[time-nuts] GPS down converter question

[Attila Kinali]

On Mon, 30 Nov 2015 19:54:54 -0500
paul swed <paulswedb at gmail.com> wrote:

> Magnus you are right.
> Its interesting in that several parts are easily available at
> semi-reasonable cost.
> Mini- circuits has a all in one synthesizer module dsn-2036 for the LO and
> they also have very nice IF filters. The BPF-a76 appears to be exactly the
> right bandwidth for a GPS IF.
> There are some things to work through but they seem reasonable.
> Regards

I suggest adding a 2MHz SAW filter infront of the first LNA. This will
save you a lot of trouble with noise and out of band interference.
These SAW filters relatively common and available form Mouser and digikey.

If you are not afraid of soldering QFN and having a uC (anything that
can push some bits over I2C), then I would suggest using a tuner IC
like the MAX2121B. This does most of the job and all you have to do
is to add some output bandpass (unless you trust the SAW filter
at the front) and some feedback for the AGC.

			Attila Kinali



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