Tuesday, July 03, 2007

Using the Crystal Oscillator

Our Band is 73-74.6. How do we use a Oven Controlled Crystal Oscillator, referred in the earlier post? We need to generate an LO signal (between 70-80 MHz) to bring RF signal to an IF of 2-5 MHz. We also need to use one frequency for our sampler.

We have a few frequencies at our disposal, 10, 12.8, and 16.384 MHz, etc. We should use 10 MHz for sampling, after some downconversion (0.5 MHz for 0.25 MHz band). This would be easy, using a digital counter. How do we go about LO? we need one frequency such that a bandwidth of 0.25 MHz in the above band gets down converted at IF.

It depends upon a combination of IF, and bandwidth we choose. The problem is, if the band has a lot of interference, we should be able to switch to some other location nearby (within 73-74.6). A smaller bandwidth makes this possible, while bringing down data rates.

I have a couple of solutions, I will detail two in the next post.

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