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Re: RFID - the Disney way, two frequency bands

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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...

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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

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