From: wb9omc@dynamo.ecn.purdue.edu (Duane P Mantick)
Subject: Re: Equipment/information Wanted (please :-)
Organization: Purdue University Engineering Computer Network
Date: 20 Nov 92 17:48:40 GMT

mcsbc2msd@dct.ac.uk writes:



>	Oh yeah... anybody got technical specs on any Quasar/laserquest/
>	zappzone/lazer tag equipment?

	On LazerTag (r) I can give you some specs - I have been working on
a Technical Guide for this which is in progress but not ready to be
released (and is also waiting on some legal/patent/registered trademark/
copyright mumbo-jumbo).

	For openers, the LazerTag (r) signal uses approx. a 58.8 KHz
carrier.  This is modulated at approx 1.1 KHz - said modulation being
decoded by an NE567 or LM567 Tone Decoder IC in the sensor.

(as a point of interest, I recently measured a TOMY/HASBRO Electronic
Survivor Shot and the sample I had used a 1.8 KHz "magic" frequency.
Survivor Shot and Lazertag (r) are compatible......)

	The whole thing is arranged as a "pulse train" which I don't
have all the specs for in front of me, sorry.

	It seems that the IRLED radiates a wavelength of 880 nM 
(nanometers) or pretty darned close to it.  I have experimented with
920 and 940 stuff and it didn't work very well - which is to say, the
sensor seemed to not like it as well as 880 nM.  One of my data books
says that most photodiodes have their peak sensitivity around 880 to 890
and assuming that LazerTag (r) sensors use a fairly standard photodiode,
they would be no exception.

	(one fellow here is looking at trying some stuff at shorter
wavelengths, I think.....haven't heard anything on this - but 880
does seem to be good, if not best.)

	[as a point of reference, visible red LED's tend to emit
at around 635 nM.....interestingly enough, a red LED can output the
"signal" and will even trigger a Lazertag (r) sensor.....over a distance
of a few inches  :-)  ]

	I have NOT had access to a direct-reading power meter to read the
strength of the output from a stock Starlyte (r) pistol.  My guesstimate
is that it is between <1 mW and possible up to 3 mW.

	Range from a stock pistol appears to be anywhere between 120
feet and 160 feet as an AVERAGE maximum.  There are considerable variations
from gun to gun.

	If you want anything specific, let me know and I'll see what I
either have/can find.  Keep in mind that everything *I* have is based on
taking the thing apart and sticking an oscilloscope in it.  The measurements
are based upon the test articles I have/had IN HAND and that since
there do seem to be some acceptable variations in those measurments,
your mileage may vary.  :-)

	On my main modified pistol output should be somewhere around
500 or 600 mW (changed the IRLED and twiddled a few signals) and max.
range is 300+ feet.  Before anyone has a cow and says it should be more,
keep in mind that optics for this is NOT a directly proportional law.
Rather, there is some inverse square thing (I'm NOT an optics professional -
it is the electronics of the thing that is my strong suit) that says
to double the range I need to increase power by 10 or something like that.

	And THAT is for an ideal case.  Atmospheric conditions, battery
power, and so forth will conspire to change that.  The rather cheesy
optics of the Starlyte (r) also work against getting a real tight beam,
doing a bit of spreading.  It should be said that since LazerTag (r) 
isn't really a laser at all, you don't get a parallel beam of light
like you would from a coherent laser source.  Which is why I can get away
with emitting 500 mW and NOT burning holes in my opponents....  :-)

	Anyhow, like I said - if you are interested in anything real
specific, let me know and I'll see if I can help you.  Other systems
may have differing specifics, but if they are LazerTag (r) 
compatible, the basics will be pretty close.

Duane