[time-nuts] What equipment can I economically use to measure jitter and noise sidebands?

Peter Vince pvince at theiet.org
Sun Jul 15 05:12:35 EDT 2007

Thanks for your reply, John.

>Too many dimensions to that question. :)
>What carrier frequencies...

3.57 MHz, 4.43 MHz, 5.0 MHz, 10.0 MHz, 135 MHz, and maybe 742 MHz.  Yes,
you guessed, those used in television.

>...and offsets are you interested in;

What can be done without a King's ransom?

>what noise levels are you interested in measuring; and what's the

What can be achieved with, say, $2000 for good second-hand equipment from
ebay? Or is that just wishful thinking?  Is the equipment necessary to do
these sort of measurements going to cost a lot more than that?

>An 8662A ($2000 minimum for a good one, usually) plus an 11729B/C
>($500-$2000 depending on options?) plus a good baseband spectrum
>($1000-$2000) is clean enough to measure many sources, and much better
>than any spectrum analyzer by itself.  That is the minimum amount of
>money you will have to spend for serious HF-to-microwave measurement,
>I think.

Ah, OK.

>The next step down is an HP 8568A or -B which sells for not much more
>than its weight in scrap metal, and is a great analyzer for PN
>measurement as long as you don't need to look below -110 dBc/Hz, at
>offsets below 100 Hz, or at carriers beyond 1500 MHz.  Most of the
>hardcore 'nuts' will not be satisfied with this noise-measurement floor,
>but if you are just playing with homebrew UHF PLLs, it will probably do
>If your work is limited to DC-HF measurement then you certainly can't
>beat the Wavecrest units people have been talking about...

>I don't know anything about measurements on modulated signals; most of
>the time these measurements are made on CW carriers or perhaps on pulsed
>ones (see HP's AN 386).  Maybe the Wavecrest software helps with this?
>Since the BER of a digitally-modulated signal depends on carrier phase
>noise and phase hits among other things, I would guess that running your
>link's existing BER diagnostics under controlled conditions would be the
>easiest way to observe noise.

The 135 MHz signal has simple cycle-by-cycle NRZ on-off modulation. 
While we have a BER test, we don't have a way of measuring the jitter
other than eyeballing it!

Again, thank for your comments - I'll look out for the equipment you



>-- john, KE5FX
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
>> Behalf Of Peter Vince
>> Sent: Saturday, July 14, 2007 4:34 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: [time-nuts] What equipment can I economically use to measure
>> jitterand noise sidebands?
>> ); SAEximRunCond expanded to false
>> Errors-To: time-nuts-bounces+jmiles=pop.net+jmiles=pop.net at febo.com
>> Might I ask what you guys are using to measure jitter and oscillator
>> noise-sidebands?  I think Mike was lucky to pick up the Wavecrest
>> recently, but is that the only option?  Is there anything else, maybe
>> older and cheaper, if not quite so high-tech?
>> I would like to be able to characterise both the usual frequency
>> oscillators, but also other odd frequencies, and digitally modulated
>> signals - any suggestions?
>>      Thanks,
>>           Peter

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