I am new.

What is a blanked AP task?
Thanks

Merle,

I was hoping one of the others would tackle this but since no one has I'll give it a go. Blanking is a method that is used to remove interference from the data. Whether it is manmade, terrestrial or know source. I'll copy here what is listed and also provide the source in a link

http://www.researchgate.net/profile/Eric_Korpela/publication/232906106_Astropulse_A_Search_for_Microsecond_Transient_Radio_Signals_UsingDistributed_Computing._I._Methodology/file/d912f50f7380fa6ffb.pdf

I tried to link the pdf paper here but it won't let me. Originally it downloaded the paper to my harddrive so I not sure why I can't link it here. It's a very technical paper so I just posted the part that might interest you here.

3.6. RFI Rejection
We expect to see radio frequency interference (RFI) from terrestrial sources, which
must be eliminated from the data in order to distinguish the signals from astrophysical
sources. The RFI is certain to overwhelm any pulsars, black holes, etc. in the data.
One RFI source at Arecibo Observatory is a nearby military radar, which emits one of 6
repeating patterns. It sometimes produces chirped pulses that are detectable by Astropulse.
We reject RFI using several methods:
1. Hardware blanker
Arecibo Observatory provides us with a hardware blanking signal, a single bit which
is supposed to be turned on when the military radar is present in the data, and off
when the radar is not present.
2. (Server side) Software blanker
The software blanker runs in our splitter, examining the data for the repeating
patterns that signify radar. Unlike the hardware blanker, it looks for several different
types of radar signals, and can’t get out of phase with the radar.
3. Client blanker
One characteristic of the radar noise is that it’s strong enough to overwhelm our
electronics, producing a long string of bits all set to the same (1 or 0) position. We
blank all data within 400, 000 samples of the detected event. The software blanker is
located in the Astropulse client. It may even be profitable to blank all workunits that
detect even one such event.
4. DM repetition
If we see a signal at the same DM repeatedly, but this repetition spans more than 13
seconds (the beam transit time), we conclude that it came from a terrestrial source.
Since the beam was pointing at different parts of the sky, there’s no reason that the
same DM should have been observed.
5. Frequency profile
We are looking for broadband pulses with a short intrinsic timescale. Thus, the pulse
should have the same mean power at all frequencies. We perform a chi square test, to
determine whether the mean power is the same everywhere. 18 –
6. Multibeam observations
If we see the same pulse in multiple beams, it must come from a terrestrial source.
7. Examining pulse images
We will examine the remaining pulses by eye in a time vs. frequency plot, and take
note of any unusual characteristics.

Hope this helps

Zalster

Thanks Zalster,
To a certain extent I understand what you are saying. Now I have to go back to the discussion of the v0.42 where this term comes up to try and understand in a general sense what is being said.

Is it true then that this blanking produces "holes" or missing time and data in a given wu which would then shorten the amount of time it would take to process a wu? Or have I misinterpreted what was said?

Look this post from Richard, it´s explain a lot about: http://setiathome.berkeley.edu/forum_thread.php?id=75391&postid=1561564

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The way I understand it. (And I could most certainly could be wrong) is that Work units that end up having high blanking, initially have lots of data to them. In the paper, he describes the method by which they decide to analyze the data starting at 1 point and moving downward from there. In the case of blanking, the repetition of signals of certain wavelengths are then removed from the data to uncover any unseen signal hidden or masked by the repeating wavelengths (in this case there is a database where they know the frequency of local interferences or not so local) after the interfering "noise" is removed what is left gets analysed. Per the link that Juan posted, the original code was specific for CPUs, so that is why it ends up taking longer to process. At least, that is what I get from this.....I could and probably am wrong..But that is how I read this....


Zalster

It sounds as though they make two passes of the data and that is why it takes longer to process those blanked wu's.

You say 'specific for CPU's'? I assume that there would be another process for eliminating the "bad data" from the gpu wu's.

I'm stretching my brain 'muscle'.:-)

Per Juan's link. Currently dealing with blanking is a CPU process since the original code was written only for CPU many, many years ago. v7 will have new code for dealing with blanking on the GPUs. So until then, we must muddle thru the best we can

Zalster

edit... The brain is all muscle, lol..... ;)

So when it comes to gpu's wu's the blanking is still there (needs to be processed) but it is done by the cpu.?

Edit...

In short, yes. There is still some blanking that needs to be done. If you look at my original posting, there are several steps when different kinds of blanking along the way. Ours is just another step in that process.


Zalster

Tremendous thanks for working this thru for me.

Tremendous thanks for working this thru for me.

Now that you have that sorted. Blanking is said to work completely different in the forthcoming Astropulse v7.

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OK, good.

Can you give me a laymen's view of how v7 works differently?

OK, good.

Can you give me a laymen's view of how v7 works differently?

So far I only know that "it's different". There might be a detailed explanation in the AP threads at Beta, but I have not read all of the threads yet.

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OK thanks. I really wasn't expecting to be able to digest it in any event.
My brain only takes me so far in physics and astronomy and it isn't ever far enough. I am reading a book by Issacson, I think it is, about Einstein's life and his theories and am astounded by how much I can't grasp even though I enjoy reading about it nonetheless. It feels as though this universe is a big question mark that continues to expand at a growing rate.:-)

OK, good.

Can you give me a laymen's view of how v7 works differently?

Basically, V7 will allow the GPU to complete the blanked task just a little longer than a non-blanked task instead of up to 4 times longer with V6. If your GPU completes a non-blanked task in 30 minutes, it will complete a blanked one in about 35 minutes instead of 2+ hours. The real advantage is with the CPU which completely skips the blanking. A blanked cpu task that takes 10 hours with V6 can finish in just a couple hours with V7.

Now if we can just get V7 released...

OK, good.

Can you give me a laymen's view of how v7 works differently?

Basically, V7 will allow the GPU to complete the blanked task just a little longer than a non-blanked task instead of up to 4 times longer with V6. If your GPU completes a non-blanked task in 30 minutes, it will complete a blanked one in about 35 minutes instead of 2+ hours. The real advantage is with the CPU which completely skips the blanking. A blanked cpu task that takes 10 hours with V6 can finish in just a couple hours with V7.

Now if we can just get V7 released...

I think the v6 CPU app has already been updated. I have seen several 100% blanked tasks run about 3 seconds on my CPUs.

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Funny guy. I do hope you're trying to be funny...

Funny guy. I do hope you're trying to be funny...

About the 100% blanked tasks?
Nope: http://setiathome.berkeley.edu/result.php?resultid=3668070364

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Funny guy. I do hope you're trying to be funny...

About the 100% blanked tasks?
Nope: http://setiathome.berkeley.edu/result.php?resultid=3668070364

Well..... Do you think the fact that 100% blanking, meaning there isn't any data, has anything to do with it?
BTW, 100% blanked APs have Always finished in a few seconds, 'cause, there's nothing there to compute. Try it with an AP that's 99% blanked with V6.

Funny guy. I do hope you're trying to be funny...

About the 100% blanked tasks?
Nope: http://setiathome.berkeley.edu/result.php?resultid=3668070364

Well..... Do you think the fact that 100% blanking, meaning there isn't any data, has anything to do with it?
BTW, 100% blanked APs have Always finished in a few seconds, 'cause, there's nothing there to compute. Try it with an AP that's 99% blanked with V6.

I had not noticed any in the past few months, but it may been the lack of 100% blanked work.
Recently I was getting times for benchmarking so I was paying more attention to the blanked percentage.

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