Id wire the TX pins to the IR Leds. Then Id send the bot's ID out pins as data bytes. That will in turn, will fire the Leds and pulse them in a unique pattern based on the data pulses. The receiving sensors are then wired up to an amp and a UART to boost the signal and convert it back to byte format which is then read into the receiving bot. The receiving bot then just has to examine the data byte(s) to determine who is nearby. You dont need to measure it at all. Let a UART chip do the work and just give you the pulse-data in byte format. If every bot has a unique ID, of say, three bytes (ASCII 155 - 068 - 197 for example) then no two bots will ever read the same signal and they will know right off who is nearby based on the transmitted bytes. You could set up the transmissions a couple of times a second. .db. -----Original Message----- From: yellow_monstertruck [mailto:] Sent: Monday, September 02, 2002 2:57 PM To: Subject: [BasicX] Re: omni-directional IR emitter??? Hi, I'm not merely looking for a pulse count but have to measure the length of each pulse in a string of 10 pulses. hmmm.... measuring the rising edge only... sounds promising, only reservaion is the greater range of error now that we are measuring a high pulse followed by a low pulse, the tolerence of each pulse would add up. Then again I could be entirely wrong cause either way, I'll be measuring sequential pulse lengths one after the other in the first approach. Edmund --- In basicx@y..., "Dave Houston" <dhouston1@f...> wrote: > On 31 Aug 2002, at 3:22, yellow_monstertruck wrote: > > > I'm manipulating timer1 to read the string of consequent pulses. > > Basically a repetitve loop that looks at the ICF flag for a edge > > transition, takes the reading, reset flags and flips the settings for > > timer1 to look for the opposite edge transition. I repeat this to look > > for the desired number of pulses. > > If all you want is a pulse count, why not use CountTransitions? > > Or you could merely count rising edges. This would save the time it > takes to flip the settings. > > --- > http://www.laser.com/dhouston/

Hi, I'm not merely looking for a pulse count but have to measure the length of each pulse in a string of 10 pulses. hmmm.... measuring the rising edge only... sounds promising, only reservaion is the greater range of error now that we are measuring a high pulse followed by a low pulse, the tolerence of each pulse would add up. Then again I could be entirely wrong cause either way, I'll be measuring sequential pulse lengths one after the other in the first approach. Edmund --- In basicx@y..., "Dave Houston" <dhouston1@f...> wrote: > On 31 Aug 2002, at 3:22, yellow_monstertruck wrote: > > > I'm manipulating timer1 to read the string of consequent pulses. > > Basically a repetitve loop that looks at the ICF flag for a edge > > transition, takes the reading, reset flags and flips the settings for > > timer1 to look for the opposite edge transition. I repeat this to look > > for the desired number of pulses. > > If all you want is a pulse count, why not use CountTransitions? > > Or you could merely count rising edges. This would save the time it > takes to flip the settings. > > --- > http://www.laser.com/dhouston/

On 31 Aug 2002, at 3:22, yellow_monstertruck wrote: > I'm manipulating timer1 to read the string of consequent pulses. > Basically a repetitve loop that looks at the ICF flag for a edge > transition, takes the reading, reset flags and flips the settings for > timer1 to look for the opposite edge transition. I repeat this to look > for the desired number of pulses. If all you want is a pulse count, why not use CountTransitions? Or you could merely count rising edges. This would save the time it takes to flip the settings. --- http://www.laser.com/dhouston/

hi again, sorry for not being able to reply earlier. thank u for all the ideas, gonna try the radiating convex mirror idea, seems fairly feasible also will play around with the light diffuser cause its easy to construct. also a comment, I'm not really modulating the IR pulses the way TV remotes do. the twice a second IR pulse is meant for robots to measure intensity and hence distance not reaslly for passing infomation or weeding out stray IR (set up will be conducted under controlled enviroment). each bot will take turns in flashing the IR pulse so the other bots know who they are looking at. also as mentioned, I have my reservations about the intensity of the IR rays being constant when modulated. on another issue, I'm trying to get the BX24 to measure a string of pulses without using the pulse in function. pulses will be generated by the BX24 and communicated through RF. I'm manipulating timer1 to read the string of consequent pulses. Basically a repetitve loop that looks at the ICF flag for a edge transition, takes the reading, reset flags and flips the settings for timer1 to look for the opposite edge transition. I repeat this to look for the desired number of pulses. Issue is, each loop takes about 400us to run. In other words, I can only read pulses that are longer than 400us or risk skipping one pulse. Is there anyway to bring the duration of the cycle down? Pulsein function is able to read transitions about 2us apart, how does it do that? is there anyway to get near that? thank u for all the input so far, edmund --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > I was thinking about those very struts to hold the proposed mirror > technique, last night after I posted. > > Since IR is known to bounce and reflect, the doughnut parameter should be > fairly stable despite the fact that struts may obscure the beam. Unlike > laser-light which is almost rigid, IR will spread somewhat once it bounces > off that mirror. By the time it hits the floor (depending on the height of > his bot) it should be spread wide enough to cover the slight shadow made by > the struts, depending on how narrow they are. > > If he makes the struts out of a material that is transparent to IR, then it > will be as if the struts aren't even there. There are a lot of materials > that are transparent to IR that seem solid to normal light or to the naked > eye. Most of the time a spec sheet of the material will tell you if it is > IR transparent. An acrylic tube that the mirror could slide up and down > inside, could work in place of 3 or 4 struts. A locking mechanism to hold > the mirror in place is designed above (on the back) of the mirror. That way > the IR is omni-directional, the tube acts as the struts and holds the > mirror, and depending on the construction material, can be totally > transparent to the device as a whole. > > Smokey colored acrylic would be a good choice if it can be determined that > it is transparent to IR. The smokey color would help assist in cutting out > visible light reflections but allow the IR to travel thru unimpeded. Have > another tube that slips over the IR-transparent one to serve as the mirror > shroud. That one is not transparent to IR and helps define the doughnut's > outer parameter. Between the two tubes then, one could adjust the mirror > height in the inner tube and the shroud with the outer tube. That should be > fairly flexible then in defining the actual parameters of that doughnut > beam. Hook them to servos and you could have automation control over the > doughnut. > > The flat-black paper disk serves as the inner doughnut parameter. > Personally, if I built something like this though, I'd mask off that disk > and spray paint the actual mirror directly with flat-black. That way there > would never be a chance of that disk falling off later on down the road. > > Id also paint the inside of the tube that houses the IR LED with chrome or > reflective paint. That would assist in boosting the beam up onto that > mirror. Any stray reflections are just bounced around inside that tube and > the only way out is up thru the top opening. Bounce around long enough and > they will find their way out. Make the bottom of that tube angled with > triangles or with a simple automobile reflector or another flat mirror and > that would speed up those stray reflections and aim them out the top opening > at the convex mirror. > > Going back to the modulation comment a bit..... > Id pulse a defined pattern of some type. > Instead of just on or off, twice every second. > That way the receiving devices are able to obtain an exact reading. > If the exact pattern is not present, then the pickups are just receiving > stray IR beams and can ignore them. > The pattern could be anything....just as long as both devices, the > transmitters and the receivers, know and understand the pattern. > > See...now this whole IR thread has me wanting to build the thing just to see > it in action...... > > *** > > On a side note...I own a commercial version of a laser device that uses a > rotating mirror. My son Chris uses it in his stage performances. You can > run it in random mode or patch in a line-level and it responds to music, > drawing patterns based on the tempo and volume of what it "hears". Its > awesome when placed behind the drummer kit and fed from the mics of the drum > kit. We project it onto the wall behind the stages. Its a great show > piece. > > .db. > -----Original Message----- > From: twesthoff [mailto:twesthoff@f...] > Sent: Thursday, August 15, 2002 5:29 AM > To: basicx@y... > Subject: Re: [BasicX] Re: omni-directional IR emitter??? > A white laser will indeed be hard to find as by definition a laser > produces only one wavelength of light and white is made up of all > colors. > > I once made a laser scanner by pointing the laser straight up and using > a motor to rotate a mirror (at 45 degree angle) above it. The reflected > light bounced back to the same mirror and was collected by a photodiode > near the laser. Later I rotated the laser and the detector with the > motor so as to get full 360 degree unbroken coverage. That way the beam > was not broken by the struts needed to hold the mirror over the top of > the laser. You could do the same with the IR LED. This would be a > scanning type beam rather than a continuous field, but the motor speed > is usually fast enough so that the effect is the same. > > Dan Bielecki wrote: > > > Ahhh....Now you know why I prefer laser light over IR. > > The beam is so bright and intense that nothing comes close to it in > > day-to-day usage. > > It allows you configure the collectors to respond only to the intense > > beam > > and ignore the rest. > > Cant do that as easily with IR. > > IR is everywhere in nature and you have to modulate and/or filter out > > unwanted photons. > > Laser can be tailored to a particular spectrum or color, spread, > > focused, > > centered or lined. > > > > I was thinking just last week about doing something new with 18 Texas > > Instruments optical chips that I just obtained, and using a red, a > > green, > > and a blue laser......by having the optics sample each color as it > > reflects > > off an object, route them up to the PC via the BX and map out the > > image in > > color on the display. > > > > In theory, it should produce one pixel of VGA True-Color, but I might > > have > > to add an extra superbrite LED or white-laser (if I can find one) for > > shadow > > depth. If I can scan and manipulate the beams properly with servos > > and > > obtain a patterned array image, I should be able to produce a fairly > > good > > rendition of a color 3-D environment with the BX. Its just theory > > though at > > this point. Cant seem to find a low priced blue laser and have yet > > to find > > a white one. Red ones are abundant, green ones are fairly > > obtainable....but the blue ones are very hard to find....and not cheap > > when > > ya do. Have yet to find a white one. I've read that they > > exist....just > > never seen one yet. > > > > Oops! strayed from the thread topic....Its IR related. > > Soooo.....let us all know what you decide on doing and how the project > > turns > > out. > > Post if you need anything from any of us. > > > > .db. > > > > > > > > > > > > > > -----Original Message----- > > From: v8fd [mailto:lesd@e...] > > Sent: Wednesday, August 14, 2002 7:48 PM > > To: basicx@y... > > Subject: [BasicX] Re: omni-directional IR emitter??? > > > > > > You are right, you can get rid of the DC offset from background IR > > by > > modulating the leds. You would then still need to look at the analog > > > > intensity after subtracting the low from the high value. I'd still > > worry about reflections and shadows making the method not work very > > well. > > > > -Les > > > > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > > Modulation will still work. Modulate the signal, period. > > > The receivers look only for the modulated signal. > > > It doesn't have to be for data, he's just looking for pulses. > > > If he modulates the pulses and has the receivers look only for > > modulated > > > pulses he can eliminate stray interference. > > > > > > He was looking to pulse twice a second. > > > Thats a modulated pulse. > > > The receivers look only for that pulse and ignore anything else. > > > > > > > > > > > > -----Original Message----- > > > From: v8fd [mailto:lesd@e...] > > > Sent: Wednesday, August 14, 2002 5:56 PM > > > To: basicx@y... > > > Subject: [BasicX] Re: omni-directional IR emitter??? > > > > > > > > > No, that won't help him. > > > He is trying to measure distance with the inverse square law of > > > optical radiation intensity fall off. It's not a data > > transmission > > > reliability problem. It's an analog issue. > > > That's my understanding of his post. > > > -Les > > > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > > > Modulated IR will overcome normal room reflections and > > admissions > > > without a > > > > diffuser. > > > > That is how your television and stereo remotes work, even in > > full > > > sunlight. > > > > They are modulated. > > > > > > > > Modulated and diffused will be even more reliable then just > > > diffused. > > > > > > > > .db. > > > > > > > >ed] > > > > > > > > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of > > Service. > > > > > > > > > > > > > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. > > > > > > > > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. >

I was thinking about those very struts to hold the proposed mirror technique, last night after I posted. Since IR is known to bounce and reflect, the doughnut parameter should be fairly stable despite the fact that struts may obscure the beam. Unlike laser-light which is almost rigid, IR will spread somewhat once it bounces off that mirror. By the time it hits the floor (depending on the height of his bot) it should be spread wide enough to cover the slight shadow made by the struts, depending on how narrow they are. If he makes the struts out of a material that is transparent to IR, then it will be as if the struts aren't even there. There are a lot of materials that are transparent to IR that seem solid to normal light or to the naked eye. Most of the time a spec sheet of the material will tell you if it is IR transparent. An acrylic tube that the mirror could slide up and down inside, could work in place of 3 or 4 struts. A locking mechanism to hold the mirror in place is designed above (on the back) of the mirror. That way the IR is omni-directional, the tube acts as the struts and holds the mirror, and depending on the construction material, can be totally transparent to the device as a whole. Smokey colored acrylic would be a good choice if it can be determined that it is transparent to IR. The smokey color would help assist in cutting out visible light reflections but allow the IR to travel thru unimpeded. Have another tube that slips over the IR-transparent one to serve as the mirror shroud. That one is not transparent to IR and helps define the doughnut's outer parameter. Between the two tubes then, one could adjust the mirror height in the inner tube and the shroud with the outer tube. That should be fairly flexible then in defining the actual parameters of that doughnut beam. Hook them to servos and you could have automation control over the doughnut. The flat-black paper disk serves as the inner doughnut parameter. Personally, if I built something like this though, I'd mask off that disk and spray paint the actual mirror directly with flat-black. That way there would never be a chance of that disk falling off later on down the road. Id also paint the inside of the tube that houses the IR LED with chrome or reflective paint. That would assist in boosting the beam up onto that mirror. Any stray reflections are just bounced around inside that tube and the only way out is up thru the top opening. Bounce around long enough and they will find their way out. Make the bottom of that tube angled with triangles or with a simple automobile reflector or another flat mirror and that would speed up those stray reflections and aim them out the top opening at the convex mirror. Going back to the modulation comment a bit..... Id pulse a defined pattern of some type. Instead of just on or off, twice every second. That way the receiving devices are able to obtain an exact reading. If the exact pattern is not present, then the pickups are just receiving stray IR beams and can ignore them. The pattern could be anything....just as long as both devices, the transmitters and the receivers, know and understand the pattern. See...now this whole IR thread has me wanting to build the thing just to see it in action...... *** On a side note...I own a commercial version of a laser device that uses a rotating mirror. My son Chris uses it in his stage performances. You can run it in random mode or patch in a line-level and it responds to music, drawing patterns based on the tempo and volume of what it "hears". Its awesome when placed behind the drummer kit and fed from the mics of the drum kit. We project it onto the wall behind the stages. Its a great show piece. .db. -----Original Message----- From: twesthoff [mailto:] Sent: Thursday, August 15, 2002 5:29 AM To: Subject: Re: [BasicX] Re: omni-directional IR emitter??? A white laser will indeed be hard to find as by definition a laser produces only one wavelength of light and white is made up of all colors. I once made a laser scanner by pointing the laser straight up and using a motor to rotate a mirror (at 45 degree angle) above it. The reflected light bounced back to the same mirror and was collected by a photodiode near the laser. Later I rotated the laser and the detector with the motor so as to get full 360 degree unbroken coverage. That way the beam was not broken by the struts needed to hold the mirror over the top of the laser. You could do the same with the IR LED. This would be a scanning type beam rather than a continuous field, but the motor speed is usually fast enough so that the effect is the same. Dan Bielecki wrote: > Ahhh....Now you know why I prefer laser light over IR. > The beam is so bright and intense that nothing comes close to it in > day-to-day usage. > It allows you configure the collectors to respond only to the intense > beam > and ignore the rest. > Cant do that as easily with IR. > IR is everywhere in nature and you have to modulate and/or filter out > unwanted photons. > Laser can be tailored to a particular spectrum or color, spread, > focused, > centered or lined. > > I was thinking just last week about doing something new with 18 Texas > Instruments optical chips that I just obtained, and using a red, a > green, > and a blue laser......by having the optics sample each color as it > reflects > off an object, route them up to the PC via the BX and map out the > image in > color on the display. > > In theory, it should produce one pixel of VGA True-Color, but I might > have > to add an extra superbrite LED or white-laser (if I can find one) for > shadow > depth. If I can scan and manipulate the beams properly with servos > and > obtain a patterned array image, I should be able to produce a fairly > good > rendition of a color 3-D environment with the BX. Its just theory > though at > this point. Cant seem to find a low priced blue laser and have yet > to find > a white one. Red ones are abundant, green ones are fairly > obtainable....but the blue ones are very hard to find....and not cheap > when > ya do. Have yet to find a white one. I've read that they > exist....just > never seen one yet. > > Oops! strayed from the thread topic....Its IR related. > Soooo.....let us all know what you decide on doing and how the project > turns > out. > Post if you need anything from any of us. > > .db. > > -----Original Message----- > From: v8fd [mailto:] > Sent: Wednesday, August 14, 2002 7:48 PM > To: > Subject: [BasicX] Re: omni-directional IR emitter??? > You are right, you can get rid of the DC offset from background IR > by > modulating the leds. You would then still need to look at the analog > > intensity after subtracting the low from the high value. I'd still > worry about reflections and shadows making the method not work very > well. > > -Les > > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > Modulation will still work. Modulate the signal, period. > > The receivers look only for the modulated signal. > > It doesn't have to be for data, he's just looking for pulses. > > If he modulates the pulses and has the receivers look only for > modulated > > pulses he can eliminate stray interference. > > > > He was looking to pulse twice a second. > > Thats a modulated pulse. > > The receivers look only for that pulse and ignore anything else. > > > > > > > > -----Original Message----- > > From: v8fd [mailto:lesd@e...] > > Sent: Wednesday, August 14, 2002 5:56 PM > > To: basicx@y... > > Subject: [BasicX] Re: omni-directional IR emitter??? > > > > > > No, that won't help him. > > He is trying to measure distance with the inverse square law of > > optical radiation intensity fall off. It's not a data > transmission > > reliability problem. It's an analog issue. > > That's my understanding of his post. > > -Les > > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > > Modulated IR will overcome normal room reflections and > admissions > > without a > > > diffuser. > > > That is how your television and stereo remotes work, even in > full > > sunlight. > > > They are modulated. > > > > > > Modulated and diffused will be even more reliable then just > > diffused. > > > > > > .db. > > > > > >ed] > > > > > > > > > > > > > > >

A white laser will indeed be hard to find as by definition a laser produces only one wavelength of light and white is made up of all colors. I once made a laser scanner by pointing the laser straight up and using a motor to rotate a mirror (at 45 degree angle) above it. The reflected light bounced back to the same mirror and was collected by a photodiode near the laser. Later I rotated the laser and the detector with the motor so as to get full 360 degree unbroken coverage. That way the beam was not broken by the struts needed to hold the mirror over the top of the laser. You could do the same with the IR LED. This would be a scanning type beam rather than a continuous field, but the motor speed is usually fast enough so that the effect is the same. Dan Bielecki wrote: > Ahhh....Now you know why I prefer laser light over IR. > The beam is so bright and intense that nothing comes close to it in > day-to-day usage. > It allows you configure the collectors to respond only to the intense > beam > and ignore the rest. > Cant do that as easily with IR. > IR is everywhere in nature and you have to modulate and/or filter out > unwanted photons. > Laser can be tailored to a particular spectrum or color, spread, > focused, > centered or lined. > > I was thinking just last week about doing something new with 18 Texas > Instruments optical chips that I just obtained, and using a red, a > green, > and a blue laser......by having the optics sample each color as it > reflects > off an object, route them up to the PC via the BX and map out the > image in > color on the display. > > In theory, it should produce one pixel of VGA True-Color, but I might > have > to add an extra superbrite LED or white-laser (if I can find one) for > shadow > depth. If I can scan and manipulate the beams properly with servos > and > obtain a patterned array image, I should be able to produce a fairly > good > rendition of a color 3-D environment with the BX. Its just theory > though at > this point. Cant seem to find a low priced blue laser and have yet > to find > a white one. Red ones are abundant, green ones are fairly > obtainable....but the blue ones are very hard to find....and not cheap > when > ya do. Have yet to find a white one. I've read that they > exist....just > never seen one yet. > > Oops! strayed from the thread topic....Its IR related. > Soooo.....let us all know what you decide on doing and how the project > turns > out. > Post if you need anything from any of us. > > .db. > > -----Original Message----- > From: v8fd [mailto:] > Sent: Wednesday, August 14, 2002 7:48 PM > To: > Subject: [BasicX] Re: omni-directional IR emitter??? > You are right, you can get rid of the DC offset from background IR > by > modulating the leds. You would then still need to look at the analog > > intensity after subtracting the low from the high value. I'd still > worry about reflections and shadows making the method not work very > well. > > -Les > > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > Modulation will still work. Modulate the signal, period. > > The receivers look only for the modulated signal. > > It doesn't have to be for data, he's just looking for pulses. > > If he modulates the pulses and has the receivers look only for > modulated > > pulses he can eliminate stray interference. > > > > He was looking to pulse twice a second. > > Thats a modulated pulse. > > The receivers look only for that pulse and ignore anything else. > > > > > > > > -----Original Message----- > > From: v8fd [mailto:lesd@e...] > > Sent: Wednesday, August 14, 2002 5:56 PM > > To: basicx@y... > > Subject: [BasicX] Re: omni-directional IR emitter??? > > > > > > No, that won't help him. > > He is trying to measure distance with the inverse square law of > > optical radiation intensity fall off. It's not a data > transmission > > reliability problem. It's an analog issue. > > That's my understanding of his post. > > -Les > > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > > Modulated IR will overcome normal room reflections and > admissions > > without a > > > diffuser. > > > That is how your television and stereo remotes work, even in > full > > sunlight. > > > They are modulated. > > > > > > Modulated and diffused will be even more reliable then just > > diffused. > > > > > > .db. > > > > > >ed] > > > > > > > > > > > > > > >

Ahhh....Now you know why I prefer laser light over IR. The beam is so bright and intense that nothing comes close to it in day-to-day usage. It allows you configure the collectors to respond only to the intense beam and ignore the rest. Cant do that as easily with IR. IR is everywhere in nature and you have to modulate and/or filter out unwanted photons. Laser can be tailored to a particular spectrum or color, spread, focused, centered or lined. I was thinking just last week about doing something new with 18 Texas Instruments optical chips that I just obtained, and using a red, a green, and a blue laser......by having the optics sample each color as it reflects off an object, route them up to the PC via the BX and map out the image in color on the display. In theory, it should produce one pixel of VGA True-Color, but I might have to add an extra superbrite LED or white-laser (if I can find one) for shadow depth. If I can scan and manipulate the beams properly with servos and obtain a patterned array image, I should be able to produce a fairly good rendition of a color 3-D environment with the BX. Its just theory though at this point. Cant seem to find a low priced blue laser and have yet to find a white one. Red ones are abundant, green ones are fairly obtainable....but the blue ones are very hard to find....and not cheap when ya do. Have yet to find a white one. I've read that they exist....just never seen one yet. Oops! strayed from the thread topic....Its IR related. Soooo.....let us all know what you decide on doing and how the project turns out. Post if you need anything from any of us. .db. -----Original Message----- From: v8fd [mailto:] Sent: Wednesday, August 14, 2002 7:48 PM To: Subject: [BasicX] Re: omni-directional IR emitter??? You are right, you can get rid of the DC offset from background IR by modulating the leds. You would then still need to look at the analog intensity after subtracting the low from the high value. I'd still worry about reflections and shadows making the method not work very well. -Les --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > Modulation will still work. Modulate the signal, period. > The receivers look only for the modulated signal. > It doesn't have to be for data, he's just looking for pulses. > If he modulates the pulses and has the receivers look only for modulated > pulses he can eliminate stray interference. > > He was looking to pulse twice a second. > Thats a modulated pulse. > The receivers look only for that pulse and ignore anything else. > > -----Original Message----- > From: v8fd [mailto:lesd@e...] > Sent: Wednesday, August 14, 2002 5:56 PM > To: basicx@y... > Subject: [BasicX] Re: omni-directional IR emitter??? > No, that won't help him. > He is trying to measure distance with the inverse square law of > optical radiation intensity fall off. It's not a data transmission > reliability problem. It's an analog issue. > That's my understanding of his post. > -Les > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > Modulated IR will overcome normal room reflections and admissions > without a > > diffuser. > > That is how your television and stereo remotes work, even in full > sunlight. > > They are modulated. > > > > Modulated and diffused will be even more reliable then just > diffused. > > > > .db. > > > >ed]

You are right, you can get rid of the DC offset from background IR by modulating the leds. You would then still need to look at the analog intensity after subtracting the low from the high value. I'd still worry about reflections and shadows making the method not work very well. -Les --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > Modulation will still work. Modulate the signal, period. > The receivers look only for the modulated signal. > It doesn't have to be for data, he's just looking for pulses. > If he modulates the pulses and has the receivers look only for modulated > pulses he can eliminate stray interference. > > He was looking to pulse twice a second. > Thats a modulated pulse. > The receivers look only for that pulse and ignore anything else. > > -----Original Message----- > From: v8fd [mailto:lesd@e...] > Sent: Wednesday, August 14, 2002 5:56 PM > To: basicx@y... > Subject: [BasicX] Re: omni-directional IR emitter??? > No, that won't help him. > He is trying to measure distance with the inverse square law of > optical radiation intensity fall off. It's not a data transmission > reliability problem. It's an analog issue. > That's my understanding of his post. > -Les > --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > > Modulated IR will overcome normal room reflections and admissions > without a > > diffuser. > > That is how your television and stereo remotes work, even in full > sunlight. > > They are modulated. > > > > Modulated and diffused will be even more reliable then just > diffused. > > > > .db. > > > >ed] > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. >

BTW...plain ol wax paper makes for a good home-made diffuser. So does the side of a plastic milk carton. Its a bit thicker but can withstand more punishment then the wax-paper. .db. -----Original Message----- From: v8fd [mailto:] Sent: Wednesday, August 14, 2002 4:04 PM To: Subject: [BasicX] Re: omni-directional IR emitter??? Assuming you will use this in a dark room, because normal room lights have tons of IR that will fool the didtance measurements. Now, use a fairly heavy amount of diffusion on the LED. You will loose a LOT of light in diffusing it enough to get some uniformity ( one or two orders of magnitude ), but in a non IR flooded room, it might work. The diffuser will look like a white piece of plastic. You want non directional diffuse light if you want this to work. Test the diffuser by using a red LED, and hold a white paper around the light, There should be no structure or pattern to the light. That's what diffuse light is. The inverse square law might work now! Good luck with the project, -Les --- In basicx@y..., "yellow_monstertruck" <wm_edmund@h...> wrote: > > the idea is for each robot to give off IR 360 degrees uniformly so > that other robots can read the intensity of the IR radiation using 8 > IR sensors mounted all round each robot. > > it has to be uniform in all directions so that the intensity of the > IR reading can translate accurately into distance regardless of > which direction the robot is facing. >

Modulation will still work. Modulate the signal, period. The receivers look only for the modulated signal. It doesn't have to be for data, he's just looking for pulses. If he modulates the pulses and has the receivers look only for modulated pulses he can eliminate stray interference. He was looking to pulse twice a second. Thats a modulated pulse. The receivers look only for that pulse and ignore anything else. -----Original Message----- From: v8fd [mailto:] Sent: Wednesday, August 14, 2002 5:56 PM To: Subject: [BasicX] Re: omni-directional IR emitter??? No, that won't help him. He is trying to measure distance with the inverse square law of optical radiation intensity fall off. It's not a data transmission reliability problem. It's an analog issue. That's my understanding of his post. -Les --- In basicx@y..., "Dan Bielecki" <Dan.Bielecki@A...> wrote: > Modulated IR will overcome normal room reflections and admissions without a > diffuser. > That is how your television and stereo remotes work, even in full sunlight. > They are modulated. > > Modulated and diffused will be even more reliable then just diffused. > > .db. > >ed]