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Author Topic: Removing the cell band monitoring restrictions  (Read 2375 times)
N7SZF
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« on: November 24, 2010, 10:32:10 AM »

Ok, it's 2010. Analog mobile phone is dead. AMPS had a good run, but we've moved on.  Encryopted digital cell conversations are now the norm.

Is it time to begin petitioning to have the block on the old analog mobile phone band monitoring gear removed? It serves no purpose now, other than to make USA radio different from world radios.  Removing the block might reduce complexity and as such, reduce cost to the ham.

Thoughts?
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WB2WIK
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« Reply #1 on: November 24, 2010, 01:27:37 PM »

My only thoughts are:

Why would anyone want to listen there, when nothing in that part of the spectrum can be demodulated with analog detection?  (I.e., there's really nothing to listen to.)

-and-

I doubt this would reduce the cost of anything, since the "lockout" is done in firmware and there's no extra circuitry involved in locking out a frequency range.
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W6RMK
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« Reply #2 on: November 25, 2010, 08:01:23 AM »

Actually, it *would* reduce costs.   A significant part of the cost of new radios (particularly those manufactured in small volumes) is demonstrating compliance with the rules. That is, you have to test the radio to prove that it can't receive cell bands, even in non-standard ways (e.g. image frequencies or harmonics).

It also opens up the design space.  A lot of radios do not have "re-flashable" firmware because of this rule; since the FCC doesn't allow designs that can enable the prohibited bands by means of a "simple modification", which they take to mean installing/removing a jumper or diode, or loading a new software version in.  As a result, you have to go to a onetime programmable part or even a mask programmed ROM.
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WB2WIK
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« Reply #3 on: November 29, 2010, 03:20:40 PM »

Actually, it *would* reduce costs.   A significant part of the cost of new radios (particularly those manufactured in small volumes) is demonstrating compliance with the rules. That is, you have to test the radio to prove that it can't receive cell bands, even in non-standard ways (e.g. image frequencies or harmonics).

This is semantics, but I don't think that test, which is done on a single sample and not repeatedly (so it adds nothing to production cost), actually adds any compatibility lab cost at all.   The receiver has to go through Part 15 testing anyway to be eligible for sale here, and the labs charge a flat fee for that, generally -- whether the sequence includes this "lockout" test or not.  I used to run a compatibility/compliance lab (FCC licensed and NVLAP accredited) and we never charged extra for such tests.

Quote
It also opens up the design space.  A lot of radios do not have "re-flashable" firmware because of this rule; since the FCC doesn't allow designs that can enable the prohibited bands by means of a "simple modification", which they take to mean installing/removing a jumper or diode, or loading a new software version in.  As a result, you have to go to a onetime programmable part or even a mask programmed ROM.

I honestly don't see how that adds any cost, either.  Whatever technology is used for releases, updates and revisions can be maintained as proprietary code not available to the public and then you can lawfully use whatever you wish to store it.
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KD4LLA
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« Reply #4 on: December 06, 2010, 12:43:54 PM »

"Is it time to begin petitioning to have the block on the old analog mobile phone band monitoring gear removed?"

For what reason?  Most 800 mhz isn't encrypted, it is digital.
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N1DVJ
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« Reply #5 on: December 14, 2010, 11:49:08 AM »

First off, it DOES add cost.  If you don't realize that then you don't understand the issue.  Inventory item count for one.  Inventory  tracking and management for another.  Compliance testing (and not at certification).  Compliance management.  Additional complexity in development.  The list goes on.  (Sure, it's just a firmware switch, for the people that don't understand firmware)

But there ARE valid reasons for removing it.  Would you ever buy a spectrum analyzer that had blocks cut out of coverate?  Sure you would, because you don't understand the issue!!

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