Reply by Jim Thompson April 30, 20172017-04-30
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
Reply by Jeff Liebermann April 30, 20172017-04-30
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
Reply by Jeff Liebermann April 30, 20172017-04-30
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
Reply by bitrex April 30, 20172017-04-30
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...
Reply by bitrex April 30, 20172017-04-30
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.
Reply by Jim Thompson April 30, 20172017-04-30
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
Reply by bitrex April 30, 20172017-04-30
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?
Reply by Jeff Liebermann April 29, 20172017-04-29
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
Reply by Jim Thompson April 29, 20172017-04-29
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
Reply by Jeff Liebermann April 29, 20172017-04-29
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