[hpsdr] spectrum increased frequency resolution?

[Dan Quigley]

Now I finally understand the "Bill Tracey may have been here" comments
salted into the PowerSDR codebase..

 

J

Dan

 

From: hpsdr-bounces at lists.openhpsdr.org
[mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of Frank Brickle
Sent: Monday, June 08, 2009 4:36 PM
To: David McQuate
Cc: hpsdr at openhpsdr.org
Subject: Re: [hpsdr] spectrum increased frequency resolution?

 

Stuff the samples into a longer FFT and pad with zeros.

Remember, though, that what you gain in frequency resolution you lose in
time resolution. That's Heisenberg Uncertainty.

You also have to be a little careful about how you window the data. Google
is your friend.

73
Frank
AB2KT

On Mon, Jun 8, 2009 at 5:57 PM, David McQuate <mcquate at sonic.net> wrote:

***** High Performance Software Defined Radio Discussion List *****

If I have a block of samples (say N = 4096, fs = 122.88 Msps),
a straightforward FFT produces data with frequency resolution of 30kHz.

Is there a technique that will allow me to obtain information on a finer
frequency grid (say 1kHz or 300Hz or ...)--other than "simply" acquiring
additional data, extending the length of the time record?

I've looked at Chirp-Z transforms and polyphase decimation, but neither
seems to produce higher frequency resolution.  I've also looked into DttSP,
but not found a solution there.

Am I hoping for the impossible?

Suggestions please.

73,
Dave
wa8ywq
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