Quick) Metering System, what I considered the best of three decks ever made including Nakamichi Dragon, Studer Revox B215



Example of typical average (ie; sluggish) metering system with same music track as previous video example

Radar detectors that exhibit peak-type (ie; quick) metering systems include the Whistler XTR-690/695SE and Pro-78SE and Valentine 1.

Radar detectors that possess overall good management of dynamic range and its related elements (ie; provide good signal ramp) include the Whistler XTR-690SE, XTR-695SE, Pro-78SE, Valentine 1, Escort Passport 8500/8500 X50, Beltronics Pro RX-65.

It is my assertion that for a radar detector to be considered one of the best, it must nicely balance all of these different (and sometimes competing) performance attributes.


Happy and Safe Motoring!

Veil Guy

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