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Guidelines for Aligning the Ronja devices

Aligning the Loopipe

AS Loopipe operates on 875 nm, which is infrared, the alignment is more difficult than in the case of Lucifer. You first have to replace the IR diodes (HSDL4220) with high-brightnes diodes with the same package size (I used HLM-DL16 but it is not important). The beam is very well visible if you stare into. Then someone must be at the other side to signal you the target hit. As soon as you hit the target you tighten up the screws and have the alignment complete. Then you must alight the transmitter in the opposite direction and replace the LED's back with HSDL4220's.

You have to align the receivers. Tell the Linux at the transmitter side to transmitsome garbage texts and waggle with the receiver. Connect a high-impedance speaker to the output of the amplifier (to the live wire of the coaxial cable) and listen to the data. Secure the position with the strongest signal. Then repeat the procedure for the other direction.

Aligning the Lucifer

Simple. Place a retroreflector to the location of the receiver and place the visible spot onto the retroreflector, to see the brightest light. Then secure the bolts. Put some data into the transmitter and place some kind of meter (I don't exactly know what as this are only hypotheses at the moment) and waggle the receiver diode to get the strongest signal. Remember that as soon as you approach you hand to the receiving diode you get a signal, but it is not a signal from the other side, but from some local radio station. Then remove or turn the retroreflector in order to eliminate unwanted reflections which could derate the Bit Error Rate.

Aligning the Sunprick

Place a retroreflector to the location of the receiver. Move the laser during night to hit the retroreflector, which is indicated by brightness of the spot suddenly cranking up. Connect a speaker to the receiver output and find a place where silence is heard instead of the noise. Procedure is almostcomplete. Now connect a tape recorder to the output and tune the receiver alignment to get the most accurate sound.
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