More Northern Lights


G3PHO's Laser as seen from Emley Moor

After days of gales and rain, yesterday was bright and clear here, so Peter and I used my Tx and Rx last night (Sept 15) to send signals over a 20.3km path between Edgemount, about 8k NW of Sheffield, to the base of the Emley Moor TV mast.

G8AGN's Laser Receiver

We started proceedings at dusk and I used one of these 'cheapo' 1 million candlepower spotlights to indicate to Peter (Tx) exactly where I was at Emley. Immediately I saw the laser dimly as it was not yet precisely aligned. A weak tone was also received straight away. Peter is still having trouble aligning the laser as his pan and tilt head is rather imprecise, but I have almost finished modifying the optical lever system(driven by micrometers for X and Y) which I made some years ago for the HeNe tube - this will be used in the next test (whenever that is!). The laser beam was markedly elliptical. (I've never touched the optics in the laser pen that I use as the Tx).

G8AGN's Laser Transmitter

As the sky got darker, we aligned the sytem better using 2m for relaying the signal back and got cw at about S6 across to verify that we were indeed receiving what we hoped. The received note is very scratchy but I know that the power waveform for the laser is not exactly a square wave.

Updated 17 SEPT 2004

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