After reading about military Ground Surveillance Radar that had a Doppler (Wiki) output and how just be the sound you can tell what's making it by instinct. This is exactly how I feel about the PSR-1 seismic outdoor intrusion sensor where when the infrasonic energy is upconverted to sound, when you hear it you know what is making the infrasound. I'd like to get one of the Ground Surveillance Radars like the AN/PPS-4 or AN/PPS-15, but they are hard to find and expensive.
The next best thing may be to get a Doppler Radar module but a RADAR Gun was recommended because it has much more range. So got the Bushnell Velocity RADAR gun. Note I know it does not have an audio output, but I think one can be added. Here's a web page showing inside photos.
Teardown Tuesday: Radar Gun -
While the first genertion radar speed guns (Wiki) worked at 10.525 GHz. This model works at 24 GHz (Wiki: K band). This is one of the Industrial Scientific Medical bands (Wiki) that can be used, with some minor limitations, without a specific license.
D470785 Speedster radar gun, Jordan Vermillion, Bushnell Performance Optics, 2003-02-25 - the Design of this radar gun.
6683558 Speed measurement device with statistic gathering capability, Jordan Vermillion, Bushnell Performance Optics, 2004-02-12 - 14 citations (Nov 2018)
4117464 Microwave motion-detection apparatus employing a gunn oscillator in a self-detecting mode, Erno B. Lutz, SOLFAN SYSTEMS Inc, 1978-09-26 - This is intended for opening doors.
I remember that these guys were Sick Of Looking For A Name and hence their company name of SOLFAN.3633104 USPTO High-Stability Electromagnetic Resonator, Douglas Gray, William Heinz, Hewlett-Packard Co., Jan 4, 1972 - Doppler Module - We had one of these at Aertech to evaluate and there was a design defect.
The Solfan Doppler Modules -
2859435 Speed measuring system,
Jr John H Auer, Hugh C Kendall,Alstom Signaling Inc, 1958-11-04 - Railroad, tubes, Doppler
2629865 Radio echo apparatus for detecting and measuring the speed of moving objects, John L Barker, Eastern Ind Inc, Filed: 1946-06-13, Pub: 1953-02-24 - for roadways such as streets and highways
2402464 Velocity measuring system, Suter Henry, Filed: 1941-07-12, Pub: 1946-06-18 - UHF artillery projectiles, cars, airplanes
ME-400 Indoor Doppler Intrusion Sensor - 328 Mhz
AN/GSQ-160, Detecting-Transmitting Set, Electromagnetic - 57.5 & 60 MHz, military outdoor version of the ME-400
Radar Warning Receivers - Police Radar Warning Receivers -
PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale