Cortland,
That makes sense to me. I think it will be easier to sell on a case
by case basis at first. If the fcc made it part of the rules right away,
they would have to deal with all the people who will now try it for the
first time in their lives.
If you, for instance, did a test like that, then you wrote it up
carefully and you answered all their questions or even did a demo, they
would probably buy it ( after trying it themselves, and having a lot of fun
doing it too!) I have found them to be pretty competent and reasonable.
Evaluating a lot of reports like yours on a case-by-case basis, they
will find that some will get it right, some will be way off, and some will
get some free coaching. Eventually most people will get the hang of it.
When it stops being new and controversial, and becomes a tried-and-true
ho-hum technique, it will become part of the rules.
If I were trying to sell this technique, I would definitely get at
least one or two FCC approvals under my belt first. Customers will
inevitably ask: "has the FCC bought this yet?" Smart customers won't even
ask the salesman. they'll ask the fcc.
Best Regards,
Lou
At 04:00 PM 5/9/99 -0400, you wrote:
>Lou,
>
>It turns out not to be that critical. The ambient generator is a LOT
>further away, so about all that changes is amplitude. And often you don't
>need _complete_ cancellation, just 10 or 20 dB. Example: broadband noise
>from a nearby TV video signal can mess up a front-end. Cutting it 10 dB is
>often all it takes to be able to see "below" the limit.
>
>Tedious? Yes. But if one must measure emissions in the presence of
>on-frequency or nearby ambients, then tedious is the BEST we can do! And if
>SA with the system installed meets their requirement, the FCC could approve
>it. Just has to be demonstrated to the Commission's satisfaction. Not
>trivial!
>
>Cheers,
>
>Cortland
>
>====================== Original Message Follows ====================
>
> >> Date: 08-May-99 06:39:18 MsgID: 1068-10160 ToID: 72146,373
>From: Lou Gnecco >INTERNET:[email protected]
>Subj: Re: Phase cancellation
>Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1
>
>
>Cortland:
> I wonder how well that cancellation system works as you move the
>receive antenna up and down the hoist, and as you rotate its polarization.
>You would have to re-adjust the cancellation system every step of the way.
> This sounds like a lot of work. It would be simpler to run the test
>at night or on a weekend when the most troublesome ambients are usually
>down.
> If you don't keep tweaking it just right, it seems to me that the
>cancelling signal could actually make the problem worse. A system like this
>makes testing much more complicated. When you make a test more complicated,
>the probability of human error goes way up.
> I think you are going to have to wait a long time for the FCC to
>buy
>off on this, if ever, and as for the europeans? forget it!
>
>Lou
>
>
>At 11:19 PM 5/7/99 -0400, you wrote:
>>We had the benefit of a fairly simple, flat environment, both at the (now
>>closed) Fountain Valley location and the main OATS in Irvine. It was
>>possible to put a bicon in an area where almost every ambient could be
>>canceled, but tedious in the extreme, because the location was peculiar to
>>each ambient.
>>
>>Using a delay line and variable gain/attenuation, and careful siting of
>the
>>ambient antenna, seems to me appropriate for _most_ OATS except those in
>>hilly country - and those generally are there because of the low ambients.
>>
>>by the way, this is NOT a new idea; indeed, I believe there have been
>>Papers in the IEEE EMC Proceedings on this kind of a a setup. The
>>stumbling block seems to have been FCC reluctance to approve a
>non-standard
>>setup. But if SA were taken with an ambient canceler going, it seems to
>me
>>that would effectively demonstrate equivalence.
>>
>>Cortland
>>
>>Cortland
>>
>>====================== Original Message Follows ====================
>>
>> >> Date: 07-May-99 10:05:24 MsgID: 1068-8273 ToID: 72146,373
>>From: "Brent DeWitt" >INTERNET:[email protected]
>>Subj: Phase cancellation
>>Chrg: $0.00 Imp: Norm Sens: Std Receipt: No Parts: 1
>>
>>
>>I have also played with phase cancellation, and found one very serious
>>limitation, multipath. Unless you are out in a situation where the
>>ambients
>>look pretty much like point sources, you will be limited in the depth of
>>the
>>null that you can create, since you can only cancel one phase front with
>>one
>>"reference" antenna. Since many folks build sites in the hills, mountains
>>or gullies to try to avoid ambients, this puts the site in a worst case
>>location for using phase cancellation.
>>
>>Maybe in Topeka.........
>>
>>Best regards,
>>
>>Brent DeWitt
>>
>>====================== End of Original Message =====================
>>
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>
>
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