Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #457928 > unrolled thread

RFID - the Disney way, two frequency bands

Back to article view | Back to sci.electronics.design

Contents

  RFID - the Disney way, two frequency bands Winfield Hill <hill@rowland.harvard.edu> - 2017-04-28 19:10 -0700
    Re: RFID - the Disney way, two frequency bands piglet <erichpwagner@hotmail.com> - 2017-04-29 07:50 +0100
    Re: RFID - the Disney way, two frequency bands Mikko OH2HVJ <mikko.syrjalahti@nospam.fi> - 2017-04-29 11:53 +0300
      Re: RFID - the Disney way, two frequency bands Winfield Hill <hill@rowland.harvard.edu> - 2017-04-29 05:08 -0700
        Re: RFID - the Disney way, two frequency bands Phil Allison <pallison49@gmail.com> - 2017-04-29 05:30 -0700
    Re: RFID - the Disney way, two frequency bands Jeff Liebermann <jeffl@cruzio.com> - 2017-04-29 11:00 -0700
      Re: RFID - the Disney way, two frequency bands Jeff Liebermann <jeffl@cruzio.com> - 2017-04-29 12:58 -0700
        Re: RFID - the Disney way, two frequency bands Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-04-29 13:39 -0700
          Re: RFID - the Disney way, two frequency bands Jeff Liebermann <jeffl@cruzio.com> - 2017-04-29 17:49 -0700
            Re: RFID - the Disney way, two frequency bands Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-04-30 08:45 -0700
              Re: RFID - the Disney way, two frequency bands bitrex <bitrex@de.lete.earthlink.net> - 2017-04-30 13:01 -0400
              Re: RFID - the Disney way, two frequency bands Jeff Liebermann <jeffl@cruzio.com> - 2017-04-30 10:55 -0700
            Re: RFID - the Disney way, two frequency bands bitrex <bitrex@de.lete.earthlink.net> - 2017-04-30 13:14 -0400
              Re: RFID - the Disney way, two frequency bands Jeff Liebermann <jeffl@cruzio.com> - 2017-04-30 11:28 -0700
                Re: RFID - the Disney way, two frequency bands Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-04-30 11:41 -0700
        Re: RFID - the Disney way, two frequency bands bitrex <bitrex@de.lete.earthlink.net> - 2017-04-30 08:36 -0400

#457928 — RFID - the Disney way, two frequency bands

Disney theme park customers have special RFID bands, called MagicBand, helping
them use the parks.  A 13-month old Wired article called this a $1B bet on their
MagicBands, but such an expenditure would have been more on the back end, rather
than on the bands themselves.  https://www.wired.com/2015/03/disney-magicband/

At the time, Disney was quite forthcoming with tech details, photos and
teardowns about the RFID bands.  EETimes has a video,
http://www.eetimes.com/author.asp?section_id=69&doc_id=1320977  

At one level the MagicBands operated as 2.4GHz devices, but they also had a
longer-range low-frequency capability they didn't discuss.  This was explored by
the fellow at AtDisneyAgain.  See
https://atdisneyagain.com/2014/01/27/making-the-band-magicband-teardown-and-more/

Their design has recently dramatically changed, which is obvious by comparing
this photo I took, see dropbox, to the earlier teardowns.
https://www.dropbox.com/s/sl5c4sh22idv4mp/2017_Disney_MagicBand_pcb.jpg?dl=0

I wasn't able to identify the new 32-pin primary RFID controller IC.  But note
the coupling components and the 1/4 turn 2.4GHz antenna.

I also wasn't able to identify the large RF driver-IC / module connected to the
outer five-turn low-frequency antenna loop (outer diameter 0.85 x 1.0 inches). 
Nor could I find any information about the low-frequency system, except that it
could work at longer ranges.

Perhaps somebody here can help.


-- 
 Thanks,
    - Win

[toc] | [next] | [standalone]

#457955

On 29/04/2017 03:10, Winfield Hill wrote:
> Disney theme park customers have special RFID bands, called MagicBand, helping
> them use the parks.  A 13-month old Wired article called this a $1B bet on their
> MagicBands, but such an expenditure would have been more on the back end, rather
> than on the bands themselves.  https://www.wired.com/2015/03/disney-magicband/
>
> At the time, Disney was quite forthcoming with tech details, photos and
> teardowns about the RFID bands.  EETimes has a video,
> http://www.eetimes.com/author.asp?section_id=69&doc_id=1320977
>
> At one level the MagicBands operated as 2.4GHz devices, but they also had a
> longer-range low-frequency capability they didn't discuss.  This was explored by
> the fellow at AtDisneyAgain.  See
> https://atdisneyagain.com/2014/01/27/making-the-band-magicband-teardown-and-more/
>
> Their design has recently dramatically changed, which is obvious by comparing
> this photo I took, see dropbox, to the earlier teardowns.
> https://www.dropbox.com/s/sl5c4sh22idv4mp/2017_Disney_MagicBand_pcb.jpg?dl=0
>
> I wasn't able to identify the new 32-pin primary RFID controller IC.  But note
> the coupling components and the 1/4 turn 2.4GHz antenna.
>
> I also wasn't able to identify the large RF driver-IC / module connected to the
> outer five-turn low-frequency antenna loop (outer diameter 0.85 x 1.0 inches).
> Nor could I find any information about the low-frequency system, except that it
> could work at longer ranges.
>
> Perhaps somebody here can help.
>
>

125-128kHz and 13.56Mhz are two other RFID frequencies much used. 
Clearly not enough turns for LF so my guess is they use 13.56Mhz and 2.4GHz.

There are a lot of microcontroller+RF chips made for Zigbee/bluetooth 
usage that would be candidates for the 32pin device, for example I have 
seen Chipcon CC2xxx parts used for just that kind of RFID token.

Are you sure that larger object you think is an RF driver-IC is some 
kind of semiconductor? I wonder if it is a capacitor or filter?

piglet

[toc] | [prev] | [next] | [standalone]

#457958

Winfield Hill <hill@rowland.harvard.edu> writes:

> I wasn't able to identify the new 32-pin primary RFID controller IC.  But note
> the coupling components and the 1/4 turn 2.4GHz antenna.

From the part number it's Nordic Semiconductors nRF31512. There's not
much information in the web about it, but nRF has had a lot of chips
that offer reduced functionality with lower price.

I could not find any datasheets or detailed information, but they've had
a lot of proprietary 900MHz, 2.4GHz, BLE chips with 8051 and
Cortex-M0/M4.

--
mikko

[toc] | [prev] | [next] | [standalone]

#457961

Mikko OH2HVJ wrote...
>
> Winfield Hill writes:
>
>> I wasn't able to identify the 32-pin primary RFID IC...
>
> From the part number it's Nordic Semiconductors nRF31512.
> There's not much information in the web about it, but nRF has had
> a lot of chips that offer reduced functionality with lower price.

 Yes, that sounds right.  A special reduced-functionality
 part.  No doubt Disney bought millions at a reduced price.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#457962

Winfield Hill wrote:
> Mikko OH2HVJ wrote...
> 
> >
> >> I wasn't able to identify the 32-pin primary RFID IC...
> >
> > From the part number it's Nordic Semiconductors nRF31512.
> > There's not much information in the web about it, but nRF has had
> > a lot of chips that offer reduced functionality with lower price.
> 
>  Yes, that sounds right.  A special reduced-functionality
>  part.  No doubt Disney bought millions at a reduced price.
> 


** Right - a "Micky Mouse" part at a "Minnie Mouse" price. 

 
   
  

...  Phil 

[toc] | [prev] | [next] | [standalone]

#457996

On 28 Apr 2017 19:10:39 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>Disney theme park customers have special RFID bands, called MagicBand, helping
>them use the parks.

You might find this site easier to navigate than the FCCID mess:
<https://fccid.io/Q3E-MB-R1G1>

If you go to the FCCID search page at:
<https://apps.fcc.gov/oetcf/eas/reports/GenericSearch.cfm>
and enter:
  Grantee Code = Q3E
  Show [99] records (at bottom of page)
and click "start search", you'll get all 12 of Disney's listings.  The
latest is dated Jan 2016 for the molded watch band.

Also, notice the lower and upper frequencies in the 2.4GHz band.  A
few seem to be specific frequencies rather than ranges, such as 2482.0
MHz for the Q3E-xBR-R1G1 reader.  From:
<https://apps.fcc.gov/eas/GetApplicationAttachment.html?id=1819645>
  "The model xBR V3 device, with the FCC product code Q3E-xBR-R1G1,
  has multiple receiving radios to receive signals from wristband
  transmitters. The device also transmits using a single radio to 
  control the wrist bands."
It would be interesting to know what they "control" on the wrist band?
Perhaps a Star Trek style "Agonizer"?

The design was by Synapse (A Cambridge Consultants Company):
<http://www.synapse.com/projects>

The use of "UHF" in the tag was removed from the FCC certification in
2013 making the tag operational only on 2.4GHz:
<https://apps.fcc.gov/eas/GetApplicationAttachment.html?id=1948649>
Strictly speaking, UHF means 300-3000MHz, so 2.4GHz would be
considered UHF.
<https://en.wikipedia.org/wiki/Ultra_high_frequency>

The 5 turn outer loop is 13.56MHz.  Try this calculator to be sure:
<https://www.medo64.com/2014/11/rectangular-nfc-antenna-calculator/>
For something that isn't going to be used, the loop has appeared in
all the known versions.

Somewhat later versions of the band:
<https://atdisneyagain.com/2014/01/27/making-the-band-magicband-teardown-and-more/>
<https://atdisneyagain.files.wordpress.com/2014/01/making-the-band-025.jpg?w=1000&h=>
show the 13.56MHz loop buried in a flex PCB.  The chip in the photo is
someone's RFID chip which appears to be only connected to the 13.56MHz
antenna.  

My guess(tm) is that there are actually two RFID devices in the
package.  One non-removable battery powered active device for 2.4GHz,
and one passive device for 13.56MHz.  Using the "follow the money"
principle, my guess(tm) would be that the 13.56MHz section is for some
kind of NFC payment device for a future "Disney Pay" contrivance as
illustrated in the FCCID pages:
<https://apps.fcc.gov/eas/GetApplicationAttachment.html?id=1979266>

Yet another guess(tm).  The 2.4GHz device might be transmitting a
beacon at some random interval, which would likely be used for
tracking visitors in the park.  If the band you tore apart is still
functional, you might check for this feature.

Did the device you posted at:
<https://www.dropbox.com/s/sl5c4sh22idv4mp/2017_Disney_MagicBand_pcb.jpg?dl=0>
have a different FCCID number from the previous mutations?
(Q3E-MB-R1G1)



-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

[toc] | [prev] | [next] | [standalone]

#458015

On Sat, 29 Apr 2017 11:00:27 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
(...)

Disney also has some other FCC ID prefixes.
<https://fccid.io/Q3E>
<https://fccid.io/2AJS4>

2AJS4-TP-R1G2 
<https://fccid.io/document.php?id=3354163>
  "The TPv2 is a second generation Digital Access Point. 
  The primary function of the device is to read multiple media 
  types and relay that information using an Ethernet connection. 
  The TPv2 is able to read HF RFID tags. The TPv2 can read UHF 
  RFID tags embedded in cards. The TPv2 also has 2.4 GHz transmit 
  and receive radios."
So, it's a reader with 3 frequency bands, 13.56MHz, 900MHz(UHF), and
2.4GHz (bi-directional).

This reader was added recently (Apr 11, 2017):
2AJS4-TP-R1G2
<https://fccid.io/2AJS4-TP-R1G2>
I'm not sure what this device really looks).  Notice that it transmits
on 900MHz and 2.4GHz, and receives on 13.56, 900MHz, and 2.4GHz.  The
RF test report includes tests for all 3 bands, so I guess 900MHz is
back in the picture.


-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

[toc] | [prev] | [next] | [standalone]

#458023

On Sat, 29 Apr 2017 12:58:48 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sat, 29 Apr 2017 11:00:27 -0700, Jeff Liebermann <jeffl@cruzio.com>
>wrote:
>(...)
>
>Disney also has some other FCC ID prefixes.
><https://fccid.io/Q3E>
><https://fccid.io/2AJS4>
>
>2AJS4-TP-R1G2 
><https://fccid.io/document.php?id=3354163>
>  "The TPv2 is a second generation Digital Access Point. 
>  The primary function of the device is to read multiple media 
>  types and relay that information using an Ethernet connection. 
>  The TPv2 is able to read HF RFID tags. The TPv2 can read UHF 
>  RFID tags embedded in cards. The TPv2 also has 2.4 GHz transmit 
>  and receive radios."
>So, it's a reader with 3 frequency bands, 13.56MHz, 900MHz(UHF), and
>2.4GHz (bi-directional).
>
>This reader was added recently (Apr 11, 2017):
>2AJS4-TP-R1G2
><https://fccid.io/2AJS4-TP-R1G2>
>I'm not sure what this device really looks).  Notice that it transmits
>on 900MHz and 2.4GHz, and receives on 13.56, 900MHz, and 2.4GHz.  The
>RF test report includes tests for all 3 bands, so I guess 900MHz is
>back in the picture.

Low frequency receive and high frequency transmit are quite common...
saves power since receiver is either on all the time, or keyed on to
listen every fraction of a second or so... the chip designs I did for
SAVI Technology (was independent, then Lockheed-Martin, now private:
LaSalle Capital Group) were like that... since they're primarily used
to track trucks and pallets.
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

"It is not in doing what you like, but in liking what you do that
is the secret of happiness."  -James Barrie

[toc] | [prev] | [next] | [standalone]

#458054

On Sat, 29 Apr 2017 13:39:46 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Sat, 29 Apr 2017 12:58:48 -0700, Jeff Liebermann <jeffl@cruzio.com>
>wrote:
>
>>On Sat, 29 Apr 2017 11:00:27 -0700, Jeff Liebermann <jeffl@cruzio.com>
>>wrote:
>>(...)
>>
>>Disney also has some other FCC ID prefixes.
>><https://fccid.io/Q3E>
>><https://fccid.io/2AJS4>
>>
>>2AJS4-TP-R1G2 
>><https://fccid.io/document.php?id=3354163>
>>  "The TPv2 is a second generation Digital Access Point. 
>>  The primary function of the device is to read multiple media 
>>  types and relay that information using an Ethernet connection. 
>>  The TPv2 is able to read HF RFID tags. The TPv2 can read UHF 
>>  RFID tags embedded in cards. The TPv2 also has 2.4 GHz transmit 
>>  and receive radios."
>>So, it's a reader with 3 frequency bands, 13.56MHz, 900MHz(UHF), and
>>2.4GHz (bi-directional).
>>
>>This reader was added recently (Apr 11, 2017):
>>2AJS4-TP-R1G2
>><https://fccid.io/2AJS4-TP-R1G2>
>>I'm not sure what this device really looks).  Notice that it transmits
>>on 900MHz and 2.4GHz, and receives on 13.56, 900MHz, and 2.4GHz.  The
>>RF test report includes tests for all 3 bands, so I guess 900MHz is
>>back in the picture.

>Low frequency receive and high frequency transmit are quite common...

I'll assume that you're talking about the tag, not the reader.

>saves power since receiver is either on all the time, or keyed on to
>listen every fraction of a second or so...

I don't see how that saves power.  

As I understand it, having both 13.56Mhz and 2.4GHz gives the tag the
advantage of still being functional if the battery dies in the active
tag and/or can do full duplex with data to the tag on 13.56MHz and
from the tag on 2.4GHz.  A passive 13.56MHz tag is cheap but a limited
range of about 8 meters max as I recall.  Meanwhile, the active 2.4Ghz
tag can do very long distances.  For example:
<http://www.synometrix.com/synotag-2/active-rfid/>
Judging by the button cell used by the Disney MagicBand, I would
guess(tm) that these have about the same range as an automotive alarm
key fob (30 meters).  Since the MagicBand battery is small and cannot
be replaced, methinks the intended lifetime might be rather short. So,
rather than have someone show up at the gate with a dead battery in
their MagicBand, the reader can at least identify the owner on
13.56MHz, which somewhat explains the 2nd tag.  However, I'm guessing
(as usual).

>the chip designs I did for
>SAVI Technology (was independent, then Lockheed-Martin, now private:
>LaSalle Capital Group) were like that... since they're primarily used
>to track trucks and pallets.
>		
>                                        ...Jim Thompson

I believe that their biggest customers are NATO and the US military:
<http://www.savi.com/company/customers/nato/>
-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

[toc] | [prev] | [next] | [standalone]

#458109

On Sat, 29 Apr 2017 17:49:38 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sat, 29 Apr 2017 13:39:46 -0700, Jim Thompson
><To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
[snip]
>
>>Low frequency receive and high frequency transmit are quite common...
>
>I'll assume that you're talking about the tag, not the reader.

Yes.

>
>>saves power since receiver is either on all the time, or keyed on to
>>listen every fraction of a second or so...
>
>I don't see how that saves power.

SAVI Technology (battery-powered) tag for tracking trucks and pallets
(at/near loading docks), original design early 2001, with
embellishments thru 2009, received on 132kHz, transmitted on 434MHz.

Nominal current when not active, 5uA... wake-up, listen for request of
THAT particular tag serial number, if not heard, go back to sleep.
ONLY if proper serial number heard did 434MHz transmitter respond.

This was prior to Lockheed-Martin acquisition.

Then development ceased, except for some low-noise preamp development
for the receiver (original chip was all CMOS).
  
[snip]

In late 2011, early 2012, I was called back to assist as expert
witness to defend the patents... one of those patent scammer companies
had a patent "if it looks like our vague description of tag it must
infringe our patent".

One of their attorney's was harassing me trying to elicit from me that
my design was as described by the scammer patent... but it was nothing
like it.

Round and round we went until finally she said, "Well!  I just don't
understand, Mr. Thompson".

In a fit of pique I responded, "Maybe that's because you're a lawyer,
and I'm an engineer!".

Brought down the house >:-}

Lockheed-Martin ultimately paid off the scammer... apparently cheaper
than legal fees... I, alone, was billing $8-10K/week ;-)

>
>>the chip designs I did for
>>SAVI Technology (was independent, then Lockheed-Martin, now private:
>>LaSalle Capital Group) were like that... since they're primarily used
>>to track trucks and pallets.
>>		
>>                                        ...Jim Thompson
>
>I believe that their biggest customers are NATO and the US military:
><http://www.savi.com/company/customers/nato/>

That's now.  When this thread started I reached out to see who was
left of the original SAVI team... none.

One whose private E-mail I knew, responded yesterday with...

"Hi Jim,

Good to hear your still at it.  They sold Savi 4-5 years ago and fired
every last one of us. Moved it to east coast. I don't think they
really design anything anymore.

Tim"
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

"It is not in doing what you like, but in liking what you do that
is the secret of happiness."  -James Barrie

[toc] | [prev] | [next] | [standalone]

#458115

On 04/30/2017 11:45 AM, Jim Thompson wrote:

> Lockheed-Martin ultimately paid off the scammer... apparently cheaper
> than legal fees... I, alone, was billing $8-10K/week ;-)

Lame, payouts like that is why those actual corporate parasites exist.

There should be some kind of scam-artist insurance fund that companies 
with IP can pay into so that when the scammers show up they can just 
grind them in court until they run out of money.

[toc] | [prev] | [next] | [standalone]

#458120

On Sun, 30 Apr 2017 08:45:05 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>>>saves power since receiver is either on all the time, or keyed on to
>>>listen every fraction of a second or so...
>>
>>I don't see how that saves power.

>SAVI Technology (battery-powered) tag for tracking trucks and pallets
>(at/near loading docks), original design early 2001, with
>embellishments thru 2009, received on 132kHz, transmitted on 434MHz.
>
>Nominal current when not active, 5uA... wake-up, listen for request of
>THAT particular tag serial number, if not heard, go back to sleep.
>ONLY if proper serial number heard did 434MHz transmitter respond.

Ah, got it.  LF receive doesn't draw much (or any) power and
433.925MHz is a good compromise between TX power and range.  Much of
this stuff was moved to 900MHz, where the antennas could be made
smaller and less interference from key fobs and wireless weather
stations.  That worked fine until spread spectrum smart meters took
over most of the 915-928MHz band.  The powered tags are apparently now
on 2.4GHz and a few on 5GHz leaving the passive tags on 900MHz.  Also,
in 2001, we didn't have the benefits of cheap 2.4GHz chips,
components, and technology.

>This was prior to Lockheed-Martin acquisition.
>
>Then development ceased, except for some low-noise preamp development
>for the receiver (original chip was all CMOS).

A friend worked for Savi just after Lockheed bought them.  We would
have dinner and he would ask me to interpret some of the political
intrigues that were happening at the time.  That gave me a rather
biased view of the company, which I'll keep to myself.

When Lockheed decided to sell the company, there were numerous rounds
of layoffs intended to reduce costs and make the business look
profitable.  When that didn't quite work, they moved the "leadership
team" to the east coast, and continued the layoffs on the west coast:
<https://www.govconexecutive.com/2010/08/lockheed-to-move-savi-technology-to-northern-va/>
Oddly, they laid off from the top, so my low paid friend was one of
the last to go.

Things apparently settled down when the company was sold to LaSalle:
<http://www.rfidjournal.com/articles/view?9944>
Some clues on GlassDoor.com:
<https://www.glassdoor.com/Reviews/Savi-Technology-Reviews-E13697.htm>

>Round and round we went until finally she said, "Well!  I just don't
>understand, Mr. Thompson".
>In a fit of pique I responded, "Maybe that's because you're a lawyer,
>and I'm an engineer!".
>Brought down the house >:-}

Nicely done.  


-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

[toc] | [prev] | [next] | [standalone]

#458116

On 04/29/2017 08:49 PM, Jeff Liebermann wrote:
> On Sat, 29 Apr 2017 13:39:46 -0700, Jim Thompson
> <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:
>
>> On Sat, 29 Apr 2017 12:58:48 -0700, Jeff Liebermann <jeffl@cruzio.com>
>> wrote:
>>
>>> On Sat, 29 Apr 2017 11:00:27 -0700, Jeff Liebermann <jeffl@cruzio.com>
>>> wrote:
>>> (...)
>>>
>>> Disney also has some other FCC ID prefixes.
>>> <https://fccid.io/Q3E>
>>> <https://fccid.io/2AJS4>
>>>
>>> 2AJS4-TP-R1G2
>>> <https://fccid.io/document.php?id=3354163>
>>>  "The TPv2 is a second generation Digital Access Point.
>>>  The primary function of the device is to read multiple media
>>>  types and relay that information using an Ethernet connection.
>>>  The TPv2 is able to read HF RFID tags. The TPv2 can read UHF
>>>  RFID tags embedded in cards. The TPv2 also has 2.4 GHz transmit
>>>  and receive radios."
>>> So, it's a reader with 3 frequency bands, 13.56MHz, 900MHz(UHF), and
>>> 2.4GHz (bi-directional).
>>>
>>> This reader was added recently (Apr 11, 2017):
>>> 2AJS4-TP-R1G2
>>> <https://fccid.io/2AJS4-TP-R1G2>
>>> I'm not sure what this device really looks).  Notice that it transmits
>>> on 900MHz and 2.4GHz, and receives on 13.56, 900MHz, and 2.4GHz.  The
>>> RF test report includes tests for all 3 bands, so I guess 900MHz is
>>> back in the picture.
>
>> Low frequency receive and high frequency transmit are quite common...
>
> I'll assume that you're talking about the tag, not the reader.
>
>> saves power since receiver is either on all the time, or keyed on to
>> listen every fraction of a second or so...
>
> I don't see how that saves power.

Saves power by only having continual dynamic power dissipation at the 
lower frequency (charging and discharging all those CMOS gate 
capacitances in whatever IC you're using) and not having to bias the RF 
receiver amps at the relatively high static currents required for the 
speedy-speedy I'd guess...

[toc] | [prev] | [next] | [standalone]

#458126

On Sun, 30 Apr 2017 13:14:10 -0400, bitrex
<bitrex@de.lete.earthlink.net> wrote:

>Saves power by only having continual dynamic power dissipation at the 
>lower frequency (charging and discharging all those CMOS gate 
>capacitances in whatever IC you're using) and not having to bias the RF 
>receiver amps at the relatively high static currents required for the 
>speedy-speedy I'd guess...

Jim mentioned that his Savi tag receiver is running at 132KHz.  CMOS
only draws power when transitioning from a 0 to 1 or 1 to 0.
Therefore, the lower the frequency, the lower the power consumption
for an active tag.  132KHz will use less power than 13.56MHz.

What's a "speedy-speedy"?  If you mean while the tag is moving, that's
taken care of by the modulation scheme.  Most tags are OOK (On Off
Keying).  The doppler shift that screws up tags using FM modulation is
not a problem with OOK.  That's not to say that doppler is useless.
There are some schemes that determine the tag direction of travel and
location by its doppler shift.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

[toc] | [prev] | [next] | [standalone]

#458129

On Sun, 30 Apr 2017 11:28:46 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Sun, 30 Apr 2017 13:14:10 -0400, bitrex
><bitrex@de.lete.earthlink.net> wrote:
>
>>Saves power by only having continual dynamic power dissipation at the 
>>lower frequency (charging and discharging all those CMOS gate 
>>capacitances in whatever IC you're using) and not having to bias the RF 
>>receiver amps at the relatively high static currents required for the 
>>speedy-speedy I'd guess...
>
>Jim mentioned that his Savi tag receiver is running at 132KHz.  CMOS
>only draws power when transitioning from a 0 to 1 or 1 to 0.
>Therefore, the lower the frequency, the lower the power consumption
>for an active tag.  132KHz will use less power than 13.56MHz.

Not to mention... for all intents and purposes, chip was an analog
amplifier with two digital outputs, (1) signal strong enough to trust
(RSSI), and (2) data... very slow stuff... 300uS bit width.

[snip]
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

"It is not in doing what you like, but in liking what you do that
is the secret of happiness."  -James Barrie

[toc] | [prev] | [next] | [standalone]

#458083

On 04/29/2017 03:58 PM, Jeff Liebermann wrote:

> This reader was added recently (Apr 11, 2017):
> 2AJS4-TP-R1G2
> <https://fccid.io/2AJS4-TP-R1G2>
> I'm not sure what this device really looks).  Notice that it transmits
> on 900MHz and 2.4GHz, and receives on 13.56, 900MHz, and 2.4GHz.  The
> RF test report includes tests for all 3 bands, so I guess 900MHz is
> back in the picture.

Disney theme parks have a lot of rides and attractions that are 
completely indoors, say Space Mountain, the Epcot dome, and whatever 
else they've built in the 2 decades or so since I was last at the Magic 
Kingdom.

Could they be using some kind of system where they have local 2.4 GHz 
receivers for the wristbands within the indoor attractions, but are then 
transmitting at a higher power on a lower frequency from a centralized 
location to achieve wall penetration, so they don't have to also install 
a transmitting system in every single building?

[toc] | [prev] | [standalone]

Back to top | Article view | sci.electronics.design

csiph-web