[time-nuts] 75Z vs 50Z for GPS receivers

Magnus Danielson cfmd at bredband.net
Tue Feb 6 05:33:08 EST 2007

From: Brooke Clarke <brooke at pacific.net>
Subject: Re: [time-nuts] 75Z vs 50Z for GPS receivers
Date: Mon, 05 Feb 2007 20:20:53 -0800
Message-ID: <45C80225.6080101 at pacific.net>

> Hi Didiere:
> There's also an app note at Linear Technology for making pulses so fast 
> they are used to calibrate sampling scopes.
> Some years ago I made a very simple circuit that pulses a LED with many 
> amps (very short time) based on a transistor going into avalanche.

You can actually use a 1N4148 for below 1 ns risetimes. NBS/NIST used a 1N4148
as a 100 MHz to 700 MHz stepup in a ionic measurement setup GPS receiver design
so that they fed 100 MHz up to the antenna, stepped it up to 700 MHz and used
that into the mixdown step in the antenna assembly. I think their use of a
1N4148 was a twist of a culprit just to show it is the methods and not the
tools which is important. :)

This design is burried somewhere in the NIST archive.


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