To Power M+

Is it possible to power the M+ over the S1 port but still use USB for data transmission? I currently using the USB port both for power supply and data transmission. I just found out the power over the USB is not enough for the imlid reach that the Satellite SNR is lower when other my USB peripheral’s on the PC side is running (which means it is pulling power away from the M+). So I wondering is there a way to power the M+ over the S1 port but still able to use the USB to PC interface. I realize on the doc it said do not use S1 interface and the USB interface at the same time but I just would like to confirm if there is absolutely no way to use S1 and USB-to-PC at the same time. Thanks!

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Hi Bohan,

No, you should not power the M+ device over UART if it’s additionally connected over USB. It may damage the device.

Are there any issues with using USB both for data transmission and powering?

I am currently using USB for both data transmission and powering. What I have found is that my laptop USB cannot provide enough power to the M+ when there are other USB peripherals also connected to the other USBs on the same laptop. The symptom I have seen is the antenna SNR drops on the ReachView when other USB peripherals are running. I am able to reproduce it by turn on and turn off my other USB peripherals on the laptop (such as USB camera).


Any chance you can share a video or screencast of this behavior with us? Usually, if Reach M+ doesn’t get enough power, it just turns off.

I’d also recommend you check if it works better when you use a USB hub. USB hubs should provide more stable power.

Sorry it takes me so long to get back to this thread. Here is an example. You can see at half way of the gif when I turn on other USB peripherals on the same laptop. The SNR bar from each satellite uniformly all dropped about 5 dB. This can be reproducible by turn on and off other USB peripherals on the laptop, which shares the power with the M+.

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Sharp eyes Bohan!

What your seeing makes sense to me. Very interested in this thread.

Power supply to GNSS is pretty crucial, i just finished reading a white paper on the effect of voltage ripple on GNSS accuracy. Even small fluctuations in voltage can affect measurement.

Could you power it from an USB charge hub? Then the charge lines would be isolated from the computer, but the data would still pass?

Hi Bohan,

Thank you for the example!

Please note that the influence of electronics nearby can cause such behavior. The signals transmitted by other USB peripherals may interfere with the satellite signals. That’s why SNR can drop. I’d suggest taking the Reach M+ antenna far from all the electronics to check if it may help.

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