======================COMPONET_LIGHT=========================== NEW CHEATSHEETS http://www.idea2ic.com/CheatSheet_2/CHEATSHEETS_2.html These are my personal cheatsheets designed to make access to detailed information much easier to find. They are being put on the web mainly because for now it is easy to do. The new rev of cheatsheets are the ones being continually upgraded. Don Sauer 10/17/09 dsauersanjose@aol.com -------------------------------------------------------------------------------------- ----------------------DISPLAY_LED---------------------- Bit size = 7 micro inches = 0.18 micro meters "common cathode" 7-seg displays. ------ ----- +5V 5| |2,3,6,7,10 - Gnd 8| |13 -270ohm-|>-| sw 14|7490|1,12 ------------ 7|7448|12 -270ohm-|>-| | |9 --------------- 1| |11 -270ohm-|>-| | |8 --------------- 2| |10 -270ohm-|>-| | |11 -----*-------- 6| |9 --270ohm-|>-| ---- +5V 16| |15 -270ohm-|>-| | |14 -270ohm-|>-| ---- Gnd + **[Just a note from me, need a DE-BOUNCED switch circuit or the counter be counting the bounces of switch!! "switch point" sw is connected to +5V the counter will count by one. If you want to add a second digit, take a wire off the point marked * and connect this into sw point of an identical circuit. Those on the right are the bits of the LED display, by the way. You need to connect the "8" with its pins as follows: 13 ------ 15 | | 12 14 ------ 9 | | 11 ------ 10 can use 74LS90/74LS48 or even 74HC90/74HC48s, ======================COMPONENTS_LASER=========================== Apertur small opening which electromagnetic radiation pass. Beam Diamete diameter of circular beam at certain point where intensity drop to fraction of maximum value. common definitions are 1/e (0.368) and 1/e2 (0.135) of maxvalue. Beam Divergenc Angle of beam spread,in (milli)radians. approximated for small angle by ratio beam diameter to distance from laser aperture. Divergenc Increase in beam diameter with distance from aperture Coherence electromagnetic waves in phase in both time space. Coherent light Monochromaticity low beamdivergence, canconcentrated to high power densities. Diffraction wave property create deviation from straight line when beam pass near an edge of an opaque object. Irradiance (E Radiant flux (radiant power) per unit area in Watts per square centimeter. (Sometimes referred to as power density, although not exactly correct). Laser acronym for Light Amplification by Stimulated Emission of Radiation. an optical cavity, with mirrors at ends, filled with crystal, glass, liquid, gas or dye. produces an intense beam of light with the unique properties of coherence, collimation monochromaticity. Amplification process which electromagnetic radiation inside active medium within laser optical cavity increase by process of stimulated emission. Amplitude maximum value of a wave, measured from its equilibrium. Anode positive electrode ofgas laser, used for excitation of the gas in tube. Argon Lase gas laser which argon ions arethe active medium. emits blue-green visible spectrum, primarily 448 and 515nm Brewster Window Windows at ends of gas laser, used to produce polarized electromagnetic radiation. window at Brewster angle to optical axis of the laser, only polarization can pass through. Carbon Dioxide (CO2) Lase gas laser which CO2 molecules emits infrared spectrum, primarily at 9-11 [µm], strongest emission line at 10.6 [µm]. Cathod negative electrode gas laser, for excitation of gas in tube. Diode Laser Semiconductor Laser Excimer Lase gas laser emits in UV spectrum. active medium is "Excited Dimer" does not have stable ground state. Gas Laser laser i active medium is a gas. gas can be composed of molecules (like CO2), Atoms (like He-Ne), ions (Ar+). Ground State Lowest energy level of an atom or molecule. Helium-Neon (He-Ne) Laser A gas laser Helium (He) and Neon (Ne) atoms active medium. emits primarily in Visible spectrum, primarily 632.8 [nm], some lines in near Infrared. Hologram interference phenomena on plate (or film). contain enormous amount information 3 dimensional image constructed from it. Injection Laser laser which produces output from semiconductor materials such as GaAs. Injection Lase See Diode Laser. Ion Laser active medium is composed of ions of a Nobel gas (like Ar+ or Kr+). excited by high discharge voltage at the ends of a small bore tube. Laser Accessorie hardware and options available for lasers, as Brewster windows, Q-switches optical components to control laser radiation. Laser Mediu (See Active Medium) Laser Ro solid-state, rod-shaped active medium which excitation caused byintense light (optical pumping),as flash lamp. used for the rod, the earliest of which was synthetic ruby crystal (see Solid State Laser). Laser Pulse discontinuous burst of laser radiation, a true laser pulse achieves higher peak powers than that attainable in a CW output. Limit Accessible Emission Level (AEL permitted within a particularly class. In ANSI Z-136.1, AEL is product Accessible Emission Maximum Permissible Exposure limit (MPE) and area limiting aperture (7mm for visible and near infrared lasers). Limiting Apertur maximum circular area which radiance and radiant exposure can be averaged when determining safety hazards. Longitudinal (Axial) Mode Specific wavelengths in laser output, determined by standing waves within laser cavity. Only longitudinal modes under the laser gain curve, above laser threshold found in laser output. Maximum Permissible Exposure (MPE may be exposed without hazardous effect or adverse changes in eye or skin. Metastable Stat The upper laser level. excited state of atom or molecule, which have a long lifetime. Micro Micro-meter, one millionth of a meter (10-6 [m]). Milliradia unit to measure angles, one thousandth of a radian. 1 milliradian [mrad] = 0.057Ä. Mode locke method controlling the length of output laser pulse . Produce very short (10-12 [sec]) burst of pulses. Monochromatic Ligh Theoretically, light at one specific wavelength. with very narrow bandwidth. light out of a laser most monochromatic source known to man. Nanometer [nm one billionth of a meter (10-9 [m]). Nd:Glass Lase A solid-state laser in which a Nd dope active medium, to produce 1064 [nm] wavelength. Nd:YAG Lase solid-state laser which Neodymium doped Yttrium Aluminum Garnet used as active medium, produce 1064 [nm] wavelength YAG is a synthetic crystal. Neodymium (Nd rare earth element is active element in Nd:YAG laser and Nd:Glass lasers. Optical Cavity (Resonator Space between laser mirrors where lasingoccurs. Optical Densit logarithmic expression for attenuation produced by an attenuating medium, such as an eye protection filter. Optical Fibe filament of quartz or other optical material, capable of transmitting light by multiple internal reflection and emitting it at the end. Optical Pumpin excitation of active medium r by the application of light, rather than electrical discharge. can be from a conventional source like Xenon or Krypton lamp, or laser. Optical Radiatio Ultraviolet, visible and infrared spectrum (0.35-1.4 mm) in the region of transmittance of the human eye. Optical Resonato mirrors (or reflectors) making up laser cavity including laser rod or tube. mirrors reflect back and forth to up amplification. Output Couple part of laser which enable light come out of laser. Usually a partially reflecting mirror at end of laser optical cavity. Output Powe energy per second (measured in Watts) emitted from laser form of coherent light. Pulse Duratio "On" time of pulsed laser. Pulsed Lase Laser delivers in single or train of laser pulses. Pumpin (See Optical Pumping). Addition of energy (thermal, electrical, or optical) active laser medium. to produce a state of population inversion. Q-Switch Laser laser which store energy in active medium, produce short pulse with high energy. by blocking resonatorability to oscillate, keeping the "Q-Factor" of optical cavity low. Ruby Laser first laser type. use a crystal of sapphire (aluminum oxide) containing trace amounts of chromium oxide as an active medium. Scanning Laser laser having a time-varying direction, origin or pattern propagation with respect to a stationary frame reference. Semiconductor Laser (see diode laser) produces its output from semiconductor materials such as GaAs. Solid State Laser laser in which the active medium is solid state (usually not including semiconductor lasers). Spontaneous Emission Random emission of photon by decay of an excited state to a lower level. Determined by lifetime of the excited state. Spot Size diameter of the beam of laser radiation. Stimulated Emission Coherent emission of radiation, stimulated by a photon absorbed by an atom (or molecule) in its excited state. Transverse Mode geometry of power distribution in cross section of laser beam. Transverse Electro-Magnetic (TEM) Mode Used to designate shape of cross section of laser beam. TEM00 lowest order transverse mode possible. power distribution across beam is of a gaussian shape. Tunable Laser laser system can be "tuned" to emit laser light over continuous range of wavelengths or frequencies. Tunable Dye Laser laser whose active medium a liquid dye, pumped by another laser or flash lamps, produce various colors of light. color may be tuned by adjusting optical tuning elements and/or changing the dye used. Radian measurement of angles. 2p [rad] = 360Ä, 1 [rad] = 57.3Ä. Radiant Energy (Q) Energy in form of electromagnetic waves usually ex units of Joules (watt-seconds). Radiant Exposure (H) total energy per unit area upon a given surface. express exposure to pulsed laser radiation inJ/cm2. Reflection return radiant energy (incident light) by surface, with no change in wavelength. Refraction change of direction of propagation of wave, when it passes from one medium to another in which the wave velocity is different. Len curved transparent material which depending on its shape, is used to either converge or diverge light. Ligh visible spectrum. 400 to 700 nanometers. Excitatio Energizing active medium to state of populationinversion. Fluorescenc Emission light particular wavelength, result ofabsorption light shorter wavelength. a property of some materials, each material has wavelength of absorption and emission. Frequency (n) (nu number times wave oscillates per second (The number of periods of oscillations per second). Electromagnetic Radiation (Spectrum wave propagate vacuum with speedlight, simultaneous oscillations of electric field and magnetic field perpendicular each other perpendicular to direction of propagation Created by accelerating electric charge, X-rays, visible spectrum, infrared , microwave etc. Electron Volt [eV Unit of energy: energyelectron accuire while accelerating through 1 [Volt].1 [eV] = 1.6*10-19 [Joule] Photon The elemental unit of light. Qu proportional to wavelength (l) (lambda) (or frequency f). E = hf = hc / l (lambda). ( l (lambda) = wavelength, c = speed of light, h = Planks constant). Polarizatio Vibration of electric field vector in specific direction perpendicular to direction of propagation of wave. Population Inversio excited state of matter, imore atoms (or molecules) in upper state than ilower one. a required for a laser action. Powe rate energy delivery in unit of time, expressed in Watts (Joules per second). Thus: 1 [Watt] = 1 [Joule]/1 [sec]. Infrared Spectrum (IR between 0.7-1,000 [µm]. Solid Angle ratio of area on surface of sphere to square of radius of that sphere. in steradians (sr). Ultraviolet (UV) Radiation Electromagnetic radiation with wavelengths between soft X-rays and visible violet light, broken down into UV-A (315-400 [nm]), UV-B (280-315 [nm]), and UV-C (100-280 [nm]). Visible Spectrum (light) can be detected by the human eye. wavelengths which lie in the range between 400 nm and 700-780 nm. Wavelength (l) (Lamda length of light wave. shortest distancewhich wave pattern fully repeats itself, from crest to crest. wavelength of light in visible spectrum determines color. units of measurement are micrometer (micron),nanometer, and (old unit) the Angstrom unit. YAG Yttrium Aluminum Garnet widely used solid-state crystal composed of yttrium and aluminum oxide doped with a small amount of rare-earth neodymium. ======================PROTOCOLS_IR====================== Infra Red Remote Transponder cheif problem is just stray environmental noise with any slowly changing amplitude modulated IR signal (lots of 60 Hz noise, and sunlight noise). Most IR remotes work around a 40KHz carrier, so that they can just pulse this digitally, and just bandpass filter it at receiving end. This boosts range of unfocused IR remotes to tens of feet (around 20-30 feet). Adding two IR Leds helps alot, by sending out more IR signals. IR DETECTOR CIRCUIT 30Hz BANDPASS FILTER gain = 1 Q = 4 30Hz BANDPASS FILTER gain = 1 Q = 4 +5V .1uF | || 330K \ +---||--+-----/\/\/------+ / | || | | \ 100K | | | / | | | \ | | | | | .1uF | ___ | | 39K | || | | \___ | +--\/\/--+---||--+--|- \___ | IR | | || | \ | Detector | | | LM3900 -+ | | | ___/ | ||---+ \ +--|+ ___/ | || / | |___/ | ||---+ \ 5.6K \ | | / / | | \ \ 1M | | | / | | | \ | GND GND | | +5V | | | +---------------------------------- | | ___ | 120K | \___ +-------\/\/\---|- \___ SCHMITT TRIGGER | \ | LM3900 -+-- Vout | ___/ | +--|+ ___/ | | |___/ | | | | | 1.1M | 1.1M | +5V --\/\/\-----+-------\/\/\----+ | ----- 1uF ----- | | GND IR EMITTER CIRCUIT IR EMITTER CIRCUIT +5V 555 +5V | TIMER | / +-----------+ | \ 1| |8 | / 10ohms GND -----|GND Vcc|-----+ \ | | \ / | | / | 3| | \ 2.2K +-------------------|OUT | / | | |7 \ | | DISCH|-----+ | 4|- | \ D ||--+ +5V -----|R | / <||IR LED | | \ 200K ||--+ | | / | 2| |6 \ | +---|TRIG THRES|-----+----+ | | | | | | | | +-----------+ | | GND | | ----- | .1uF | ----- +---------------------+ | | GND Notes: Adding more IR LED's will increase range of IR detector. The signal on pin 3 of 555 is 30Hz and has a duty cycle of 50% Due to very small pull-up resistor 555 sinks about 109mA. The specs say 555 can sink up to 225mA so it's well below danger level. Cheap 40KHz clock (From Sebastian Filzek) Use a 40KHz Xtal and a 74C14 schmitt trigger: ________ <---- 2.2 M resistor ___| 2M2 |___ | |________| | | | | | | |\ |Output 40KHz | | \ | +-----| O------+--------> | | / | |/ gate 1 of 74C14 | | --+-- XXX 40KHz Xtal --+-- | | ----- --- - This circuit has worked for me in many applications. (it might be an idea to buffer signal befor using it. (There are still 5 unused gates in 'C14.. very STABLE 40khz generator A circuit that I have used before is based on CD4060 (14stage binary counter) and a 640Khz ceramic resonator. The CD4060 is basically an oscillator and a ripple counter to divide 640khz down to something more usable. Here is pinout of CD4060 (frequencies are assuming a 640khz input signal into pins 10/11/12 - circuit shown below): +-\/-+ 160hz 1 | | 16 Vcc 80hz 2 | | 15 625hz 40hz 3 | | 14 2.5khz 10khz 4 | | 13 125hz 20khz 5 | | 12 \ 5khz 6 | | 11 >---- 40khz 7 | | 10 / GND 8 | | 9 NC +----+ see sub-circuit below Sub-circuit for a 640khz ceramic resonator: 12 >----------------------+ 740pf | 11 >-------+----+---|(----+ | | | 640khz --- \ | res. O / 1Mohm | --- \ | | | | 10 >-------+----+---|(----+ 740pf | GND >----------------------+ (you may be able to obtain a resonator with builtin capacitors and three leads) A nice part about this circuit is that it delivers a STABLE 40khz signal, as well as delivering several other frequencies that can be used to modulate 40khz carrier. For example, person that designed this circuit (Ken Boone, member of Triangle Amateur Robotics) used it to build several beacons in his yard to serve as navigation points for a robotic lawnmower. By diode-OR'ing results of 40khz carrier and one of lower frequencies (such as 125Hz) line to drive a ring of IR-LEDs, he could locate beacon and tell which, of several, beacons he had found. This circuit has proven to be VERY stable, and is fairly inexpensive (about $1.50 for CD4060 and 640Khz ceramic resonator). infrared remote controls communicate using an identical carrier scheme. At transmitter, a 38Khz or 40Khz square wave is gated by a logic signal of no more than about 1Kbps. signal is fed to one or more infrared emitters. most efficient pulse duty cycle is 50%. The reciever circuit consists of a photodiode, a preamplifier, and a demodulator circuit. preamplifier contains a bandpass filter limits sensitivity to about +/- 2Khz, near centre . An AGC circuit adjusts incoming level to demodulator, which explains presence of long leading pulse in many of protocols. This allows reciever to stabilize its AGC circuit, prior to reception of bitstream. output of reciever is a binary bitstream, like to original modulation signal at transmitter It is often an open collector pull-down. signal is active low, so that "ones" in terms of carrier signal appear as "zeros" at demodulator. Protocol 1 code consists of two main types of packet. first is a normal packet which indicates that a certain key has been pressed. second is sent repeatedly while a key is held down. This repeat packet is devoid of information, consisting only of an AGC pulse and one stop bit. normal packet consists of an AGC pulse, a pause, and 50 consecutive information bits. Each one of these 50 bits is made up of two parts. first part conveys binary information. second part is a stop bit, always a zero. It is important when you are dealing with this protocol, that some equipment sends say 48 or 49. best policy is to treat these as incoming zeroes. It is possible that these bits somehow represent fewer bits through some unknown encoding scheme, for example, bit position modulation. Timing Summary: Single Keypress packet: Signal Duration Polarity ------ -------- -------- AGC Pulse 9.15ms 1 Pause 4.33ms 0 data bit 750us transmitted data stop bit 375us 0 "held down" packet: Signal Duration Polarity ------ -------- -------- AGC Pulse 9.15ms 1 Pause 2.10ms 0 stop databit 750us 1 time till next packet 38.6ms 0 ****************************************** Protocol 2 Sony specific protocol, transmitting 12 information bits comprising a 5-bit device ID followed by a 7-bit command code. These bits are transmitted least significant bits first. an AGC pulse of 2.4 ms. is first transmitted, followed immediately by 12 databits. Each databit consists of 600 us. of logic zero, followed by either 600 us. and 1200 us. of logic one,representing "0" and "1" databit respectively total packet length is fixed at 45 ms. Further information is available in Scott Coleman's file "zapper.txt". Signal Duration Polarity ------ -------- -------- AGC Pulse 9.15ms 1 databit = 0 0.6ms 0 0.6ms 1 databit = 1 0.6ms 0 1.2ms 1 total length 45.0ms ****************************************** Protocol 3 "Japanese-Format."(JF) (Toshiba) and (Pioneer) both use same format, while my TV (RCA) uses a completely different format. JF allows for 256 different devices to be controlled, so it is possible that each manufacture could have been allocated a range of numbers. Then again it might just be coincidence. A JF consists of 3 parts. first part is preamble. 8 ms wide pulse of carrier followed by 4ms of no carrier ( carrier is an IR light beam modulated at 40 KHz. RCA TV uses about a 36 KHz carrier. second part of code is 16 bits of data. first 8 bits are what I call Device Code(DC), followed 8 bits are logical not of preceeding 8 bits(DC). (This apparently is used as a checksum to insure data validity. and protect against random noise.) third part is 16 more bits of data, first 8 being what I call Function Code (FC). then followed by its logical NOT as was DC. provides ability to control up to 256 different devices, each having up to 256 functions. most functions are controlled with a single JF frame. The timing of data is as follows: Each bit cell is proceeded by IR pulse about (600us). then followed by a no-carrier period .4ms or 1.2ms long. A zero is sent if off period is .4ms, one is sent if off period is 1.2 ms. a 0 is bit cell who's total time is about 1 ms, a 1 is a bit cell who's total time is about 2 ms, i.e. pulse period modulation. The DC and FC are sent LSB first. So in time it looks like: DC LSB->MSB, NOT-DC LSB-MSB , FC LSB-MSB , NOT-FC LSB-MSB The DCs I know are: (all numbers in hex) A5 Pioneer amp A4 Pioneer tuner A2 Pioneer CD A1 Pioneer cassette deck. (I've wondered what A3 might be, open reel tape deck perhaps) 44 Toshiba SV-771 VCR The FCs share great commonalty across 8] Minimizing SUN's noise in IR reception A 'baffle' is a perforated disk or disks spaced inside your 'shade tube'. The idea is to trap all reflections, leaving only light coming in on exact axis of tube to strike IR Detector. __________________________________ | | | | DET <- IR LIGHT | | | | ---------------------------------- ^Baff ^Baff ^Baff Off-axis light, 'noise', will be caught by baffles and dissipated through reflection between baffles. Paint inside of your tube black ... in fact, check into what paints/coatings are 'black' to IR wavelenghts. Just because a paint LOOKS black does not mean it won't reflect IR. Check into an astronomy or optics group to get formula for ideal spacing of baffles and how big a hole should be in them. Getting this right will improve your system performance. Build an Infrared night scope Building a night scope is easy if you have heart of it which is image intensifier part. I would recommend using PVS-5 module which uses 'MCP' or Micro Channel Plate technology. This is a U.S. 2nd generation device and is rated at 15,000 times light gain. The resolution is one of best on market. It was used in Desert Storm and released to surplus market about 2 1/2 years ago. However, it can't be exported out of U.S. :-( The device can be found for between $350 to $700 depending on quality you want in terms how new it is or if it used. I will list a couple of vendors at end. I have built several of these scopes with and without targeting lasers. The laser will kill your battery in no time and I recommend not using one for normal use as PVS-5 has excellent response without it (unless you want to scare crap out of someone in total darkness running around your yard. Just put a laser dot on his forehead and let him figure out where it came from and what is at end of it....like a 30.30 :-) Anyway, you will need following: 10" length of 1 3/4" PVC plastic pipe (thinwall) 6" length of 3/4" PVC pipe and end caps (thinwall) 1- 35mm lens with shutter 1- eyepiece (see text) 1- lens mount (I use Minolta lens adaptors and lenses which I pick up at pawn shops dirt cheap) 1- 3/4" washer 1- small spring 1- micro pushbutton switch 1- 3 volt lithium battery (I use DL123A which Radio Shaft...ahhh..Shack sells for $7.99) 1- tube of silicon rubber (black) And of course, one PVS-5 MCP module When you receive your module do not pull on power wires or they will break off inside of power supply and you now have a several hundred dollar paper weight! Do no handle front screen if possible. If you do, wipe it clean with a optical lens cleaner. DO NOT TWEEK THE TWO POTS IN THE POWER SUPPLY!! These pots adjust ABC (Automatic Brightness Control) and AGC (Automatic Gain Control). If pots are set too high, a flashover will occur in Micro Channel Plates and burn out one or more which means that part of display is dead. This is noticed by a black spot on display when PVS-5 is turned on. With that out of way, lets continue... Using fine sandpaper or cheesecloth, smooth out inside surface of larger PVC pipe. Test fit PVS-5 module by sliding it into PVC pipe. It should fit snug but not tight. Continue sanding until fit is snug. Next, remove module and wipe down inside of pipe. Spray inside flat black and let it dry. Once its dry, mount front lens mount to PVC pipe and mount lens. Slide PVS-5 into other end and slide it to about 2">from lens. Focus lens to infinity and close shutter all way so that only a pinhole is open. Point it towards an object 10 feet or better away. Apply 3 volts to PVS-5 and slide it back and forth until clearest image can be seen on display screen. Move focus on lens in and out and insure image remains clear. Secure PVS-5 into housing with silicon rubber. DO NOT GET IT ON THE DISPLAY OR THE FRONT SCREEN! In case you are wondering why you can use PVS-5 in normal lighting (like a shop or lab) its because of automatic brightness function. The PVS-5 was designed to eliminate blooming problems with muzzle flash and bright light sources such as gun fire and explosions. Just don't open shutter all way (though it wouldn't hurt it). After silicon rubber is cured, we now start on 'fun' (ugh !) part. This is time consuming (about an hour) and requires a little patience. The eyepiece that I use is a 35mm lens that is 'reversed' I.E. you look through front of it rather than back. The reason I do this is to eliminate pincushion effect of PVS-5's concave screen. But you can use anything that will magnify image (even a 8X jeweler's eye loupe which I used on my first one with 'passable' results). Anyway, if you choose to use a 35mm lens like I did, then we have to rework lens. First unscrew whole body of lens. Most will have a small screw stop that won't allow you to unscrew it completely unless screw is removed. Once lens is separated from shutter and rear optic, clean grease off of threads. Next, try a fit test into PVC housing. If lens is too tight, grind threads down until lens fits snug, but not overly tight. Next, drill a small hole 1/2" from rear of PVS-5 at top to pass power wires through. Now, put lens onto PVC and press it as far in as it will go. Now apply power to PVS-5. The image will be blurred. Here is fun part. Remove power and lens and using a hacksaw or bandsaw, cut 1/2" off of PVC pipe and try it again. Continue doing this until it 'starts' to come into focus. Once it starts to come into focus, saw PVC in 1/8" sections. Continue until display is crystal clear. This has to be done whether you use a 35mm lens or not. Whatever you choose, housing has to be cut to focus eyepiece correctly. At this point, you need to remove eyepiece, front lens mount and front lens. Cover front and rear of housing with paper and masking tape. Now you can spray paint housing whatever color you choose. I do mine in flat satin black and they come out great ! Set it aside to dry. After its dry, remove paper and masking tape. Blow out any particles. Insure that PVS-5 is secure with silicon rubber. Touch up any scrapes of flat black paint on inner surface to eliminate reflections. Clean front and back of PVS-5 with optical lens cleaner. Re-assemble front lens mount and front lens. Insert eyepiece. Drill two 1/16" hole about 1/2" from rear of housing on either side of eyepiece. Secure eyepiece with two small 2-56 screws. Apply power and insure all is well so far. Now for battery holder. This is what 3/4" PVC pipe and end caps are for. Put an end cap on one end and place it on main housing so that front end cap is against front lens mount. Measure back from eyepiece about 3/4" and put a mark on small PVC pipe. Cut pipe on mark and place other end cap on small pipe. Put whole thing on main housing and check fit. If it is to close to eyepiece, mark and cut it where it is at a suitable distance. Next, mark exactly where wires are coming out of housing on bottom of battery holder pipe and drill a small hole there so that wires go straight into battery holder. Next, drill a hole for pushbutton about 1/2" from end of front end cap. Remove both caps and set aside for now. Measure 1 1/2" from rear of battery holder and place a mark here. Now saw with a hacksaw about 3/4 of way through battery holder to form a slot. Grind washer so it fits flush into slot (I.E. round top is even with round top of battery holder). Next nip a small slot out of side of washer so that ground wire can pass through it. Insert washer into slot and insure it is flush then epoxy it into place by putting a dab of epoxy OPPOSITE slotted side inside of battery holder. Next, take a small piece of insulated hookup wire and strip one end. Form a loop that will let a 4-40 screw pass through it and solder loop. Next place a 4-40 flat head screw into hole in center of washer with head pointing towards battery. Place loop of wire on other side and secure it with a 4-40 nut. Solder other end to one side of pushbutton switch. Connect positive wire from PVS-5 to other side of switch. Route ground wire from PVS-5 through slot in washer and out back of housing. Next we make rear battery connection by using a spring secured into rear end cap. I used a spring from a 'D' cell battery holder and secured it into place with a 2-56 screw and nut. I also soldered ground wire to spring after I determined length so that cap would just come off and let battery slide free. But use your ingenuity on this. Install battery with positive side pointing towards front of scope and put on rear end cape. Press button and viola, check for a working scope. Finally (whew) install front end cap and secure battery housing to main housing with a bead of silicon rubber along both sides of battery housing. Smooth silicone down so it looks like it was made like that. Let silicon dry. Next, paint housing whatever color you want. Again, I used flat satin black. DO not point your scope at sun or other really bright light source. Even though scope has automatic gain control, a bright IR source could burn MCP. One reason for using lens adaptor was so that a telephoto lens could be used or just a standard 35mm lens. Also, 35mm eyepiece lens makes it nice for mounting to other devices like a camera (with a 80mm extension) with threaded lens front. I have built maybe 14 of these and they are great scopes. Far better than Russian stuff in terms of resolution and clarity. Below is vendors for MCP modules: MWK Industries 1269 W. Pomona Corona, CA 91720 1-800-356-7714 1-909-278-0563 Cost: $395 item number NIGTU2 (ask for Martin) Meredith Instruments P.O. Box 1724 5035 N. 55th Ave. #5 Glendale, AZ 85301 1-800-722-0392 1-602-934-9387 Have fun with it and let me know how it goes :-) (particularly if you get some foxy lady that likes nude moonbathing and you get some nice 8 x 11's :-) My e-mail is wellison@kuhub.cc.ukans.edu. And if you need an IR filter for that spotlight so you can use it to 'help out' above project, here's a little something: The large amounts of IR plastic filter sheet are no longer available, but here's a hint. Go to a theatrical lighting supplier and buy two filter gels, one for "congo blue" and one for primary red. Overlap them and you get black. However, these dyes are transparent to IR. Lay them between thin plexi for a big filter sheet. They aren't entirely black, you can see sun through them. for darker filtering, overlap more sheets. The standard sheet is 18" x 24" (I think) and costs $3 to $5. and (From John De Armond) Edmund Scientific sells surplus sniperscope illuminator IR filters for about $20. This is a glass filter that can stand heat of a large lamp. Decoding IR Remote Controls The origin of this posting was question what to do with an old TV. I suggested to use infrared remote control as an input keyboard for a microcontroller board and mentioned a piece of code I had written for 8052 microcontroller. I was asked by some people to share my information about remote controls, so here it is: There are at least two international standards which are used by remote controls to encode commands, RC5 and RECS 80 code. The RECS 80 code uses pulse length modulation. Each bit to be transmitted is encoded by a high level of duration T followed by a low level of duration 2T representing a logical '0' or 3T representing a logical '1'. T 2T T 3T T 2T _ _ _ | | | | | | _| |__| |___| |__ 0 1 0 Notice that a '1' takes more time to be transmitted than a '0'. The RC 5 code instead has a uniform duration of all bits. A transition in middle of time interval assigned to each bit encodes logical value. A '0' is encoded by a high to low transition and a '1' by a low to high transition. Therefore we need additional transitions at beginning of each bit to set proper start level if a series of equal bits is sent. We don't need this additional transition if next bit has a different value. This is also called a 'biphase' code. |1.Bit|2.Bit|3.Bit|4.Bit| __ __ __ __ | | | | | | |__| |_____| |__| 0 0 1 1 Instead of being fed direct into IR emitter, most remote controls modulate a 20-30 kHz carrier with this signal. A logic one is represented by a burst of oscillations. ______/\/\/\/\_______/\/\/\/\________ 0 1 0 1 0 The reason is, that you can use a filter tuned to carrier frequency to distinguish signal from noise in ambient light. Fluorescent lamps are main source of such noise. Photodiodes behind an optical filter which transmits infrared light but blocks visible light are used as detectors. The signal from photodiode is fed through a filter tuned to carrier fequency and then amplified. The amplified signal is demodulated just like carrier is demodulated in any AM radio receiver. + | _|_ photodiode /_\ demodulator | |\ _|_ ____| \_____| |__ __|\|___ __L and C form a | | | / | | | |/| | circuit resonant | / |/ _|_ | out to the carrier === \ amplifier /_\ === |C / L | | |___|_________________|________|____ It can be a lot of pain to design a sensitive receiver that does'nt start to oscillate. It is also necessary to have some automatic gain control to avoid overload of amplifier at close distance to emitter. It is easier to use some integrated circuit that does all of job. The best i have ever seen (and used) is SFH505A manufactured by SIEMENS (no, I don't work for this company). It looks like one of this three legged voltage regulators and uses a single 5V supply. It incorporates an optical filter, photodiode, a filter tuned to about 30 kHz , amplifier with automatic gain control and demodulator. If you don't know which code your remote control is transmitting you can identify it by viewing output of your receiver with an oscilloscope. The RECS 80 code uses high pulses of uniform length while low pulses differ in length. If there are high and low pulses of two different lengths it might be RC5 code. Note that your receiver may invert levels. How are commands like volume control or channel selction encoded? In case of RC5 code there is an international standard. Every command is encoded by 14 bits. The first two bits S are startbits to allow receiver to adjust automatic gain control and to synchronize. Next a bit T follows, that toggles with every new keystroke. Next is address A of device which shall respond to command. At last command itself follows. | S | S | T | A4 | A3 | A2 | A1 | A0 | C5 | C4 | C3 | C2 | C1 | C0 | Some important addresses and commands: Address: Device: Command: 0 TV1 0...9 Numbers 0...9 (channel select) 1 TV2 12 Standby 5 VCR1 16 Master Volume + 6 VCR2 17 Master Volume - 17 Tuner 18 Brightness + 18 Audio Tape 19 Brightness - 20 CD Player 50 Fast rewind 52 Fast run forward 53 Play 54 Stop 55 Recording There are integrated decoder circuits which have inputs to select device address and parallel outputs activated by commands. Since this is comp. robotics devices you wish to control will have a microcontroller on board which can do all decoding. Here is an input routine I have written for 8052 microcontroller family to receive RC5 codes. My cousin has written a similar routine for RECS80 code which i will try to make available also. Perhaps we can start a collection of such routines and archive them somewhere. ---------==========----------==========---------=========--------- ; Interrupt Driven Receiving Routine for RC5 code ; written by Juergen Putzger (juergen.putzger@physik.uni-regensburg.de) ; Address: Device: Command: 0 TV1 0...9 Numbers 0...9 (channel select) 1 TV2 12 Standby 5 VCR1 16 Master Volume + 6 VCR2 17 Master Volume - 17 Tuner 18 Brightness + 18 Audio Tape 19 Brightness - 20 CD Player 50 Fast rewind 52 Fast run forward 53 Play 54 Stop 55 Recording ---------==========----------==========---------=========--------- $MOD52 INPUT EQU P3.2 ; Port3,Bit2 is used as input. The demodulated signal ; with active low level is connected to this pin LF EQU 0AH ; Linefeed CR EQU 0DH ; Carriage return SPC EQU 20H ; Space RB0 EQU 000H ; Select Register Bank 0 RB1 EQU 008H ; Select Register Bank 1 ...poke to PSW to use DSEG ; This is internal data memory ORG 20H ; Bit adressable memory FLAGS: DS 1 CONTROL BIT FLAGS.0 ; toggles with every new keystroke NEW BIT FLAGS.1 ; Bit set when a new command has been received COMMAND: DS 1 ; Received command byte SUBAD: DS 1 ; Device subaddress BUFFER: DS 30 ; Buffer to store length of transmitted pulses STACK: DS 1 ; Stack begins here CSEG ; Code begins here END Also see http://www.awi-bremerhaven.de/~cdodge/PCIR/ IR 'slotted switch' sensor There is a type of detector known as a "slotted switch" that consists of a phototransistor/LED pair mounted on a solid frame with a small air gap between two elements. A typical circuit might be: o +5v o +5v | | | | \ \ 220 ohms / / 4.7K \ \ / / | | | +-------> Vout _|_ / \ / |/ ----- |\ NPN | \ | | | | | | GND GND | air gap | When air gap is unobstructed, transistor saturates, pulling Vout to ground; when gap is blocked, transistor cuts off and Vout is +5 volts. ----- IR REMOTE CONTROLS DECODING IR REMOTE CONTROLS by Juergen Putzger The origin of this posting was the question what to do with an old TV. I suggested to use the infrared remote control as an input keyboard for a microcontroller board and mentioned a piece of code I had written for the 8052 microcontroller. I was asked by some people to share my information about remote controls, so here it is: There are at least two international standards which are used by remote controls to encode the commands, the RC5 and RECS 80 code. The RECS 80 code uses pulse length modulation. Each bit to be transmitted is encoded by a high level of the duration T followed by a low level of duration 2T representing a logical '0' or 3T representing a logical '1'. T 2T T 3T T 2T _ _ _ | | | | | | _| |__| |___| |__ 0 1 0 Notice that a '1' takes more time to be transmitted than a '0'. The RC 5 code instead has a uniform duration of all bits. A transition in the middle of the time interval assigned to each bit encodes the logical value. A '0' is encoded by a high to low transition and a '1' by a low to high transition. Therefore we need additional transitions at the beginning of each bit to set the proper start level if a series of equal bits is sent. We don't need this additional transition if the next bit has a different value. This is also called a 'biphase' code. |1.Bit|2.Bit|3.Bit|4.Bit| __ __ __ __ | | | | | | |__| |_____| |__| 0 0 1 1 Instead of being fed direct into the IR emitter, most remote controls modulate a 20-30 kHz carrier with this signal. A logic one is represented by a burst of oscillations. ______/\/\/\/\_______/\/\/\/\________ 0 1 0 1 0 The reason is, that you can use a filter tuned to the carrier frequency to distinguish the signal from noise in the ambient light. Fluorescent lamps are the main source of such noise. Photodiodes behind an optical filter which transmits infrared light but blocks visible light are used as detectors. The signal from the photodiode is fed through a filter tuned to the carrier fequency and then amplified. The amplified signal is demodulated just like the carrier is demodulated in any AM radio receiver. + | _|_ photodiode /_\ demodulator | |\ _|_ ____| \_____| |__ __|\|___ ____ L and C form a | | | / | | | |/| |signal circuit resonant | / |/ _|_ | out to carrier === \ amplifier /_\ === |C / L | | |___|_________________|________|____ It can be a lot of pain to design a sensitive receiver that does'nt start to oscillate. It is also necessary to have some automatic gain control to avoid overload of the amplifier at close distance to the emitter. It is easier to use some integrated circuit that does all of the job. The best i have ever seen (and used) is the SFH505A manufactured by SIEMENS (no, I don't work for this company). It looks like one of this three legged voltage regulators and uses a single 5V supply. It incorporates an optical filter, the photodiode, a filter tuned to about 30 kHz , the amplifier with automatic gain control and the demodulator. If you don't know which code your remote control is transmitting you can identify it by viewing the output of your receiver with an oscilloscope. The RECS 80 code uses high pulses of uniform length while the low pulses differ in length. If there are high and low pulses of two different lengths it might be RC5 code. Note that your receiver may invert the levels. How are commands like volume control or channel selction encoded? In the case of the RC5 code there is an international standard. Every command is encoded by 14 bits. The first two bits S are startbits to allow the receiver to adjust the automatic gain control and to synchronize. Next a bit T follows, that toggles with every new keystroke. Next is the address A of the device which shall respond to the command. At last the command itself follows. | S | S | T | A4 | A3 | A2 | A1 | A0 | C5 | C4 | C3 | C2 | C1 | C0 | Some important addresses and commands: Address: Device: Command: 0 TV1 0...9 Numbers 0..9 (channel select) 1 TV2 12 Standby 5 VCR1 16 Master Volume + 6 VCR2 17 Master Volume - 17 Tuner 18 Brightness + 18 Audio Tape 19 Brightness - 20 CD Player 50 Fast rewind 52 Fast run forward 53 Play 54 Stop 55 Recording There are integrated decoder circuits which have inputs to select the device address and parallel outputs activated by the commands. Since this is comp. robotics the devices you wish to control will have a microcontroller on board which can do all the decoding. Here is an input routine I have written for the 8052 microcontroller family to receive RC5 codes. My cousin has written a similar routine for the RECS80 code which i will try to make available also. Perhaps we can start a collection of such routines and archive them somewhere. Juergen Putzger (still looking for that public domain 8052 C-compiler....) ------------------------ source text begins here ------------------------- ; ---------==========----------==========---------=========--------- ; Interrupt Driven Receiving Routine for RC5 code ; written by Juergen Putzger (juergen.putzger@physik.uni-regensburg.de) ; ---------==========----------==========---------=========--------- $MOD52 INPUT EQU P3.2 ;Port3,Bit2 is input. demodulatedsignal ; active low level connected to this pin LF EQU 0AH ; Linefeed CR EQU 0DH ; Carriage return SPC EQU 20H ; Space RB0 EQU 000H ; Select Register Bank 0 RB1 EQU 008H ; Select Register Bank 1 ..poke to PSW DSEG ; This is internal data memory ORG 20H ; Bit adressable memory FLAGS: DS 1 CONTROL BIT FLAGS.0 ; toggles with every new keystroke NEW BIT FLAGS.1 ; Bit set when new command received COMMAND: DS 1 ; Received command byte SUBAD: DS 1 ; Device subaddress BUFFER: DS 30 ; Buffer to store length of trans pulses STACK: DS 1 ; Stack begins here CSEG ; Code begins here ;---------==========----------==========---------=========--------- ;PROCESSOR INTERRUPT AND RESET VECTORS ;---------==========----------==========---------=========--------- ORG 00H ; Reset JMP MAIN ORG 0003H ; External Interrupt0 JMP RECEIVE ; ---------==========----------==========---------=========--------- ; Output routines ;Don't forget to set up serial port and Baud rate ! ; ---------==========----------==========---------=========--------- N_OUT: ADD A,#30H ;Convert BCD number to ASCII C_OUT: JNB TI,$ ;Wait until transmission completed. CLR TI ;Clear interrupt flag. MOV SBUF,A ;Write out character to serial port. RET BIN2BCD: ;Convert 8 bit value in Acc to 3 digit BCD MOV B,#100 DIV AB CALL N_OUT XCH A,B MOV B,#10 DIV AB CALL N_OUT XCH A,B CALL N_OUT RET ; ---------==========----------==========---------=========--------- ;Interrupt routine entered by first high to low transition ;at Port3-Bit2. Stores length of all pulses occuring ;in buffer Analyzes thetiming of startbits to calculate ;threshold between short and long pulses. routine is ;independent of CPU speed. device address and command are ;extracted from bit stream. Two flags are set upon exit, ;control bit which toggles with every new keystroke and ;NEW bit indicating that a new command has been received. ; ---------==========----------==========---------=========--------- RECEIVE: PUSH PSW ; save current registerset MOV PSW,#RB1 PUSH ACC MOV R0,#BUFFER REC: MOV A,#0 REC0: INC A ; Measure duration of low-level NOP NOP ; Delay NOP NOP JZ TIMEOUT ;End transmission if exeeds256 counts JNB INPUT,REC0 MOV @R0,A INC R0 MOV A,#0 REC1: INC A ; Measure duration of high-level NOP NOP ; Delay NOP NOP JZ TIMEOUT ; End of transmission JB INPUT,REC1 MOV @R0,A INC R0 JMP REC TIMEOUT: MOV A,BUFFER ; calc between short/long pulses INC R0 ; length of first low-pulse ADD A,BUFFER+1 ; plus length of first high-pulse CLR C RRC A ; divided by two MOV R1,A CLR C RRC A ; plus half of the time ADD A,R1 MOV R5,A ; yields threshold MOV R0,#BUFFER MOV R1,#1 ; initial value MOV R2,#13 ; Number of bits to decode DECODE: MOV A,@R0 INC R0 CLR C SUBB A,R5 ; compare length with threshold MOV A,#0 CPL C ; short=1 RLC A JNZ NOSKIP INC R0 ; if short skip over next pulse NOSKIP: XRL A,R1 ; new bit XOR with previous bit MOV R1,A ;Store new bit RRC A MOV A,R3 ; Store new Bit in R3/R4 by rotating RLC A MOV R3,A MOV A,R4 RLC A MOV R4,A DJNZ R2,DECODE MOV A,R3 ANL A,#00111111B ; extract command from R3 MOV COMMAND,A MOV A,R3 RLC A ; do some rotating to extract XCH A,R4 RLC A ;device address XCH A,R4 RLC A XCH A,R4 RLC A CLR CONTROL JNB ACC.5,TZ ; Check control bit SETB CONTROL TZ: ANL A,#00011111B ; mask device address MOV SUBAD,A POP ACC ; Restore old registerset POP PSW SETB NEW ;Set flag to indicate new command RETI ; ---------==========----------==========---------=========--------- ;Main routine.Program execution here.Don't forget to add ;code to initialize serial port and Baud rate if monitor ;program doesn't do that.Main loop waits until a command ;been received.control bit, subaddress and command byte ;are printed separated by spaces. zeroes not suppressed. ;When standby command (12) received, main loop is ;terminated and program returns to monitor. ; ---------==========----------==========---------=========--------- MAIN: MOV TCON,#00H ; MAKE SURE TIMERS ARE SHUT DOWN. MOV PSW,#RB0 ; Select register bank 0 MOV SP,STACK SETB EX0 ; Enable external Interrupt0 CLR IT0 ; triggered by high to low transition SETB EA CLR NEW LOOP: JNB NEW,LOOP ; Wait until command been received MOV A,#CR CALL C_OUT ; Ouput carriage return and linefeed MOV A,#LF CALL C_OUT MOV A,FLAGS ANL A,#00000001B CALL BIN2BCD ; Output control Bit MOV A,#SPC CALL C_OUT MOV A,SUBAD CALL BIN2BCD ; Output subaddress MOV A,#SPC CALL C_OUT MOV A,COMMAND CALL BIN2BCD ; Output command MOV A,COMMAND CLR C SUBB A,#0CH ; compare for standby command CLR NEW JNZ LOOP ; go on receiving CLR EX0 ; stop receiving CLR EA ; and JMP 8000H ; return to monitor which has entry ; point at 8000H END ========================IRDA===================================== 500_mW/cm^2 = 500_mW/sr@ 1cm sr =sterradians Radian_Sensitive_Area_mm^2 7_mm^2 \ | / |\ Max_power_mW _____ \ | / | \ ___\ | | | ___ LED ___ \ | ___ > 8.75_mW _|_ / | Max_Idiode / | \ \| / ^ \ | 4.4_mA / | \ /_\ / V <---20mm---> |_____| Max_power_mW/sr Spect_Sensitive_uA/uW 500_mW/sr 0.5_uA/uW Max_power_mW = 500_mW/sr*(7mm^2/(20m)^2) Radian_Sensitive_Area_mm^2 \ | / |\ Min_power_mW _____ \ | / | \ ___\ | | | ___ LED ___ \ | ___ > 0.04_uW _|_ / | Min_Idiode / | \ \| / ^ \ | 0.14_uA / | \ 7_mm^2 /_\ / V |_____| Min_power_mW/cm^2 Spect_Sensitive_uA/uW 0.4_uW/cm^2 0.5_uA/uW Radian_Sensitive_Area_mm^2 \ | / |\ Sun_power_mW _____ \ | / | \ ___\ | | | ___ SUN ___ \ | ___ > 7mW _|_ / | Sun_Idiode / | \ \| / ^ \ | 3.5mA / | \ 7_mm^2 /_\ / V |_____| Sun_power_mW/cm^2 Spect_Sensitive_uA/uW 1mW/cm^2 0.5_uA/uW ^ 5V /|\ | re_ohms= .026/Idc = 2600_ohms _| ____|' NPN I_shot_A/rt(Hz) = sqrt(q*2*Idc) | |`-> I_shot = 1.7pA/rt(Hz) _|_ | 10uA V_shot = 4.65_nV/rt(Hz) /// / | \ V V_therm_nV /rt(Hz)=4*sqrt(R/1K_ohm) 1Mohm / V_therm = 126.5_nV/rt(Hz) \|/ V -10.7V ^ 5V /|\ | _| ____|' NPN | |`-> re_ohms= 2600_ohms _|_ _|_ /// / \ V_shot = 4.65_nV/rt(Hz) \___/ __ |____| | 10uA | |__| V_shot(2.6K) = 4.65_nV/rt(Hz) | / NOTE ! V \ V_therm(2.6K)= 6.44_nV/rt(Hz) / 1Mohm _|_ / \ V_therm = 126.5_nV/rt(Hz) \___/ | | \|/ V -10.7V re_ohms= 2600_ohms ____________ _|_ | _|_ /// | / _ \ _|_ \/ \/ | I_shot = 1.7pA/rt(Hz) \ / /\_/\ V _V_ \___/ ___ |_______|____| | V_shot = 4.65_nV/rt(Hz) _|_ |___| / _ \ 10uA \/ \/ | /\_/\ V \___/ | \|/ V -10.7V _____ ___\ | | | ___ >.043pW/rt(Hz) _|_ / | Noise_Idiode / ^ \ | .021pA/rt(Hz) /_\ / V |_____| Noise_power_W/rt(Hz) Spect_Sensitive_uA/uW .043pW/rt(Hz) 0.5_uA/uW Dark_Current 2nA ________________ | _|_ _|_ _|_ / _ \ / _ \ ^ | \/ \/ \/ \/ Dark_shot_I=.025pA/rt(Hz) /_\ | /\_/\ /\_/\ | V \___/ \___/ |_______|________| Noise_Floor_Dark = Dark_shot_I*SQRT(BandWidth_Hz) = .025pA/rt(Hz)*SQRT(10_MHz) = .075nA_@10MHz Noise_Floor_Sun = Sun_shot_I*SQRT(BandWidth_Hz) = 34pA/rt(Hz)*SQRT(10_MHz) = 106nA_@10MHz Noise_Floor_LTC = 1.79pA/rt(Hz)*SQRT(10_MHz) = 5.6nA_@10MHz If I_signal >> I_noise .. jitter is low (spec +/1%) Want Bit_Error_Rate (BER) less than 10^-8 _______ | | C_diode=C_zero/(1-V_diode/phi)^M _|_ __|__ ^ _____ C_zero_pf = 72 /_\ | phi_mV = 700 | | M = .45 |_______| C_diode_@2V = 40pF Start Stop bit <----------Data_Perfect_Signal------------> bit _ _ lsb_ _ _ _ _ _ _ msb | | | | | | | | | | | | | | | | | | | | _| |__| |__| |__| |__| |__| |__| |__| |__| |__V__V || <---Jitter-> || Defined at rising edge _ _ _ _ _ _ | | | | | | | | | | | | | | _| |_| |___| |________| |___________| |__| |__V__V ^ Measured Signal /|\ |____ Used as reference TEST PATTERNS for Jitter 01111111 7F 01010101 5A 00001111 0F 00110011 33 01110111 77 01000000 40 00000000 00 distance 0 to 1meter Signal Modulation Pulse Jitter BW_MHz Rate 115.2kb/s RZI 1.63us +/-445n 5 1.152Mb/s RZI 217ns +/-56n +/-25ns 4Mb/s 4PPM 125ns +/-10n +/-10ns 100 ____ _________ ____ | 1 | 0 0 | 1 1 | 0 | 1 | 0 NRZ _| |_________| |____| |____ ^ ^ ^ ^ ^ ^ ^ ^ ^ Transmit a infared when ever a zero. _ _ _ _ | | | | | | | | ________| |__| |____________| |_______| |____ 1.152Mb/s ^ ^ ^ ^ ^ ^ ^ ^ ^ expect +/-12.5ns jitter from 40MHz clock and +/-5ns jitter LED and driver _________ _________ | 1 | 0 0 | 1 | ___| |___________________| |_______ 4Mb/s ^ chip1 ^ chip2 ^ chip3 ^ chip4 ^ <--------------Dt=500ns----------------> Data Bit Pair 4PPM Data (DBP) Symbol(DD) 00 1000 01 0100 10 0010 11 0001 noise peaking interference filtering tail simulations