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In terms of object tracking, I'm working on making a small device/tag that uses bluetooth technology to keep track of objects but a friend told me about RFIDs which are supposedly cheaper and also works with NFC enabled phones. SO I'm wondering, I don't know much about the technical aspects of RFIDs, bluetooth also looks like a promising solution but can be quite costly. So keeping this in mind, what would you advice as the best approach? RFID? Bluetooth? Or something I never thought of?

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Tell us more about the tracking part. How closely you want to track? At what range? How many objects? Use precise numerical values please. – AndrejaKo Mar 24 '12 at 12:36
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"more or less tiny" is not a very useful description if you know the actual desired dimension range. That makes a vast difference to the answer and ideally should have been in the original question.' – Russell McMahon Mar 24 '12 at 13:49
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@opatachibueze I've taken a look at your previous question and it too was vague. I'll try to explain this nicely and I hope you won't get offended by the explanation of the problem with this question: First the question is bad! It is bad because you don't have solid design requirements and you haven't clearly explained the purpose of the apparatus you're building. Some of the key points are: How long do you want the tag to work? A day, a week, only while the tracker is transmitting? At which range you want to operate? A room, a building, 100 m, 500 m, more? – AndrejaKo Mar 24 '12 at 16:07
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@opatachibueze How precise do you want to be? Do you want to find the tag on a cluttered desk, know the building in which it is, know in which room it is, know in which part of the room it is and so on. How clear should be the information provided by the tracker? Should it show the exact location or just the general direction? Would it be enough to just beep when the tracker is pointed into the direction of the tag? Next how expensive do you want each tag to be? $0.1, $0.5 $1, $5, $10 and so on. – AndrejaKo Mar 24 '12 at 16:10
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@opatachibueze How expensive do you want tracker to be? Should tracker be fixed or mobile? Does it need to be a stand-alone unit or can it be connected to a personal computer? How many units in total do you want to make? Some manufacturers don't even want to hear that you exist if you don't want to make say 500000 units a year. Which components can you easily obtain? There are definitely more points that need to be considered before a final answer can be made to this question and all of this can make a big impact on which technology is the best for you. – AndrejaKo Mar 24 '12 at 16:14
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2 Answers

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Best choice depends on many factors - only some of which are range, security, amount of data required to be known, number of items to track, number of locations, powered versus unpowered, acceptable size, acceptable cost for nodes and masters, ... .

The best choice is something you haven't heard of, but we may not have heard of it either :-).

RFID

  • low cost tags

  • tags usually small and flat (under 1mm thick).

  • relatively short range 0.1 - 1 metre typically

  • longer range possible but aerial size MAY grow.

  • simple tags are usually unpowered - using energy pickup from interrogator

  • tag usually just has an ID but can also interact with tag to exchange fixed or variable data. If desired tag can be a processor equipped.

  • Uses NFC (near field communications) - whether these work with the NFC equipped phones etc you are using is a purchasing choice.

Bluetooth:

  • Typically a short range telemetry system with own powering and formal transmitter receiver.

  • More complex and more capable than typical RFID tags.

  • More range than most RFID but still limited. (Metres to tens of metres - more possible but not the norm).

  • More expensive than typical tags

  • Smallest bluetooth is probably a few cm^3 volume. I may be wrong.

  • Work with almost any bluetooth enabled system including many phones, laptops/netbooks/tablets, dedicated bluetooth equipment.

Other:

  • WiFi: Dearer, more range, battery power, higher power drain unless custom made to poll, no practical limit to functionality.

  • Custom NFC. like RFID but non standard. May be suited to some niche larger volume tasks where a need exists that std RFID doesn't address.

  • Infrared: May be chosen in selected circumstances.

  • Simple low cost RF transceivers- ASK and similar. Less complex and cheaper than Bluetooth. Range as desired out to say 100+ metres.Battery powered. May be system of choice in higher volume custom system. No interface with std phones or PCs without extra interfacing.

  • Capacitive - just maybe. Excellent in some cases.

  • Other we haven't heard of ... :-)

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so, you'd suggest I continue with bluetooth right? And what's the capacitive choice in other about? – Chibueze Opata Mar 24 '12 at 14:26
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No - I'd make no final recommendation as you have not yet refined you size spec. Even if you had I don't know which BT parameters made it more attractive. Explaining your need more would help. BT des not do "tiny" but may or may not suit your need. Capacitive is just that - signal transfer by capacitors. Good when it's good. Your requurement needs to be better known before one could advise re capacitance or anything else. – Russell McMahon Mar 24 '12 at 15:19
My major problem was determining whether RFID was an alternative but your answer made things straight to me. There's actually a 6mm by 6mm Bluetooth module by Texas which is difficult to get at the moment so I'll probably stick with a bulky Bluetooth arduino module for the moment, but I'll definitely consider transceivers in the future. – Chibueze Opata Mar 24 '12 at 21:24
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See also this thread. Also take a look at a Cricket from MIT.

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