On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote:>krw@att.bizzzzzzzzzzzz wrote: >> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> krw@att.bizzzzzzzzzzzz wrote: >>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> krw@att.bizzzzzzzzzzzz wrote: > >[...] > >>> If one or more were way above limits then you pack up and >>> come back after some redesign. >> >> BTDT. >> > >Me, too :-( > >But those weren't wasn't my designs ...My worst case was on my board but it wasn't my design (legacy crap). I guess I should have expected problems with the 100th thru 120th harmonic. ;-) I'm slowly convincing them that split ground planes are a bad idea, though (just found the source of some of our 2.4GHz "buzz" problem).>>> If none were above or just vy a smidgen >>> everything gets trundled out to the open space setup. There's a hut with >>> a big fat receiver in there and (hopefully) some hot coffee. The DUT >>> gets placed on a rotary table outside. Now they take the list of close >>> calls and check all those again. >>> >>> This is because chamber measurements are not very precise. >> >> Hmm. The chamber is the gold standard. A 3M isn't worth much, but we've had >> no trouble with the 10M. The rotary table and all that jazz is in there. >> > >That would be up to the EMC lab I guess. If they sign on the dotted line >without open range measurements, well, dicey. The labs I went to never >did that unless all the nasties were way under the limits.They've never even suggested open range measurements. The company with the 3m chamber couldn't get the same numbers twice, though.>>>>>>>> ... We had a nasty >>>>>>>> experience were it took many attempts and several weeks. $5K would have been >>>>>>>> a bargain. That disaster was at least half the fault of the testing lab, >>>>>>>> though, so we try to not go there anymore. >>>>>>>> >>>>>>> That's why I urge clients to send an experienced engineer along _and_ do >>>>>>> pre-compliance checks inhouse. >>>>>> In our case, these were useless. With our equipment I can't even get a decent >>>>>> sniff. >>>>>> >>>>> Mostly I just use a computer-controlled scanner. If there is a nasty >>>>> emission somewhere it'll find it. Sure, I can't quantify it here in the >>>>> lab but after a couple of decades on the beat you know what'll cause >>>>> problems, just like an older cop can look a guy in the eyes and tell >>>>> that "he dunnit". >>>> Scanner? Does it cover the entire range (30mHz to a few GHz)? >>>> >>> Not 30 millihertz :-) >> >> No? ;-) >> >>> Goes from close to DC to a little above 3GHz. >> >> What sort? >> > >Mine is the Icom R-1500. Has a mini console for quick checks when I >don't want to fire up the PC. If you go PC-only then there's the similar >PCR-1500 for about $100 less.I'll take a look at it. Thanks.>Nice thing is, you can listen to stuff in SSB, on every frequency. This >is valuable beyond belief if you must knock a few dB off stuff that's >already in the noise. With an analyzer that has only a display and maybe >some rather crude AM detector with headphones your eyes will hurt at >night, especially for guy like me who need a different set of glasses >between 0603/0402 soldering and looking at screens. Civilian class A/B >are easy. Aircraft category M, different thing. > >I can crank up the big stereo speakers here and don't even have to don >headphones. Of course, this means I can't listen to Bluegrass while >doing EMC work. But the Shepherd doesn't like these funny gargles and >warbles, leaving her pillow and walking out of the room, giving me "the >look". She likes Bluegrass :-)Evidently she doesn't like acid rock. ;-)>>>>>>>> It is silly to just ship stuff off to the lab. If anything goes wrong (it >>>>>>>> always does) there is no one there to fix it. I'm the one who generally goes. >>>>>>>> I kinda like Atlanta. ;-) >>>>>>>> >>>>>>>>> If you build thousands of units a year it certainly makes sense. Of >>>>>>>>> course, you also have to factor in and amortize your own design work on >>>>>>>>> the RF portions of the project that would otherwise already have been >>>>>>>>> handled by the module vendor. That often gets overlooked. >>>>>>>> I'm not talking about designing the RF section, rather only the certification >>>>>>>> part. specifically, whether to use the RF module's certification and then >>>>>>>> certify your box as an unintentional radiator or certifying the entire box as >>>>>>>> an intentional radiator. >>>>>>> For small qty stuff (meaning not millions/year) it's almost always >>>>>>> better to use the module's cert and slap that extra sticker from its mfg >>>>>>> onto the client's box. Only one more sticker, next to all the other >>>>>>> mandatory ones like "Do not put in mouth" and all that :-) >>>>>> But the module's cert doesn't certify the whole box, unless there isn't >>>>>> anything else in the box. >>>>> For the intentional part it usually does, the mfg would tell you that >>>>> (and supply the cert/sticker). Unless you do some unauthorized mods. The >>>>> unintentional part needs to be tested just like it is with non-RF gear. >>>> Understood, but my point is that the intentional limits are considerably >>>> higher than the unintentional, outside some forbidden zones, so it's far >>>> easier to pass. Actually, they're so lax that you'd have to *try* to fail >>>> them. ;-) >>>> >>> It doesn't matter, you still have to pass regular (unintentional) EMC >>> outside your intentional transmit band. That part doesn't get any >>> easier. But why pay the extra chunk of money for field strength >>> measurements on the ISM band or wherever you are transmitting, when you >>> don't have to? That's like paying sales tax for the same item in two states. >> >> If you read the regs, at least for FHSS radiators in the ISM bands, anything >> outside the band, and outside one or two do-not-collect-$200 bands, must only >> be 20dB down from the in-band radiation. Easy-peasy, when you're radiating a >> hundred or two milliwatts. >> > >Huh? So you can be way above class B limits in, say, the aircraft bands?"outside one or two do-not-collect-$200 bands"> Do you have a link there?I meant to look it up again today but got busy doing real work. (Some nitwit decided to save $20 and leave off the solder mask on a proto board).>If you also know anything like that in the >tax code I think lots of people would be all ears :-);-)>>>>> If the mfg waffles on the stickers and cert copies, run. >>>> That's not my point. >>> >>> Ok. Then why not just slap on the sticker, do only the regular EMC and >>> be done with it? Of course the EMC lab needs to know about the >>> intentional radiator part so they don't flag that. >> >> Because the intentional limits are almost impossible to fail. We pass easily, >> now, so there isn't any point in gaming the system, but the rules leave the >> door wide open. > > >Sure, when you are a good designer or use pre-cooked modules they are >easy. But why spend that extra money to test if it's already done?Because it makes passing a piece of cake. Can't fail! It probably wouldn't have worked for the product we had real trouble with because we needed CE (and all the rest of the alphabet soup, too)
Wireless that's "Fall off a log" easy?
Started by ●October 11, 2010
Reply by ●October 19, 20102010-10-19
Reply by ●October 19, 20102010-10-19
krw@att.bizzzzzzzzzzzz wrote:> On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote: > >> krw@att.bizzzzzzzzzzzz wrote: >>> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> krw@att.bizzzzzzzzzzzz wrote: >>>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> krw@att.bizzzzzzzzzzzz wrote:[...]>>>> This is because chamber measurements are not very precise. >>> Hmm. The chamber is the gold standard. A 3M isn't worth much, but we've had >>> no trouble with the 10M. The rotary table and all that jazz is in there. >>> >> That would be up to the EMC lab I guess. If they sign on the dotted line >> without open range measurements, well, dicey. The labs I went to never >> did that unless all the nasties were way under the limits. > > They've never even suggested open range measurements. The company with the 3m > chamber couldn't get the same numbers twice, though. >Some of my stuff must be measured at 1m. At 3m you wouldn't be able to see much anymore, certainly not on a spectrum analyzer. At 10m there'd be nothing. But the standard is rather detailed about how the chamber must look like. For example, numerous antennas, several rotating stirrer plates, and so on. [...]>>>> Goes from close to DC to a little above 3GHz. >>> What sort? >>> >> Mine is the Icom R-1500. Has a mini console for quick checks when I >> don't want to fire up the PC. If you go PC-only then there's the similar >> PCR-1500 for about $100 less. > > I'll take a look at it. Thanks. >An hour ago it did another fine job. Got three little transmitters here that are stuck. In order to diagnose this I had to see if the various data packets were still being transmitted, over all that din these things created. Fired up the Icom and sure enough, could hear a distinct faint "brrripp" whenever a packet was sent and the sound of it changed when I sent different packets. Very deep inside of what sounded like Niagara Falls from 10ft away. Now try that with an analyzer ... [...]>>> If you read the regs, at least for FHSS radiators in the ISM bands, anything >>> outside the band, and outside one or two do-not-collect-$200 bands, must only >>> be 20dB down from the in-band radiation. Easy-peasy, when you're radiating a >>> hundred or two milliwatts. >>> >> Huh? So you can be way above class B limits in, say, the aircraft bands? > > "outside one or two do-not-collect-$200 bands" >Well, I bet you'd get in trouble no matter what if anything leaked. FM band, police, air, even TV. And if you step on some Lt.Colonel's radio link, oh boy ...>> Do you have a link there? > > I meant to look it up again today but got busy doing real work. (Some nitwit > decided to save $20 and leave off the solder mask on a proto board). >Oh great! He's earned himself a spot in the hall of blame I suppose :-)>> If you also know anything like that in the >> tax code I think lots of people would be all ears :-) > > ;-) > >>>>>> If the mfg waffles on the stickers and cert copies, run. >>>>> That's not my point. >>>> Ok. Then why not just slap on the sticker, do only the regular EMC and >>>> be done with it? Of course the EMC lab needs to know about the >>>> intentional radiator part so they don't flag that. >>> Because the intentional limits are almost impossible to fail. We pass easily, >>> now, so there isn't any point in gaming the system, but the rules leave the >>> door wide open. >> >> Sure, when you are a good designer or use pre-cooked modules they are >> easy. But why spend that extra money to test if it's already done? > > Because it makes passing a piece of cake. Can't fail! It probably wouldn't > have worked for the product we had real trouble with because we needed CE (and > all the rest of the alphabet soup, too)Well, I know for sure the Europeans won't let you get away with that. But I can't imagine the FCC would either. Because then just about everybody could put in intentional radiator in their product whether it's needed or not, just to dodge the smog check. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Reply by ●October 20, 20102010-10-20
On Tue, 19 Oct 2010 17:42:24 -0700, Joerg <invalid@invalid.invalid> wrote:>krw@att.bizzzzzzzzzzzz wrote: >> On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> krw@att.bizzzzzzzzzzzz wrote: >>>> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>> >>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: > >[...] > >>>>> This is because chamber measurements are not very precise. >>>> Hmm. The chamber is the gold standard. A 3M isn't worth much, but we've had >>>> no trouble with the 10M. The rotary table and all that jazz is in there. >>>> >>> That would be up to the EMC lab I guess. If they sign on the dotted line >>> without open range measurements, well, dicey. The labs I went to never >>> did that unless all the nasties were way under the limits. >> >> They've never even suggested open range measurements. The company with the 3m >> chamber couldn't get the same numbers twice, though. >> > >Some of my stuff must be measured at 1m. At 3m you wouldn't be able to >see much anymore, certainly not on a spectrum analyzer. At 10m there'd >be nothing. But the standard is rather detailed about how the chamber >must look like. For example, numerous antennas, several rotating stirrer >plates, and so on.?? If I can't see it at 3m or 10m, for that matter, why do I care? I let the compliance lab worry about their chamber. That's what they get paid the big bux for.>[...] > >>>>> Goes from close to DC to a little above 3GHz. >>>> What sort? >>>> >>> Mine is the Icom R-1500. Has a mini console for quick checks when I >>> don't want to fire up the PC. If you go PC-only then there's the similar >>> PCR-1500 for about $100 less. >> >> I'll take a look at it. Thanks. >> > >An hour ago it did another fine job. Got three little transmitters here >that are stuck. In order to diagnose this I had to see if the various >data packets were still being transmitted, over all that din these >things created. Fired up the Icom and sure enough, could hear a distinct >faint "brrripp" whenever a packet was sent and the sound of it changed >when I sent different packets. Very deep inside of what sounded like >Niagara Falls from 10ft away. Now try that with an analyzer ... > >[...] > > >>>> If you read the regs, at least for FHSS radiators in the ISM bands, anything >>>> outside the band, and outside one or two do-not-collect-$200 bands, must only >>>> be 20dB down from the in-band radiation. Easy-peasy, when you're radiating a >>>> hundred or two milliwatts. >>>> >>> Huh? So you can be way above class B limits in, say, the aircraft bands? >> >> "outside one or two do-not-collect-$200 bands" >> > >Well, I bet you'd get in trouble no matter what if anything leaked. FM >band, police, air, even TV. And if you step on some Lt.Colonel's radio >link, oh boy ...Why? It's an intentional radiator. It passes that test.>>> Do you have a link there? >> >> I meant to look it up again today but got busy doing real work. (Some nitwit >> decided to save $20 and leave off the solder mask on a proto board). >> > >Oh great! He's earned himself a spot in the hall of blame I suppose :-) >It's worse than that. The board is 2-layer (fortunately rather simple) with ground and Vcc pours top and bottom. It's almost impossible to solder anything without bridging. Getting solder to flow under the LEDs was a RPITA. "He" doesn't much care about blame, though it's not going to happen to me again.>>> If you also know anything like that in the >>> tax code I think lots of people would be all ears :-) >> >> ;-) >> >>>>>>> If the mfg waffles on the stickers and cert copies, run. >>>>>> That's not my point. >>>>> Ok. Then why not just slap on the sticker, do only the regular EMC and >>>>> be done with it? Of course the EMC lab needs to know about the >>>>> intentional radiator part so they don't flag that. >>>> Because the intentional limits are almost impossible to fail. We pass easily, >>>> now, so there isn't any point in gaming the system, but the rules leave the >>>> door wide open. >>> >>> Sure, when you are a good designer or use pre-cooked modules they are >>> easy. But why spend that extra money to test if it's already done? >> >> Because it makes passing a piece of cake. Can't fail! It probably wouldn't >> have worked for the product we had real trouble with because we needed CE (and >> all the rest of the alphabet soup, too) > > >Well, I know for sure the Europeans won't let you get away with that. >But I can't imagine the FCC would either. Because then just about >everybody could put in intentional radiator in their product whether >it's needed or not, just to dodge the smog check.That's what the regs say. I checked my interpretation with our test lab and it agrees with theirs. The problem is that it takes a few more hours to guarantee that it meets the "no go zone" edges. I stumbled onto this because the radio module does *not* meet the unintentional limits by itself. I turned it off and our box passes with 12dB to spare. If they can radiate like radium, why can't we? ;-) Seems all it takes is a redefinition of what the "intentional radiator" is.
Reply by ●October 20, 20102010-10-20
In comp.arch.embedded, krw@att.bizzzzzzzzzzzz <krw@att.bizzzzzzzzzzzz> wrote:> On Tue, 19 Oct 2010 17:42:24 -0700, Joerg <invalid@invalid.invalid> wrote: > >>krw@att.bizzzzzzzzzzzz wrote: >>> On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> krw@att.bizzzzzzzzzzzz wrote: >>>>> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >> >>[...] >> >>>>>> This is because chamber measurements are not very precise. >>>>> Hmm. The chamber is the gold standard. A 3M isn't worth much, but we've had >>>>> no trouble with the 10M. The rotary table and all that jazz is in there. >>>>> >>>> That would be up to the EMC lab I guess. If they sign on the dotted line >>>> without open range measurements, well, dicey. The labs I went to never >>>> did that unless all the nasties were way under the limits. >>> >>> They've never even suggested open range measurements. The company with the 3m >>> chamber couldn't get the same numbers twice, though.The company that does most of our testing does initial testing in the chamber and if everything is 10dB under the limits, they will pass the product. If there are higher peaks, but still under the limit, they will re-measure those at the OATS (Open Area Test Site). Another company seems to have a little more confidence in their chamber, but they still do OATS measurements. The OATS is the gold standard, because that is how it is defined in the standards. A test company that passes your product when it is just under the limits in the chamber must have great confidence in that chamber.>>>> Sure, when you are a good designer or use pre-cooked modules they are >>>> easy. But why spend that extra money to test if it's already done? >>> >>> Because it makes passing a piece of cake. Can't fail! It probably wouldn't >>> have worked for the product we had real trouble with because we needed CE (and >>> all the rest of the alphabet soup, too) >> >> >>Well, I know for sure the Europeans won't let you get away with that. >>But I can't imagine the FCC would either. Because then just about >>everybody could put in intentional radiator in their product whether >>it's needed or not, just to dodge the smog check. > > That's what the regs say. I checked my interpretation with our test lab and > it agrees with theirs. The problem is that it takes a few more hours to > guarantee that it meets the "no go zone" edges. I stumbled onto this because > the radio module does *not* meet the unintentional limits by itself. I turned > it off and our box passes with 12dB to spare. If they can radiate like > radium, why can't we? ;-) Seems all it takes is a redefinition of what the > "intentional radiator" is.If you use a pre-cooked module with a datasheet that says it meets certain limits, it will only meet those limits if you use it exactly as the manufacturer says (ask for those test conditions if they are not in the datasheet!). And even if you do that, as soon as you add more stuff you need to worry that the sum of emissions will not go over the limit. If you only use tested modules in prescribed ways, you may get away with adding the emissions and pass it on paper if that sum is well below limits. For CE you are not required to do measurements, you just have to show somehow you are under the limits. But doing measurements is in most cases the only practical way to prove that. Most test companies ask you to put the product in some mode that will produce (expected) worst case emissions. Just switching off emitters on your board for the test is just fooling yourself (and your test company). If you are later caught in the field with too much emissions, you will have a hard time explaining why it was valid to turn off that emitter during your tests. -- Stef (remove caps, dashes and .invalid from e-mail address to reply by mail) You can't take damsel here now.
Reply by ●October 20, 20102010-10-20
I dont knwo if the OP is still interested but this might be useful: http://www.atmel.com/dyn/products/tools_card.asp?tool_id=4538 It is licensed and cos 30 Dolars... can go up to 250kb/s and is zigbee. Cya --------------------------------------- Posted through http://www.EmbeddedRelated.com
Reply by ●October 20, 20102010-10-20
krw@att.bizzzzzzzzzzzz wrote:> On Tue, 19 Oct 2010 17:42:24 -0700, Joerg <invalid@invalid.invalid> wrote: > >> krw@att.bizzzzzzzzzzzz wrote: >>> On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> krw@att.bizzzzzzzzzzzz wrote: >>>>> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >> [...] >> >>>>>> This is because chamber measurements are not very precise. >>>>> Hmm. The chamber is the gold standard. A 3M isn't worth much, but we've had >>>>> no trouble with the 10M. The rotary table and all that jazz is in there. >>>>> >>>> That would be up to the EMC lab I guess. If they sign on the dotted line >>>> without open range measurements, well, dicey. The labs I went to never >>>> did that unless all the nasties were way under the limits. >>> They've never even suggested open range measurements. The company with the 3m >>> chamber couldn't get the same numbers twice, though. >>> >> Some of my stuff must be measured at 1m. At 3m you wouldn't be able to >> see much anymore, certainly not on a spectrum analyzer. At 10m there'd >> be nothing. But the standard is rather detailed about how the chamber >> must look like. For example, numerous antennas, several rotating stirrer >> plates, and so on. > > ?? If I can't see it at 3m or 10m, for that matter, why do I care? ...The RTCA/DO-160 standard does care, and some of the stuff here has to comply. Else the FAA will have a bone to pick.> ... I let the > compliance lab worry about their chamber. That's what they get paid the big > bux for. >Yup. And there one has to do everything to minimize those bux. Like not doing de-facto pre-compliance runs there, which surprisingly many companies end up doing.>> [...] >> >>>>>> Goes from close to DC to a little above 3GHz. >>>>> What sort? >>>>> >>>> Mine is the Icom R-1500. Has a mini console for quick checks when I >>>> don't want to fire up the PC. If you go PC-only then there's the similar >>>> PCR-1500 for about $100 less. >>> I'll take a look at it. Thanks. >>> >> An hour ago it did another fine job. Got three little transmitters here >> that are stuck. In order to diagnose this I had to see if the various >> data packets were still being transmitted, over all that din these >> things created. Fired up the Icom and sure enough, could hear a distinct >> faint "brrripp" whenever a packet was sent and the sound of it changed >> when I sent different packets. Very deep inside of what sounded like >> Niagara Falls from 10ft away. Now try that with an analyzer ... >> >> [...] >> >> >>>>> If you read the regs, at least for FHSS radiators in the ISM bands, anything >>>>> outside the band, and outside one or two do-not-collect-$200 bands, must only >>>>> be 20dB down from the in-band radiation. Easy-peasy, when you're radiating a >>>>> hundred or two milliwatts. >>>>> >>>> Huh? So you can be way above class B limits in, say, the aircraft bands? >>> "outside one or two do-not-collect-$200 bands" >>> >> Well, I bet you'd get in trouble no matter what if anything leaked. FM >> band, police, air, even TV. And if you step on some Lt.Colonel's radio >> link, oh boy ... > > Why? It's an intentional radiator. It passes that test. >It's not supposed to intentionally radiate at, say, 155MHz because the local sheriff will have something against that.>>>> Do you have a link there? >>> I meant to look it up again today but got busy doing real work. (Some nitwit >>> decided to save $20 and leave off the solder mask on a proto board). >>> >> Oh great! He's earned himself a spot in the hall of blame I suppose :-) >> > It's worse than that. The board is 2-layer (fortunately rather simple) with > ground and Vcc pours top and bottom. It's almost impossible to solder > anything without bridging. Getting solder to flow under the LEDs was a RPITA. > "He" doesn't much care about blame, though it's not going to happen to me > again. > >>>> If you also know anything like that in the >>>> tax code I think lots of people would be all ears :-) >>> ;-) >>> >>>>>>>> If the mfg waffles on the stickers and cert copies, run. >>>>>>> That's not my point. >>>>>> Ok. Then why not just slap on the sticker, do only the regular EMC and >>>>>> be done with it? Of course the EMC lab needs to know about the >>>>>> intentional radiator part so they don't flag that. >>>>> Because the intentional limits are almost impossible to fail. We pass easily, >>>>> now, so there isn't any point in gaming the system, but the rules leave the >>>>> door wide open. >>>> Sure, when you are a good designer or use pre-cooked modules they are >>>> easy. But why spend that extra money to test if it's already done? >>> Because it makes passing a piece of cake. Can't fail! It probably wouldn't >>> have worked for the product we had real trouble with because we needed CE (and >>> all the rest of the alphabet soup, too) >> >> Well, I know for sure the Europeans won't let you get away with that. >> But I can't imagine the FCC would either. Because then just about >> everybody could put in intentional radiator in their product whether >> it's needed or not, just to dodge the smog check. > > That's what the regs say. I checked my interpretation with our test lab and > it agrees with theirs. ...Got any links there?> ... The problem is that it takes a few more hours to > guarantee that it meets the "no go zone" edges. ...Now wait, are you now saying there are areas where it must meet class B? If so, that's what I was saying all along.> ... I stumbled onto this because > the radio module does *not* meet the unintentional limits by itself. I turned > it off and our box passes with 12dB to spare. If they can radiate like > radium, why can't we? ;-) Seems all it takes is a redefinition of what the > "intentional radiator" is. >Ok, intentional in the allowed band. I can't imagine they allow excessive radiation _outside_ the permitted band. That would swing the doors wide open to abuse. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Reply by ●October 20, 20102010-10-20
Does anyone know the status on the wirelessUSB modules from Cypress. I was planning to use them awhile back, but now I see that Cypress doesn't want us to use them in new designs. Shame, that is, since the modules were pre-certified and in two formats - 10 and 20 meters. I don't see that the new technology 'CyFi' is modularized like the older wirelessUSB. Chris
Reply by ●October 20, 20102010-10-20
On Wed, 20 Oct 2010 09:57:14 +0200, Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> wrote:>In comp.arch.embedded, >krw@att.bizzzzzzzzzzzz <krw@att.bizzzzzzzzzzzz> wrote: >> On Tue, 19 Oct 2010 17:42:24 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>>krw@att.bizzzzzzzzzzzz wrote: >>>> On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>> >>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>>>> >>>>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>> >>>[...] >>> >>>>>>> This is because chamber measurements are not very precise. >>>>>> Hmm. The chamber is the gold standard. A 3M isn't worth much, but we've had >>>>>> no trouble with the 10M. The rotary table and all that jazz is in there. >>>>>> >>>>> That would be up to the EMC lab I guess. If they sign on the dotted line >>>>> without open range measurements, well, dicey. The labs I went to never >>>>> did that unless all the nasties were way under the limits. >>>> >>>> They've never even suggested open range measurements. The company with the 3m >>>> chamber couldn't get the same numbers twice, though. > >The company that does most of our testing does initial testing in the chamber >and if everything is 10dB under the limits, they will pass the product. If >there are higher peaks, but still under the limit, they will re-measure those >at the OATS (Open Area Test Site).The two companies we've used rely on their chambers exclusively. Note that one of them I don't trust - can't get the same answer twice. The other calibrates all their chambers across the company periodically (better than monthly). Neither has ever suggested OATS, even when we were on the cusp.>Another company seems to have a little more confidence in their chamber, >but they still do OATS measurements. > >The OATS is the gold standard, because that is how it is defined in the >standards. A test company that passes your product when it is just under >the limits in the chamber must have great confidence in that chamber.Like I said, both have confidence in their chambers (even though I have no confidence in one of them).>>>>> Sure, when you are a good designer or use pre-cooked modules they are >>>>> easy. But why spend that extra money to test if it's already done? >>>> >>>> Because it makes passing a piece of cake. Can't fail! It probably wouldn't >>>> have worked for the product we had real trouble with because we needed CE (and >>>> all the rest of the alphabet soup, too) >>> >>> >>>Well, I know for sure the Europeans won't let you get away with that. >>>But I can't imagine the FCC would either. Because then just about >>>everybody could put in intentional radiator in their product whether >>>it's needed or not, just to dodge the smog check. >> >> That's what the regs say. I checked my interpretation with our test lab and >> it agrees with theirs. The problem is that it takes a few more hours to >> guarantee that it meets the "no go zone" edges. I stumbled onto this because >> the radio module does *not* meet the unintentional limits by itself. I turned >> it off and our box passes with 12dB to spare. If they can radiate like >> radium, why can't we? ;-) Seems all it takes is a redefinition of what the >> "intentional radiator" is. > >If you use a pre-cooked module with a datasheet that says it meets >certain limits, it will only meet those limits if you use it exactly as >the manufacturer says (ask for those test conditions if they are not in >the datasheet!). And even if you do that, as soon as you add more stuff >you need to worry that the sum of emissions will not go over the limit. >If you only use tested modules in prescribed ways, you may get away with >adding the emissions and pass it on paper if that sum is well below >limits.That's not the issue.>For CE you are not required to do measurements, you just have to show >somehow you are under the limits. But doing measurements is in most >cases the only practical way to prove that.Again, that's not the issue. The FCC has some funky rules for some intentional radiators that I'm sure CE doesn't have.>Most test companies ask you to put the product in some mode that will >produce (expected) worst case emissions. Just switching off emitters on >your board for the test is just fooling yourself (and your test company).That's what they demanded. Otherwise it was an intentional radiator. <shrug>>If you are later caught in the field with too much emissions, you will >have a hard time explaining why it was valid to turn off that emitter >during your tests.Because the emitter is over the line for an unintended radiator.
Reply by ●October 20, 20102010-10-20
On Wed, 20 Oct 2010 11:32:00 -0700, Joerg <invalid@invalid.invalid> wrote:>krw@att.bizzzzzzzzzzzz wrote: >> On Tue, 19 Oct 2010 17:42:24 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> krw@att.bizzzzzzzzzzzz wrote: >>>> On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>> >>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>>>> >>>>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>> [...] >>> >>>>>>> This is because chamber measurements are not very precise. >>>>>> Hmm. The chamber is the gold standard. A 3M isn't worth much, but we've had >>>>>> no trouble with the 10M. The rotary table and all that jazz is in there. >>>>>> >>>>> That would be up to the EMC lab I guess. If they sign on the dotted line >>>>> without open range measurements, well, dicey. The labs I went to never >>>>> did that unless all the nasties were way under the limits. >>>> They've never even suggested open range measurements. The company with the 3m >>>> chamber couldn't get the same numbers twice, though. >>>> >>> Some of my stuff must be measured at 1m. At 3m you wouldn't be able to >>> see much anymore, certainly not on a spectrum analyzer. At 10m there'd >>> be nothing. But the standard is rather detailed about how the chamber >>> must look like. For example, numerous antennas, several rotating stirrer >>> plates, and so on. >> >> ?? If I can't see it at 3m or 10m, for that matter, why do I care? ... > > >The RTCA/DO-160 standard does care, and some of the stuff here has to >comply. Else the FAA will have a bone to pick.Ok, we're not concerned with the FAA.>> ... I let the >> compliance lab worry about their chamber. That's what they get paid the big >> bux for. >> > >Yup. And there one has to do everything to minimize those bux. Like not >doing de-facto pre-compliance runs there, which surprisingly many >companies end up doing.Turns out that our "pre-compliance" runs were worthless. The results couldn't be duplicated.>>> [...] >>> >>>>>>> Goes from close to DC to a little above 3GHz. >>>>>> What sort? >>>>>> >>>>> Mine is the Icom R-1500. Has a mini console for quick checks when I >>>>> don't want to fire up the PC. If you go PC-only then there's the similar >>>>> PCR-1500 for about $100 less. >>>> I'll take a look at it. Thanks. >>>> >>> An hour ago it did another fine job. Got three little transmitters here >>> that are stuck. In order to diagnose this I had to see if the various >>> data packets were still being transmitted, over all that din these >>> things created. Fired up the Icom and sure enough, could hear a distinct >>> faint "brrripp" whenever a packet was sent and the sound of it changed >>> when I sent different packets. Very deep inside of what sounded like >>> Niagara Falls from 10ft away. Now try that with an analyzer ... >>> >>> [...] >>> >>> >>>>>> If you read the regs, at least for FHSS radiators in the ISM bands, anything >>>>>> outside the band, and outside one or two do-not-collect-$200 bands, must only >>>>>> be 20dB down from the in-band radiation. Easy-peasy, when you're radiating a >>>>>> hundred or two milliwatts. >>>>>> >>>>> Huh? So you can be way above class B limits in, say, the aircraft bands? >>>> "outside one or two do-not-collect-$200 bands" >>>> >>> Well, I bet you'd get in trouble no matter what if anything leaked. FM >>> band, police, air, even TV. And if you step on some Lt.Colonel's radio >>> link, oh boy ... >> >> Why? It's an intentional radiator. It passes that test. >> > >It's not supposed to intentionally radiate at, say, 155MHz because the >local sheriff will have something against that.As long as it's 20dB below the fundamental, apparently the local sheriff can go scratch.>>>>> Do you have a link there? >>>> I meant to look it up again today but got busy doing real work. (Some nitwit >>>> decided to save $20 and leave off the solder mask on a proto board). >>>> >>> Oh great! He's earned himself a spot in the hall of blame I suppose :-) >>> >> It's worse than that. The board is 2-layer (fortunately rather simple) with >> ground and Vcc pours top and bottom. It's almost impossible to solder >> anything without bridging. Getting solder to flow under the LEDs was a RPITA. >> "He" doesn't much care about blame, though it's not going to happen to me >> again. >> >>>>> If you also know anything like that in the >>>>> tax code I think lots of people would be all ears :-) >>>> ;-) >>>> >>>>>>>>> If the mfg waffles on the stickers and cert copies, run. >>>>>>>> That's not my point. >>>>>>> Ok. Then why not just slap on the sticker, do only the regular EMC and >>>>>>> be done with it? Of course the EMC lab needs to know about the >>>>>>> intentional radiator part so they don't flag that. >>>>>> Because the intentional limits are almost impossible to fail. We pass easily, >>>>>> now, so there isn't any point in gaming the system, but the rules leave the >>>>>> door wide open. >>>>> Sure, when you are a good designer or use pre-cooked modules they are >>>>> easy. But why spend that extra money to test if it's already done? >>>> Because it makes passing a piece of cake. Can't fail! It probably wouldn't >>>> have worked for the product we had real trouble with because we needed CE (and >>>> all the rest of the alphabet soup, too) >>> >>> Well, I know for sure the Europeans won't let you get away with that. >>> But I can't imagine the FCC would either. Because then just about >>> everybody could put in intentional radiator in their product whether >>> it's needed or not, just to dodge the smog check. >> >> That's what the regs say. I checked my interpretation with our test lab and >> it agrees with theirs. ... > > >Got any links there?I had a little time today (emphasis on "little"): "15.215 Additional provisions to the general radiated emission limitations. (c) Intentional radiators operating under the alternative provisions to the general emission limits, as contained in ��15.217 through 15.257 and in Subpart E of this part, must be designed to ensure that the 20 dB bandwidth of the emission, or whatever bandwidth may otherwise be specified in the specific rule section under which the equipment operates, is contained within the frequency band designated in the rule section under which the equipment is operated. The requirement to contain the designated bandwidth of the emission within the specified frequency band includes the effects from frequency sweeping, frequency hopping and other modulation techniques that may be employed as well as the frequency stability of the transmitter over expected variations in temperature and supply voltage. If a frequency stability is not specified in the regulations, it is recommended that the fundamental emission be kept within at least the central 80% of the permitted band in order to minimize the possibility of out-of-band operation." Both test labs (the module manufacturer likes one, we prefer the other) interpret this the same way; that the intentional radiator has to be 20dB down outside its band. Now, this (prior) paragraph contradicts this... "(b) In most cases, unwanted emissions outside of the frequency bands shown in these alternative provisions must be attenuated to the emission limits shown in �15.209. In no case shall the level of the unwanted emissions from an intentional radiator operating under these additional provisions exceed the field strength of the fundamental emission. ..except for the "most cases". The interpretation from both labs is that (c) overrules (b). Harmonics from the hopping are certainly above 12.209. Our box, without the radiator passes 12.209 (below for information) but the radio does not, outside its band. The radio has a separate cert. <scratches head>> >> ... The problem is that it takes a few more hours to >> guarantee that it meets the "no go zone" edges. ... > > >Now wait, are you now saying there are areas where it must meet class B? >If so, that's what I was saying all along.In the restricted zones, yes. Outside of those zones it apparently does *NOT* have to meet class A/B. They looked at the spectrum and saw one place where we were close. They made sure that pup was outside the (frequency) window and all was goodness. It *was* over the Class-A line but would have passed (and actually did when the module had its cert done).> ... I stumbled onto this because >> the radio module does *not* meet the unintentional limits by itself. I turned >> it off and our box passes with 12dB to spare. If they can radiate like >> radium, why can't we? ;-) Seems all it takes is a redefinition of what the >> "intentional radiator" is. >> > >Ok, intentional in the allowed band. I can't imagine they allow >excessive radiation _outside_ the permitted band. That would swing the >doors wide open to abuse.No, out-of-band must be 20dB below the in-band. ...didn't make any sense to me, either.
Reply by ●October 20, 20102010-10-20
krw@att.bizzzzzzzzzzzz wrote:> On Wed, 20 Oct 2010 11:32:00 -0700, Joerg <invalid@invalid.invalid> wrote: > >> krw@att.bizzzzzzzzzzzz wrote: >>> On Tue, 19 Oct 2010 17:42:24 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> krw@att.bizzzzzzzzzzzz wrote: >>>>> On Tue, 19 Oct 2010 09:13:10 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>> On Mon, 18 Oct 2010 18:53:20 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>>> On Mon, 18 Oct 2010 11:24:11 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>>>>>>>>> On Sun, 17 Oct 2010 17:14:42 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>>>>>> >>>>>>>>>>>> krw@att.bizzzzzzzzzzzz wrote: >>>> [...] >>>> >>> ... I let the >>> compliance lab worry about their chamber. That's what they get paid the big >>> bux for. >>> >> Yup. And there one has to do everything to minimize those bux. Like not >> doing de-facto pre-compliance runs there, which surprisingly many >> companies end up doing. > > Turns out that our "pre-compliance" runs were worthless. The results couldn't > be duplicated. >Strange. They should have shown you the heavy hitters. Mine worked, every single time.>>>> [...] >>>> >>>>>>>> Goes from close to DC to a little above 3GHz. >>>>>>> What sort? >>>>>>> >>>>>> Mine is the Icom R-1500. Has a mini console for quick checks when I >>>>>> don't want to fire up the PC. If you go PC-only then there's the similar >>>>>> PCR-1500 for about $100 less. >>>>> I'll take a look at it. Thanks. >>>>> >>>> An hour ago it did another fine job. Got three little transmitters here >>>> that are stuck. In order to diagnose this I had to see if the various >>>> data packets were still being transmitted, over all that din these >>>> things created. Fired up the Icom and sure enough, could hear a distinct >>>> faint "brrripp" whenever a packet was sent and the sound of it changed >>>> when I sent different packets. Very deep inside of what sounded like >>>> Niagara Falls from 10ft away. Now try that with an analyzer ... >>>> >>>> [...] >>>> >>>> >>>>>>> If you read the regs, at least for FHSS radiators in the ISM bands, anything >>>>>>> outside the band, and outside one or two do-not-collect-$200 bands, must only >>>>>>> be 20dB down from the in-band radiation. Easy-peasy, when you're radiating a >>>>>>> hundred or two milliwatts. >>>>>>> >>>>>> Huh? So you can be way above class B limits in, say, the aircraft bands? >>>>> "outside one or two do-not-collect-$200 bands" >>>>> >>>> Well, I bet you'd get in trouble no matter what if anything leaked. FM >>>> band, police, air, even TV. And if you step on some Lt.Colonel's radio >>>> link, oh boy ... >>> Why? It's an intentional radiator. It passes that test. >>> >> It's not supposed to intentionally radiate at, say, 155MHz because the >> local sheriff will have something against that. > > As long as it's 20dB below the fundamental, apparently the local sheriff can > go scratch. >Below the one watt (!) carrier of your legit 900MHz TX module? That would be 10mW on a police band. Unless I see that in writing (meaning the law) I cannot believe this.>>>>>> Do you have a link there? >>>>> I meant to look it up again today but got busy doing real work. (Some nitwit >>>>> decided to save $20 and leave off the solder mask on a proto board). >>>>> >>>> Oh great! He's earned himself a spot in the hall of blame I suppose :-) >>>> >>> It's worse than that. The board is 2-layer (fortunately rather simple) with >>> ground and Vcc pours top and bottom. It's almost impossible to solder >>> anything without bridging. Getting solder to flow under the LEDs was a RPITA. >>> "He" doesn't much care about blame, though it's not going to happen to me >>> again. >>> >>>>>> If you also know anything like that in the >>>>>> tax code I think lots of people would be all ears :-) >>>>> ;-) >>>>> >>>>>>>>>> If the mfg waffles on the stickers and cert copies, run. >>>>>>>>> That's not my point. >>>>>>>> Ok. Then why not just slap on the sticker, do only the regular EMC and >>>>>>>> be done with it? Of course the EMC lab needs to know about the >>>>>>>> intentional radiator part so they don't flag that. >>>>>>> Because the intentional limits are almost impossible to fail. We pass easily, >>>>>>> now, so there isn't any point in gaming the system, but the rules leave the >>>>>>> door wide open. >>>>>> Sure, when you are a good designer or use pre-cooked modules they are >>>>>> easy. But why spend that extra money to test if it's already done? >>>>> Because it makes passing a piece of cake. Can't fail! It probably wouldn't >>>>> have worked for the product we had real trouble with because we needed CE (and >>>>> all the rest of the alphabet soup, too) >>>> Well, I know for sure the Europeans won't let you get away with that. >>>> But I can't imagine the FCC would either. Because then just about >>>> everybody could put in intentional radiator in their product whether >>>> it's needed or not, just to dodge the smog check. >>> That's what the regs say. I checked my interpretation with our test lab and >>> it agrees with theirs. ... >> >> Got any links there? > > I had a little time today (emphasis on "little"): > > "15.215 Additional provisions to the general radiated > emission limitations. > > (c) Intentional radiators operating under the alternative provisions > to the general emission limits, as contained in ��15.217 through 15.257 > and in Subpart E of this part, must be designed to ensure that the > 20 dB bandwidth of the emission, ...That's indeed remarkable. Seems you can let 20mW spill over past 902MHz or 928MHz. But, reading on ...> ... or whatever bandwidth may otherwise > be specified in the specific rule section under which the equipment > operates, is contained within the frequency band designated in the > rule section under which the equipment is operated. The requirement > to contain the designated bandwidth of the emission within the specified > frequency band includes the effects from frequency sweeping, frequency > hopping and other modulation techniques that may be employed as well > as the frequency stability of the transmitter over expected variations > in temperature and supply voltage. If a frequency stability is not > specified in the regulations, it is recommended that the fundamental > emission be kept within at least the central 80% of the permitted band > in order to minimize the possibility of out-of-band operation." > > Both test labs (the module manufacturer likes one, we prefer the other) > interpret this the same way; that the intentional radiator has to be 20dB down > outside its band. > > Now, this (prior) paragraph contradicts this... > > "(b) In most cases, unwanted emissions outside of the frequency bands > shown in these alternative provisions must be attenuated to the > emission limits shown in �15.209. ...Aha! That means no free lunch after all.> ... In no case shall the level of the > unwanted emissions from an intentional radiator operating under these > additional provisions exceed the field strength of the fundamental > emission. > > ..except for the "most cases". The interpretation from both labs is that (c) > overrules (b). Harmonics from the hopping are certainly above 12.209. >It doesn't matter what the lab interprets. If the sheriff has this brought to court and you lose, a major recall may follow because the judge said so. Possibly wiping out the EMC lab and shaking up the place where you work.> Our box, without the radiator passes 12.209 (below for information) but the > radio does not, outside its band. The radio has a separate cert. <scratches > head> >If the radio doesn't pass I'd be rather concerned.>>> ... The problem is that it takes a few more hours to >>> guarantee that it meets the "no go zone" edges. ... >> >> Now wait, are you now saying there are areas where it must meet class B? >> If so, that's what I was saying all along. > > In the restricted zones, yes. Outside of those zones it apparently does *NOT* > have to meet class A/B. They looked at the spectrum and saw one place where > we were close. They made sure that pup was outside the (frequency) window and > all was goodness. It *was* over the Class-A line but would have passed (and > actually did when the module had its cert done). >Hopefully they are right ...>> ... I stumbled onto this because >>> the radio module does *not* meet the unintentional limits by itself. I turned >>> it off and our box passes with 12dB to spare. If they can radiate like >>> radium, why can't we? ;-) Seems all it takes is a redefinition of what the >>> "intentional radiator" is. >>> >> Ok, intentional in the allowed band. I can't imagine they allow >> excessive radiation _outside_ the permitted band. That would swing the >> doors wide open to abuse. > > No, out-of-band must be 20dB below the in-band. ...didn't make any sense to > me, either.Way I read the law above it ain't so. Not across the whole frequency range. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
