maemo.org - Talk - Antenna issue

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- Nokia N800 (https://talk.maemo.org/forumdisplay.php?f=25)

- - Antenna issue (https://talk.maemo.org/showthread.php?t=7135)

Re: Antenna issue

[QUOTE=TheSkyIsFalling;55390In my opinion it sounds quite stupid to use two separate antennas for the systems which operate in the same frequency... [/QUOTE]

Actually, it's somewhat clever. This approach is called "diversity reception," and depending on how it's implemented, is something as simple as selecting the antenna that has the stronger signal strength to something called "maximum ratio combining" where the two signals are summed together in a special way (this is actually the precursor of MIMO systems). Diversity reception has been around for decades -- and is pretty much ubiquitous in all laptops today for WiFi. It significantly improves the average signal strength a device receives, particularly when the devices is in motion: Just walking around often creates short-term fading in one antenna that can easily reduce its output to 1/100 or even 1/1000 or the typical signal strength; having a second antenna that's in a different location gives you a very good chance that at least one of the antennas is still getting a decent signal.

---Joel

Re: Antenna issue

Quote:

Originally Posted by JKolstad (Post 56520)

Actually, it's somewhat clever. This approach is called "diversity reception," and depending on how it's implemented, is something as simple as selecting the antenna that has the stronger signal strength to something called "maximum ratio combining" where the two signals are summed together in a special way (this is actually the precursor of MIMO systems). Diversity reception has been around for decades -- and is pretty much ubiquitous in all laptops today for WiFi. It significantly improves the average signal strength a device receives, particularly when the devices is in motion: Just walking around often creates short-term fading in one antenna that can easily reduce its output to 1/100 or even 1/1000 or the typical signal strength; having a second antenna that's in a different location gives you a very good chance that at least one of the antennas is still getting a decent signal.

---Joel

confirmed by a chat I had with s-o inside Nokia about this subject in the N800

Re: Antenna issue

Quote:

Originally Posted by JKolstad (Post 56520)

Oh yes, I'm aware of transmit/receive diversity and their advantages. And if in our case, N800, diversity is used, it would explain those two? antennas. But if the diversity is not used and we still have two antennas and BT/wifi uses only one of them, why there is two pieces? And what is the frequency of other one? Would be great if someone could calculate the frequency, I don't know what kind of effect the angle has, if it has.

Re: Antenna issue

Quote:

Originally Posted by Seb Per (Post 56524)

confirmed by a chat I had with s-o inside Nokia about this subject in the N800

So, There is a diversity combiner in N800?

Re: Antenna issue

Quote:

Originally Posted by TheSkyIsFalling (Post 56573)

So, There is a diversity combiner in N800?

Not sure. What I was told : "It is correct that there can be 2 antennas for the same "activity"* in our devices"

No comment at all on the fact that there is this 0,234 W emitter. Damn... However I was told by the same source before that the clue would be the output power.

* : I don't recall the exact term used. was it module?