
---------------------- 
NOTES FROM THE BIKELAB 
Issue #1 -- 12/9/90
by Steven K. Roberts
----------------------

Copyright (C) 1990 by Steven K. Roberts.  All Rights Reserved.

	IN THIS ISSUE:
		Introduction to the series 
		Brief overview of the BEHEMOTH project 
		Bicycle-mobile HF dipole antenna
		Microwave security sensor

	Welcome to the electronic edition of Nomadness!  This article
	has been sent to you because your name is on the Nomadness
	mailing list.  You may have requested this, or I may have just
	assumed you would be interested.  If you are NOT interested --
	or if you don't like receiving electronic bulk mail -- please
	send a note to wordy@bikelab.Sun.com and ask me to remove your
	name.

	I want to spend a moment establishing a context for all this,
	then dive into the details...

	First, this will be a more-or-less weekly publication, which
	will somewhat overlap the print edition of "High-tech
	Nomadness," but without the graphics <sigh>.  It will also be
	considerably more detailed and technical, and certainly more
	timely -- given the distribution method.  Sometimes it will
	doubtless contain material you don't care about... but that's
	the way with all publications.

	Distribution starts with an alias on my SPARCstation here in
	the bikelab sponsored by Sun Microsystems, and includes a wide
	variety of friends and fellow techies out in the Net.  A subset
	of this alias for more specific Sun-related issues is included
	(details of IPC board implementation on the bike, announcements
	of on-site bike demos, unix help requests, etc).  The text is
	also emailed to my Portal account for retransmission to the CAA
	area on GEnie, forwarding to other people not on the Net, and
	subsequent use in print media.

	Feel free to propagate, repost, or forward these reports, but
	be aware of copyright issues.  My interpretation of this is
	inspired by the author of the "copyleft":  you may freely
	distribute this as long as your recipients can.  And if you
	received this via someone who did just that, you can get your
	very own subscription by sending a request to:
			wordy@bikelab.Sun.com  
	or to any of the direct email addresses shown at the end.

	PLEASE DO NOT EMAIL ANYTHING to nomadness@bikelab.Sun.com or
	use the Reply command indiscriminately, since that will
	distribute your text to hundreds of time-conscious people out
	there in Dataspace!  If you have any comments or suggestions on
	the project, email me DIRECTLY and I'll respond likewise,
	perhaps including your comments in my next posting.  We must
	keep traffic volume down or people will start unsubscribing.
	Perhaps this will evolve into a newsgroup someday, but until
	then...

	Anway, enough fine print.  Let's get on with it!

				* * *

BRIEF Overview of the BEHEMOTH Project
--------------------------------------

	I had great dreams of starting this series with a complete
	description of the new bike system, now renamed from Winnebiko
	to BEHEMOTH (Big Electronic Human-Energized Machine... Only Too
	Heavy).  But the last time I wrote an overview, the file
	exceeded 50K.  Within Sun, I can distribute that file via FTP
	(once I learn how :-), but if you are Out There in Netland, a
	hardcopy of the backgrounder and a flyer on other publications
	can be had by sending $2.00 (to cover the pain and agony) to
	Nomadic Research Labs, P.O. Box 2390, Santa Cruz, CA 95063.  If
	you are on GEnie, it's free for the downloading in CAA (page
	320) main menu choice #6; on AOL it's in the MCM library.

	As you probably already know, BEHEMOTH is a computerized
	recumbent bicycle that is getting completely out of hand.  It's
	about 350 pounds fully loaded, carries a whole suite of
	networked computers, and provides extensive radio
	communications ranging from a robust ham shack to cellular
	phone modem and satcom.  It has a heads-up display, binary
	handlebar keyboard, and speech I/O.  It uses GPS satellite
	navigation for mapping and the highest level of security
	response.  It is becoming a unixycle, with an embedded
	SPARCstation for mapping, CAD, and file serving.  The GUI is
	implemented in a Mac Portable on the console, driving a trio of
	FORTH 68CH11s.  There's a Peltier refrigerator, linked by a
	fluid loop to a heat exchanger in the helmet for body cooling.
	Power is provided by 82 watts of solar panels, and a
	regenerative braking system.  It has something like 330 Meg of
	hard disk and at least 20 meg of RAM.  And so on.

	This project is obviously driven by passion, a recurring
	theme.  It's a blend of obsessions technoid and otherwise --
	and has been going on for 7 years.  I've already pedaled about
	16,000 miles around the US, and my tires itch violently... I'll
	be back on the road full time in July, starting in western Iowa
	with the famed RAGBRAI madness (10,000 people pedaling across
	the state) and then continuing on from there, somewhere...

	About 130 sponsors are making the whole thing possible, along
	with help from a wide variety of wizards, techies, machinists,
	engineers, gurus, friends, and consultants.  In a sense, I am
	only project coordinator, though I do end up soldering into the
	wee hours, coding, fiberglassing, hacking, staring at the wall,
	piloting the CAD system, fashioning widgets, cussing at the
	greasier jobs, and eventually, I hope, pedaling.  The point is
	that these updates should not be viewed as the techno-boasting
	of a solo inventor, but instead as a succession of reports on
	what this whole crazy industry can accomplish when the
	objective is high-tech adventure and the bottom line is pure,
	non-competitive FUN (though there may be a few commercial
	spinoffs).  I will also give hard technical data and access to
	vendors wherever appropriate.

	So.  Rather than maunder on for the next hour trying to give
	you a complete description of the system, I'll establish the
	pattern of this series up front:  focused commentary on
	whatever I happen to be working on at the moment, followed
	(beginning in July) by tales from the road.  But first, I
	suppose I should mention the basic design spec:

	BEHEMOTH, whether moving or parked, must provide maximum
	possible autonomy in power generation, computation capability,
	file storage, communication, navigation, and maintainability --
	anywhere in the world, all controlled via a flexible graphic
	user interface.  It must also be an elegant blend of art and
	engineering... and very comfy to ride.

	On with this week's details...

				* * *

Bicycle-mobile HF Dipole Antenna 
--------------------------------

	If you're into ham radio and have ever operated mobile, you
	know that it's not quite the same as flinging textbook-perfect
	wire dipoles into the trees or erecting a beam on a tall
	tower.  There are all kinds of variables:  imperfect grounds,
	effects of nearby objects, vehicle noise, impedance changes
	from wind-driven wiggling, etc.  Move to a bicycle and it gets
	even worse:  there's not much of a counterpoise to work with,
	making the SWR of a normal vertical whip at anything lower than
	15 meters unacceptable.

	I use a half-wave Larsen antenna for 2 meters, and will build
	stacked J-poles for the Microsats.  But the HF problem has
	bugged me for quite a while.  Stopping to erect wire dipoles
	works, but eliminates the fun of mobile operation.  Restricting
	activity to the high bands is unacceptable.  Making an
	effective ground plane, even on a BIG bicycle like this, is
	impossible.  And the spectre of RF dancing around in my
	microprocessors was almost enough to make me scrap the whole
	idea.

	The solution is an antenna that does not depend upon an
	external ground.  This boiled down to two choices:  a dipole or
	a loop.  The loop I tried is really quite an astonishing
	product -- the AEA IsoLoop, available for about $350 from
	Amateur Electronic Supply (800-558-0411) or direct from AEA
	(206-775-7373).  It is about 32" across, and carries a big
	black enclosure that houses an open-air variable capacitor
	driven by a stepper motor.  This is controlled from the shack
	via a little box (which could easily be hacked to run under
	software control), and requires constant vigilance since tuning
	is VERY narrow.  But performance is dramatic -- I've had the
	IsoLoop outshine a wire dipole on some bands, even when mounted
	only 10 feet off the ground.  This is an ideal choice for an
	attic antenna or someone with seriously limited space, but
	packaging constraints on the bike made it impossible for me.

	The dipole made of HF whips makes a lot of sense, and my first
	experiments were with a whole thicket of Hustlers
	(800-327-9076), using the shortened MO-4 mast and a little $8
	steel dipole bracket from Burk Electronics (708-482-9310).  The
	Hustlers are notably broader band than the IsoLoop, but do
	require accurate physical changes of tip rod position whenever
	retuning is necessary (as well as resonator changes between
	bands).  Though I maintained an effective sked for some time
	with these, the packaging problem got me again:  the complete
	system for 80-10 meters required 14 resonators as well as the
	two masts.  The back of the trailer would look like a
	quiver...

	It looks like I have found the solution, however, and yesterday
	morning's tests pretty well convinced me.  The antenna of
	choice is the Outbacker, made in Australia and available in the
	US via Outbacker Antenna Sales ($169 to $259, depending on
	model -- 615-899-3390).  This odd-looking thing is a
	brightly-colored fiberglass lance, either 4 or 6 feet long
	(mine are 4, the "Jr." model), studded with 8 female banana
	jacks in streamlined nacelles.  There is a "wander lead" that
	begins near the base, is coiled counterclockwise around the
	body, and is plugged into the socket for the band you want.

	This sounds arcane, but is really quite elegant.  I took two of
	the all-band 4-foot units and mounted them as a dipole atop the
	BYP (Big Yellow Pole) that rises from the back of the trailer
	(this is nominally 6 feet long, but can be extended to 12 when
	conditions permit).  No tuner or balun is required -- I just
	drive the array directly from my Icom 725 transceiver.  And
	performance is unmistakably HOT:  band changing is easy,
	bandwidth is quite acceptable with only occasional tweaks of
	the tip rods, and overall weight is minimal (sorry, I don't
	have a scale).  This morning's tests in the Sun MTV-4 parking
	lot yielded QSOs with 17 states and two provinces on 10 meters
	(mostly east coast), as well as easy voice and code chats on
	12, 15, and 40.  On 10 meters, anyone I could hear could also
	hear me, and signal reports were symmetrical even if they were
	relatively big guns.  I was running 50 watts from the bike's
	solar panels with the micro-dipole up 12 feet... and all in
	all, the experience was every bit as gratifying as ham radio
	should be.

	A future article in this series will detail the mounting scheme
	that will let the Outbackers and the stacked J-poles fold out
	from a tight cluster on the BYP.  Ham radio is becoming a very
	large part of this project, and a lot of the system engineering
	is devoted to making it effective in a variety of
	environments.  You'll be hearing more about all this as the
	weeks pass.  (N4RVE here, by the way, pleased to meetcha!)

				* * *

Microwave Security Sensor 
-------------------------

	One of the most common questions I hear about the bike, now
	worth somewhere near $1 million, is:  "Mah gawd, man, how do
	you LOCK that thing?"

	Well, I do have a cable lock, but it is seldom used.  Instead,
	there is a very robust security system that includes 7 levels
	of sensors, opens voice and data links to my backpack during an
	alert, and even beacons latitude and longitude on ham packet
	frequencies if the Trimble GPS satellite navigation receiver
	starts reporting changes in coordinates without the right
	password.  It can lock its own wheel, call 911 and deliver a
	synthesized message if it thinks it's being stolen, and even do
	a few things I probably shouldn't write about.  Like ham radio,
	security is a complex subsystem that will appear in these
	reports often.

	The most recent security project involved the "level-1" sensor
	-- a microwave doppler motion detector made by Alpha Industries
	(617-935-5150).  The model number is MSM10200, available direct
	as a developer's kit for $195.  With a power drain of only 10
	mA from a 10-26V source, this device provides a closure to
	ground in response to movement within its field of view (which
	depends on choice of antenna -- two come with the unit).  Four
	trimpots let you set sensitivity and other operating
	characteristics... and coverage of an unobstructed area out to
	100 feet or more is no problem.

	The motion sensor is very sensitive, but there was one catch.
	I want BEHEMOTH to know when someone has moved within 8-10
	feet.  This is not necessarily an alarm condition (consider a
	restaurant parking lot), but it can be... or it may simply help
	eliminate falsing of other sensors due to wind or rumbling
	trucks.  So how do we take a narrow 10 GHz microwave beam and
	turn it into a tight 360 degree pattern that surrounds a
	12-foot-long bicycle?

	Behind the seat of the recumbent, there is an area known as the
	RUMP (Rear Unit of Many Purposes).  This is reasonably central,
	including the trailer, and also one of the highest points on
	the bike.  The sensor is mounted inside the RUMP, with its
	feedhorn pointing straight up through a PVC fitting designed to
	interface a gutter downspout with 4" pipe.  This penetrates the
	fiberglass body, with a good seal to keep water out of other
	electronics in the enclosure.

	Glued into the downspout part is a PVC 4"-to-2" adapter, and
	inside that there is a copper cone made from Micaply (thin
	flexible PC board material).  The cross-section of the cone is
	90 degrees, and its apex is roughly even with the exit aperture
	of the microwave feedhorn.  Atop all this is a 2" cap, carrying
	the 7" yellow barricade flasher (see future story on the
	lighting system).

	Outdoor tests last week demonstrated that I got lucky (working
	with microwaves involves either great expertise on the subject
	-- which I lack -- or a healthy dose of luck).  The radiation
	pattern appears to extend 360 degrees from the RUMP, spreading
	24 degrees on either side of a horizontal plane even with the
	top of the seat.  I was unable to get close enough to the bike
	to touch it without being noticed.

	This output will be available to the RUMP Control Processor
	(one of the New Micros 68HC11 FORTH machines that handle all
	the real-time control) along with the UNGO system, optical
	sensors on all access panels, and various other inputs.  The
	action taken in response to an alert depends entirely on
	software, and will be the subject of a future story...

				* * *

	I hate to stop, but there will be plenty of other opportunities
	to do this.  No sense burning out on issue #1.  Next week, I'll
	tell you about making bicycle taillights out of high-brightness
	LEDs, a non-trivial task that was well worth the effort.

	Please write me DIRECTLY if you have any specific questions or
	comments (again, please don't reply to the nomadness alias
	itself).  Thanks for your interest in the project, and cheers
	from the bikelab!

		Steven K. Roberts 
		Nomadic Research Labs 
		P.O. Box 2390 
		Santa Cruz, CA 95063

		wordy@bikelab.Sun.com 
		GEnie, MCI, or AOL:  wordy

