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=2015-09-23_03:,, signatures=0
X-Proofpoint-Spam-Details:	rule=notspam policy=default score=0
	kscore.is_bulkscore=5.24148724423412e-10 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-1509230116
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:	<0958473E-0115-4C08-860F-EF92B84B7404@icloud.com>
Date:	Wed, 23 Sep 2015 07:50:33 +0100
References:	<70C4A238-D361-4A6C-A81D-CBF019CADC4F AT icloud DOT com>
	<5601AE56 DOT 2050706 AT neurotica DOT com>
In-reply-to:	<5601AE56.2050706@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 t8N6p5o5019855
Reply-To:	geda-user AT delorie DOT com

> On 22 Sep 2015, at 20:39, Dave McGuire (mcguire AT neurotica DOT com) [via geda-user AT delorie DOT com] <geda-user AT delorie DOT com> wrote:
> 
> On 09/22/2015 02:51 AM, Chris Smith (space DOT dandy AT icloud DOT com) [via
> geda-user AT delorie DOT com] wrote:
>> Can anyone recommend any good texts or online resources dealing with
>> the practical considerations of wireless communication, particularly
>> discussion of techniques to improve performance in non-optimal
>> environments?
>> 
>> I have a project using an off-the-shelf 433 MHz transmitter and
>> receiver, which works well at home but fails in other environments.
>> I obviously can’t change the transmitter/receiver hardware, but I’m
>> interested in anything I can change, such as antenna choice, encoding
>> algorithms, transmission strategy, which would help produce a robust
>> system.
>> 
>> I’m also interested in methods of measuring what’s happening in the
>> environment, to figure out what’s causing the problem.
> 
>  This is a really, really big subject.  I hope you have an appreciation
> for that.  It isn't something like "This GPIO line isn't toggling when
> it should be, what could be wrong?"  ...there's a whole very large field
> behind what you're doing, and people study it for years to be able to
> wrangle it.  That's why nobody has responded to your question.

I do appreciate that, and I realise there is no magic solution either.

>  A good start for practical-almost-to-a-fault RF stuff is the ARRL
> Handbook, whether you have any interest in amateur radio or not.
> 
>  That said...if you describe what actual problem you're having, someone
> here might be able to assist, if people would tolerate the off-topicness
> of it.

I'm not too bothered about the actual problem I'm having -- there's clutter in the environment which is obviously degrading the signal. If I move an antenna sideways a few feet the problem goes away. (For the record, I'm using a pair of Radiometrix BIM2A-64 modules wired as a simplex transmitter and receiver for digital data transmission.)

My problem is that I'm developing the code blind, based on intellect and reasoned guesswork and I don't like that. There are many wireless products out there which are quite robust and I'm sure they weren't developed by guesswork either. 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.

Thanks for the OT prompt. I've amended the subject line and will let the thread die out -- I wasn't looking for lengthy discourse anyway, just a few pointers. I will look at the ARRL handbook.

Thanks,
Chris

- Raw text -