A while ago we came across a website on infrared remote controls which suggested a simple way to view IR signals using an Oscilloscope. The idea is to use a standard IR Led mounted into a BNC/RCA plug using a spare channel making an Oscilloscope infrared receiver. So we set about ordering the connectors, which arrived in the post today. Another way of looking at this device is as a ‘poor-mans’ IR receiver, but if you have an Oscilloscope to plug it into then maybe you are not so poor after all.
Many electronics enthusiasts will be familiar with how Infrared receivers demodulate IR signals. In this post we show a visualisation of the time lag and distortion of the signals as they pass through the IR receiver for demodulation and noise filtering. Most DIY projects use the raw timings from the IR receiver to decode individual signals. However, not many will be aware that IR receivers can distort the signal timings by significant amounts. Fortunately, common IR decoders take this into account and compensate for timing distortions introduced by infrared demodulators / receivers.
Since introducing support into AnalysIR for the USB IR Toy we haven’t played too much with setting the different infrared carrier frequencies. After reading some mixed experiences on the Dangerous Prototypes forum we decided to put it to the test. So to start off we implemented a feature in AnalysIR to set the carrier frequency and to default to 38kHz at start up. Next we checked the mechanism described on the DP website about configuring the carrier frequency and everything seemed to work out OK. Continue reading USB IR Toy – Infrared Carrier frequency review