[time-nuts] Reciprocal Counters

Bob Camp lists at rtty.us
Thu Jun 10 16:28:07 UTC 2010


You could always set up a Beckman EPUT meter to do period and get
effectively the same sort of result. No solid state in them at all. Full of
warm glowing stuff (some of it glowed yellow, some of it glowed purple).


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of gsteinba52 at aol.com
Sent: Thursday, June 10, 2010 11:13 AM
To: time-nuts at febo.com
Subject: [time-nuts] Reciprocal Counters

Hi Jim,

You're showing your age (you young whippersnapper!).

?? "They've been around at least since the 80s,..."

Well, my General Radio 1159 Recipromatic Counters are from 1968 - built
using those new transistor thingies and with the warm glow of Nixie tube

Message: 2 
Date: Thu, 10 Jun 2010 06:55:15 -0700 
From: jimlux <jimlux at earthlink.net> 
Subject: Re: [time-nuts] TPLL secret reveled 
To: Discussion of precise time and frequency measurement 
    <time-nuts at febo.com> 
Message-ID: <4C10EEC3.2030004 at earthlink.net> 
Content-Type: text/plain; charset=ISO-8859-1; format=flowed 
Ulrich Bangert wrote: 
> The next improvement to the old fashioned pure counter was the
invention of 
> subclock interpolation schemes. A counter using this works so: After
> beginning of the gate time it waits of the next zero crossing and then 
> measures the time up to the last zero crossing within the gate time
with a 
> fixed resolution of say 1 ns (like the well known Racal Dana 
> 1992/1996/1998). The frequency value is then the result of a
computation. If 
> you consider this working principle you notice that this is even more a

> phase meter like thing than the original counter only thing. For that
> frequency measurements with a counter like that are suited as well for
> calculation. 
I've always referred to these style counters as "reciprocal" counters..  
(because the frequency is calculated as the reciprocal of the length of  
N periods of the input signal).  They've been around at least since the  
80s, especially for applications where you need short gate time, but  
measurement precision greater than 1/gate time. It was very popular for  
applications like intercept receivers in the signals intelligence area  
before straight digital processing (ADC and FFT) was practical. 

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