Do we have to lease out 24GHz?

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 NOAA's Advanced Technology Microwave Sounder (ATMS),
 passively-measures water-vapor levels, using weak
 signals at 23.8 GHz.  NOAA uses this data for their
 critical hurricane forecasting.  
  
 FCC Chairman Ajit Pai wants to lease the 24 GHz band
 for 5G networks.  NOAA and many scientists, have said
 this will ruin the measurements, severely degrading
 the storm forecasts we now rely on.  Ajit Pai says,
 fuck off, the State Dept (!) says it's OK.  With that,
 he's not going to attend the next scheduled meeting.


--  
 Thanks,
    - Win

Re: Do we have to lease out 24GHz?

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I'm not sure Ajit Pai has the authority to make such a decision alone. It  
might require rulings by Congress to implement.
  
A similar situation occurred recently with GPS. A company called  
LightSquared wanted to use frequencies adjacent to the GPS frequencies for  
broadband cellular transmissions. Here is some background information:

https://insidegnss.com/?s=lightsquared

This appeared to end the threat:

"Lobbying and new spectrum: One last shot for LightSquared"

http://arstechnica.com/business/2013/08/lobbying-and-new-spectrum-one-last-
shot-for-lightsquared/

It appears there may be other factors involved other than the decision of  
one man.

Re: Do we have to lease out 24GHz?

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The FCC needs to be run less by crooked lawyers and more by people
that understand what is needed and how this stuff (RF) works and the
science of why what frequencies need to be used for what.


Re: Do we have to lease out 24GHz?
On a sunny day (Fri, 24 May 2019 00:17:02 -0700) it happened boB

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Spectrum is big money,
here in Europe governments are auctioning spectrum for 5G now,
and asking a LOT, driving the price up, as if the spectrum is theirs.
Big mony may win. It is a capitalist system after all.

They are also trying to get the ham bands,
I pay more every year for my license,
and they make it more difficult to pay each time.
Tactics

One day perhaps alien empire will auction solar system spectrum to them humans and then you work for them.


Re: Do we have to lease out 24GHz?
On 05/24/2019 10:12 AM, Jan Panteltje wrote:
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And the ham bands are mostly shoddy narrowband ones anyways. What do they even want those for?


Re: Do we have to lease out 24GHz?
On a sunny day (Fri, 24 May 2019 15:20:01 +0200) it happened Johann Klammer

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Well, ehh
this is from my list:
 http://panteltje.com/pub/higher_frequency_ham_bands_IMG_6931.JPG
the left column is how many watts I am allowed to output,
the most right column is 'S' for shared with other services,
and 'P' for hams only.

As we move into the 24 GHz we have 50 MHz wide there,
and an other 200 MHz wide shared.
The higher up you go the more bandwidth.

The 24 GHz part could be very attractive for 5G and other future systems.

The 70 cm / 430 MHz band could be in danger too.


Re: Do we have to lease out 24GHz?
On Fri, 24 May 2019 15:33:19 GMT, Jan Panteltje

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Some historical background information about the amateur microwave
radio frequency allocations.

Previously huge microwave segments were allocated for "radiolocation"
i.e. radar with bad frequency stability. Of course, any serious user
would not like to be colocated with radar, so these bands were also
given to hams on a secondary basis.

With improved radar technology, these radar bands were reduces, which
also reduced the amateur secondary allocations, giving large chunks of
spectrum to other uses.

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This is a good question.  

Previously several hundred MHz wide microwave allocations were handy
e.g. for running unstable 10 GHz or 24 GHz 10 mW Gunplexer frequency
modulated by  analog ATV.  

These days generating reasonable good stability carriers with a few
MHz wide digital TV signals is not a problem, so quite high SNR can be
achieved with reasonable bandwidths.

Apart for some UWB (Ultra Wide Band) experiments, I do not understand,
why hams would need frequency segments larger than about 10 MHz. For
UWB experiment some large segment shared with other UWB services would
suffice.

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Realistically, what data could you put into that range at least a few
hours each week. ?

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At least in Europe, the 5G mm-wave allocation starts at 26 GHz.


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That low range is of interest only for very rural systems.



Re: Do we have to lease out 24GHz?
On a sunny day (Fri, 24 May 2019 22:47:02 +0300) it happened
snipped-for-privacy@downunder.com wrote in

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Good question, in some city areas with many hams with DVB channels perhaps?

  
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The range is big, compared to that 24 GHz stuff...

We will see where it goes.
At least some HF band stuff was allocated to hams, nobody else seems to use it
until the sats are shot down..

About sats:  
That Space-X thing did a show here in the Netherlands last night:
  
https://www.youtube.com/watch?v=ytUygPqjXEc


He will have to spread those out I think?
How does that work, do those sats have their own propulsion?
I want that internet !

Re: Do we have to lease out 24GHz?
On 25/05/19 08:29, Jan Panteltje wrote:
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Has he published any figures about the aggregate
bandwidth available? He touts a headline figure
of 50Mb/s, but that's boring.

Re: Do we have to lease out 24GHz?
On a sunny day (Sat, 25 May 2019 09:35:05 +0100) it happened Tom Gardner

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If you are at sea on a boat that would be great,
if it is a lot cheaper than iridium etc..
I mean places out of reach of 4G and 5G towers.
Competition will get the pices down.

Re: Do we have to lease out 24GHz?

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ViaSat1 covers North America and part of Canada.  I do not know what  
areas ViaSat2 or any newer placements service.

  But ViaSat1 is like $79 a month and I think it is like 15Mb/s.
That is on what was the fastest satellite up there until they  
launched more.  The first was over 140Gb/s.

  I have serious doubts that Musk's devices will be delivering  
50Mb/s ever.

  And what is he going to do for ground stations?

  Every satellite would need access to an Earth based/Internet  
hooked Satellite Gateway with dishes and feeds onto the main  
backbone.

  ViaSat has Earth Gateway stations in 15 US cities from anchorage  
to Honolulu.  Each one has two 8 meter dishes and a set of ten racks  
of gear for the hooks.  It is Ka-band.

Re: Do we have to lease out 24GHz?
On 25/05/19 10:28, Jan Panteltje wrote:
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Or in many locations on land where the infrastructure
is inadequate.

While I doubt investment could be recouped from maritime
use alone, I expect the land-based demand to be *much*
more than necessary - hence the question.

For cellular systems, a prime figure of merit is
bits/s / MHz / km^2, i.e. how closely the Shannon
limit is approached plus how densely the frequencies
can be reused by adjacent cells. I would expect
something similar for this system.


Re: Do we have to lease out 24GHz?
On 2019/05/26 3:06 a.m., Tom Gardner wrote:
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er

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Like China? North Korea?

John


Re: Do we have to lease out 24GHz?
On Sat, 25 May 2019 07:29:08 GMT, Jan Panteltje

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You might get sufficient usage with a digital amateur TV (DATV)
repeater in a large city.

I haven't recently heard much of DATV experimentation. About a decade
ago, there were some experimentation using DVB-S. The DVB-S was
initially designed for satellite reception and thus is not very good
in handling multipath, preferably line-of-sight paths would be
preferable.  

OTOH, DVB-T (or other multitone OFDM) is designed for terrestrial
multipath environment and would be better suited for DATV.  

A single program stream could be put into a 2 MHz bandwidth or
multiple program stream in a 8 MHz multiplex, so not much frequency
demand on higher frequency bands.


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That is partially a myth. While it is true that vegetation will absorb
higher frequencies quite effectively  In urban areas the higher
frequencies are reflected very well from hard surfaces and the signal
level drop  is not much worse than on lower frequencies.

While the gain is a good quality measurement for transmitting
antennas, for receiving antennas, the antenna capture area is the
critical thing. Of course gain can be converted to capture area and
visa versa for a specific wavelength.

The antenna capture area  is proportional to the square of wavelength,
thus for a constant field strength the received power will drop
rapidly. The capture area for a half-wave dipole is little more than
0.1 square wavelengths. On HF, the capture area is as big as hangar
doors, while up in the microwave bands about the size of a coin, thus
much less power is delivered to the receiver.

To increase the received power, an array of dipoles can be used. This
may also increase directivity (and gain) which might be desirable or
undesirable feature depending of the situation. Too much directivity
is a bad thing, if multipath reflected signals come from different
directions. One way o handle this problems to use antennas with
steerable radiation patterns, such as MIMO antennas.

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Every time someone announces some new satellite based internet system,
I have wondered, where do you get sufficient spectrum to handle the
large number of simultaneous customers. The whole idea of any cellular
system is the frequency reuse, so you want to keep the cell size small
and avoid spilling over signals into neighbor cells. With satellites,
one would need very good steerable antennas which is hard, if the
satellites are small.

OK, so don't even try to serve urban customers, since the local cell
towers will handle them with lower cost. What  is left, customers on
high seas, in the tundra and in the desert. But are these customers
capable of paying for the satellite constellation ?

Since the oceans occupy a huge part of the earth, thus LEO satellites
will fly over the water for quite a long time each orbit, Does the
island and cruise ship users generate enough revenue ?


Re: Do we have to lease out 24GHz?
On a sunny day (Sat, 25 May 2019 20:51:34 +0300) it happened
snipped-for-privacy@downunder.com wrote in

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Yes, I did (and do) the DVB-S stuff:
 http://panteltje.com/panteltje/raspberry_pi_dvb-s_transmitter/

Modified version now for QO100 satellite.


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True, but I know little about DVB-T, did read up on it. but have not desihned or build anything for it,
I do have plenty DVB-T USB sticks ;-)

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This may interest you for spectrum usage, lots of experiments going on with DVB-S2 and some DVB-S
 https://eshail.batc.org.uk/wb/

Anyways a few MHz is enough, lower symbolratea are possible.


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Antenna height rules of course.
There is a 70 cm repeater network here that covers much of the NE part of the country
 http://www.pi2non.nl/systeem17.html
and an other one that does the west.
Not much here on 24 GHz that I know about?
QO100 satellite is a geostationary sat and can be accessed with a small commercial TV dish
and just a few watts for SSB. from almost anywhere.
2.4 GHz uplink. Even S Africa and Brasil is easy from here, but local chatting via that
sat happens too, all of Europe, Russia, Middle East.
So much for the large antennas....




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Yes good question, Elon Musk making profit ? SpaceX does.
Geostationary sats would be an other approach, dish pointing at sea is
possible, for 1000$ you have a stabilized pointing system to a geo sat,
no problem for a cruiseship, gives them TV too.
I am sure somebody at SpaceX did the math...  
We will see where it goes.

  



Re: Do we have to lease out 24GHz?
On Sun, 26 May 2019 04:50:03 GMT, Jan Panteltje

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I am not sure if those "satellite Internet" companies can do the math.

First of all, they seem to assume that they get 100 % market share
(both terrestrial as well as orbital) of both customers and microwave
spectrum.  

In high density urban areas, this is clearly impossible. Assuming 10
GHz of spectrum available and 50 Mbit/s for each customer (at least 10
MHz bandwidth), a cell could support only 1000 simultaneous customers.
At high density population areas ten cells on each square kilometers
would be required. Even with LEO satellites thousands of beams would
be required.

This is clearly inadequate to handle urban areas with satellite, hence
most of the revenue sources are lost. Does the rural/cruise customers
make such systems viable ?


Re: Do we have to lease out 24GHz?
snipped-for-privacy@downunder.com wrote...
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 They assume 3%, which they calculate works out
 to $30B.  They'd probably be happy with 1%.


--  
 Thanks,
    - Win

Re: Do we have to lease out 24GHz?
On a sunny day (Sun, 26 May 2019 16:09:11 +0300) it happened
snipped-for-privacy@downunder.com wrote in

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Yes, almost like Tesla electric cars, the grid here cannot cope with all cars being electric.
But things must sell.
There is an other problem with geosats, and that is latency,
you clearly have to wait for a reply on SSB on QO100, 2 x 40,000 km at least...
Plus the delay for all the digital processing.
So in internet use, a mouse click in a browser would need a few seconds wait to take effect.
For the lower orbiting sats it is not be so bad, but then you need smooth sat switching.
So we will have to see what it does,  
For a ship it would be really nice to have weather charts, phone and email exchange at a lower price.
Maybe there are also military applications.
More possibilities is better :-)

Re: Do we have to lease out 24GHz?
On 27/05/19 06:22, Jan Panteltje wrote:
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They aren't geosats; their altitude is 273 miles vs 22000
miles. That reduces the latency by a factor of 10.

They also have the same advantage that caused the fintech
sector to buy up the microwave links between Chichago and
New York: the speed of light is ~50% faster than in fibres.


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I'd like to know how many simultaneous Windows Updates
the spacex system can cope with. To me that is more
interesting than the peak point-to-point bandwidth.

Re: Do we have to lease out 24GHz?
On a sunny day (Mon, 27 May 2019 07:32:42 +0100) it happened Tom Gardner

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I know, see the previous part of the discussions, but geosats do have some advantages,

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Yes, that 'auto update' is sort of based on 1) bad software and 2) the fear creating sell more system
Like for example. in my view, the fear for Russian and Chinese hacking and back-doors these days as used in US politics
against Huawei is very similar to what happened in the Joseph McCarthy days:
 https://en.wikipedia.org/wiki/Red_Scare
national security used or misused.

Soon EU will make MS windows illegal, it is a clear security risk, a system that spies on EU citizens and companies.
:-)

Anyways, Huawei now is bringing out their own OS, seems to be droid compatible?
I'd love to see a full Linux on cellphones, I think Ubuntu tried, not sure why that did not take on.
Not much of a droid user, my HTC (with real keyboard) is in storage, using a simple Nokia.
No windows here of course for security reasons :-)
Do have many different versions of Linux in many different partitions on may computers...
Auto update? No Way!
I see software as a part of the hardware, once you have a working system do not fix it!
New features, but really not much is new since win-3.1 and trumpet winsock, now is it?, when Billy the Gates stated
that internet was really not important.
OK sorry for the rant / tangent.

  

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