[hpsdr] spectrum increased frequency resolution?

[David McQuate]

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
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