These devices do their measurement in a completely different way. Laser distance meters are essentially tiny radar units operating with light instead of radio

These devices do their measurement in a completely different way. Laser distance meters are essentially tiny radar units operating with light instead of radio waves (lidar). With a pulse radar, you need the pulse itself to be of extremely short duration, especially when you're measuring short distances. You need to have stopped transmitting by the time you begin receiving the reflection to have any hope of actually finding the reflection (because the return "sounds" exactly like what you're transmitting). In order to reliably detect a short unmodulated pulse, the transmitted power generally has to be pretty high so that the reflection is loud enough that you don't miss it. Short pulses and high power are generally hard to do with cheap semiconductor devices (big radar pulse generators tend to use vacuum tubes and exotic and expensive hardware). A better approach for lower power devices is to modulate the carrier wave itself and then transmit a longer, lower power pulse. One way to do this is to transmit a "chirp" (a transmission that starts at a low frequency and ramps up to a high frequency). When you receive the radar return, you'll start receiving the initial low frequency while the transmitter has moved on to transmitting a higher frequency. You can then use this frequency difference and the chirp rate to compute the time of flight and therefore the distance. This also has an added advantage of allowing you to integrate the received signal for a much longer period of time, so it tends to be a lot less noisy and error prone than a pulse radar. [1] http://en.wikipedia.org/wiki/FMCW#Modulated_continuous-wave http://en.wikipedia.org/wiki/FMCW#Modulated_continuous-wave