Operating on 915MHz ISM Bands without certification  - Page 1
Forum section: electronics / rf-microwave

author: envisionelec
author_rank: Frequent Contributor
timestamp: September 09, 2016, 04:13:07 pm
content: Let's say there is a company that is selling a lot of product (~$2MM/year) which operates on the so-called ISM bands to link digitally modulated TX and RX. They've been in business for over 25 years, sell to major corporations and even the US Government but have zero FCC labeling or testing on any of its products. I'm curious how they have been able to operate this way and what the consequences could be for these alleged misdeeds.Obviously I can't give my relationship to this company (it's not my company) as it could jeopardize some friends careers.I'm just looking for opinions and perhaps some examples.

author: cncjerry
author_rank: Unknown
timestamp: September 09, 2016, 10:25:48 pm
content: they probably aren't making the actual tx/rx modules.

author: envisionelec
author_rank: Frequent Contributor
timestamp: September 09, 2016, 10:27:46 pm
content: Yes, they absolutely are.

author: LabSpokane
author_rank: Super Contributor
timestamp: September 09, 2016, 11:01:50 pm
content: Not legal. Full stop.$2MM/yr is a very small business to be building commercial radios. That explains why they didn't go out for certification.

author: Delta
author_rank: Super Contributor
timestamp: September 09, 2016, 11:34:02 pm
content: What's an MM?

author: envisionelec
author_rank: Frequent Contributor
timestamp: September 10, 2016, 01:30:55 am
content: Quote from: Delta on September 09, 2016, 11:34:02 pmThousand Thousand.AKA Million.

author: hendorog
author_rank: Super Contributor
timestamp: September 10, 2016, 03:57:05 am
content: Quote from: LabSpokane on September 09, 2016, 11:01:50 pmWhat would it cost realistically for a small operation to certify a _simple_ transmitter?

author: LabSpokane
author_rank: Super Contributor
timestamp: September 10, 2016, 12:49:18 pm
content: Quote from: hendorog on September 10, 2016, 03:57:05 amThe certification costs as I understand them generally run into the tens of thousands, but the engineering costs of designing and validating the radio could be a couple hundred thousand, excluding overhead. It's why pre-certified radios get to carry the premium price tag.I'm surprised that the government sales are being permitted, because I used to have to submit the radio's FCC identifiers to the frequency coordinators and get approval prior to using a radio on US government property. It sounds like there's a whole host of things going wrong there.

author: envisionelec
author_rank: Frequent Contributor
timestamp: September 10, 2016, 01:50:17 pm
content: The radios themselves are, in fact, precertified by the manufacturer, Linx. However, the system in which its used is not tested for compliance to FCC standards. Does this change my original question?

author: LabSpokane
author_rank: Super Contributor
timestamp: September 10, 2016, 06:18:54 pm
content: Quote from: envisionelec on September 10, 2016, 01:50:17 pmYes, radically different question, and the answer may be that there is no problem at all. The two big certifications are EMC compliance for unintended RF emissions, and FCC certification that the radio complies with the conditions for band that it will operate in.Depending on the end use, no EMC certification at all may be required. There is a clear exemption is for industrial use only, i.e. the device is not advertised and/or sold via retail channels, then FCC A or B compliance may not be required.For intentional RF emissions, typically this is all contingent on the integrator using a pre-certified combination of radio/antenna as specified by the radio manufacturer, in this case Linx.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 10, 2016, 07:16:19 pm
content: This conversation has confused me, You don't need FCC certification in the ISM bands right? One thing that has also wonder WTF is the 315mhz band, and the 433 band in the U.S. Almost every key fob uses 315mhz but that is not acually designed as an ISM band, and 433 is a European and not american band if i am correct, but I have plenty of devices using this band too!

author: LabSpokane
author_rank: Super Contributor
timestamp: September 10, 2016, 07:37:13 pm
content: Quote from: rwgast_lowlevellogicdesin on September 10, 2016, 07:16:19 pmThe *operator* does not need a license in the ISM band. The RF *device* MUST be tested for compliance at a FCC authorized laboratory. Furthermore, the device in the 902-928 MHz band has a maximum permissible transmitter power output of 30dBm (1W) and can only use an RF output level + antenna gain for a maximum EIRP output of 36 dBm.While ISM is an unlicensed band for radio *operators*, there are rules that must be followed by both operators and radio manufacturers.

author: envisionelec
author_rank: Frequent Contributor
timestamp: September 10, 2016, 11:42:00 pm
content: More information. Both TX are used continuously on 433Mhz and 902-928Mhz (frequencies are fixed, selected from this range). Their systems are monitoring physical attributes of mechanical strain and transmitting with 12-bit resolution to a RX.Almost every RX uses a custom antenna that is not specified for use with the Linx TX, often it is just a length of coax with a section stripped back to expose the center conductor. Almost every TX uses an antenna made from enamelled wire wrapped around a fiberglass core. The length is just a wire(!) - no ground plane or shielding. In some systems, the TX modules are powered by an inductive loop with a carrier of 500kHz. In others, the RX is powered by Mains voltage through a AC/DC transformer.They are used for industrial purposes, but are in use on aircraft (manned and unmanned), watercraft of all types and automobiles on test tracks, drilling rigs and pump stations - almost any system that uses mechanical transmission shafts.But then I read the "Top 10 FCC Exemptions" athttp://www.emcfastpass.com/could-your-product-be-exempt-from-emc-testing-altogether/and industrial use is considered an exemption. Presumably EMC compliance and RF compliance are separately tested, correct?

author: LabSpokane
author_rank: Super Contributor
timestamp: September 10, 2016, 11:53:26 pm
content: Well... many cheap radios use what amounts to just a wire for the antenna. No biggie there. If it's 915MHz only, then they are allowed to transmit continuously. And frankly, the application sounds clearly industrial, so it's likely they are in compliance, but only the FCC can issue a definitive ruling. If you really have a concern that this device is outside the law and is causing destructive interference, then you should file a complaint with the FCC. The form is available online.But the additional detail you are providing would lead me to believe that they are at least complying with the intent of the law.

author: envisionelec
author_rank: Frequent Contributor
timestamp: September 10, 2016, 11:57:07 pm
content: Thank you. It has helped tremendously to have your expert opinion.