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[DPRG]Wall-E -> 1GHZ computers laser rangefinding

Subject: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
From: Kenneth Maxon kmaxon at qwest.net
Date: Wed Jul 23 19:18:35 CDT 2008


Ray,

What frequency range are the laser and receiver pair.  In general this will
be a problem with most visible light laser systems as the sun (and many
other sources) put out energy across a large portion of the spectrum.   So
adding high-Q notch filter can help if the sensitivity of the receiver
extends beyond the frequency range of the signal to be sampled, however if
the interference is on the same frequency range as the signal to be
detected, then the problem is more complex and a simple optical filter *may*
not help.

In the paragraph above I use the word *may* not help as there are cases
where it can.   If the broad spectrum that is bleeding across the frequency
of interest is of a much lower amplitude than the signal returned to the
senor, then an optical filter can indeed help.   In this case an appropriate
optical filter can be used to drop the transmission of ALL frequencies
reaching the sensor.  This helps because all frequencies can be lowered to
the point where the undesired broad band noise no longer triggers or is
measurable by the sensor.

If the sensor has an analog output and modulation is the method of choice,
then an electronic filter *May* be of use.  The limiting issue here again
will be how much the returned signal stimulates the sensor vs how much the
background noise stimulates the sensor.  (SNR = Signal to Noise Ratio)  If
there is significant difference between the two, then an electronic band
pass filter and a modulated source will be able to detect the signal.  (This
of course assumes the sensor is not being used near saturation point,
otherwise both methods will be necessary (optical and electronic))...

-Kenneth

-----Original Message-----
From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org]On
Behalf Of ray xu
Sent: Wednesday, July 23, 2008 3:48 PM
To: dprglist at dprg.org
Subject: RE: [DPRG]Wall-E -> 1GHZ computers laser rangefinding


My receiver is picking up ambient light.  Are there any ways to filter that
out?  Should I modulate my laser and put a bandpass filter on the receiver
end?

___________________
Ray Xu
rayxu at tx.rr.com
DPRG member
OOPic group member
Seattle Robotics group member
My Blog


-----Original Message-----
From: Dale Wheat [mailto:dale at dalewheat.com]
Sent: Tuesday, July 15, 2008 12:13 PM
To: ray xu
Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding

Ray,

Bring your LCD to RBNO this evening and I can show you how to solder a
header on it.


Thanks,

Dale Wheat

(972) 486-1317
(877) DALE WHEAT
http://dalewheat.com


ray xu wrote:
> No problem.  Just ordered today; but the package is going to arrive on
> Wednesday (SO CLOSE!!).  Looks like I will need one of my dad's friends to
> solder the diode...
>
> Also, I decided to use a 650nm laser diode with an 800nm photodiode (650nm
> is 75% sensitivity).  As for the driver, I finally got some information on
> it.  I was stressing out whether or not to build my own or buy one.  I
> decided to do both; building my own as my backup.
>
> ___________________
> Ray Xu
> rayxu at tx.rr.com
> DPRG member
> OOPic group member
> Seattle Robotics group member
> My Blog
>
>
> -----Original Message-----
> From: Dale Wheat [mailto:dale at dalewheat.com]
> Sent: Monday, July 14, 2008 6:48 PM
> To: ray xu
> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>
> Ray,
>
> Sorry for the delay but I am just now returning from out of town.
>
>
> Thanks,
>
> Dale Wheat
>
> (972) 486-1317
> (877) DALE WHEAT
> http://dalewheat.com
>
>
> ray xu wrote:
>> Sorry if this is the second email I sent you with the same content, but
> I'm
>> planning to order my laser and all that stuff at latest by Monday
morning.
>
>> My dad and I decided to use a laser diode driver instead of making our
> own.
>> The attachment is what I plan to buy.  Am I missing anything?  (My dad
> gets
>> very ticked off when I forgot to order something and I have to re-order)
>>
>> Just in case you didn't get my last message; I have no Sent box.
>>
>> ___________________
>> Ray Xu
>> rayxu at tx.rr.com
>> DPRG member
>> OOPic group member
>> Seattle Robotics group member
>> My Blog
>>
>>
>> -----Original Message-----
>> From: Dale Wheat [mailto:dale at dalewheat.com]
>> Sent: Saturday, July 12, 2008 7:14 PM
>> To: ray xu
>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>
>> Ray,
>>
>> That might be possible.  The problem is that it won't come on at all
until
>> it
>> gets to the threshold current (3-5 mA) and then maxes out at 7 mA.  It
> would
>> be
>> kind of tricky.  A constant current driver is not much more complex and
>> would
>> produce more accurate results.
>>
>>
>> Thanks,
>>
>> Dale Wheat
>>
>> (972) 486-1317
>> (877) DALE WHEAT
>> http://dalewheat.com
>>
>>
>> ray xu wrote:
>>> So I cannot just hook it up to the 5V with a resistor in series?
>>>
>>> ___________________
>>> Ray Xu
>>> rayxu at tx.rr.com
>>> DPRG member
>>> OOPic group member
>>> Seattle Robotics group member
>>> My Blog
>>>
>>>
>>> -----Original Message-----
>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>> Sent: Saturday, July 12, 2008 7:02 PM
>>> To: ray xu
>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>
>>> Ray,
>>>
>>> Yes, I would be especially careful when handing this component until it
> is
>>> installed in the circuit.
>>>
>>> Also, you will have to build some sort of driver circuit for this
device.
>>> It
>>> does not have any sort of power conditioning circuitry of its own.  I
>> could
>>> not
>>> find any information on the company web site.  Since they are in
>> Carrollton
>>> TX
>>> it might be easier to just call and ask for an example circuit.  The
main
>>> thing
>>> that you want to avoid is too much current through the device.  A
> constant
>>> current driver is not especially difficult to build.
>>>
>>> Also, the beam angle of this device is 20 degrees.  You will have to
come
>> up
>>> with some sort of optics to get it focused into a parallel beam.  This
>> will
>>> be
>>> more difficult because it is infrared and therefore invisible to human
>> eyes.
>>> Thanks,
>>>
>>> Dale Wheat
>>>
>>> (972) 486-1317
>>> (877) DALE WHEAT
>>> http://dalewheat.com
>>>
>>>
>>> ray xu wrote:
>>>> Since I'm going to be using lasers, are there any precautions I should
>>> take
>>>> to avoid damaging a VCSEL laser diode from electric static?  This is
the
>>> one
>>>> I'm planning to use:
>>>>
>
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=365-1145-ND
>>>> .  I read in an electronics book that they are very prone to ESD.  I
> have
>>>> not worked with lasers before.
>>>>
>>>> ___________________
>>>> Ray Xu
>>>> rayxu at tx.rr.com
>>>> DPRG member
>>>> OOPic group member
>>>> Seattle Robotics group member
>>>> My Blog
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>>> Sent: Saturday, July 12, 2008 6:27 PM
>>>> To: ray xu
>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>
>>>> Ray,
>>>>
>>>> My wife, Anne, will be attending RBNO on Tuesday with me.  Thank you
for
>>>> your
>>>> cooperation.  Please bring your mom if she is interested.  She might be
>>> able
>>>> to
>>>> give us some interesting information, and she might like the robot
club.
>>>> Who knows?
>>>>
>>>> I have some header pins that we can solder to your LCD that will let
you
>>>> plug it
>>>> in to a breadboard easily.  I am assuming it's got a 1 x 14 or 1 x 16
> pin
>>>> header
>>>> along one edge.  I have several similar displays here.
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Dale Wheat
>>>>
>>>> (972) 486-1317
>>>> (877) DALE WHEAT
>>>> http://dalewheat.com
>>>>
>>>>
>>>> ray xu wrote:
>>>>> Ok I'll volunteer to be interviewed.  Rarely I have a headache, and I
>> get
>>>>> sick with the common cold like once sometimes twice a year.  It's
>>> probably
>>>>> because my mom is making my wear these "negative ion" clothing (it
>> really
>>>>> works).  Ask my mom more about it.  Maybe my mom can come with us to
>> DPRG
>>>> or
>>>>> her email is lgnhs at tx.rr.com.  Also, I went to tanner electronics with
>> my
>>>>> dad, again, and we bought a 4x20 LCD that has soldering pads on it.
> I'm
>>>>> still not sure if I need it soldered anytime soon, but I will bring it
>>>> with
>>>>> me to DPRG.  I do not have the header pins, but wires I can provide
and
>>>> will
>>>>> be okay.
>>>>>
>>>>> ___________________
>>>>> Ray Xu
>>>>> rayxu at tx.rr.com
>>>>> DPRG member
>>>>> OOPic group member
>>>>> Seattle Robotics group member
>>>>> My Blog
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>>>> Sent: Friday, July 11, 2008 11:13 PM
>>>>> To: ray xu
>>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>>
>>>>> Ray,
>>>>>
>>>>> Yes, it is getting late and I'm also waorking late on a project.
>>>>>
>>>>> If you are up to it, I would like to ask you a favor.  My wife is in
>>>> nursing
>>>>> school and is required to interview someone that was born here with
>>>> parents
>>>>> that
>>>>> are from another country.  The general questions will be stuff like,
>>> "when
>>>>> do
>>>>> you consider yourself sick" and "what do you do for a headache" and
>>> things
>>>>> along
>>>>> that line.
>>>>>
>>>>> A)  Do you meet the requirements? and B)  Would you be willing to be
>>>>> interviewed?  It should not take very long and my wife can provide the
>>>> list
>>>>> of
>>>>> questions ahead of time.  Questions you are not sure of can be
forwared
>>> to
>>>>> your
>>>>> parents.
>>>>>
>>>>> If it is possible, I would vertainly appreciate it.  If not, I
>>> understand.
>>>>> Thanks,
>>>>>
>>>>> Dale Wheat
>>>>>
>>>>> (972) 486-1317
>>>>> (877) DALE WHEAT
>>>>> http://dalewheat.com
>>>>>
>>>>>
>>>>> ray xu wrote:
>>>>>> Oh oops I meant the 15th...sorry I'm just a little tired right
now...I
>>>>> will
>>>>>> also bring my robot arm again for nick swan.
>>>>>>
>>>>>> ___________________
>>>>>> Ray Xu
>>>>>> rayxu at tx.rr.com
>>>>>> DPRG member
>>>>>> OOPic group member
>>>>>> Seattle Robotics group member
>>>>>> My Blog
>>>>>>
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>>>>> Sent: Friday, July 11, 2008 10:52 PM
>>>>>> To: ray xu
>>>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>>>
>>>>>> Ray,
>>>>>>
>>>>>> So you will not be at the next RBNO (15th)?
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Dale Wheat
>>>>>>
>>>>>> (972) 486-1317
>>>>>> (877) DALE WHEAT
>>>>>> http://dalewheat.com
>>>>>>
>>>>>>
>>>>>> ray xu wrote:
>>>>>>> Now that my SRF04 has arrived, would you mind soldering on some
wires
>>> on
>>>>>> it
>>>>>>> for me?  Thanks.  I will be at 22nd RBNO.
>>>>>>>
>>>>>>> ___________________
>>>>>>> Ray Xu
>>>>>>> rayxu at tx.rr.com
>>>>>>> DPRG member
>>>>>>> OOPic group member
>>>>>>> Seattle Robotics group member
>>>>>>> My Blog
>>>>>>>
>>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>>>>>> Sent: Friday, July 11, 2008 1:45 PM
>>>>>>> To: ray xu
>>>>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>>>>
>>>>>>> Ray,
>>>>>>>
>>>>>>> If you're using an external counter to measure the time of flight,
it
>>>>>>> doesn't
>>>>>>> matter what you use to control it.  You can use a PC or a
>>>> microcontroller
>>>>>> or
>>>>>>> even just a display with some buttons.  The main thing is what is
>> going
>>>>> to
>>>>>>> be
>>>>>>> doing the actual time measurement.
>>>>>>>
>>>>>>> If I remember correctly, a PIC running at 20 MHz can only execute
>>>>>>> instructions
>>>>>>> at 5 MHz.  There may be some faster ones available now;  I have not
>>>>> worked
>>>>>>> with
>>>>>>> PICs in many years.
>>>>>>>
>>>>>>> The Hammer board from TinCanTools is probably the fastest MCU that
> you
>>>>> can
>>>>>>> put
>>>>>>> on a breadboard.  I think it runs 100-200 MHz.  I have a couple of
> the
>>>>>>> ATNGW100
>>>>>>> boards from Atmel that run at 130 MHz but can be overclocked to 200
>>> MHz.
>>>>>>> They
>>>>>>> are ~$73 from Mouser or Digikey.  They run Linux.
>>>>>>>
>>>>>>> Building a microcontroller circuit from scratch is not an easy thing
>> to
>>>>> do
>>>>>>> to
>>>>>>> begin with.  The AVRs that many of the DPRG members work with can
run
>>> up
>>>>>> to
>>>>>>> 20
>>>>>>> MHz and execute 20 million instructions per second.  Philips makes
an
>>>>> ARM7
>>>>>>> line
>>>>>>> of processors that are faster, running 60 or 70 MHz.  ST makes an
ARM
>>>>>>> Cortex-M3
>>>>>>> part that runs at 72 MHz.  All of these chips are in the $10 range.
>>>>>>>
>>>>>>> I'd start with getting the emitter and detector circuits working
>>>> reliably
>>>>>>> first
>>>>>>> and then figure out what is going to be required to measure these
>> teeny
>>>>>> tiny
>>>>>>> time spans.
>>>>>>>
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Dale Wheat
>>>>>>>
>>>>>>> (972) 486-1317
>>>>>>> (877) DALE WHEAT
>>>>>>> http://dalewheat.com
>>>>>>>
>>>>>>>
>>>>>>> ray xu wrote:
>>>>>>>> Also, everything will be controlled via the serial port.  At the
>> other
>>>>>>> end,
>>>>>>>> there will be a controller (most likely a PIC) that will handle the
>>>>>>>> transmitting, etc.  The pic will be operating at 20mHz, so will the
>>>>> clock
>>>>>>>> speed be a problem?  Are there any other through-hole MCU that are
>>>>> faster
>>>>>>>> and easy to program?
>>>>>>>>
>>>>>>>> ___________________
>>>>>>>> Ray Xu
>>>>>>>> rayxu at tx.rr.com
>>>>>>>> DPRG member
>>>>>>>> OOPic group member
>>>>>>>> Seattle Robotics group member
>>>>>>>> My Blog
>>>>>>>>
>>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>>>>>>> Sent: Friday, July 11, 2008 12:39 PM
>>>>>>>> To: ray xu
>>>>>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>>>>>
>>>>>>>> Ray,
>>>>>>>>
>>>>>>>> I'm unsure about the dark current adjustment.  I would build up a
>>>>> similar
>>>>>>>> circuit and see what it does.
>>>>>>>>
>>>>>>>> You're right about determining the "system delay".  By setting the
>>>>>>>> time-of-flight to zero you can measure the other delays in the
total
>>>>>>> system.
>>>>>>>> I don't think you're goning to be able to use a x86 type processor
> to
>>>>>>>> measure
>>>>>>>> the pulse directly.  As has been pointed out earlier, even if the
>>>>>>> processor
>>>>>>>> cores is running at 1 GHz, the IO will be much, much slower.
>>>>>>>>
>>>>>>>> If you have the meitter and detector circuits built up and tested
by
>>>>>>>> Tuesday, I
>>>>>>>> will bring my frequency counter and we can see what kind of timing
> we
>>>>> can
>>>>>>>> get.
>>>>>>>>
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>>
>>>>>>>> Dale Wheat
>>>>>>>>
>>>>>>>> (972) 486-1317
>>>>>>>> (877) DALE WHEAT
>>>>>>>> http://dalewheat.com
>>>>>>>>
>>>>>>>>
>>>>>>>> ray xu wrote:
>>>>>>>>> So for this circuit, there is no need to adjust the "dark current"
>>> and
>>>>>>> try
>>>>>>>>> to eliminate the ambient light using the digital potentiometer?
>>> Also,
>>>>>> to
>>>>>>>>> figure out the delay, can I just apply logic HIGH directly to the
>>>> anode
>>>>>>>> (or
>>>>>>>>> via a mosfet) of the photodiode to "simulate" that it has detected
> a
>>>>>>> laser
>>>>>>>>> beam and the pico-ITX can time it to see how long the delay is?  I
>>>>>>> usually
>>>>>>>>> see op-amps more than transistor amplifiers.
>>>>>>>>>
>>>>>>>>> ___________________
>>>>>>>>> Ray Xu
>>>>>>>>> rayxu at tx.rr.com
>>>>>>>>> DPRG member
>>>>>>>>> OOPic group member
>>>>>>>>> Seattle Robotics group member
>>>>>>>>> My Blog
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>>>>>>>> Sent: Friday, July 11, 2008 10:32 AM
>>>>>>>>> To: ray xu
>>>>>>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>>>>>>
>>>>>>>>> Ray,
>>>>>>>>>
>>>>>>>>> He also has this circuit that should work better for your
>>> application:
>>>>>>>>> http://www.discovercircuits.com/DJ-Circuits/20mrvr2.htm
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>>
>>>>>>>>> Dale Wheat
>>>>>>>>>
>>>>>>>>> (972) 486-1317
>>>>>>>>> (877) DALE WHEAT
>>>>>>>>> http://dalewheat.com
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ray xu wrote:
>>>>>>>>>> If you have time, could you please look at the schematic of the
>>>>>> receiver
>>>>>>>>>> circuit?  Thanks.  I based part of it from here:
>>>>>>>>>> http://www.discovercircuits.com/DJ-Circuits/2mhzrvr1.htm .  IC2
> and
>>>> Q1
>>>>>>>> are
>>>>>>>>>> part of the "auto-calibrating" system.  SL2 is where the power
> will
>>>> be
>>>>>>>>>> entering.  Thanks.
>>>>>>>>>>
>>>>>>>>>> ___________________
>>>>>>>>>> Ray Xu
>>>>>>>>>> rayxu at tx.rr.com
>>>>>>>>>> DPRG member
>>>>>>>>>> OOPic group member
>>>>>>>>>> Seattle Robotics group member
>>>>>>>>>> My Blog
>>>>>>>>>>
>>>>>>>>>> -----Original Message-----
>>>>>>>>>> From: Dale Wheat [mailto:dale at dalewheat.com]
>>>>>>>>>> Sent: Thursday, July 10, 2008 7:31 PM
>>>>>>>>>> To: ray xu
>>>>>>>>>> Cc: dprglist at dprg.org
>>>>>>>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>>>>>>>
>>>>>>>>>> Ray,
>>>>>>>>>>
>>>>>>>>>> The difference between 4.23 mW and 5 mW will only make a very
> small
>>>>>>>>>> difference
>>>>>>>>>> in the range.  Having a properly matched emitter and detector
pair
>>>>> will
>>>>>>>>> make
>>>>>>>>>> a
>>>>>>>>>> big improvement in the performance of the circuit.
>>>>>>>>>>
>>>>>>>>>> An analog-to-digital converter would be much, much too slow to
> give
>>>>> any
>>>>>>>>> sort
>>>>>>>>>> of
>>>>>>>>>> meaningful result in this application.  You will need to build a
>>> very
>>>>>>>> fast
>>>>>>>>>> amplifier that introduces a minimum of delay into the detector
>>>>> circuit.
>>>>>>>>>> Thanks,
>>>>>>>>>>
>>>>>>>>>> Dale Wheat
>>>>>>>>>>
>>>>>>>>>> (972) 486-1317
>>>>>>>>>> (877) DALE WHEAT
>>>>>>>>>> http://dalewheat.com
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> ray xu wrote:
>>>>>>>>>>> Hello guys, I have another question.  Since I'm changing the
>>>>>> photodiode
>>>>>>>>>> I'm
>>>>>>>>>>> using o a very fast response one, I will need to use a 650nm
>>>>>>>>>> laser/detector.
>>>>>>>>>>> But the 850nm one only outputs 4.23mW of light and the one I was
>>>>>>>> planning
>>>>>>>>>> to
>>>>>>>>>>> use originally outputs 5mW of light.  Will that affect my range?
>>>>>> Also,
>>>>>>>> I
>>>>>>>>>>> need some help in building the receiver which means using
op-amps
>>>>> (I'm
>>>>>>>>> not
>>>>>>>>>>> very experienced in that area), or could I use a pre-amplifier
>> then
>>>>>> use
>>>>>>>> a
>>>>>>>>>> AD
>>>>>>>>>>> converter?
>>>>>>>>>>>
>>>>>>>>>>> ______________
>>>>>>>>>>> Ray Xu
>>>>>>>>>>> rayxu at tx.rr.com
>>>>>>>>>>>
>>>>>>>>>>> -----Original Message-----
>>>>>>>>>>> From: dprglist-bounces at dprg.org
> [mailto:dprglist-bounces at dprg.org]
>>>> On
>>>>>>>>>> Behalf
>>>>>>>>>>> Of John Swindle
>>>>>>>>>>> Sent: Wednesday, July 09, 2008 9:46 PM
>>>>>>>>>>> To: dprglist at dprg.org
>>>>>>>>>>> Subject: Re: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
>>>>>>>>>>>
>>>>>>>>>>> Folks:
>>>>>>>>>>>
>>>>>>>>>>> I think we all like the idea of direct time-of-flight
measurement
>
>>>>>>>>>>> of light because it seems so straightforward and cool, but as
you
>
>>>>>>>>>>> probably already know, the laser rangefinders do it with the
>>>>>>>>>>> phase of the light, not the flight time. Indeed, it can be done
>>>>>>>>>>> with cheap parts at about 25MHz, not 1GHz. When I was playing
>>>>>>>>>>> around with rangefinder ideas, I found the plans for the
circuit,
>
>>>>>>>>>>> but I discarded the link. It didn't take much searching.
>>>>>>>>>>>
>>>>>>>>>>> When I was in college, I thought I could directly measure the
>>>>>>>>>>> speed of light using a strobe, a photodetector, and a fast
>>>>>>>>>>> digitizing oscilloscope. It is considerably harder than it would

>>>>>>>>>>> seem. I only got a C on that project. Ouch!
>>>>>>>>>>>
>>>>>>>>>>> Back to my passive sonar stuff now.
>>>>>>>>>>>
>>>>>>>>>>> John Swindle
>>>>>>>>>>>
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> DPRGlist mailing list
>>>>>>>>>>> DPRGlist at dprg.org
>>>>>>>>>>> http://list.dprg.org/mailman/listinfo/dprglist
>>>>>>>>>>> No virus found in this incoming message.
>>>>>>>>>>> Checked by AVG - http://www.avg.com
>>>>>>>>>>> Version: 8.0.138 / Virus Database: 270.4.7/1542 - Release Date:
>>>>>>> 7/9/2008
>>>>>>>>>>> 6:50 AM
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> DPRGlist mailing list
>>>>>>>>>>> DPRGlist at dprg.org
>>>>>>>>>>> http://list.dprg.org/mailman/listinfo/dprglist
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>> ------------------------------------------------------------------------
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
>
>


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