RE: FCC and Hi Temp operation
My recommendation is to look at the radio performance issues as well as the regulatory. It is possible that you have no FCC compliance issues but the radio does not perform! The FCC could not care less if your radio works or not. Kurt Kurt Fischer HYPER Corporation 1279 Quarry Lane, Suite B Pleasanton, CA 94566-8499 +1.925.462.9105 ext. 205 (Voice) +1.925.577.5517 (PCS) +1.925.280.7751 (Fax) mailto:kurt.fisc...@hyperinterop.com www.hyperinterop.com From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: Wednesday, June 11, 2003 9:58 AM To: chuck.bu...@cubic.com; emc-p...@majordomo.ieee.org Subject: RE: FCC and Hi Temp operation My recommendation is for the supplier to provide you with a device that they certify to operate within the scope of their FCC Grant at your specified temp range. In other words, place the ownership of the problem back on the supplier. Let them determine if they need to resumit data to the FCC for the higher temp operation. Richard Woods Sensormatic Electronics Tyco International From: Burns, Chuck [mailto:chuck.bu...@cubic.com] Sent: Wednesday, June 11, 2003 11:25 AM To: emc-p...@majordomo.ieee.org Subject: FCC and Hi Temp operation Hello, everyone. We are integrating a purchased 802.11b device into our product, but face ambient temperature requirements up to 80 degrees C. This brings up two problems: 1. Will it work at that temperature? One vendor advertises 55 degrees max, another 70 but with an offer to screen products at 80. 2. What are the FCC requirements? The FCC Rules for the 2.45 GHz band, 15.249, specify a frequency tolerance of 0.001% over the -20 to +50 degree range, but do not specifically address higher temperatures. Do we simply fall back onto the more general provisions of 15.215, keeping the 20dB bandwidth signal within the designated band, with a recommendation to keep it within the central 80% of the permitted range? Since we are not manufacturing the transmitter, which already carries FCC certification, who is responsible to the FCC for ensuring compliance at our extreme temperature? Regards, Chuck Burns Manager of Compliance Cubic Transportation Systems, Inc. 5650 Kearny Mesa Road San Diego, CA 92111 Tel.: (858) 627-4562 Fax: (858) 292-9987 chuck.bu...@cubic.com
RE: FCC and Hi Temp operation
Hi Chuck, The device in question would fall under 15.247, which has no extreme temperature requirement in the U.S. If the WLAN device was tested for use in the EU the European Norm (EN 300 328) does involve extreme temperature testing of -20 to +55 C, unless it is for indoor use or controlled environment only, in which case they would still have to test from 0 to + 35 C. If it is a plug in device for use in a host system, the standard only requires that the WLAN device meet the temperature extremes declared for the host system. I hope that you find this info helpful. Best Regards, Barbara From: Burns, Chuck [mailto:chuck.bu...@cubic.com] Sent: Wednesday, June 11, 2003 8:25 AM To: emc-p...@majordomo.ieee.org Subject: FCC and Hi Temp operation Hello, everyone. We are integrating a purchased 802.11b device into our product, but face ambient temperature requirements up to 80 degrees C. This brings up two problems: 1. Will it work at that temperature? One vendor advertises 55 degrees max, another 70 but with an offer to screen products at 80. 2. What are the FCC requirements? The FCC Rules for the 2.45 GHz band, 15.249, specify a frequency tolerance of 0.001% over the -20 to +50 degree range, but do not specifically address higher temperatures. Do we simply fall back onto the more general provisions of 15.215, keeping the 20dB bandwidth signal within the designated band, with a recommendation to keep it within the central 80% of the permitted range? Since we are not manufacturing the transmitter, which already carries FCC certification, who is responsible to the FCC for ensuring compliance at our extreme temperature? Regards, Chuck Burns Manager of Compliance Cubic Transportation Systems, Inc. 5650 Kearny Mesa Road San Diego, CA 92111 Tel.: (858) 627-4562 Fax: (858) 292-9987 chuck.bu...@cubic.com
Re: FCC and Hi Temp operation
The first thing to do is to check the component temperature ratings to see if you will even meet the parts manufacturers operating limits. Many commercial components are rated at 70C, meaning that the parts vendors only guarantee the operation up to that point, after that you are on you own. They will likely have some level of safety margin, but I wouldn't be betting my equipment and company reputation on what the vendor's sales guys told you. If the equipment hasn't been designed for that kind of ambient it may well pass the relatively short duration screening test but you will see a sharp reduction in the life of the product. The major stress on integrated circuits, etc., is temperature. As the ambient and component temperatures increase the failure rate increases exponentially and conversely life, and reliability decrease exponentially. Screening the parts by the vendor will only tell you that these particular units made it for an extremely short time (compared to expected product life). How they play with the rest of the system and there associated variables is nothing but a crap shoot, and its going to be a new risk for every lot the vendor produces. The last time I checked the FCC mainly identified the test ambient as between 50F and 100F (but I'm fuzzy on the upper limit), and that the equipment be in a well warmed condition. That implies that the testing done under a normal test site condition would be acceptable. However, I have had a couple of instances when increased temperatures changed, and indeed failed, some equipment. The components and impedances change somewhat, but the problem I encountered was more mechanical in nature. There were some spring tension components that were used for grounding of flex PCB's etc, that expanded under the higher temperatures and they lost there ground contact. I would at least confirm the emissions compliance at the higher temperatures. Gary McInturff
