Hi,

I suspect that certain requirements exist for the periodic maintenance of police speed measuring devices; is there a legislative source for these requirements ?

Any maintenance required on speed-measuring devices is set by the manufacturer and not by legislation. What type of maintenance is required, and when, is usually outlined in the manual.

I would think that as a measuring device it would have to be on some sort of maintenance schedule; perhaps annually

no maintenance schedule

Would the before and after the short test be considered the standard check-up procedure?

racer wrote:Would the before and after the short test be considered the standard check-up procedure?

I would think that the transmitter and receiver would have to be verified at some point in time. The self checks are internal only.......hhmmm.

There is a way of testing the device internally... Quartz crystals oscillate at perfect 27 MHz, when placed under a specific voltage (not all that important), if it is cut to a specific shapes (much more important than voltage being 10% off, which would produce no change in the resulting frequency of oscillation), and that can be used to determine whether or not the unit is functioning properly through modulation of the sent signal, as well as determining whether the signal being sent out is at a proper frequency. There are many frequencies that can be produced with a piezoelectric quartz crystal, too.

However, the manufacturer of the unit would have to provide a source code for the device for independent testing/review and to see that it actually uses that property. For all I know otherwise, there can be a random number generator in place of the check...