www.delorie.com/archives/browse.cgi | search |
X-Authentication-Warning: | delorie.com: mail set sender to geda-user-bounces using -f |
X-Recipient: | geda-user AT delorie DOT com |
X-Proofpoint-Virus-Version: | vendor=fsecure engine=2.50.10432:,, |
definitions=2015-09-24_02:,, signatures=0 | |
X-Proofpoint-Spam-Details: | rule=notspam policy=default score=0 |
kscore.is_bulkscore=7.53686002497034e-12 compositescore=0.99972376455583 | |
phishscore=0 kscore.is_spamscore=0 rbsscore=0.99972376455583 | |
recipient_to_sender_totalscore=0 spamscore=0 urlsuspectscore=0.99972376455583 | |
adultscore=0 kscore.compositescore=0 circleOfTrustscore=0 suspectscore=5 | |
recipient_domain_to_sender_totalscore=0 bulkscore=0 | |
recipient_domain_to_sender_domain_totalscore=0 | |
recipient_to_sender_domain_totalscore=0 classifier=spam adjust=0 reason=mlx | |
scancount=1 engine=8.0.1-1412110000 definitions=main-1509240120 | |
From: | "Chris Smith (space DOT dandy AT icloud DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com> |
MIME-version: | 1.0 (1.0) |
Subject: | Re: [geda-user] [OT] Wireless communication 101 |
Message-id: | <CDEC178F-5B26-4251-B4BB-83A985DC3F5E@icloud.com> |
Date: | Thu, 24 Sep 2015 07:36:10 +0100 |
References: | <70C4A238-D361-4A6C-A81D-CBF019CADC4F AT icloud DOT com> |
<5601AE56 DOT 2050706 AT neurotica DOT com> | |
<0958473E-0115-4C08-860F-EF92B84B7404 AT icloud DOT com> | |
<56025516 DOT 3050403 AT ecosensory DOT com> <56030319 DOT 3070008 AT neurotica DOT com> | |
In-reply-to: | <56030319.3070008@neurotica.com> |
To: | geda-user AT delorie DOT com |
X-Mailer: | iPad Mail (13A344) |
X-MIME-Autoconverted: | from quoted-printable to 8bit by delorie.com id t8O6aP0m024057 |
Reply-To: | geda-user AT delorie DOT com |
> On 23 Sep 2015, at 20:52, Dave McGuire (mcguire AT neurotica DOT com) [via geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote: > > On 09/23/2015 03:30 AM, John Griessen wrote: >>> What I'm looking for are any texts or references that discuss the >>> principle of digital encoding for wireless transmission, which >>> algorithms and strategies are used in what circumstances and why. As I >>> said, I can't influence the RF part, only the ones and zeros that are >>> encoded onto the carrier. I also can't change at this stage the >>> simplex operation. >> >> I don't have a reference, but I've heard that reed solomon encoding has >> been used by nasa for telemetry >> to get signals through under the noise. > > Reed-Solomon is a FEC (Forward Error Correction) algorithm that embeds > enough error correction data in the bitstream to be able to fix some > errors on the receiving end without retransmission. It doesn't really > do much for the noise floor. > > That said, though, it's an excellent suggestion. > > One other thing to do is bit-stuffing to maintain DC balance. That's > particularly important if the modulation is FM and the RX-side RF tuning > is automatic. A time-averaged DC value of 0 is very important in that case. Yes, I'm already Manchester encoding the data and transmitting a significant amount of 0xAA preamble for the RX to lock on to. Chris
webmaster | delorie software privacy |
Copyright © 2019 by DJ Delorie | Updated Jul 2019 |