9 ms·

The Quectel modems are fun parts. We are using one in a project as a kind of theft protection. I couldn't belive at first "this is a whole computer with Linux o

The Quectel modems are fun parts. We are using one in a project as a kind of theft protection. I couldn't belive at first "this is a whole computer with Linux on it". I really wonder why modem manufacturers feel the need to encapsulate everything so much. Is it for regulatory reasons, to protect their secret sauce, or for our convenience? On the one hand it makes simple things really easy with some AT commands, on the other hand it makes debugging quite frustrating because it is a black box.

Tuna-Fish 6y ago
Regulatory reasons. There are a lot of things that FCC regs say that devices that transmit either must or must not do, which made more sense back when everything was analog. Now that the device is a full computer and can be programmed to do whatever you want, the way the industry has decided to best fulfill all those requirements is to make the computer do exactly and only what is required and then lock it down into a black box. If you just unlocked everything, it would probably be better at what it does, but it would also not be possible to sell to consumers.
- unnah 6y ago
  Do those regulations explicitly say that the RF device is not allowed to be programmable by the user? And isn't the user legally forbidden from substantially modifying the RF behaviour in any case?
  - tomxor 6y ago
    I can't find it now but there was an article posted a while ago that explained the existence of just such rules back when the very first mobile phones used analogue transmission, which of course was easy to intercept. So the FCC forced radio manufacturers to prevent users being able to tune to those frequencies and additionally specified that manufacturers be responsible for making this limitation very hard to defeat... rather than fix the original problem of course. Those rules exist to this day but have no relevance. However I suspect there are other similar but slightly more sane rules in play since modems are now just software defined radios that can be made to do nearly anything you want given the right access - i.e you can cause a lot of trouble, even if you don't intend to.
    - gary_0 6y ago
      https://news.ycombinator.com/item?id=25403163 https://news.ycombinator.com/item?id=25403163 "Why radio receivers won’t tune 800-900 MHz"
  - dtech 6y ago
    Requiring a device to not allow illegal RF behavior is significantly easier to require and audit than policing the actions of millions of consumers.
    - hansvm 6y ago
      Off-topic, abstracting laws away from the harm they aim to prevent has always bothered me a bit. By punishing behaviors (e.g., making a device with a certain set of capabilities) other than the ones people care about (e.g., careless or malicious RF activity) you're nearly guaranteed to introduce unwanted loopholes and second-order effects. E.g., CA requires tags for your vehicles (fair enough -- gotta charge people for the privilege of driving at all, not just incrementally through gas taxes and whatnot /s), but the law isn't that your vehicle be registered and have tags purchased; it's that valid tags must be displayed on the vehicle. That makes enforcement super easy because an officer can just walk up and down a line of cars handing out tickets, but it also means that people can break the law for no fault of their own even after having taken the action the law was intending to promote (paying CA in this case). If you tried to renew your tags at the right time in 2020, even months before they were set to expire, you couldn't pick them up in person (covid) and wouldn't receive them in the mail till after the governor's order temporarily allowing you to drive with expired tags had expired. Moreover, at least one police department was excited to cash in on that discrepancy :) The problem in that example is that the behavior the law is supposed to encourage (paying CA if you own a car) only partially aligns with what the law punishes (not displaying a valid tag on your car). That lack of alignment leaves room for exploitation. That's just a small example (intentionally so -- hopefully it's simple enough so as to not be controversial), but it's a constant pattern in our legal system: - Taser-immune meth-heads robbing people at knife point is bad, so let's make a hint of a whiff of any kind of drug anywhere near an individual for any reason a felony. - Child pornography is bad, so let's (try to) make encryption illegal. - Pump-and-dump scams are bad, so let's make [thousands of pages of financial legalese] illegal. - (intentional hyperbole on this point) Low quality medical devices hurting people is bad, so let's give a private corporation the privilege to write up a set of standards, never change them no matter how far the world progresses, and charge people for the privilege of reading them to know what's legal or not.
scoutt 6y ago
> I really wonder why modem manufacturers feel the need to encapsulate everything so much. The alternative would be using an RTOS of some sort, implementing a full network stack (with > 100Mb throughput) and a USB device, as the bare minimum. Then you also have I2S audio, GNSS, etc. It probably makes more sense using an entire OS at some point. BTW, this is typical Qualcomm, that makes the chipsets for these modems.
- Nextgrid 6y ago
  Why not offload all that to the driver running on the main application processor? The risk of having a second, black-box running Linux is that it’ll get outdated and/or compromised and used as a persistence mechanism for malware.
  - scoutt 6y ago
    Because you can also use the modem coupled with a low-end MCU, communicating through a serial port. This configuration is more common than one might think (I was personally involved in many of projects with that configuration).
    - seba_dos1 6y ago
      It's actually the main use case for these modem modules.
  - swiley 6y ago
    Drivers on Linux usually mean GPL which freaks out modem manufacturers.
    - gsich 6y ago
      Yes, mainly because their code quality is absolute shit.
  - kelnos 6y ago
    Most of these can probably receive updates from the host OS if it's really needed, but I think what it boils down to is that the manufacturers just don't care, unfortunately.
jcims 6y ago
Sounds like it would make a good payload for a high-altitude balloon ride to send live data on the way up and back down (to whatever range limits)
gsich 6y ago
Baseband: yes Rest: no. Some modem manufacturers have SDKs to get your application on the device as a feature.

Tuna-Fish 6y ago

Regulatory reasons. There are a lot of things that FCC regs say that devices that transmit either must or must not do, which made more sense back when everything was analog. Now that the device is a full computer and can be programmed to do whatever you want, the way the industry has decided to best fulfill all those requirements is to make the computer do exactly and only what is required and then lock it down into a black box. If you just unlocked everything, it would probably be better at what it does, but it would also not be possible to sell to consumers.

unnah 6y ago
Do those regulations explicitly say that the RF device is not allowed to be programmable by the user? And isn't the user legally forbidden from substantially modifying the RF behaviour in any case?
- tomxor 6y ago
  I can't find it now but there was an article posted a while ago that explained the existence of just such rules back when the very first mobile phones used analogue transmission, which of course was easy to intercept. So the FCC forced radio manufacturers to prevent users being able to tune to those frequencies and additionally specified that manufacturers be responsible for making this limitation very hard to defeat... rather than fix the original problem of course. Those rules exist to this day but have no relevance. However I suspect there are other similar but slightly more sane rules in play since modems are now just software defined radios that can be made to do nearly anything you want given the right access - i.e you can cause a lot of trouble, even if you don't intend to.
  - gary_0 6y ago
    https://news.ycombinator.com/item?id=25403163 https://news.ycombinator.com/item?id=25403163 "Why radio receivers won’t tune 800-900 MHz"
- dtech 6y ago
  Requiring a device to not allow illegal RF behavior is significantly easier to require and audit than policing the actions of millions of consumers.
  - hansvm 6y ago
    Off-topic, abstracting laws away from the harm they aim to prevent has always bothered me a bit. By punishing behaviors (e.g., making a device with a certain set of capabilities) other than the ones people care about (e.g., careless or malicious RF activity) you're nearly guaranteed to introduce unwanted loopholes and second-order effects. E.g., CA requires tags for your vehicles (fair enough -- gotta charge people for the privilege of driving at all, not just incrementally through gas taxes and whatnot /s), but the law isn't that your vehicle be registered and have tags purchased; it's that valid tags must be displayed on the vehicle. That makes enforcement super easy because an officer can just walk up and down a line of cars handing out tickets, but it also means that people can break the law for no fault of their own even after having taken the action the law was intending to promote (paying CA in this case). If you tried to renew your tags at the right time in 2020, even months before they were set to expire, you couldn't pick them up in person (covid) and wouldn't receive them in the mail till after the governor's order temporarily allowing you to drive with expired tags had expired. Moreover, at least one police department was excited to cash in on that discrepancy :) The problem in that example is that the behavior the law is supposed to encourage (paying CA if you own a car) only partially aligns with what the law punishes (not displaying a valid tag on your car). That lack of alignment leaves room for exploitation. That's just a small example (intentionally so -- hopefully it's simple enough so as to not be controversial), but it's a constant pattern in our legal system: - Taser-immune meth-heads robbing people at knife point is bad, so let's make a hint of a whiff of any kind of drug anywhere near an individual for any reason a felony. - Child pornography is bad, so let's (try to) make encryption illegal. - Pump-and-dump scams are bad, so let's make [thousands of pages of financial legalese] illegal. - (intentional hyperbole on this point) Low quality medical devices hurting people is bad, so let's give a private corporation the privilege to write up a set of standards, never change them no matter how far the world progresses, and charge people for the privilege of reading them to know what's legal or not.

scoutt 6y ago

> I really wonder why modem manufacturers feel the need to encapsulate everything so much. The alternative would be using an RTOS of some sort, implementing a full network stack (with > 100Mb throughput) and a USB device, as the bare minimum. Then you also have I2S audio, GNSS, etc. It probably makes more sense using an entire OS at some point. BTW, this is typical Qualcomm, that makes the chipsets for these modems.

Nextgrid 6y ago
Why not offload all that to the driver running on the main application processor? The risk of having a second, black-box running Linux is that it’ll get outdated and/or compromised and used as a persistence mechanism for malware.
- scoutt 6y ago
  Because you can also use the modem coupled with a low-end MCU, communicating through a serial port. This configuration is more common than one might think (I was personally involved in many of projects with that configuration).
  - seba_dos1 6y ago
    It's actually the main use case for these modem modules.
- swiley 6y ago
  Drivers on Linux usually mean GPL which freaks out modem manufacturers.
  - gsich 6y ago
    Yes, mainly because their code quality is absolute shit.
- kelnos 6y ago
  Most of these can probably receive updates from the host OS if it's really needed, but I think what it boils down to is that the manufacturers just don't care, unfortunately.

jcims 6y ago

Sounds like it would make a good payload for a high-altitude balloon ride to send live data on the way up and back down (to whatever range limits)

gsich 6y ago

Baseband: yes Rest: no. Some modem manufacturers have SDKs to get your application on the device as a feature.