Speed radar and laser guns are primarily used in law enforcement to detect the speed of a passing vehicle. With the introduction of video recording systems in police vehicles it has been natural requirement to interface the speed gun with the video system. This will produce an indisputable video recording of the actual vehicle along with the speed of the vehicle overlayed in the video
simultaneously. Review in court or reviewed at the scene, lends itself to higher prosecution rates therefore high revenues for the police department. The rulebook of the Amateur Trapshooting Association specifies that a Singles or Handicap target should fly 49 to 51 yards, and a Doubles target 44 to 52 yards, both measured in still air. A radar gun can aid you in meeting those rules by setting the targets’ speed when launched. When the air is still, radar-setting is as quick, easy, consistent, and accurate as setting by distance. When the weather is windy, the radar gun remains trustworthy.
Equipment: Low- and high-power radar guns
There are two distinct types of target-setting radar guns being used at clubs today, distinguished primarily by the power of the radar beam they emit and the resulting differences in the best ways to use them. Low-power guns are most-widely used. They include the Sports Radar 3400, available from Bob Schultz Target Shotguns, (800-684-6329), and the Bushnell Speedster, which you should be able to find on e-Bay or elsewhere in the web, where they sell new for about $150. Though more expensive, the Sports Radar 3400 comes equipped with a tripod socket, and can run on “continuous mode” (requiring no trigger-pull), both of which are advantages.
High-power guns–The Stalker Pro, Decatur’s Pro Speed, & others–offer advantages in ease-of-use, but are no more inherently accurate or usable than the others. What’s the main difference between the two types of guns? The high-power guns work from the 16-yard and beyond while the low-power ones need to be closer to the house.
Lock the trap, set the height first, & use a tripod The trap must be locked (not oscillating) when speed is measured. The target should be flying directly away from the setter; even small angles of deviation cause too-slow readings and lead you to set a target which is faster than you want. Set the height of the target at least close to what
you want before fine-tuning its speed. You can hold the gun in your hand or mount it on a tripod. It is worth it to tripod-mount the gun if possible; it’s just easier. Where and how high to place the gun Since this guide is a precursor to eventual ATA rules about target-speed it promotes methods of use which will lead to the same results with all
guns. Low-power guns: The readings of the Sports Radar 3400 and the Bushnell Speedster are extremely sensitive to the height the gun is held above the ground. The higher they are held, the slower is the reading they report and this difference can be 4 or 5 miles an hour. Since a difference of 1 MPH is a yard or more in target-flight, variations in height can amount to as much as 5 yards in distance. If the height varies, the target speeds will be too inconsistent to get any use from the gun at all. The best place to put the gun is right behind the house, as close to it as you can get. You want the radar down low, just looking over the top of the house. This will give you the fastest speed reading. Laying the gun u instructions sent with the Sports Radar 3400–is not recommended since the resulting speed-readings are too slow. You can point it up at the crossbar or just aim it
straight out horizontally; it makes little difference. Though horizontal is recommended you can try both and use the method which give you the most consistent readings. Using the low position and a tripod, a little RV level stuck to the top or side of the gun will help you keep the gun horizontal. Such a level is pictured on the front page. Alternatively, you can tilt it up 12 degrees to make it simulate pointing at the crossbar. Small errors in that angle make no difference. High-power guns: The main advantage of the Stalker and Pro Speed guns is that they can be used from the 16-yard line where height is far less of an issue. Just held standing or mounted on a 5-foot tripod the
guns provide good readings. Point it straight out & read the speed; it’s that simple.
Singles and Handicap: The low-power guns–used as described from the level of the back of the traphouse–will need a speed of 42 or 43 MPH to get the legal distance with a 9- or 10-foot-high target. Forty-two MPH is a good speed with the Stalker, while the Decatur Pro-Speed may get away with 41.5 MPH. Doubles: birds clocked at 39 MPH with all guns are about right most places but some clubs–and shooters–may prefer 40 MPH. The surest and recommended way to determine how your radar gun will work at your club is to test it. Pick a dead-calm morning; see how much speed you need for your preferred height and distance. Do the same for doubles. There is a form on the back of this guide to help you do the test and record the results. Do the test; fill out the form; and store it with the radar gun so the next user will know what was done and how best to use your radar gun to set targets the way your club likes them. In the future, ATArules will probably name speed as the “standard” way of setting targets. Likely minimum speeds are those described above: about 42 MPH for singles and handicap, 39 MPH for doubles. We’d like some feedback on how these speeds work at various clubs. Your results c
Radar Gun Basics
A speed radar gun is basically a mini-radar that normally detects objects in one direction. The gun emits a burst of high frequency radio waves in the Gigahertz range. The electronics computes the amount of time it takes for those radio waves to travel to a vehicle, reflect back from the vehicle and
return to the source. Doing this many times per second will allow the electronics to compute the change in position of the vehicle per second. This data is then converted to miles per hour. Sophisticated signal processing, error detection, multi-direction detection, multi target discrimination, portability are some of the features that make one manufacturer’s product different in the
marketplace. Laser guns do basically the same thing as radar guns but they use Laser light to compute the vehicle speed.
Radar Gun Design
Radar guns have been around for many years and have improved greatly in performance and safety from the early units. Most of the early units had LED readouts and a discrete design. This means all the electronics was TTL and transistors with no microprocessors on board. The readouts were driven
directly and the units had no direct digital output for use as the interface to the video system. Some radar guns had wired remote units with an auxiliary display that can be interfaced by an additional black box. As the technology progressed, remote units got more sophisticated with serial control and
finally the actual radar units started appearing with RS-232 direct outputs.
Once the data from the radar gun is converted to a readable format this data can be sent to the device that overlays the data onto the video picture. Some manufacturers of video systems incorporate this feature within their system or make it an option. For systems that do not have this feature, an add on box or text inserter called the VSI-Pro is required. Most all video systems use standard video cameras that send video signals to the VCR or DVR. The text inserter is placed between the camera and the VCR. When the data from the radar is valid the text inserter then superimposes it on the video picture just like the scores of modern sports programs. This inclusion of a text inserter into the video path has no effect on the rest of the system since the text inserter merely appends the data to the existing video signal. The standard data input to most text inserters is the industry standard RS-232. When the radar gun outputs this format, it can be directly connected to the text inserter and no other black box is required.
Since older units and some current models of radar guns do not have an RS-232 output, they require an additional black box or RG2RS for conversion of the radar gun signals to the industry standard RS-232. Various connection techniques exist, but the most popular is emulating or tapping the data
to the remote hand held control. Whatever data is then displayable on the remote unit will be converted to RS-232 and sent to the text inserter for display. As mentioned before when the radar gun outputs RS-232, this data can directly go to the text inserter. Radar Gun Calibration Radar gun calibration has to do with the accuracy of signals transmitted and received. Since the radar gun interface merely taps the electronic data, it is impossible for any interface to affect the gun calibration. Some manufacturers void the warranty or will not guarantee calibration when a third party
interface is installed. This policy has no technical grounds for enforcement but is merely a deterrent for the customer to buy the radar gun manufacturer’s video system and appropriate interface.
The newer model recording systems use DVR or Digital Video Recorders. These DVRs can accept the digital data from the Radar or Laser Speed Gun directly. The overlay can be optional but all the data is stored as an associated data file along with the audio/video recording. This allows fast or remote data search to find speeds, T/D or user license plate numbers or other data quickly and form a play list to review those incidents that meet the search criteria. This advanced feature makes producing court ready records quick and easy
In short, all car police video systems can be retrofitted with a radar gun interface. This is only true of course if the radar gun has an available interface. The text inserter portion can be retrofitted on any in car video system. The cost effectiveness of improving the conviction rate of speed offenders and
reducing the in court time will quickly pay back the small investment of a radar gun interface, if a police department has already invested in radar guns and have the video system in place.