Re: [AFMUG] TVWS feasibility

Tue, 23 Jun 2020 09:46:04 -0700

At this point, the so-called "development" of TVWS is little more than an extremely long-duration beta test.
I would now be looking toward Starlink as being a viable alternative as long as the service area(s) is/are not absolutely buried in trees. I am expecting Starlink service to be demonstrably better than geo-stationary satellite service, and close to competitive to land-based wireless service. Time will tell, and we may know by the end of the year. I don't expect TVWS to become viable in my lifetime. 


bp
<part15sbs{at}gmail{dot}com>

On 6/23/2020 9:22 AM, D. Bernardi wrote:




The areas I'm initially considering are NLOS and this exercise was 
just for considering TVWS only so I wasn't necessarily referring to 
frequency/gain impacts.



If TVWS has the same level of performance (and resulting range) with 1 
tree or a dense forest between base station and CPE, that would make 
modelling easier.



And since most folks are saying the TVWS database can be problematic, 
does anyone know if there are ways to correct inconsistencies?


Again, thanks for all the input.



At 11:45 AM 6/23/2020, you wrote:

I calculated it once.  Always good to go up in frequency if antenna 
gain and path loss are the only considerations.



If you increase the frequency, it works out that the system margin 
increases by the increase of gain of one of the antennas assuming 
identical antennas at both ends.


-----Original Message----- From: Ken Hohhof
Sent: Tuesday, June 23, 2020 9:21 AM
To: 'AnimalFarm Microwave Users Group'
Subject: Re: [AFMUG] TVWS feasibility

Lower frequencies do have lower free space loss, but for the same size
antenna you have less antenna gain.  And with 2 antennas (xmt and rcv),

antenna gain wins.  All else being equal, higher frequency usually 
wins.  Of

course with TVWS you usually accept using ginormous antennas.

I think people are telling you that TVWS is a niche technology, one that

isn't even a clear winner in its niche, and shouldn't be used outside 
its

niche.  If you have clear LOS, use something else.  If you have 99 NLOS

customers and 1 who happens to have LOS, I guess you could put him on 
the

TVWS system too.


-----Original Message-----
From: AF <[email protected]> On Behalf Of D. Bernardi
Sent: Tuesday, June 23, 2020 10:09 AM
To: AnimalFarm Microwave Users Group <[email protected]>
Subject: Re: [AFMUG] TVWS feasibility



Clearly RF isn't my specialty... Instead of SNR I guess I really meant

noise. If the noise floor is equal wouldn't there be less attenuation 
of the

signal in an open environment (resulting in a better SNR)?



At 10:41 AM 6/23/2020, you wrote:


> On Jun 23, 2020, at 10:32 AM, D. Bernardi <[email protected]>

wrote:

>
>
>
> I was thinking more in terms of foliage or other object density,
or mountains/hills, to help estimate range.  Wouldn't TVWS still have
better performance in an open area compared to dense forest given
equal SNR?
>

If SNR is identical then you will get identical performance,
assuming the same channel size and modulation.    TVWS channel size
is considerably smaller than the higher frequency alternatives and has
lower modulation levels (at least that I have seen).

Mark
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