Vogt Antenna for TMS3705A1 ?

Ray -

Vogt is a company which was purchased by Sumida. http://www.sumida.com/investors/ma/vogt.html

They make the "keylock" antenna which we put on the basestation for the TMS37157 kit.

this is just ~440uH-470uH coil, which is resonant with the parallel cap on that board. the UCC part is for amplifying the signal and on some of the boards, some clamping diodes are there which were mis-populated and clip the output, so these can be removed if they are present to realize full potential of using the UCC portion of the circuit with a higher rail voltage.  

Thanks Josh...

I'm getting there now... the aerial needs a low or zero ohm source impedance (for series resonance) and obviously the 27424 is lower than the basic 3705...now the clamping "zeners" perform a safety function...surely the full potential of the 27424 is not yet fully realized?....a matter for later...I have enough on this now, thank you.

bit worried though, that TI made such a PCB manufacturing mistake ( what's this about "mis-populated"?)....is all under control now?

Just a couple more little questions :- 

on the schematic RI-ACC-ADR2-00 from a reference given elsewhere to Colin Watson...there are several components (R26,R3....R29) marked as N.M , what does R.M mean...perhaps just now I realized it probably means Remove....yes/no?

While skimming through your TMS37157 document I landed on page 20....I see you are using 134.7 and 123.7 khz....the time of 16 cycle of each agrees with 118.8/129.3uS so it is not a typing mistake...so why are you not using 134.2Khz...where did 134.7kHz come from?

Plus while on this frequency matter....what is your experience in europe with inerference from the Amatuer Ham Radio bad called the "2200 metre band" (135.7-137.8 kHz) ?

is it causing issues for hdx over there? as it is starting to be used here by experimenters here....the inference to us is obvious....

While HDX may survive close frequency inteference "thank god" for the FM capture effect) but bad luck for FDX readers....what experience can you recount.?

Thanks for answering me

Regards

Ray Seidel

Ray -

N.M. means "not mounted", same as DNP (do not populate) or DNI (do not install) - for example, if you have a look at R34 and R35, if you want to change the rail voltage for the UCC part as an amplifier, you need to supply +12VDC into X1 and move the 0 ohm resistor at R35 to R34 position. R26 is NM because R1 and R2 are already forming the Rf/Ri pair needed for the input to establish the gain on the RX in. R3 and R4 are NM because the signal goes through the UCC all the time. if the UCC was removed, then you would then populate them with the resistors installed at positions R27 and R28.

Zener placement was copied from another design done for automotive and is valid part of the design - and this was just a BOM typo.

134.2kHz is used for ASK downlink to the tags, while they respond using FSK...we have most certainly enjoyed a better signal to noise ratio performance over anyone using the FDX approach since then. this is AM vs. FM...after all. RE: your experience with Ham folks...one thing you might be able to try is wireless sync feature of the RFMs. this is useful perhaps to you since the reader will listen and try to transmit during some quiet time...but this may not help if they are directly on top of you. 

Appendix F may also be some good reading ==> http://www.ti.com/lit/ug/scbu022/scbu022.pdf 

You can also check out this document too just to double check that your system is not to blame for any of it. http://www.ti.com/lit/an/scba021/scba021.pdf

Regarding the amplifier stuff that Colin mentioned...the concepts around what is being done there are shown in the reference manual for the RI-RFM-006A http://www.ti.com/lit/ug/scbu036/scbu036.pdf in section 11...

also - some notes i took on the topic around using the TMS3705 with the RO/RW tags.

0753.Notes on TMS3705A1DRG4 & Read.ppt

Thanks for reply Josh

I am happy with your N.M  clarification.

Will let your BOM typo "go through to the keeper"....this happens to us all.

The references you pointed me towards are useful thank you...still, where did 134.7kHz come from?

Regarding your suggestion about "inteference" from the recently opened 2200metre Ham Radio band..... I would like to discuss this further with you...if you have spare time.

Am I correct that you or other forum members have not yet experienced this matter?...or is it a "non-issue" over there?

First, over here.... I know of some people who have so much vacant land and spare cash that they can and do build radio towers so tall they "almost reach the sky"....these people can and will put up long aerials for 135.7- 137.8 kHz.  

plus they are not adverse to "testing???"  with near kilowatt power levels...so... from hundreds if not thousands of kilometre away, we expect to see microVolt field strengths compatible to that emitted from the HDX tag ...which is only an arms length away.... 

I advise you to do a simple test....connect a tunable signal generator to a rough-coil and set it near  a Reader listening to a HDX, tag at the verge of perception (CRC validated etc...)....now sweep across the span 123kHz to beyond the 137.8kHz of the 2200Metre band...with any luck you will witness the HDX detection ceases...

now reduce the signal generator power level down...down...down and observe as we did, that even a weak "coherent" inteferance will "blot out" the desired reading of a tag.

So your suggestion of invoking wireless sync and just wait for the inteference to stop has a problem.....the inteference may "never" stop to allow the reader to "slip in" during the "sunspot like" quiet time when the distant operator feels like it or his batteries have gone flat.

Remember we are trying to read passing cattle...if inteferance mutes the detection capability (ie by wireless sync) then a lot of animals will be missed....the consequence of this is ALL the cows that were "run-through" must be rounded up and "run-through" again.....worse for us, we will get angry cattle handlers ringing us up saying your "dam thing does not work!...come and fix it" ...and "it" may be a thousand kilometre away"....hmmmmm.... and when I say "us" I mean us here and you there as we use your TI readers.

So....it is a vexing question and I do not expect you to have all the answers and there in fact be none easily come by...we are preparing for this hopefully rare cause of "missed reads"... I ask you again...have you experienced the consequence of adjacent frequency continuous interference..perhaps from Ham radios?

We know FDX is even more sensitive to near-frequency continusious inteferance.... this is not yours or our problem to ponder.

Allow me to recount one more "very subtle" instance that works badly for FDX and makes HDX shine even brighter....this concerns metal surfaces that vibrate;, in our case when cattle run up/down a truck ramp....with an FDX reader illuminating the rap it also illuminates the opposite walls/rails of the ramp...

the heavy hoof-steps of the cattle vibrate the whole structure, eddy surface currents in the nearby metal surfaces now re-radiate back to the listening FDX receiver and this is now a new Amplitude modulation superimposed on top of the desired tags "AM" modulation....the hetrodyne/mixing/unpredictable vector summation causes such corruption that tags will be "missed" ie the nexas of the FDX telegram+CRC is  destroyed......HDX does not suffer from this.....all power to HDX.

Just thought this might interest yoJosh though my hope is it is not new for you.

Again, Josh... thanks for your help...I expect to talk more with you and other form members.... I still have a lot to learn....

by way is Mr  Shureman the inventor of HDX still with us?

Regards

Ray

 Vogt is the antenna Manufacturer in Germany and has been bougth by Sumida.

Please find attached the Datasheet.

The Coil Q is about 25 at 135kHz but the system Q shall be in a range of 10 to 15 while the resonance center frequncy (Lant +Cres) shall be at about 132kHz in order to receive the 2 Transponder FSK frequncies (124&134 kHz symentrically.

Of course you can wind an own antenna. The inductance shall be between 300uH and 700uH tuned (matched) with the necessary resonace capacitance.

440uH/3.3nF = 132kHz.

The7446.581 05 042 40.pdf

I hope the Information Is halpful.

Kind regards

SDLA

 Vogt is the antenna Manufacturer in Germany and has been bougth by Sumida.

Please find attached the Datasheet.

The Coil Q is about 25 at 135kHz but the system Q shall be in a range of 10 to 15 while the resonance center frequncy (Lant +Cres) shall be at about 132kHz in order to receive the 2 Transponder FSK frequncies (124&134 kHz symentrically.

Of course you can wind an own antenna. The inductance shall be between 300uH and 700uH tuned (matched) with the necessary resonace capacitance.

440uH/3.3nF = 132kHz.

The7446.581 05 042 40.pdf

I hope the Information Is helpful.

Kind regards

SDLA

Hello SDLA thanks for talking with me.

I looked at the Vogt data sheet for the loop aerial....still just a little confused about all those extra pins (6off) other than two for the coil maybe one for faraday shield...so what about the others what do they do...is there a schematic or have I still missed something?

Now... a follow up question and it relates to your repeated double reference to 132khz.....should you not mean 129 kHz  ie mid way between 124 and 134 (approx)?...

.I will run a spice simulation to check about your implied  "non-symetrical"  function of a simple parallel resonant circuit...perhaps I have forgot some basic principle.....I thought the resonance "bell" curve was close enough to be considered symetrical...be back to you on this matter...

Perhaps you have another reason for choosing 132kHz.... could you tell me more this, as it  is a basic but pretty important thing.....am I wrong in my understanding that the 007 module retunes itself to 129kHz for the same reason you voice...plus the 007 adds a damping resistance to widen the bandwidth.

I understand the low Q (10-15)  will broaden the receive band width and therefore negate the need for adaption from high down to retuned low Q, as in the 007....I understand the little 3705 is not in the same league as the 007...

not sure if 003 (117uH)  has this adaption capability, can you comment and also there is another TI hybrid module (forgot its name)  that calls for a 47uh and I think 15-20 Q factor, to equally accept 123-134kHz....Is my understanding wrong on these matters? help

Sorry SDLA....are you introducing something I should be better aware of...please explain...quickly I am about to get and test a 3705+27424 and I want to be ready

Thanks again

Regards

Ray

Ray -

Reader side (Downlink is 134.2kHz)

the frequencies you are curious about are coming back from the tag, you know and they have tolerances.

on the tag IC, we specify a couple of things around this

1. Resonant Circuit Frequency ==> lets say @ 25C ==> min = 134.1kHz nom = 134.2kHz max = 134.3kHz (so you can see this is pretty tight)

2. but then we have the Low Bit and High Bit  TX frequency tolerance specs. These are specified @ room temp, too (25C) with their Qop allowed to range between 30 and 100. So then the spec table might look like this - just for your information as to where the frequencies came from. THese are min, nominal and max value (just for example here)

Thanks Josh....you placed the subject of my query (134.7)  right in the centre of your frequency distribution matrix....I appreciate your attention to detail.

The context of my persistence is this:-

We tried to better identify why Canada were reporting larger number of "missed tags" than elsewhere.....

We conducted a simple experiment with 100 tags to try and map the distribution of  "detectability"....

Our set up was a 007 reader with a 1 metre diameter (27uH} coil and a ruler.... to record the distance away that a tag was "just detectable"

Our suspicion was "off-tune-tags"... As in Canada they handle cattle in temperatures below -20 degrees...perhaps even...even colder!

(as an aside...later we put heaters in the reader enclosures to keep the 007 etc modules "warm"...we saw your TI  prefered operating temperature range earlier)

With the 100 sample tags...(which were recovered from an abbaitoir to reflect "well used" or experienced tags) we found a variation in detection distance of about  200mm

We since colour coded thee tags from this group (red/blue/yellow) and now use these in our final testings elsewhere.

We tried to correlate variance against tag manufacturer but this became inconclusive...we could not dwell forever on this matter

We tried to "measure" the down-link frequencies but lacked the tools to do frequency analysis on the "pulsating FSK frequency" comming back from the tags

We even set up a crude form of "grid dip oscillator" to find the tags natural resonant 134.2 kHz frequency....(low levels were used to avoid activating the tags)...the results were not conclusive but we "think" our simple experiment found higher and lower frequencies.

Repeatability was not good, but was enough to set our minds at rest that variance in tag performance was most probably due to factors that influence resonance in a "free-running LC oscillator"

So Josh, I guess I should have looked harder to find documentation about manufacturing tolerance....obviously tag manufacture is an "art-form"...a turn or two more or less for the person winding the tags coil, uniformity of wire gauge , mechanical tolerance of the winding bobbin....the list is endless...and we can do no more than accept it...and remember the role of chaos.

thanks for your example table, it confirms two things for us...

1. be more aware of tuning component tolerance...the issue of why the "high-Bit" is prone to different variance is probably due to that it is achieved by switching in "another" capacitor in parallel...a crude but effective technique

2. be more aware of the role of temperature in modulating both the low and high down link frequencies, you have given voice to our conclusion to work around the extremes and we will now think in terms of 120 and 136.5 kHz as these.

Hopefully you will further see into our problem... which occurs when an endless stream of tags are "not" passing in single file but in multiple abreast within the detection volume...and here I am alluding to avoiding the future use of PLL as an enhancement to achieving "better" reading percentages...ie which one would you like me to lock onto???

However you will see as we did that there is "some value" in stepping the downlink power field frequency, on three consecutive illuminations, between say 136.5/134.2/132 kHz ...so as to "perhaps better" activate/capture off tune tags in a moving population.

Josh...we are trying hard to give users what they want...the tags are as they are...it is up to us to devise better ways to handle the "dogs breakfast" called free running frequency ...I am sure the early developers of the HDX concept never envisigned the use they would one day be exposed..... 

we are assembling a design brief or "wish list"   ...perhaps one day we will apply our acquired understandings....thank you for helping...there is more to come.

Is Mr Josef H Schuermann still with you over there?

Regard

Ray