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Author Topic: Loss of Range  (Read 30298 times)

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flightchecker

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Re: Loss of Range
« Reply #75 on: February 25, 2009, 10:45:10 AM »
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Interesting and a little worrying!

me too Paul, if I was told, you could "filter" (electrostatic) " build ups". They might be bled, depleted, discharched or whatever you name it, but not "filtered". You may filter High- and Audio- Frequency by different means, depending on the results to be expected, but you can't do so with "static build up".

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Interesting and a little worrying!

Me too again, if I was told, the above "filter", or whatever the "provision" (if there is one) expected to prevent [elecrostatic] buildups to discharge is called, had been"overloaded". It simply would have been useless, as itself by definition is supposed to prevent a "follow up device" from being overloaded (by static discharge as mentioned).

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Interesting and a little worrying!

me too once more if being told "overload damage" to a receivers input might occure due to exessive field strenght (by a transmitting antenna situated in the near vicinty of a receiver as guessed) Fieldstrenght decreases by the square root of distance as High Frequency signals travel away from its radiating antenna, and you must come VERY close to the antenna itself, before a receiving devices performance might but degrade, and a "poor device" whose input circuitry should suffer damage before it almost "physically" touches a radiating antenna.  Imagine those hundreds of millions mobiles to die, if suffering  from a "susceptibility" like the one assumed above!!!

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For the default antenna we don't recommend anything. It shouldn't pick up enough static to damage unless placed in conditions with very high static.


AirNav, could you imagine the "human body" to gather electrostatic build up? At least I can, and sometimes even ought to "feel" it "discharging" when touching my car after getting out of it, to just mention a very popular among many other examples. And why do you think, you're asked to "ground" yourself by means of a metal band at your wrist connected to an"earthground"  (heater / plumbing) or at least to "discharche" yourself before touching / installing PC- components ?
The "human body model"  with its 100-250pf of [body] capacitance and 1000-2000Ohms of [body] resistance in fact being applied in civil and military ESD susceptibility test standards by discharging the above array (prior being charged to Hi Tension levels as defined by the different "standards") into for instance a receivers input, thus proving its "ESD susceptibility". (As most hopefully performed in AirNavs development lab too)

Imagine once more, a (real !) human body's static charge to discharge into a receivers input if touching an antenna "galvanically" connected to  the mentioned receivers input that might be suspect regarding ESD. The antenna of course also to be an indoor (default) antenna as it comes with RB or similar gear.

All "discussed in a lenght" as AirNav might tell again,  but also "discussed in a lenght"
that a "DC Block" is NOT an answer to the phenomenon it is about.

As already suggested, try to "google" for "DC Block", to make up your own mind if not trusting mine, that has been subject of several postings already before. Bet you won't find even one manufacturer of the above "items" (a lot of manufacturers as well as items to show up) that claims his "DC Block" to be a preventive measure against ESD. One should believe that the manufacturers mentioned "know" what they expect their components to be for. Usefull measures have been discussed (again "in a lenght" too) before, and not to be repeated again.
And, not to forget: "Lightning- and Surge- Protectors" do NOT belong to those measures.

Regards

Karl

« Last Edit: February 25, 2009, 06:56:11 PM by flight checker »