[time-nuts] Chinese Scopes

J. Forster jfor at quikus.com
Tue Apr 17 14:43:19 UTC 2012


Sometime, just for fun, I'd like to get a Tek sales 'engineer' in to demo
his latest, hideously expensive, digital toy and compare the display to a
453 from 1965 on a WW II LORAN-A simulator that works with- gasp- vacuum
tubes.

Just for laughs, of course.

-John

==============



> On 4/17/12 7:15 AM, Robert Darlington wrote:
>> I need lots of memory on scopes.  A buddy of mine I worked with in the
>> ultrasound world actually yelled at the Tek product management and
>> asked if they actually *use* oscilloscopes.  The answer was a sheepish
>> no, and yet they felt qualified to develop the products for the
>> company.
>>
>> The cheap Aktakom scope I have has plenty.  10 million samples (you
>> can select less if you want) and will write out to usb thumb drives.
>> It's definitely a toy scope with lots of noise, but it's useful for
>> some things.
>>
>> What we do is send out pulses or chirps and look at what returns.
>> There are tens of millisecond delays between what we send out and what
>> we receive and the echos.    With traditional low memory scopes we
>> simply can't get by.  Thankfully Tek is learning that memory is cheap
>> and 2500 samples was hardly sufficient in the 70s, let alone now!
>
>
> Yes, just like in the radar world (really, ultrasound and radar are
> really similar.. same kinds of pulse compression and signal processing)
>
>
> Back in 1998-1999, I was buying digitizer cards from Gage Applied
> Sciences (since acquired by Tek, as it happens), and one of their big
> markets was for ultrasound.  Same for Signatec (another mfr of fast
> digitizer cards for PCs)
>
> Another case where deep memory is nice is when you don't know exactly
> when the signal is going to arrive, it's very low SNR, so you want to
> record a long time, and then go look for the signal later.  But that's
> more a data capture problem than a bench oscilloscope problem.
>
> say you were recording off-the-air GPS signals.  You want to record a
> couple milliseconds, at least (so you get at least 1 code epoch), and
> you need to record at least 10 MHz bandwidth.  That's only, say, 64,000
> samples, but you might want to record a whole 50 bps nav message bit, so
> then you need ot record 40-50 milliseconds, and the record length starts
> to grow.
>
> Again, that's more of a data recording problem than an oscilloscope
> problem.
>
> It's the wideband pulsed waveforms where you want to compare pulse to
> pulse is where deep memory in an oscilloscope is nice.  The digitizer
> cards are ok, but "real oscilloscopes" tend to have better input
> amplifiers and such.
>
>
>
>
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