can some one give me some guidence please?
Manimal
Posts: 1
Hey guys and girls...
so first off i would like to say that i am super jealous of every one on this website, that know what the heck they are doing, i am so new at this its rediculous, and i am looking to build a couple small projects.
one project is a simple RFID scanner which by the looks of it should be pretty easy, how ever i need it to beable to scan approximatly 3-5 meters, thats about it, and also beable to read up to 200 tags, not nessicarily all at once, but in a timly fashion, also i would like it to compare the rfid tags, against a set list to verify if one tag is missing or not...
ive already checked out the parallax USB RFID scanner, how ever i read in the documentation that it has a read distance of about 4 inches or so, depending upon the RFID tag used, is there any way to modify the unit as to extend the range? i would assume that the transmitter would require more power, but im certain that the board isnt designed for that...
could any one give me 5 mins and point me in the proper direction to get it started? perhaps some books i could read, or an online course i could take to further help me design this? i swear it will be a cool project once everything is said and done!
so first off i would like to say that i am super jealous of every one on this website, that know what the heck they are doing, i am so new at this its rediculous, and i am looking to build a couple small projects.
one project is a simple RFID scanner which by the looks of it should be pretty easy, how ever i need it to beable to scan approximatly 3-5 meters, thats about it, and also beable to read up to 200 tags, not nessicarily all at once, but in a timly fashion, also i would like it to compare the rfid tags, against a set list to verify if one tag is missing or not...
ive already checked out the parallax USB RFID scanner, how ever i read in the documentation that it has a read distance of about 4 inches or so, depending upon the RFID tag used, is there any way to modify the unit as to extend the range? i would assume that the transmitter would require more power, but im certain that the board isnt designed for that...
could any one give me 5 mins and point me in the proper direction to get it started? perhaps some books i could read, or an online course i could take to further help me design this? i swear it will be a cool project once everything is said and done!
Comments
Probably a better title would help... anyway there have been a discussion on the forum about long range rfid (look for active rfid) in the recent past. You could probably find a lot of stuff to get started.
Here it is..
http://forums.parallax.com/showthread.php?125624-RFID-Reader-Distance
Massimo
It's really not about the RFID Reader.
It's the transponder cards (tags, et al.) that are low-power.
You're talking about full-fledged transceivers, two-way RF comms.
Knowing nothing, you're not going to ask some questions and "get some
answers", maybe read a page or two on "the 'net", and go cobble up
something credible in the basement.
Thing is RFID is not a radio system in the conventional sense of a radio transmitter and receiver.
It's more like a transformer where the primary winding is fed from the RFID scanner and the secondary winding is the RFID TAG. They are a coupled resonant circuit. This does not work well over more than a few tens of centi meters at best.
Having said that, I find this: http://www.prlog.org/10223510-longdistance-rfid-reader-offers-read-range-up-to-40-feet.html
I use RFID in a LOT of my projects, and I just don't think this would be a good use of the application. RFID has to transmit radio waves through the air not just strong enough to be received, but strong enough to apply power to the tag.
Normally with radio one thinks of an electromagnetic wave propagating itself out through space.
With passive RFID one is better off thinking of it as two coils coupled by an alternating magnetic field. Basically a transformer.
The passive RFID tag gets power form it's antenna coil which is the secondary winding of this transformer. When powered it can increase or decrease the load on the secondary which the transmitter sees as as varying load on it's antenna coil, the primary. These changes in load, modulation, are what carries the RFID data back to the scanner.
As a pair of magnetically coupled coils one would not expect the range to be great. Rather like you would not expect your power supply transformer to work very well if you separated the primary and secondary coils.
http://www.google.com/search?q=long+range+rfid&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1&rlz=