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| opinions on reasonably cheap mmWave radar module? |
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| JBeale:
I just noticed a fairly cheap "mmWave Radar - Human Presence Detection" module being offered by DFROBOT SKU:SEN0395. I won't directly link to it or state the price so this doesn't look like an advertisement but it should be easy to search for. It claims to be able to detect a person even if they are not moving (from micro-motions like breathing) and claims a range of 9 meters. You can configure the detection range with up to four zones with 15 cm resolution, but once configured it does not report actual range, only overall "present" or "not present" with 1 Hz update rate. I know about the mm-wave modules used for automotive applications but they start north of $500 so this is the first board like this I've seen at its price. I'm puzzled by the fact that it apparently knows the range to target, a rare ability for cheap boards, but it won't directly tell you. The sub-$10 24GHz doppler motion detectors are CW only, so they can't do ranging. This board claims FM-CW mode as well as CW. Curious what people think is the likelihood this product is for real. Has anyone tried this out? The company does have its own forum but doesn't seem to have a lot of traffic. |
| Marco:
Interesting, here's a page from someone who's started to look into it I found on google (not that specific one, but there's a lot of FMCW claiming modules out there). The SRK1101A seems to be the IC on that module working in the RF domain. I assume they are using with techniques similar to the ones from this paper. |
| JBeale:
Thank you very much for those links, so it looks like there are many FMCW modules recently, but it's unclear how well they perform. Interesting... |
| Marco:
Ultimately a cheap IC with a 24 GHz VCO and I/Q mixers isn't that far out of the realm of possibility and with those the methods from the paper could be implemented with a cheap microcontrollers with DAC&ADCs. I judge it plausible ;) |
| JBeale:
Indeed, it does seem plausible. I'll look forward to someone reporting more definite experimental results. Here is another product with an IC doing the 24 GHz Tx/Rx: http://www.iflabel.com/product/28.html https://www.seeedstudio.com/Millimeter-wave-Doppler-radar-SYH24A-p-4392.html They have some PDFs including something they call a datasheet (sketchy and light on details), and they are all dated Feb 2021 so pretty recent. They also talk about "micro-motion" and person-sensing even if they are asleep, via breathing movement, but they don't mention ranging or FM-CW. There is also this, https://www.seeedstudio.com/Grove-Doppler-Radar-BGT24LTR11-p-4572.html "based on the BGT24LTR11 Silicon Germanium MMIC which is a 24GHz radar transceiver. It is driven by an XMC1302 MCU based on Arm® Cortex®-M0" That Infineon part has a real data sheet. It does generate I/Q outputs from 24 GHz xmit/rcv, and it does have a VCO although they only suggest it for temperature stabilization, not FM-CW mode. https://www.infineon.com/dgdl/Infineon-BGT24LTR11-PB-v01_00-EN.pdf?fileId=5546d4625696ed7601569d063799153e Apparently that chip has been around since 2018. https://www.eenewseurope.com/content/bgt24ltr11-mmic-smallest-24ghz-radar-market bgt24ltr11-mmic-smallest-24ghz-radar |
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