From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?P=E4r?= Subject: Re: spread spectrum and broadband Date: Mon, 18 Nov 2002 12:22:41 +0100 Sender: linux-hams-owner@vger.kernel.org Message-ID: <3DD8CD81.3040406@home.se> References: <200211172241.gAHMf4C31685@hartford-hwp.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200211172241.gAHMf4C31685@hartford-hwp.com> List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: linux-hams@vger.kernel.org Spread spectrum and the ionosphere doesn't mix very well. A skywave path might support only a portion of the spread and I have only seen one attempt at a SS-system for hf. That system used a 1 MHz spread but was later scrapped as the performance was too bad. You'll probably get better results with a 3 or 6 kHz wide system such as any MIL-STD-188-110A/B compatible modem. The Harris RF5710a boasts a 12800 bps max datarate and I've tried 4800 & 9600 with these and on a fine day it really did work. There are only two problems with these modems: price and bandwidth. I don't know the current price but I'm guessing somewhere around 5000$. Bandwidth is minimum 3 kHz (not 2.4 kHz). 73's de sm0rwo/per Haines Brown wrote: >This is OT, but my question was stimulated by an article in Linux >Journal regarding a WAN in Guinea. > >If one sets up a HF WAN that uses TCP/IP protocol, a distinct >disadvantage is lack of bandwidth. In one case, the RF modem was >capable of 1200 baud, and in practice that amounted to about 300 baud. > >That's ok for e-mail, but not much more. > >So I wondered about the potential of spread spectrum for increasing >bandwidth from, say, 1200 baud to 56 Kbaud. I'd appreciate someone's >input on the relation of information bandwidth and RF spectrum >bandwidth when using spread spectrum. Does spread spectrum offer any >potential at all for increasing signal bandwidth of a TCP/IP HF WAN? > >Haines Brown KG1GRM >- >To unsubscribe from this list: send the line "unsubscribe linux-hams" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html > > > >