IR TxR

[SandCitySurf]

Is it possible to boost an IR signal by pulsing it?

[Dean Huster]

If you mean by pulsing it at a high current rate for more light-output-per-pulse, then yes. However, you don't want to exceed the maximum average power that the LED can withstand. So constantly pulsing the LED at its maximum average power level or operating it constantly at it's average power level will be the same thing. If you only need a very short duration operation, then pulsing the thing might "punch through" farther, extending the range.<p>But if you're intending to do this with a standard IR remote control signal, you may have problems, since the remote signal is already "pulsed" at a 40 KHz rate and then this signal is "modulated" with the code for the various desired functions. Pulsing this signal might incur some odd artifacts and render the signal useless at the receiving end.<p>If extending the range of a remote is your goal, then one idea might be to send out a single command burst at a high power with each push of the button and assume that one burst is all that's needed at the receiving end for proper decoding (rather than several correctly-received bursts). That would do what you need, but would require a PIC and some programming to achieve.<p>Dean

[Edd]

Sir Spam …:
Your suggestion of IR strength tends to suggest a range problem to the IR receiver . I might suggest a simple optical solution.
At a distance, the IR transmitter LED’s beams energy “cone” is spreading progressively more laterally (and weakening). All of the energy not hitting your sensor was wasted energy, so you might do as I have done in the past and use a small ¼-1/2 in focal length lens in front of the IR LED to collimate that otherwise wasted outwardly radiating IR signal into a tighter, more intense forward beam. I typically will sub in a visible LED replacement for the IR unit in order to be able to easier see the focus optimization of the optical adjustment aspect, and then replacement of the original IR LED back into that same mechanical positioning. A final evaluation can be made at the receive end using a camcorder for viewing (Its detector CCD mosaic is IR sensitive), which will then permit you to move about the receivers position and sight back to the LED xmitter for positional evaluation of coverage and make any fine tuning, if necessary. Some might suggest the lens use at the receive end , but of the choice of the two the transmit end is far better.(Unless you need wide spatial coverage all across the receive end location.)
73's de Edd
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<p>[ December 08, 2003: Message edited by: Edd Whatley ]</p>

[SandCitySurf]

Thanks for the replies. The IR signal in question is the one integral to the Samsung SPH-i300 cell phone. I am using Philips Pronto software for IR remote control of AV devices, light switches, etc. The only thing mssing is the revolving-code security for IR locking devices. Otherwise, this cellphone/hand-held computer is one amazingly handy little device. <p>Currently the range is about 10 feet. It needs to be closer to 30 feet to be ready for prime-time. This one-time $400 Samsung phone has been showing up on Ebay for as little as $40 per handset.

[Chris Smith]

The simple answer is yes, but its a little bit more complex in the design. <p>Pulsating a LED at amperages of 1 amp and greater for nano second durations will increase its range to a 1/4 mile or more, but then getting all those extra transistor drivers back into the remote is the hard part?

[SandCitySurf]

Without making major revisions to an existing circuit is one of the parameters. The IR transmitter is the IRda types common to Palm Pilots, etc. Is it possible to control the pulse strictly by software alone?