The detector and the LNB require 13V (a range of voltages work. I have not tested the limits) to work. This is usually supplied by the receiver box so has to be supplied. This is my set up in bench testing, looking a bit crude but working. The bent paper lip is at +13V the core of the coax from the LNB is pushed into the connector.
To turn this into a measurable signal I used an old crystal microphone an amplifier board and a multimeter that could measure a.c. In the mV range. I would say that all of this equipment has been in the school since the 1980s.
It would be easy to use a computer mic and a laptop to do the same job but this looks like science to the pupils. Each measurement has to be done by hand so the pupils have a better feeling of how the system works.
To identify the satellites we use LyngSat.com which has details of satellite positions relative to your position and info on what channels they carry, this seems to be the most fascinating bit to the pupils.
I'm finding all this fascinating! Reminds me of my early experiments in the world of radio...
ReplyDeleteLyngsat is a great resource. Not many people realise that in the UK you can get hundreds of free TV and radio channels with a very simple setup. Not a lot of them transmit in English of course, but that's part of the fascination.
Thanks Gavin. Do you just need a FreeSat box to view the channels from the satellites?
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