Radar Speeds
One of the frequently asked questions is whether the speeds reported are "relative" or "absolute". The speeds reported by the Varia are RELATIVE speeds. There are several places on the website displaying statistics related to vehicle speeds. If not mentioned specifically, the speed being reported is a RELATIVE speed.
"Incremental" speeds and ranges
Several people have noted the radar speeds seem to be incremental rather than changing smoothly. I am certainly not a radar expert, but my understanding is that to make the radar small enough to fit into a relatively tiny taillight, speeds (and object distances) are not going to be fine-grained. It will essentially pick the closest "bucket" to put the approaching vehicle into. That bucket may change from reading to reading each time the radar is activated, but not for any given vehicle. Note that there is no official documentation about this. Also, there is a reason why Garmin doesn't natively display speed and distance values. They know that it is not going to be as accurate as the typical user may expect. For my research, I want to know which roads have cars passing you at higher rates of speeds than other roads and possibly why. I have ridden nearly 50,000 miles with the radar and I do think the speed data that it reports is fairly consistent from measurement to measurement, but I do not think it is as accurate as a professional radar system.
NOTE: it is also entirely possible that speed data varies from device to device. Other people have sent me their rides, and I'm always amazed at how the passing speeds seem lower than the speeds at which people pass me. That being said, I do have two different Varias (and a third which was destroyed in vehicle collision that initiated this project) that seem to report similar speeds, but I haven't conducted a controlled test to see if there is a major difference. If somebody else out there has multiple varias and would like to help in a controlled test so that we can isolate the accuracy of the radar between devices, please reach out to me. Thanks!
Experimentation
Here are some ideas for more more scientific experimentation to figure out a definitive answer about the speeds that the Varia radar is reporting. The basic design is as follows:
- Stand beside a professional radar system and compare the speed reported by the Varia to that reported by the professional radar (e.g., speed limit signs that show approaching speeds).
- Repeat #1, but this time while riding in same direction as approaching vehicle and again compare the speed reported by the Varia to the speed reported by the professional radar system.
- Repeat #1 and #2 using a different Varia radar device and observe the difference from this device to other Varias as well as the professional radar system.
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