On 8/4/21 4:19 PM, KENT BRITAIN wrote:
Having worked with GPR, that little box is 40 or 50 dB shy in power!? hihi WA5VJB
On Wednesday, August 4, 2021, 06:12:08 PM CDT, Jim Lux <jim@...> wrote:
That depends on the penetration depth, etc.
We used something very similar to the NanoVNA (a few mW output, stepped frequencies over 100 MHz range at 3GHz) to detect human heartbeats and respirations from victims buried in rubble 10 meters deep.
The stepped frequency CW measurement requires a lot less power than a traditional impulse GPR (it's a peak vs avg power thing - the typical GPR shoots a high voltage impulse into a bowtie antenna, so the pulse is very high power, but low duty cycle).? I don't know, off hand, whether the new GPRs (e.g. from ) are using CWFM or impulse, but I'll bet CW FM.? They have kind of a weird terminology in that business: analog and digital antennas, for instance, because for them "antenna" is basically the "sensor, including the RF stuff".
