On Wednesday, September 25, 2002, at 02:04 AM, John Byrnes wrote:
> > --- Jim Thompson <[EMAIL PROTECTED]> wrote: >> 'always'? >> >> 1) only send RF (ok, and IR) out when you have data >> to send. > > I thought "dwell time" referred to the time that a > given channel is chosen, regardless of whether there > is anything to send. Either way, the other point of > course is the main thing: Yes, the radios have to stay in sync with each other, but there is no 'signal' in the air (no carrier, if you will) without data to be modulated onto it. > >> 2) higher bit-rates: less time on the air for a >> given amount of data > > I thought that the bit-rates for DS were 1 and 2 Mbps > and for FH were 1-3 Mbps. Packet size limits should > be the same (although maybe in practice people tend to > use shorter ones for one PHY or the other---I've never > heard of this). So if anything, the FH would spend > less time being active on a given frequency. My > apologies if I've misunderstood something here. I said bit rates, not symbol (baud) rates. If you can get the data through at 11Mbps, rather than 3Mbps, then you'll spend about 3.7X as long sending the data, so you'll be on the air longer, etc. "on a given frequency", sure, maybe, because you only visit a given frequency on time in 26, and the DS system is 'on frequency' the entire time its sending data. lets not stack the deck with semantics, OK? >> 1+2 = 5! > > Does 5! = 120? Does 120 = 1+2+0 = 1+2? a (small) joke. "it (fh) doesn't add up" >> >> On Tuesday, September 24, 2002, at 04:27 PM, John >> Byrnes wrote: >> >>> I don't understand Tim's comment: >>> >>>> Unfortunately, since FH has a higher dwell time >> than >>>> DS it will tend to cause more interference with >>>> other devices such as video over FM like >> television >>>> ENG uses. >>> >>> Shouldn't the "dwell time" of DS be however long >> you >>> leave the device turned on, since it always >> occupies >>> the same frequencies? I can imagine that DS >> causes >>> less interference with other users because you can >>> choose to set your DS channel away from other >> users' >>> channels, whereas FH will hit everybody's channel >> over >>> time. >>> >>> The dwell time of 802.11 FH might be longer than >> the >>> that of other hoppers, like bluetooth (I'm pretty >> sure >>> the 802.11 is adjustable, up to pretty long >> dwells), >>> which might also cause more noticeable >> interference to >>> other users. >>> >>> John >>> >>> __________________________________________________ >>> Do you Yahoo!? >>> New DSL Internet Access from SBC & Yahoo! >>> http://sbc.yahoo.com >>> -- >>> general wireless list, a bawug thing >> <http://www.bawug.org/> >>> [un]subscribe: >> http://lists.bawug.org/mailman/listinfo/wireless >>> >> > > > __________________________________________________ > Do you Yahoo!? > New DSL Internet Access from SBC & Yahoo! > http://sbc.yahoo.com > -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
