3 ms·

Ever actually read the FCC certification on products? Ever see the bit about "this device must accept even harmful interference"? That is what this is about.

by nvy 3y ago

Ever actually read the FCC certification on products? Ever see the bit about "this device must accept even harmful interference"? That is what this is about. It's not necessarily the fault of the manufacturer if a device can be harmed by deliberate RF-based (mis)use.

goodcanadian 3y ago
You have that completely backwards. That line means that even deliberately harmful interference should not break it.
- nvy 3y ago
  I don't think that's correct, because otherwise it would require all devices to have significant EM shielding which clearly they do not.
atoav 3y ago
> It's not necessarily the fault of the manufacturer if a device can be harmed by deliberate RF-based (mis)use. I am not too familiar with the FCC as I am from Europe, but even the linear motor of a standing desk will rate limit the amount of movement you can make it do within a given time frame (those linear motors are not designed for permanent operation). If your meter is rated to switch a certain current, that rating is made under the assumption of a certain ambient temperature and temperature of the switching element. Switching it heats it up, so there has to be a cooldown period if you plan to still operate it within spec. Operating components within spec is the task of the manufacturer, and checks to avoid going out of spec should be one of the first things to design into such a product to prevent house fires or malfunction. Guard mechanisms like rate limiting are cool because they can protect you against liabilty if your programmer makes an error, but they become more important the more exposed the controls are. There is a reason why e.g. a RCD cannot be permanently be fixed in the on-position (the switch is not tied to the lever internally), because you want it to switch off even in the case of misuse in order to save lives. This is magnitudes more important if your controls are exposed to external inputs (e.g. via radio, or over the network/internet), as accidental or malicious misuse might be more prevalent there. Note: I am not saying there is a strict legal requirement to do this, I say that this is what I expect from a modern design made by professional electrical engineers.

by nvy 3y ago

goodcanadian 3y ago

You have that completely backwards. That line means that even deliberately harmful interference should not break it.

nvy 3y ago
I don't think that's correct, because otherwise it would require all devices to have significant EM shielding which clearly they do not.

atoav 3y ago

> It's not necessarily the fault of the manufacturer if a device can be harmed by deliberate RF-based (mis)use. I am not too familiar with the FCC as I am from Europe, but even the linear motor of a standing desk will rate limit the amount of movement you can make it do within a given time frame (those linear motors are not designed for permanent operation). If your meter is rated to switch a certain current, that rating is made under the assumption of a certain ambient temperature and temperature of the switching element. Switching it heats it up, so there has to be a cooldown period if you plan to still operate it within spec. Operating components within spec is the task of the manufacturer, and checks to avoid going out of spec should be one of the first things to design into such a product to prevent house fires or malfunction. Guard mechanisms like rate limiting are cool because they can protect you against liabilty if your programmer makes an error, but they become more important the more exposed the controls are. There is a reason why e.g. a RCD cannot be permanently be fixed in the on-position (the switch is not tied to the lever internally), because you want it to switch off even in the case of misuse in order to save lives. This is magnitudes more important if your controls are exposed to external inputs (e.g. via radio, or over the network/internet), as accidental or malicious misuse might be more prevalent there. Note: I am not saying there is a strict legal requirement to do this, I say that this is what I expect from a modern design made by professional electrical engineers.