Wednesday, November 15, 2006

Human Tracking on Campus (update)

Students returned here again. This time they had prepared a lot more for display. They have now decided, as I suggested, to reduce the size of the gadget that everyone would carry with them.

As per the original design, the signal generator gadget sends digital codes as an identification for an individual sender. The transmission is at a given higher frequency, using FM. This would mean that all receiving stations (which are used in triangulation) operate at one frequency, and a person's id is the digital signal sent at that frequency.

Now, we will use individual frequency transmission as an id. we may have to do further tricks, since this might mean very narrow bands and FM using highly accurate filters, etc. one could explore if we could do a crude digital signaling. One could just change the ON/OFF frequency of individual receivers, providing another way of identification...

This circuitry could work close to 65 MHz, providing most of the amplifiers and filters that we need for our radio telescope ;-)

Monday, November 13, 2006

Amateur Radio Telescope at 61 MHz

We finally tested the interference environment around BITS using a TV Yagi antenna. This was at 3 pm on Monday 13th November, 2006.

The frequency region around 60-70 MHz appeared the most calm of all, particularly 61-62 MHz. We need about 500 KHz bandwidth, and we will keep it on 61 MHz. The band at 120-130 MHz appeared to be good as well. It is possible to utilize the same antenna and receiver system at 122 MHz as well, just in case there was intermittent terrestrial source at 61 MHz.