In article ,
Doug Smith W9WI wrote:

I'm a lot more worried about it as a TV engineer and semi-rural
over-the-air TV viewer. In early tests these things weren't very good at
determining whether a channel was unused. I can see that becoming a big
problem in semi-rural areas like this, where people might be using rooftop
antennas to get TV but the Internet devices will probably be on makeshift
indoor aerials.

According to an article in Moble Radio Technology magazine recently,
there's another issue in some areas (about ten major metro areas)
where various public safety agencies have already been authorized to
use the white space in the channel 14-20 range for various types of
public safety communication.

Some of these applications (e.g. video surveillance cameras) are
designed to be "indetectable" while in operation... which makes things
problematic for the proposed free-white-space-detection devices. The
police would be unamused by having their stakeout-surveillance video
feed stomped upon by web-browsing passersby!

The quick solution to this is to forbid the use of free-white-space
devices in this frequency range, in those cities where public safety
operations have already been authorized. This won't necessarily solve
the problem, if (for example) a user of such a device brings it from a
"wide open" city into a city with restrictions, and doesn't realize
that s/he has to change the device's mode to stay legal.

The pro-audio industry is also up in arms over these whitespace
proposals, as they've been depending for years on Part 15 (or similar)
wireless microphones which operate in the unused TV channel
frequencies. Having to face competition for these frequencies from a
whole bunch of non-coordinated new "find a 'free' frequency and camp
on it" devices could cause problems for them, to say the least!

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Fri, 25 Jul 2008 16:08:32 EDT, (Dave Platt)
wrote:

According to an article in Moble Radio Technology magazine recently,
there's another issue in some areas (about ten major metro areas)
where various public safety agencies have already been authorized to
use the white space in the channel 14-20 range for various types of
public safety communication.

Dave, that's old news, at least 30 years old .It was originally
pushed by the Los Angeles Sheriff's Department which up until that
time had been using VHF low-band (39 MHz) equipment.

The so-called T-Band is almost totally loaded in the major
metropolitan areas authorized for same (See FCC Rules Part 90, Sub
part L). This spectrum is allocated in such a manner as to protect
existing TV stations.

These are one type of systems that our company designs for
public-safety clients. Many agencies are asking the FCC to reassign
unused commercial channels in the T-Band for Public Safety use. We're
in the thick of that. What we are trying to do also is to get the FCC
to expand the radius around the authorized cities as urban growth
moves outward.
--

73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon

e-mail: k2asp [at] arrl [dot] net

On Sat, 26 Jul 2008 02:00:41 -0400, Phil Kane wrote:
These are one type of systems that our company designs for
public-safety clients. Many agencies are asking the FCC to reassign
unused commercial channels in the T-Band for Public Safety use. We're
in the thick of that. What we are trying to do also is to get the FCC
to expand the radius around the authorized cities as urban growth
moves outward.

I think the problem you're going to have (with both of those projects) is
that the compression of the TV band is going to make unused channels in
T-band less common. And especially in the areas outside the existing
radius where you'd like to expand it.

I think the argument you'll get is that 24MHz above channel 51 has alread
y
been set aside for public-safety, should it really need more below channe
l
21?

On Sat, 26 Jul 2008 07:01:43 EDT, Doug Smith W9WI
wrote:

I think the argument you'll get is that 24MHz above channel 51 has already
been set aside for public-safety, should it really need more below channel 21?

Now you have me talking about my business but here I go anyway:

Every petition that we have submitted for our Public Safety clients
who need expansion into non-Public Safety Pool frequencies in T-Band
has been met with what I consider a boiler-plate query from the FCC
that has to be answered formally on the record about whether our
client has considered a 700 MHz system. What we say is this:

1. This is an expansion of existing system which already operates in
T-Band and there are no more Public Safety Pool T-Band channels
available that would not result in harmful interference to another
user of that band.

2. The characteristics of 700 MHz propagation and building
penetration are such that it would require anywhere from five to ten
times as many repeater sites as a T-band system, each one costing
three to five times as much as a T-Band site costs.

3. It is dangerous and unsafe to require a public safety officer
(police or fire) to carry two radios where the possibility exists that
the "wrong" radio would be used in a life-and-death situation.

4. There is no usable 700 MHz equipment on the market at the present
time. Existing 800 MHz equipment is not compatible with the operating
schemes proposed for the 700 MHz band.

5. The systems under consideration are taxpayer funded, and it is
egregious to abandon an existing system and procure a new system just
because the 700 MHz spectrum has been designated for future use. The
taxpayers won't stand for it, even in the name of "homeland security",
the magic words du jour, and obtaining additional sites is a
protracted and expensive procedure in today's environmental-conscious
urban and suburban environment (can you say NIMBY ?).

The documentation to support all the above literally runs into the
thousands of pages - all at the taxpayers' expense.

I'd say more but it would disparage a major manufacturer of equipment.
--

73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon

e-mail: k2asp [at] arrl [dot] net

On Fri, 25 Jul 2008 16:08:32 -0400, Dave Platt wrote:
The quick solution to this is to forbid the use of free-white-space
devices in this frequency range, in those cities where public safety
operations have already been authorized. This won't necessarily solve
the problem, if (for example) a user of such a device brings it from a
"wide open" city into a city with restrictions, and doesn't realize
that s/he has to change the device's mode to stay legal.

They'll probably have to ban them from T-band altogether. But see below.

The pro-audio industry is also up in arms over these whitespace
proposals, as they've been depending for years on Part 15 (or similar)
wireless microphones which operate in the unused TV channel frequencies
..
Having to face competition for these frequencies from a whole bunch of
non-coordinated new "find a 'free' frequency and camp on it" devices
could cause problems for them, to say the least!

One proposal I saw would require wireless-microphone users to transmit a
"beacon" signal at some predetermined location within the TV channel. Th
e
white-space devices would monitor for this beacon.

(both the DTV and analog TV standards essentially already have beacons)

So I suppose you could have the public-safety organizations also transmit
the beacons.

Yes, sometimes I get the impression the pro-audio folks are more upset
about this than the broadcasters.