Rifidi Emulator Antenna-Tag Problem

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seckin.can
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Rifidi Emulator Antenna-Tag Problem

Post by seckin.can » Thu Oct 07, 2010 3:16 am

Hi,
When i add an LLRP reader with 4 antennas to the emulator and put one tag in front of that 4 antennas (same tag to each one), i get results from only one antenna. But when i put different tags in front of each antenna, i get results from all of them. Also when i put 2 different tags in front of one antenna, i only get one tag information. What do you think about that? (I just run a virtual reader and connect it from a computer, nothing else).

Matt
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Re: Rifidi Emulator Antenna-Tag Problem

Post by Matt » Thu Oct 07, 2010 2:35 pm

Hi seckin.can,
When i add an LLRP reader with 4 antennas to the emulator and put one tag in front of that 4 antennas (same tag to each one), i get results from only one antenna.
This is to be expected; I believe it is how the LLRP (and many other readers) work. If a tag is seen on more than one antenna, it picks one and uses that as the antenna the tag is seen on.
But when i put different tags in front of each antenna, i get results from all of them.
To be expected again; 1 antenna posted for each tag you see.
Also when i put 2 different tags in front of one antenna, i only get one tag information.
This is strange. Could you post a screenshot of Emulator with 2 tags on it, and then could you paste the raw message you are getting back (should be in the emulator's console). I'd like to see if the correct report is getting generated by the Emulator.

seckin.can
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Re: Rifidi Emulator Antenna-Tag Problem

Post by seckin.can » Fri Oct 08, 2010 5:56 am

Hi Matt;
This is to be expected; I believe it is how the LLRP (and many other readers) work. If a tag is seen on more than one antenna, it picks one and uses that as the antenna the tag is seen on.
No, all the real readers including llrp based readers that i used, do not work like that. If they work like you told for example, to create 4 read point you have to put 4 different readers. Reader has to send data for every antenna even if the same tag crosses.
Also when i put 2 different tags in front of one antenna, i only get one tag information.
This one is wrong, sorry, it works.

But i realized that (for emulator); if you put a tag to antenna 0, then you put same tag to antenna 1; you get data only from antenna 1.
Let's say you put 3 different tags to antenna 0, call them A,B,C. Then you put A and B to antenna 1, and then you put only A to antenna 2 and start read. In this situation antenna 0 sends only data of C, antenna 1 sends only data of B, and antenna 2 send only data of A. The higher numbered antenna cancels the lower numbered one if they have same tag and that's a problem.

Matt
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Re: Rifidi Emulator Antenna-Tag Problem

Post by Matt » Fri Oct 08, 2010 3:33 pm

seckin.can wrote:No, all the real readers including llrp based readers that i used, do not work like that. If they work like you told for example, to create 4 read point you have to put 4 different readers. Reader has to send data for every antenna even if the same tag crosses.
Well, I checked the LLRP specification, and the "TagReportData" object has a value called "AntennaID" which is an unsigned short. Unless that short is a bitmask (and neither the Impinj or Motorola LLRP readers treat that value as a bitmask in my experience of working with them) I don't really see how it can refer to multiple antennas. Could you post a ROReport XML from your reader when you make 1 tag visible to all 4 antennas?

-Matt

seckin.can
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Re: Rifidi Emulator Antenna-Tag Problem

Post by seckin.can » Thu Oct 14, 2010 3:55 am

When I put one tag to 2 antennas that are connected to motorola fx7400, i get two packages in a row. One of them is from antenna 1 and next one is for antenna 2. I don't expect the 2 antenna information in one package, it's impossible because readers scan antennas in a sequence. So they create packages according to that sequence. But in emulator it doesn't happen that's my problem actually.

Matt
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Re: Rifidi Emulator Antenna-Tag Problem

Post by Matt » Thu Oct 14, 2010 2:14 pm

seckin.can wrote:When I put one tag to 2 antennas that are connected to motorola fx7400, i get two packages in a row. One of them is from antenna 1 and next one is for antenna 2. I don't expect the 2 antenna information in one package, it's impossible because readers scan antennas in a sequence. So they create packages according to that sequence. But in emulator it doesn't happen that's my problem actually.
Well, fair enough. I didn't know the LLRP did that. Unfortunately, we don't really have any plans to update Emulator at this time. Sorry I couldn't be of more help.

-Matt

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