Re: [Discuss-gnuradio] Salon article -- off topic

[David Bengtson]

On Thu, 13 Mar 2003 18:55:21 -0800, you wrote:

>> This was an interesting read, but I'm concerned about changing
>> spectrum policy based on a bunch of powerpoint slides saying that it
>> is possible to make a smart radio. 
>
>A lot of people have done a lot of research.

I'm sure that there has been lots of research (I've read a lot of it),
and I don't dispute that it is conceptually possible to make radio's
that approach the "Cognitive Radio"  ideal that Dr. Mittola and
other's have kicked around. 

>
>> Putting my receiver engineer hat on, my mind boggles at the receiver
>> linearity specifications needed to receive a femto watt 802.11
>> transmission while not being pounded into a quivering blob by a
>> megawatt FM radio station. 
>
>Nobody said there would be no power limits.  Nobody said your 802.11
>couldn't move itself to another frequency.  Nobody said megawatt FM stations
>will continue to exist, or that they would be allowed in open spectrum
>bands.
The issue will be the transition period while the old dinosaurs are
fading away and the new, nimble smart radios are taking over. It's
tough to design radios that are wide-bandwidth and sensitive, to a
price point. 

>
>> The software to make this all work is conceptually feasible, although
>> it isn't written. The RF front ends to do this will require some major
>> technology breakthroughs. 
>
>no, not if power is limited.

The problem is that transmit power for broadcast stations will always
be high, and you will get close to a broadcast tower, and overload
your front-end. Ultimately, if smart radio's are successful, then the
broadcast station's will fade away. Until then, they will be blaring
away. SMR and Land Mobile/Public Safety radio's are also fairly high
power, and entrenched in the infrastructure. 
>
>> On the other hand, given the speed of government, perhaps it's time to
>> start kicking the tires on open spectrum. 
>
>That's what is happening now.  I don't think anyone holds out hope that this
>will happen all at once.  Spectrum will be reallocated in pieces.  When the
>FCC thinks that the only way to make use of it is to give exclusive rights,
>that's what they do.  When people point out that unlicensed services can
>make better use of a band, they may give it to the unlicensed services.
>
>
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