The operative word here is "reasonable." Al, I don't disagree with your
statement in the least, but for most of us, securing a vector signal
analyzer simply isn't an option for our measurements.
-Paul, W9AC
----- Original Message -----
From: "LORONA,AL (A-USA,ex3)" <al_lorona@agilent.com>
To: "Ten Tec" <tentec@contesting.com>
Sent: Friday, February 01, 2002 0:59 AM
Subject: [TenTec] RE: More About Clix
>
> I posted a reply about measuring "microchirp" yesterday but it never made
it
> to the list. Here's my second try:
> --------------------------------------------------------------------------
-
>
> >>You can't. In fact, I know of no electronic instrument capable of
> >>reasonably detecting it. Sometimes the ear is the best judge. The
keyed
> >>waveform oscilloscope display has no association with frequency shift.
>
> >>-Paul, W9AC
>
>
> In fact, you can. You need an instrument that can capture a signal without
> missing any data and then play it back while displaying frequency vs.
time.
> Such an instrument is called a vector signal analyzer.
>
> The VSA scrolls through a display of the spectrum of the signal. In this
> way, the horizontal axis is frequency and the vertical axis is time. If
the
> plot is in color, the color can represent amplitude. This type of display
> format is called a "spectrogram". I think some PSK-31 programs (like
> Digipan?) show the spectrum; just imagine successive spectra scrolled in
the
> display. It's hard to describe.
>
> Markers can be used to measure delta freq and delta time. This is how
folks
> measure the start-up transient behavior of PLLs and other oscillators,
and
> how law enforcement agencies positively identify a specific transmitter
by
> it's start-up "fingerprint".
>
> Al W6LX
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
|