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I need to do some NON-STANDARD signal processing operations with an RFID-reader, so I'd like to know if it is possible to extract antenna's individual analog (actually digital samples right after ADC) input signal samples with Motorola FX7500 (if you know how this works on FX7400 or FX9500, please do tell, could be helpful). Samples would be processed in a JAVA-based host computer program.

What I've already tried:

  1. Investigating Motorola's own RFID3 API's possibilities, it doesn't go deep enough to actually get in touch with input analog signal samples.

  2. Using LLRP to its full extent, it doesn't allow analog signal sample access either. RFsurvey-functionality would have been helpful to some extent, but FX7500 doesn't support it either.

  3. Accessing RFID-reader's linux terminal, trying to find the driver function(s), that could listen the input sample stream. If current input sample(s) could be extracted from the input stream, I could (in theory) make a script, that would save a few of those sample values in a txt-file in the host computer during a tag inventory round. My linux skills are kinda bad, hence I ask this question.

The only realistic way to solution seems to be via linux terminal, so if you folks have any ideas about that (where to look and what to do), please advise!

Contents of reader:

rfidadm@FX7500abcdef:/$ ls -1
apps
bin
dev
etc
home
include
lib
linuxrc
media
mnt
platform
proc
readerconfig
run
sbin
sys
tmp
usr
var
Marcus Müller
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Spere
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2 Answers2

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I cannot completely rule that out, but it's highly unlikely you can get the raw signal digitized; the devices you're looking at aren't really software defined radio devices, typically.

"speaking" RFID physically is a bit different from "usual" wireless communication: The reader doesn't only observe the energy transmitted from the tag, but more importantly the fluctuations of energy extracted from the near field of the reader's antenna coil. Hence, you don't actually have a baseband of RF bandpass signal, but hardware-specific modulations of transmitted (and inversely, antenna-reflected) energy. Demodulation is hence usually done in specialized hardware.

However, do not fret: It's totally possible to build a software defined RFID reader. There have been several approaches to that, but personally, I trust these based on Ettus USRPs and/or GNU Radio best. Look through the results IEEExplore gives you, eg. this search.

Marcus Müller
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  • While RFID-readers usually aren't software radios, this one is. Hence there must be a hidden way to get to the raw signal (contacted manufacturer, getting answers soon). Unfortunately in my job description, I need to read non-standard tags with an existing commercial RFID-reader. Thanks for input anyway! – Spere Oct 20 '15 at 11:37
  • How do you figure it's a software radio? If you know that, you're not telling us all you know in your original question! – Marcus Müller Oct 20 '15 at 16:48
  • Well I can't say for 100% (since their marketing strategies might involve exaggeration), but there is talk about software radio paired with linux architecture in the product documentary: "...makes the FX7500 easy to use, deploy and manage, the flexible software radio platform of the FX7500 ensures ease of adaptability to industry standards..." Sorry if I was a bit cryptic in the original question. :) – Spere Oct 21 '15 at 10:18
  • @Spere: Ah ok, that's a strong lead! Do you have access to one already? can you `lspci`/`lsusb` the hell out of the device? – Marcus Müller Oct 21 '15 at 10:36
  • I have the device, those commands were not found, when tried. The OS I'm dealing with here (if helpful): `rfidadm@FX7500XXXXXX:/$ uname -a` `Linux FX75007FFC8E 2.6.32.8.ti-omap3-am3517-evm #55 PREEMPT Mon Mar 3 17:00:29 IST 2014 armv7l unknown` `rfidadm@FX7500XXXXXX:/$ help` `GNU bash, version 3.2.39(1)-release (arm-mv-linux-gnu)` – Spere Oct 21 '15 at 20:47
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Most probably this is not possible with the Motorola readers. What you can do, is use one of the RFID chipsets available on the market: either the AMS RFID IC's, or the Impinj RFID IC's. As far as I know, both IC's support retrieving the digital samples that are received. They also have a development kit to test-drive the IC's.

Danny
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