Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Firas Abbas wrote: > Can you post a link to what you saw by the maximum method ? > > Best Regards, > > Firas > > This is using the "max" method, at the same resolution and scale as the average method: http://www.radio-science-labs.com/files/spectrum_example_max.ps -- Marcus Leech Principal

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Firas Abbas wrote: > Hi, > > >> From: Marcus D. Leech >> OK, so I decided to use the averaging method, rather than >> the maximum >> method. It produces reasonably good looking plots: >> Marcus Leech >> > > Can you post a link to what you saw by the maximum method ? > > Best Regards, > >

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Hi, > From: Marcus D. Leech > OK, so I decided to use the averaging method, rather than > the maximum > method. It produces reasonably good looking plots: > Marcus Leech Can you post a link to what you saw by the maximum method ? Best Regards, Firas

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Frank Brickle wrote: > > > On Tue, Mar 10, 2009 at 11:10 AM, Marcus D. Leech > wrote: > > > OK, so I decided to use the averaging method, rather than the maximum > method. It produces reasonably good looking plots: > > http://www.science-radio-labs.com/file

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Frank Brickle wrote: > > > On Tue, Mar 10, 2009 at 11:10 AM, Marcus D. Leech > wrote: > > > OK, so I decided to use the averaging method, rather than the maximum > method. It produces reasonably good looking plots: > > http://www.science-radio-labs.com/file

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Tue, Mar 10, 2009 at 11:10 AM, Marcus D. Leech wrote: > OK, so I decided to use the averaging method, rather than the maximum > method. It produces reasonably good looking plots: > > http://www.science-radio-labs.com/files/spectral_example.ps True, not bad. One surprise, though -- what's t

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Frank Brickle wrote: > On Tue, Mar 10, 2009 at 9:39 AM, > wrote: > > Oh horrors. Please let it not be true that the phrase I am > remembered most for is heuristic grass. > > > Isn't heuristic grass what gives absinthe the green color? > > Frank > > -- > For an

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Tue, Mar 10, 2009 at 10:02 AM, John Ackermann N8UR wrote: > Just remember -- absinthe makes the tart grow blonder. Sigh. With fronds like these, who needs anemones? (Sorry -- done now.) Frank -- For an omnipotent and omniscient being, God has made some really lousy earthly staffing deci

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

John Ackermann N8UR wrote: > > Just remember -- absinthe makes the tart grow blonder. > > John > You clearly know a more interesting class of tart than I do :-) -- Marcus Leech Principal Investigator, Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Frank Brickle wrote: On Tue, Mar 10, 2009 at 9:39 AM, > wrote: Oh horrors. Please let it not be true that the phrase I am remembered most for is heuristic grass. Isn't heuristic grass what gives absinthe the green color? Just remember -- absinthe makes t

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

rwmcgw...@gmail.com wrote: > Oh horrors. Please let it not be true that the phrase I am remembered > most for is heuristic grass. > I'm near-certain that you've said more memorable things than that, Bob. But that's the one that is proximate right now :-) -- Marcus Leech Principal Investigator,

Re: Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Tue, Mar 10, 2009 at 9:39 AM, wrote: Oh horrors. Please let it not be true that the phrase I am remembered most > for is heuristic grass. Isn't heuristic grass what gives absinthe the green color? Frank -- For an omnipotent and omniscient being, God has made some really lousy earthly staf

Re: Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Oh horrors. Please let it not be true that the phrase I am remembered most for is heuristic grass. Your comments about MELP were insightful and now that you have said it, more becomes crystal clear. I raise another absinthe in your honor or was that dishonor. On Mar 9, 2009 6:49pm,

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Mon, Mar 9, 2009 at 1:08 PM, Bob McGwier wrote: > So, pardon me but, is this a pretty picture exercise or a real detection > problem? If it is a detection problem, then you might as well just > compress to the largest value in the bins to be pushed together so you > assure that your thres

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Bob McGwier wrote: > Franks comments are right on median and ROM in this case.I stayed > up to 4 AM and went to work at after having breakfast and a cup of > coffee and arrived by 9. It is showing. > > The entire gist of my comments amount to nothing more than don't allow > "aliasing" of the

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Franks comments are right on median and ROM in this case.I stayed up to 4 AM and went to work at after having breakfast and a cup of coffee and arrived by 9. It is showing. The entire gist of my comments amount to nothing more than don't allow "aliasing" of the spectral changes as your t

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Bob McGwier wrote: > > I suggest that the best algorithm for this would be the rank order > mean alternated with the max so long as you are going to insert > "heuristic grass". So it would be max, ROM, max, ROM, . > > > Let [B1, B2, B3, B4, ... BN] be powers of five adjacent bins. > > Put the

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Brian Padalino wrote: > On Mon, Mar 9, 2009 at 8:47 AM, Marcus D. Leech wrote: > >> The original {1,2,4,8,16}M-bin data are used for SETI analysis, while >> the "compressed" version >> is used for a quick visual, "conventional" spectral display. >> > > In SETI analysis, is it more interes

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Mon, Mar 9, 2009 at 8:49 AM, Bob McGwier wrote: > Let [B1, B2, B3, B4, ... BN] be powers of five adjacent bins. > > Put them in rank order > > [R1, R2, R3, R4, ... RN] > > If N is even, the rank order mean is (R_(N/2) + R_/(N/2 +1))*0.5. > If N is odd, the rank order mean is R_(N/2 +0.5)

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

I suggest that the best algorithm for this would be the rank order mean alternated with the max so long as you are going to insert "heuristic grass". So it would be max, ROM, max, ROM, . Let [B1, B2, B3, B4, ... BN] be powers of five adjacent bins. Put them in rank order [R1, R2, R3,

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Sun, Mar 8, 2009 at 6:13 PM, Marcus D. Leech wrote: Seems to me that if I have 4000 1Hz-wide bins, I should sum them to give > me the total power in a single bin that > "represents" the same amount of bandwidth. But is it more subtle than > that? As usual, yes and no. If you're concerned

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Mon, Mar 9, 2009 at 8:47 AM, Marcus D. Leech wrote: > The original {1,2,4,8,16}M-bin data are used for SETI analysis, while > the "compressed" version >  is used for a quick visual, "conventional" spectral display. In SETI analysis, is it more interesting to see a wider bandwidth signal, or si

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Brian Padalino wrote: > > > As per the original question, I am wondering what the reason for > taking the time to do a 4M point FFT and then compressing the > frequency information? I would think you're just throwing away > frequency resolution at that point and, inherently, wasting CPU > cycles.

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

One thing you might look at is the "Rosenfell" algorithm used in some HP spectrum analyzers (like the 8566). As I recall, they alternately take the maximum and minimum values in the bins -- ie, if you're collapsing three bins into one and the original values are 010 050 010|010 050 010|120 13

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

On Mon, Mar 9, 2009 at 3:45 AM, Jens Elsner wrote: > Gives a good practical estimate. Code for GNU Radio is here: > > https://www.cgran.org/wiki/SpecEst Good to see CGRAN being put to good use! > Integrating the FFT bins is just fine, but you probably loose frequency > resolution that way (if th

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

> > From: Marcus D. Leech > > > > Let's say I have an FFT output that's many, many, bins wide, and I want > > to compress that information into a narrower display (let's say from 4M > > > bins down to 1024 bins). > > > > My approach has been to sum up each set of [4M/1024] bins, and use that >

Re: [Discuss-gnuradio] Correct method for "compressing" a power spectrum

Hi, > From: Marcus D. Leech > > Let's say I have an FFT output that's many, many, bins wide, and I want > to compress that information into a narrower display (let's say from 4M > > bins down to 1024 bins). > > My approach has been to sum up each set of [4M/1024] bins, and use that > as the

[Discuss-gnuradio] Correct method for "compressing" a power spectrum

Let's say I have an FFT output that's many, many, bins wide, and I want to compress that information into a narrower display (let's say from 4M bins down to 1024 bins). My approach has been to sum up each set of [4M/1024] bins, and use that as the final output. But should I be averaging acros