Comment by pinky1417 | Hacker News Reader

Comment by pinky1417 | Hacker News Reader

What fortuitous timing to see this post.

I bought an MX Master 3 for Mac mouse for my Silicon Mac Mini about a year and a half ago but quickly shelved it because the cursor would frequently make irritating little jumps. I replaced it with an Apple Magic Touchpad (I don't love the Magic Mouse) because, at least at the time, I was under the impression that the jumpiness was due to a OS-level bug affecting all non-Apple mice. I did have Airpods at the time but I don't recall if I ever attempted to use them alongside the Logitech mouse.

The timing is fortuitous because, on a whim last night, I got my MX Master 3 out of storage and put it on a charger. I figured that, with ~18 months of macOS updates, perhaps it'll work with my Mac Mini on bluetooth or using the Logi Bolt USB adapter, which I don't own yet (I guess the Bolt is different from the Unifying Receiver... although irritatingly neither comes in USB-C).

I'm intrigued by the hypothesis that Logitech is remaining quiet because their products may be violating FCC rules, specifically, part 15 of the FCC rules: "this device may not cause harmful interference". If I can replicate the AirPods issue, or if I see some other weird behavior with the Logitech mouse, I might just break out my HackRF, YARD Stick One, or Ubertooth One. I'm a total noob at radiofrequency stuff, and I'm only slightly less of a noob with running specialty software, but I wonder if I can spot some unexpected RF emissions.

> specifically, part 15 of the FCC rules: "this device may not cause harmful interference".

I think you misunderstand what harmful interference means - it has a specific regulatory meaning - and the fact that it causes you grief with your other Part 15 devices doesn’t apply. If that were the case the FCC would be spending all their time just dealing with everyone’s shitty stereo equipment not working.

https://www.law.cornell.edu/cfr/text/47/2.1

> but I wonder if I can spot some unexpected RF emissions.

I highly doubt it - this stuff was already certified. On the other hand it’s not surprising that devices physically near running in the same frequency band will have some undesired operation - this is why safety critical communications don’t operate in an unlicensed band. Spread spectrum isn’t completely magic (as an EE I’m still sometimes amazed any of this shit works at all) —- or maybe I should say it is magic but it still has to come to terms with physical realities.

>part 15 of the FCC rules

That means that the device can not cause interference to a higher priority service. All the devices are at the same priority.

It also means that the FCC doesn't have to care...

Logitech Unifying and Logi Bolt are incompatible. Both them, classic Bluetooth, Bluetooth Low Energy and almost all other input-devices with dongles all use the 2.4 GHz band, and all these types of devices can interfere with one-another — but there are no rules against that!

Logi Bolt is actually a proprietary layer on top of Bluetooth Low Energy. Logitech claims that it should suffer less in face of congestion on the band compared to regular BLE, but they have not revealed how: I wonder if they make it worse for other devices by transmitting on more BLE channels.

Reply on news.ycombinator.com