Re: [AFMUG] dumb DFS questions

[dave]

Gotta love those guys popping up trying to out sell the 10yr veteran LOL!
Been there done it twice in 15 yrs


On 11/21/19 10:31 AM, Ken Hohhof wrote:


We mostly avoid DFS frequencies on APs because of the impact if we get 
false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit 
confused about DFS on other vendor equipment like Ubiquiti as well as 
home routers.


Question 1 – what happens when there’s a DFS detection?  On the 
Cambium gear, we have to select 1 or 2 alternate frequencies.  But on 
other gear, I don’t see this. When there’s a DFS hit, does it jump to 
another random frequency?  Does it rescan the current frequency until 
it tests clear and only then resume transmission?  Is the answer right 
in front of me and I’m being stupid?  Maybe in the case of routers 
they are exempt because of low EIRP?


Question 2 – what about 40/80/160 MHz channels?  We have a competitor 
using Ubiquiti gear and advertising residential subscriber speed plans 
up to 100x100. Clearly they must be using at least 40 MHz channels if 
not 80 MHz, or else their marketing people have burning pants and long 
noses.  And I don’t see how a WISP, especially one surrounded by other 
WISPs, could use wide channels other than in DFS bands.  We have some 
PTP links using 40 MHz but only 10 and 20 MHz channels on our APs.  So 
assuming you are using 40 or 80 MHz in DFS, what happens when there’s 
a DFS detect? Does the whole 40 or 80 MHz have to find a new home?  
Can it slide over 2.5 or 5 MHz and substantially overlap the previous 
occupied spectrum?  DFS bands come with enough spectrum to use wide 
channels, but is there enough to jump around when you take a DFS hit?





-- 
AF mailing list
AF@af.afmug.com
http://af.afmug.com/mailman/listinfo/af_af.afmug.com

Re: [AFMUG] dumb DFS questions

[Mike Hammett]

Thanks. 

Due to it being a fairly manual process to enter the commercial weather 
stations into the map due to ULS complexities, the commercial weather stations 
are very incomplete. I've only added them as I've needed to. 


I'd assume that ULS is correct, but maybe not. 




- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 




- Original Message -

From: "Ken Hohhof"  
To: "AnimalFarm Microwave Users Group"  
Sent: Thursday, November 21, 2019 1:16:54 PM 
Subject: Re: [AFMUG] dumb DFS questions 



That’s pretty cool. The links to ULS are nice. 

I had always wondered whose radar that was by Routes 47 and 64 your map tells 
me it’s WLS-TV. So if ULS says the frequency is 2900-2950, that means the 
actual radar beam is in that range? Not in 5 GHz at all? 




From: AF  On Behalf Of Mike Hammett 
Sent: Thursday, November 21, 2019 1:05 PM 
To: AnimalFarm Microwave Users Group  
Subject: Re: [AFMUG] dumb DFS questions 


This is nowhere near complete, but here is a map I've been building of radar 
sites. 



https://drive.google.com/open?id=1ayAnN9KSq09zKS8WCqaQ_QA3JrY=sharing 



It has TDWR, NOAA, TV stations etc. The private radar stations (mostly TV 
stations) are the incomplete part of the map because I have to look them up in 
ULS. It is complete in our area. 



- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 







From: "Ken Hohhof" < af...@kwisp.com > 
To: "AnimalFarm Microwave Users Group" < af@af.afmug.com > 
Sent: Thursday, November 21, 2019 12:36:28 PM 
Subject: Re: [AFMUG] dumb DFS questions 
Chicago has 2 TDWRs (for OHare and Midway) and both are in the 5600-5650 MHz 
band. I think a lot of WISP equipment actually locks out those frequencies, and 
the only place a WISP would be desperate enough to use that 50 MHz apparently 
is Puerto Rico, which is apparently the Wild West of spectrum. 

http://www.wispa.org/Resources/Industry-Resources/TDWR-Resources/TDWR-Locations-and-Frequencies
 





From: AF < af-boun...@af.afmug.com > On Behalf Of ch...@wbmfg.com 
Sent: Thursday, November 21, 2019 12:16 PM 
To: 'AnimalFarm Microwave Users Group' < af@af.afmug.com > 
Subject: Re: [AFMUG] dumb DFS questions 




Those radars sweep the sky pretty slowly. Like 60 rpm. It would be 
theoretically possible to be on their frequency and just blank TX when it is 
looking your way. You could extract timing sync from the radar sweep and figure 
out when to blank. Their gain is such that you would only have to blank for 
perhaps 50 mS. 



If I had more ambition I would ask for an experimental license to play with the 
idea. 






From: Ken Hohhof 

Sent: Thursday, November 21, 2019 11:11 AM 

To: 'AnimalFarm Microwave Users Group' 

Subject: Re: [AFMUG] dumb DFS questions 



Only the APs, at least under FCC rules, I’m not sure about the rest of the 
world. 

That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
themselves. If I have a sector pointed away from some government radar, it 
won’t detect the radar, but the SMs are pointed back at the radar and are not 
required to have a detection mechanism. Probably a good point that it would be 
too complicated for one SM to detect radar and then communicate with the AP to 
request a channel change. But you really need something like a SAS for this 
spectrum sharing idea to work. 


From: AF < af-boun...@af.afmug.com > On Behalf Of Kurt Fankhauser 
Sent: Thursday, November 21, 2019 12:04 PM 
To: AnimalFarm Microwave Users Group < af@af.afmug.com > 
Subject: Re: [AFMUG] dumb DFS questions 


one thing i have always wondered is do the SM's actually look for RADAR or only 
the AP's? 



On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof < af...@kwisp.com > wrote: 




Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt. And SM à AP is the direction you may actually need a better signal because 
the AP likely has a sector antenna and is mounted higher so it sees more 
interference. 

It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi antenna 
at the SM. The antenna gain would help the rcv signal at the SM, but it would 
probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit. 

In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits). 



From: AF < af-boun...@af.afmug.com > On Behalf Of Adam Moffett 
Sent: Thursday, November 21, 2019 11:27 AM 
To: af@af.afmug.com 
Subject: Re: [AFMUG] dumb DFS questions 

There might be something I don't understand, but I thought you had flat EIRP 
limit of +30dbm whether it's an SM or an AP. 

On 11/21/2019 12:11 PM, castarritt . wrote: 




6 dBm loss for the AP transmit isn't the end of the world. It's the up to 23 
dBm loss on the SM trans

Re: [AFMUG] dumb DFS questions

[Mike Hammett]

Yes, Military radar is the primary reason for DFS complexities. 




- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 




- Original Message -

From: "Robert Andrews"  
To: af@af.afmug.com 
Sent: Thursday, November 21, 2019 2:30:05 PM 
Subject: Re: [AFMUG] dumb DFS questions 

I thought Military aircraft radars could also use DFS frequencies? 

On 11/21/2019 09:50 AM, Kurt Fankhauser wrote: 
> We are using DFS on PMP450 for customer access and AF5XHD for backhauls. 
> It works surprisingly well. On both the PMP450 and AF5XHD's you can set 
> an alternative freq and a secondary alternative for the radios to 
> immediately jump to if they detect RADAR. Radios will try the first alt 
> freq and if they get a hit on that will then go to the second freq. It 
> should happen instantly without taking the link down. If you do not set 
> the alt freqs the radios will shutdown for 30 minutes and then 
> attempt to use that freq again. I have noticed that the wider the 
> channels you use the more "susceptible" you are yo getting a radar 
> event. Try running on 20mhz channels and you wont get as many hits if 
> any. We have some AP's that have been running for 6 months+ without any 
> radar hits. We are also not anywhere near any airports so that may be 
> helping us as well. 
> 
> On Thu, Nov 21, 2019 at 12:42 PM Matt Hoppes 
>  <mailto:mattli...@rivervalleyinternet.net>> wrote: 
> 
> You do. 
> 
> On 11/21/19 12:27 PM, Adam Moffett wrote: 
> > There might be something I don't understand, but I thought you 
> had flat 
> > EIRP limit of +30dbm whether it's an SM or an AP. 
> > 
> > On 11/21/2019 12:11 PM, castarritt . wrote: 
> >> 6 dBm loss for the AP transmit isn't the end of the world. It's 
> the up 
> >> to 23 dBm loss on the SM transmit power that destroys the 
> >> usefulness of DFS for PTMP past a couple miles. The ~16 dBi gain 
> 90° 
> >> sectors 2-300' up in the air just can't hear those SMs over all the 
> >> noise they are picking up. What we need is the ability to run 
> >> downlink on DFS and uplink on 5.2 or 5.8. 
> >> 
> >> 
> >> On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett 
> mailto:dmmoff...@gmail.com> 
> >> <mailto:dmmoff...@gmail.com <mailto:dmmoff...@gmail.com>>> wrote: 
> >> 
> >> Yeah I think on most equipment you can set alternate 
> channels that 
> >> are just shifted over 5mhz from where you were. And yeah I 
> think 
> >> the channel needs to be clear for a few minutes before you 
> can go 
> >> back to it. 
> >> 
> >> Assuming you don't really have a TDWR near you, I don't 
> think DFS 
> >> events are that big of a deal. My understanding is that DFS 
> >> events are more likely if you lie to the software about antenna 
> >> gain to cheat the EIRP limit. False detects happen, but I don't 
> >> think it's a daily event. Disclaimer: I've mostly used it on 
> >> Point to point with dishes. I'm not sure if you'd pick up more 
> >> anomolies on a sector antenna. 
> >> 
> >> The biggest bummer is the EIRP limit. When you're trying to get 
> >> that 32 SNR for the 256QAM then losing 6db kind of hurts. 
> Or when 
> >> you've already got someone hooked up 10 miles away and lowering 
> >> the power ruins them. 
> >> 
> >> Where you really want to use DFS (In my opinion) is at a site 
> >> where you have a bunch of customers within 1-2 miles. 
> >> Unfortunately I don't have sites like that. 
> >> 
> >> -Adam 
> >> 
> >> 
> >> 
> >> On 11/21/2019 11:31 AM, Ken Hohhof wrote: 
> >>> 
> >>> We mostly avoid DFS frequencies on APs because of the impact if 
> >>> we get false radar detects. Also we are mostly a Cambium 
> shop. 
> >>> So I’m a bit confused about DFS on other vendor equipment like 
> >>> Ubiquiti as well as home routers. 
> >>> 
> >>> Question 1 – what happens when there’s a DFS detection? On the 
> >>> Cambium gear, we have to select 1 or 2 alternate frequencies. 
> >>> But on other gear, I don’t see this. When there’s a DFS hit, 
> >>> does it jump to another random frequency? Does it rescan the 
> >>> current frequency until it tests clear and only then resume 
> >>> transmission? Is the answer right in front of me and I’m being 
> >>> stupid? Maybe in the case of routers they are exempt 
> because of 
> >>> low EIRP? 
> >>> 
> >>> 

Re: [AFMUG] dumb DFS questions

[Robert Andrews]

I thought Military aircraft radars could also use DFS frequencies?

On 11/21/2019 09:50 AM, Kurt Fankhauser wrote:
We are using DFS on PMP450 for customer access and AF5XHD for backhauls. 
It works surprisingly well. On both the PMP450 and AF5XHD's you can set 
an alternative freq and a secondary alternative for the radios to 
immediately jump to if they detect RADAR. Radios will try the first alt 
freq and if they get a hit on that will then go to the second freq. It 
should happen instantly without taking the link down. If you do not set 
the alt freqs the radios will shutdown for 30 minutes and then 
attempt to use that freq again. I have noticed that the wider the 
channels you use the more "susceptible" you are yo getting a radar 
event. Try running on 20mhz channels and you wont get as many hits if 
any. We have some AP's that have been running for 6 months+ without any 
radar hits. We are also not anywhere near any airports so that may be 
helping us as well.


On Thu, Nov 21, 2019 at 12:42 PM Matt Hoppes 
> wrote:


You do.

On 11/21/19 12:27 PM, Adam Moffett wrote:
 > There might be something I don't understand, but I thought you
had flat
 > EIRP limit of +30dbm whether it's an SM or an AP.
 >
 > On 11/21/2019 12:11 PM, castarritt . wrote:
 >> 6 dBm loss for the AP transmit isn't the end of the world. It's
the up
 >> to 23 dBm loss on the SM transmit power that destroys the
 >> usefulness of DFS for PTMP past a couple miles. The ~16 dBi gain
90°
 >> sectors 2-300' up in the air just can't hear those SMs over all the
 >> noise they are picking up.  What we need is the ability to run
 >> downlink on DFS and uplink on 5.2 or 5.8.
 >>
 >>
 >> On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett
mailto:dmmoff...@gmail.com>
 >> >> wrote:
 >>
 >> Yeah I think on most equipment you can set alternate
channels that
 >> are just shifted over 5mhz from where you were.  And yeah I
think
 >> the channel needs to be clear for a few minutes before you
can go
 >> back to it.
 >>
 >> Assuming you don't really have a TDWR near you, I don't
think DFS
 >> events are that big of a deal.  My understanding is that DFS
 >> events are more likely if you lie to the software about antenna
 >> gain to cheat the EIRP limit.  False detects happen, but I don't
 >> think it's a daily event.  Disclaimer: I've mostly used it on
 >> Point to point with dishes.  I'm not sure if you'd pick up more
 >> anomolies on a sector antenna.
 >>
 >> The biggest bummer is the EIRP limit.  When you're trying to get
 >> that 32 SNR for the 256QAM then losing 6db kind of hurts. 
Or when

 >> you've already got someone hooked up 10 miles away and lowering
 >> the power ruins them.
 >>
 >> Where you really want to use DFS (In my opinion) is at a site
 >> where you have a bunch of customers within 1-2 miles.
 >> Unfortunately I don't have sites like that.
 >>
 >> -Adam
 >>
 >>
 >>
 >> On 11/21/2019 11:31 AM, Ken Hohhof wrote:
 >>>
 >>> We mostly avoid DFS frequencies on APs because of the impact if
 >>> we get false radar detects.  Also we are mostly a Cambium
shop.
 >>> So I’m a bit confused about DFS on other vendor equipment like
 >>> Ubiquiti as well as home routers.
 >>>
 >>> Question 1 – what happens when there’s a DFS detection?  On the
 >>> Cambium gear, we have to select 1 or 2 alternate frequencies.
 >>> But on other gear, I don’t see this.  When there’s a DFS hit,
 >>> does it jump to another random frequency?  Does it rescan the
 >>> current frequency until it tests clear and only then resume
 >>> transmission?  Is the answer right in front of me and I’m being
 >>> stupid?  Maybe in the case of routers they are exempt
because of
 >>> low EIRP?
 >>>
 >>> Question 2 – what about 40/80/160 MHz channels?  We have a
 >>> competitor using Ubiquiti gear and advertising residential
 >>> subscriber speed plans up to 100x100.  Clearly they must be
using
 >>> at least 40 MHz channels if not 80 MHz, or else their marketing
 >>> people have burning pants and long noses. And I don’t see how a
 >>> WISP, especially one surrounded by other WISPs, could use wide
 >>> channels other than in DFS bands.  We have some PTP links using
 >>> 40 MHz but only 10 and 20 MHz channels on our APs.  So assuming
 >>> you are using 40 or 80 MHz in DFS, what happens when there’s a
 >>> DFS detect?  Does the whole 40 or 80 MHz have to find a new
 >>> home?  Can it slide over 2.5 or 5 MHz and 

Re: [AFMUG] dumb DFS questions

[Chuck McCown]

That was the band of the radar I visited.

Sent from my iPhone

> On Nov 21, 2019, at 12:17 PM, Ken Hohhof  wrote:
> 
> 
> That’s pretty cool.  The links to ULS are nice.
>  
> I had always wondered whose radar that was by Routes 47 and 64 your map tells 
> me it’s WLS-TV.  So if ULS says the frequency is 2900-2950, that means the 
> actual radar beam is in that range?  Not in 5 GHz at all?
>  
>  
> From: AF  On Behalf Of Mike Hammett
> Sent: Thursday, November 21, 2019 1:05 PM
> To: AnimalFarm Microwave Users Group 
> Subject: Re: [AFMUG] dumb DFS questions
>  
> This is nowhere near complete, but here is a map I've been building of radar 
> sites.
>  
> https://drive.google.com/open?id=1ayAnN9KSq09zKS8WCqaQ_QA3JrY=sharing
>  
> It has TDWR, NOAA, TV stations etc. The private radar stations (mostly TV 
> stations) are the incomplete part of the map because I have to look them up 
> in ULS. It is complete in our area.
> 
> 
> 
> -
> Mike Hammett
> Intelligent Computing Solutions
> 
> Midwest Internet Exchange
> 
> The Brothers WISP
> 
> 
> 
> From: "Ken Hohhof" 
> To: "AnimalFarm Microwave Users Group" 
> Sent: Thursday, November 21, 2019 12:36:28 PM
> Subject: Re: [AFMUG] dumb DFS questions
> 
> Chicago has 2 TDWRs (for OHare and Midway) and both are in the 5600-5650 MHz 
> band.  I think a lot of WISP equipment actually locks out those frequencies, 
> and the only place a WISP would be desperate enough to use that 50 MHz 
> apparently is Puerto Rico, which is apparently the Wild West of spectrum.
>  
> http://www.wispa.org/Resources/Industry-Resources/TDWR-Resources/TDWR-Locations-and-Frequencies
>  
>  
>  
> From: AF  On Behalf Of ch...@wbmfg.com
> Sent: Thursday, November 21, 2019 12:16 PM
> To: 'AnimalFarm Microwave Users Group' 
> Subject: Re: [AFMUG] dumb DFS questions
>  
> Those radars sweep the sky pretty slowly.  Like 60 rpm.  It would be 
> theoretically possible to be on their frequency and just blank TX when it is 
> looking your way.  You could extract timing sync from the radar sweep and 
> figure out when to blank.  Their gain is such that you would only have to 
> blank for perhaps 50 mS. 
>  
> If I had more ambition I would ask for an experimental license to play with 
> the idea. 
>  
> From: Ken Hohhof
> Sent: Thursday, November 21, 2019 11:11 AM
> To: 'AnimalFarm Microwave Users Group'
> Subject: Re: [AFMUG] dumb DFS questions
>  
> Only the APs, at least under FCC rules, I’m not sure about the rest of the 
> world.
>  
> That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
> themselves.  If I have a sector pointed away from some government radar, it 
> won’t detect the radar, but the SMs are pointed back at the radar and are not 
> required to have a detection mechanism.  Probably a good point that it would 
> be too complicated for one SM to detect radar and then communicate with the 
> AP to request a channel change.  But you really need something like a SAS for 
> this spectrum sharing idea to work.
>  
>  
> From: AF  On Behalf Of Kurt Fankhauser
> Sent: Thursday, November 21, 2019 12:04 PM
> To: AnimalFarm Microwave Users Group 
> Subject: Re: [AFMUG] dumb DFS questions
>  
> one thing i have always wondered is do the SM's actually look for RADAR or 
> only the AP's?
>  
> On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof  wrote:
> Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
> xmt.  And SMàAP is the direction you may actually need a better signal 
> because the AP likely has a sector antenna and is mounted higher so it sees 
> more interference.
>  
> It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi 
> antenna at the SM.  The antenna gain would help the rcv signal at the SM, but 
> it would probably have to lower its conducted power by 9 dB to stay within 
> the regulatory EIRP limit.
>  
> In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
> antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits).
>  
> From: AF  On Behalf Of Adam Moffett
> Sent: Thursday, November 21, 2019 11:27 AM
> To: af@af.afmug.com
> Subject: Re: [AFMUG] dumb DFS questions
>  
> There might be something I don't understand, but I thought you had flat EIRP 
> limit of +30dbm whether it's an SM or an AP.
> 
> On 11/21/2019 12:11 PM, castarritt . wrote:
> 6 dBm loss for the AP transmit isn't the end of the world.  It's the up to 23 
> dBm loss on the SM transmit power that destroys the usefulness of DFS for 
> PTMP past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in the air 
> just can't hear those SMs over all the

Re: [AFMUG] dumb DFS questions

[Ken Hohhof]

That’s pretty cool.  The links to ULS are nice.

 

I had always wondered whose radar that was by Routes 47 and 64 your map tells 
me it’s WLS-TV.  So if ULS says the frequency is 2900-2950, that means the 
actual radar beam is in that range?  Not in 5 GHz at all?

 

 

From: AF  On Behalf Of Mike Hammett
Sent: Thursday, November 21, 2019 1:05 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] dumb DFS questions

 

This is nowhere near complete, but here is a map I've been building of radar 
sites.

 

https://drive.google.com/open?id=1ayAnN9KSq09zKS8WCqaQ_QA3JrY 
<https://drive.google.com/open?id=1ayAnN9KSq09zKS8WCqaQ_QA3JrY=sharing> 
=sharing

 

It has TDWR, NOAA, TV stations etc. The private radar stations (mostly TV 
stations) are the incomplete part of the map because I have to look them up in 
ULS. It is complete in our area.



-
Mike Hammett
 <http://www.ics-il.com/> Intelligent Computing Solutions
 <https://www.facebook.com/ICSIL>  
<https://plus.google.com/+IntelligentComputingSolutionsDeKalb>  
<https://www.linkedin.com/company/intelligent-computing-solutions>  
<https://twitter.com/ICSIL> 
 <http://www.midwest-ix.com/> Midwest Internet Exchange
 <https://www.facebook.com/mdwestix>  
<https://www.linkedin.com/company/midwest-internet-exchange>  
<https://twitter.com/mdwestix> 
 <http://www.thebrotherswisp.com/> The Brothers WISP
 <https://www.facebook.com/thebrotherswisp>  
<https://www.youtube.com/channel/UCXSdfxQv7SpoRQYNyLwntZg> 




  _  

From: "Ken Hohhof" mailto:af...@kwisp.com> >
To: "AnimalFarm Microwave Users Group" mailto:af@af.afmug.com> >
Sent: Thursday, November 21, 2019 12:36:28 PM
Subject: Re: [AFMUG] dumb DFS questions

Chicago has 2 TDWRs (for OHare and Midway) and both are in the 5600-5650 MHz 
band.  I think a lot of WISP equipment actually locks out those frequencies, 
and the only place a WISP would be desperate enough to use that 50 MHz 
apparently is Puerto Rico, which is apparently the Wild West of spectrum.

 

http://www.wispa.org/Resources/Industry-Resources/TDWR-Resources/TDWR-Locations-and-Frequencies

 

 

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of ch...@wbmfg.com <mailto:ch...@wbmfg.com> 
Sent: Thursday, November 21, 2019 12:16 PM
To: 'AnimalFarm Microwave Users Group' mailto:af@af.afmug.com> >
Subject: Re: [AFMUG] dumb DFS questions

 

Those radars sweep the sky pretty slowly.  Like 60 rpm.  It would be 
theoretically possible to be on their frequency and just blank TX when it is 
looking your way.  You could extract timing sync from the radar sweep and 
figure out when to blank.  Their gain is such that you would only have to blank 
for perhaps 50 mS.  

 

If I had more ambition I would ask for an experimental license to play with the 
idea.  

 

From: Ken Hohhof 

Sent: Thursday, November 21, 2019 11:11 AM

To: 'AnimalFarm Microwave Users Group' 

Subject: Re: [AFMUG] dumb DFS questions

 

Only the APs, at least under FCC rules, I’m not sure about the rest of the 
world.

 

That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
themselves.  If I have a sector pointed away from some government radar, it 
won’t detect the radar, but the SMs are pointed back at the radar and are not 
required to have a detection mechanism.  Probably a good point that it would be 
too complicated for one SM to detect radar and then communicate with the AP to 
request a channel change.  But you really need something like a SAS for this 
spectrum sharing idea to work.

 

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Kurt Fankhauser
Sent: Thursday, November 21, 2019 12:04 PM
To: AnimalFarm Microwave Users Group mailto:af@af.afmug.com> >
Subject: Re: [AFMUG] dumb DFS questions

 

one thing i have always wondered is do the SM's actually look for RADAR or only 
the AP's?

 

On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof mailto:af...@kwisp.com> > wrote:

Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt.  And SM-->AP is the direction you may actually need a better signal 
because the AP likely has a sector antenna and is mounted higher so it sees 
more interference.

 

It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi antenna 
at the SM.  The antenna gain would help the rcv signal at the SM, but it would 
probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit.

 

In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits).

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Adam Moffett
Sent: Thursday, November 21, 2019 11:27 AM
To: af@af.afmug.com <mailto:af@af.afmug.com> 
Subject: Re: [AFMUG] dumb DFS questions

 

There might be something I don't understand,

Re: [AFMUG] dumb DFS questions

[Mike Hammett]

This is nowhere near complete, but here is a map I've been building of radar 
sites. 


https://drive.google.com/open?id=1ayAnN9KSq09zKS8WCqaQ_QA3JrY=sharing 


It has TDWR, NOAA, TV stations etc. The private radar stations (mostly TV 
stations) are the incomplete part of the map because I have to look them up in 
ULS. It is complete in our area. 




- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 




- Original Message -

From: "Ken Hohhof"  
To: "AnimalFarm Microwave Users Group"  
Sent: Thursday, November 21, 2019 12:36:28 PM 
Subject: Re: [AFMUG] dumb DFS questions 



Chicago has 2 TDWRs (for OHare and Midway) and both are in the 5600-5650 MHz 
band. I think a lot of WISP equipment actually locks out those frequencies, and 
the only place a WISP would be desperate enough to use that 50 MHz apparently 
is Puerto Rico, which is apparently the Wild West of spectrum. 

http://www.wispa.org/Resources/Industry-Resources/TDWR-Resources/TDWR-Locations-and-Frequencies
 





From: AF  On Behalf Of ch...@wbmfg.com 
Sent: Thursday, November 21, 2019 12:16 PM 
To: 'AnimalFarm Microwave Users Group'  
Subject: Re: [AFMUG] dumb DFS questions 




Those radars sweep the sky pretty slowly. Like 60 rpm. It would be 
theoretically possible to be on their frequency and just blank TX when it is 
looking your way. You could extract timing sync from the radar sweep and figure 
out when to blank. Their gain is such that you would only have to blank for 
perhaps 50 mS. 



If I had more ambition I would ask for an experimental license to play with the 
idea. 






From: Ken Hohhof 

Sent: Thursday, November 21, 2019 11:11 AM 

To: 'AnimalFarm Microwave Users Group' 

Subject: Re: [AFMUG] dumb DFS questions 



Only the APs, at least under FCC rules, I’m not sure about the rest of the 
world. 

That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
themselves. If I have a sector pointed away from some government radar, it 
won’t detect the radar, but the SMs are pointed back at the radar and are not 
required to have a detection mechanism. Probably a good point that it would be 
too complicated for one SM to detect radar and then communicate with the AP to 
request a channel change. But you really need something like a SAS for this 
spectrum sharing idea to work. 


From: AF < af-boun...@af.afmug.com > On Behalf Of Kurt Fankhauser 
Sent: Thursday, November 21, 2019 12:04 PM 
To: AnimalFarm Microwave Users Group < af@af.afmug.com > 
Subject: Re: [AFMUG] dumb DFS questions 


one thing i have always wondered is do the SM's actually look for RADAR or only 
the AP's? 



On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof < af...@kwisp.com > wrote: 




Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt. And SM à AP is the direction you may actually need a better signal because 
the AP likely has a sector antenna and is mounted higher so it sees more 
interference. 

It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi antenna 
at the SM. The antenna gain would help the rcv signal at the SM, but it would 
probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit. 

In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits). 



From: AF < af-boun...@af.afmug.com > On Behalf Of Adam Moffett 
Sent: Thursday, November 21, 2019 11:27 AM 
To: af@af.afmug.com 
Subject: Re: [AFMUG] dumb DFS questions 

There might be something I don't understand, but I thought you had flat EIRP 
limit of +30dbm whether it's an SM or an AP. 

On 11/21/2019 12:11 PM, castarritt . wrote: 




6 dBm loss for the AP transmit isn't the end of the world. It's the up to 23 
dBm loss on the SM transmit power that destroys the usefulness of DFS for PTMP 
past a couple miles. The ~16 dBi gain 90° sectors 2-300' up in the air just 
can't hear those SMs over all the noise they are picking up. What we need is 
the ability to run downlink on DFS and uplink on 5.2 or 5.8. 





On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett < dmmoff...@gmail.com > wrote: 



Yeah I think on most equipment you can set alternate channels that are just 
shifted over 5mhz from where you were. And yeah I think the channel needs to be 
clear for a few minutes before you can go back to it. 
Assuming you don't really have a TDWR near you, I don't think DFS events are 
that big of a deal. My understanding is that DFS events are more likely if you 
lie to the software about antenna gain to cheat the EIRP limit. False detects 
happen, but I don't think it's a daily event. Disclaimer: I've mostly used it 
on Point to point with dishes. I'm not sure if you'd pick up more anomolies on 
a sector antenna. 
The biggest bummer is the EIRP limit. When you're trying to get that 32 SNR for 
the 256QAM then lo

Re: [AFMUG] dumb DFS questions

[Mike Hammett]

TDWR is the least significant user in the DFS space. 




- 
Mike Hammett 
Intelligent Computing Solutions 

Midwest Internet Exchange 

The Brothers WISP 




- Original Message -

From: "Adam Moffett"  
To: af@af.afmug.com 
Sent: Thursday, November 21, 2019 10:55:25 AM 
Subject: Re: [AFMUG] dumb DFS questions 


Yeah I think on most equipment you can set alternate channels that are just 
shifted over 5mhz from where you were. And yeah I think the channel needs to be 
clear for a few minutes before you can go back to it. 

Assuming you don't really have a TDWR near you, I don't think DFS events are 
that big of a deal. My understanding is that DFS events are more likely if you 
lie to the software about antenna gain to cheat the EIRP limit. False detects 
happen, but I don't think it's a daily event. Disclaimer: I've mostly used it 
on Point to point with dishes. I'm not sure if you'd pick up more anomolies on 
a sector antenna. 

The biggest bummer is the EIRP limit. When you're trying to get that 32 SNR for 
the 256QAM then losing 6db kind of hurts. Or when you've already got someone 
hooked up 10 miles away and lowering the power ruins them. 

Where you really want to use DFS (In my opinion) is at a site where you have a 
bunch of customers within 1-2 miles. Unfortunately I don't have sites like 
that. 
-Adam 




On 11/21/2019 11:31 AM, Ken Hohhof wrote: 




We mostly avoid DFS frequencies on APs because of the impact if we get false 
radar detects. Also we are mostly a Cambium shop. So I’m a bit confused about 
DFS on other vendor equipment like Ubiquiti as well as home routers. 

Question 1 – what happens when there’s a DFS detection? On the Cambium gear, we 
have to select 1 or 2 alternate frequencies. But on other gear, I don’t see 
this. When there’s a DFS hit, does it jump to another random frequency? Does it 
rescan the current frequency until it tests clear and only then resume 
transmission? Is the answer right in front of me and I’m being stupid? Maybe in 
the case of routers they are exempt because of low EIRP? 

Question 2 – what about 40/80/160 MHz channels? We have a competitor using 
Ubiquiti gear and advertising residential subscriber speed plans up to 100x100. 
Clearly they must be using at least 40 MHz channels if not 80 MHz, or else 
their marketing people have burning pants and long noses. And I don’t see how a 
WISP, especially one surrounded by other WISPs, could use wide channels other 
than in DFS bands. We have some PTP links using 40 MHz but only 10 and 20 MHz 
channels on our APs. So assuming you are using 40 or 80 MHz in DFS, what 
happens when there’s a DFS detect? Does the whole 40 or 80 MHz have to find a 
new home? Can it slide over 2.5 or 5 MHz and substantially overlap the previous 
occupied spectrum? DFS bands come with enough spectrum to use wide channels, 
but is there enough to jump around when you take a DFS hit? 



-- 
AF mailing list 
AF@af.afmug.com 
http://af.afmug.com/mailman/listinfo/af_af.afmug.com 

-- 
AF mailing list
AF@af.afmug.com
http://af.afmug.com/mailman/listinfo/af_af.afmug.com

Re: [AFMUG] dumb DFS questions

[chuck]

I have only been at one site.  It had a 60’ dish on the tower that was grinding 
around about 60 rpm inside a radome.  Made quite a noise.  Inside the 
transmitter shack it has the frequency listed.  Seemingly out to a decimal 
point or two.  I did not get the impression it was frequency agile.  I think 
the antenna had 60 dB gain.  The tx power was in the kW range.  

From: Ken Hohhof 
Sent: Thursday, November 21, 2019 11:36 AM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] dumb DFS questions

Chicago has 2 TDWRs (for OHare and Midway) and both are in the 5600-5650 MHz 
band.  I think a lot of WISP equipment actually locks out those frequencies, 
and the only place a WISP would be desperate enough to use that 50 MHz 
apparently is Puerto Rico, which is apparently the Wild West of spectrum.

 

http://www.wispa.org/Resources/Industry-Resources/TDWR-Resources/TDWR-Locations-and-Frequencies

 

 

 

From: AF  On Behalf Of ch...@wbmfg.com
Sent: Thursday, November 21, 2019 12:16 PM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] dumb DFS questions

 

Those radars sweep the sky pretty slowly.  Like 60 rpm.  It would be 
theoretically possible to be on their frequency and just blank TX when it is 
looking your way.  You could extract timing sync from the radar sweep and 
figure out when to blank.  Their gain is such that you would only have to blank 
for perhaps 50 mS.  

 

If I had more ambition I would ask for an experimental license to play with the 
idea.  

 

From: Ken Hohhof 

Sent: Thursday, November 21, 2019 11:11 AM

To: 'AnimalFarm Microwave Users Group' 

Subject: Re: [AFMUG] dumb DFS questions

 

Only the APs, at least under FCC rules, I’m not sure about the rest of the 
world.

 

That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
themselves.  If I have a sector pointed away from some government radar, it 
won’t detect the radar, but the SMs are pointed back at the radar and are not 
required to have a detection mechanism.  Probably a good point that it would be 
too complicated for one SM to detect radar and then communicate with the AP to 
request a channel change.  But you really need something like a SAS for this 
spectrum sharing idea to work.

 

 

From: AF  On Behalf Of Kurt Fankhauser
Sent: Thursday, November 21, 2019 12:04 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] dumb DFS questions

 

one thing i have always wondered is do the SM's actually look for RADAR or only 
the AP's?

 

On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof  wrote:

  Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt.  And SMàAP is the direction you may actually need a better signal because 
the AP likely has a sector antenna and is mounted higher so it sees more 
interference.

   

  It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi 
antenna at the SM.  The antenna gain would help the rcv signal at the SM, but 
it would probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit.

   

  In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits).

   

  From: AF  On Behalf Of Adam Moffett
  Sent: Thursday, November 21, 2019 11:27 AM
  To: af@af.afmug.com
  Subject: Re: [AFMUG] dumb DFS questions

   

  There might be something I don't understand, but I thought you had flat EIRP 
limit of +30dbm whether it's an SM or an AP.

  On 11/21/2019 12:11 PM, castarritt . wrote:

6 dBm loss for the AP transmit isn't the end of the world.  It's the up to 
23 dBm loss on the SM transmit power that destroys the usefulness of DFS for 
PTMP past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in the air 
just can't hear those SMs over all the noise they are picking up.  What we need 
is the ability to run downlink on DFS and uplink on 5.2 or 5.8.

 

 

On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett  wrote:

  Yeah I think on most equipment you can set alternate channels that are 
just shifted over 5mhz from where you were.  And yeah I think the channel needs 
to be clear for a few minutes before you can go back to it.

  Assuming you don't really have a TDWR near you, I don't think DFS events 
are that big of a deal.  My understanding is that DFS events are more likely if 
you lie to the software about antenna gain to cheat the EIRP limit.  False 
detects happen, but I don't think it's a daily event.  Disclaimer: I've mostly 
used it on Point to point with dishes.  I'm not sure if you'd pick up more 
anomolies on a sector antenna.

  The biggest bummer is the EIRP limit.  When you're trying to get that 32 
SNR for the 256QAM then losing 6db kind of hurts.  Or when you've already got 
someone hooked up 10 miles away and lowering the power ruins them.  

  Where you really want to use DFS (In my opinion) is at a site where you 
have a bunch

Re: [AFMUG] dumb DFS questions

[Ken Hohhof]

Chicago has 2 TDWRs (for OHare and Midway) and both are in the 5600-5650 MHz 
band.  I think a lot of WISP equipment actually locks out those frequencies, 
and the only place a WISP would be desperate enough to use that 50 MHz 
apparently is Puerto Rico, which is apparently the Wild West of spectrum.

 

http://www.wispa.org/Resources/Industry-Resources/TDWR-Resources/TDWR-Locations-and-Frequencies

 

 

 

From: AF  On Behalf Of ch...@wbmfg.com
Sent: Thursday, November 21, 2019 12:16 PM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] dumb DFS questions

 

Those radars sweep the sky pretty slowly.  Like 60 rpm.  It would be 
theoretically possible to be on their frequency and just blank TX when it is 
looking your way.  You could extract timing sync from the radar sweep and 
figure out when to blank.  Their gain is such that you would only have to blank 
for perhaps 50 mS.  

 

If I had more ambition I would ask for an experimental license to play with the 
idea.  

 

From: Ken Hohhof 

Sent: Thursday, November 21, 2019 11:11 AM

To: 'AnimalFarm Microwave Users Group' 

Subject: Re: [AFMUG] dumb DFS questions

 

Only the APs, at least under FCC rules, I’m not sure about the rest of the 
world.

 

That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
themselves.  If I have a sector pointed away from some government radar, it 
won’t detect the radar, but the SMs are pointed back at the radar and are not 
required to have a detection mechanism.  Probably a good point that it would be 
too complicated for one SM to detect radar and then communicate with the AP to 
request a channel change.  But you really need something like a SAS for this 
spectrum sharing idea to work.

 

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Kurt Fankhauser
Sent: Thursday, November 21, 2019 12:04 PM
To: AnimalFarm Microwave Users Group mailto:af@af.afmug.com> >
Subject: Re: [AFMUG] dumb DFS questions

 

one thing i have always wondered is do the SM's actually look for RADAR or only 
the AP's?

 

On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof mailto:af...@kwisp.com> > wrote:

Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt.  And SM-->AP is the direction you may actually need a better signal 
because the AP likely has a sector antenna and is mounted higher so it sees 
more interference.

 

It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi antenna 
at the SM.  The antenna gain would help the rcv signal at the SM, but it would 
probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit.

 

In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits).

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Adam Moffett
Sent: Thursday, November 21, 2019 11:27 AM
To: af@af.afmug.com <mailto:af@af.afmug.com> 
Subject: Re: [AFMUG] dumb DFS questions

 

There might be something I don't understand, but I thought you had flat EIRP 
limit of +30dbm whether it's an SM or an AP.

On 11/21/2019 12:11 PM, castarritt . wrote:

6 dBm loss for the AP transmit isn't the end of the world.  It's the up to 23 
dBm loss on the SM transmit power that destroys the usefulness of DFS for PTMP 
past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in the air just 
can't hear those SMs over all the noise they are picking up.  What we need is 
the ability to run downlink on DFS and uplink on 5.2 or 5.8.

 

 

On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett mailto:dmmoff...@gmail.com> > wrote:

Yeah I think on most equipment you can set alternate channels that are just 
shifted over 5mhz from where you were.  And yeah I think the channel needs to 
be clear for a few minutes before you can go back to it.

Assuming you don't really have a TDWR near you, I don't think DFS events are 
that big of a deal.  My understanding is that DFS events are more likely if you 
lie to the software about antenna gain to cheat the EIRP limit.  False detects 
happen, but I don't think it's a daily event.  Disclaimer: I've mostly used it 
on Point to point with dishes.  I'm not sure if you'd pick up more anomolies on 
a sector antenna.

The biggest bummer is the EIRP limit.  When you're trying to get that 32 SNR 
for the 256QAM then losing 6db kind of hurts.  Or when you've already got 
someone hooked up 10 miles away and lowering the power ruins them.  

Where you really want to use DFS (In my opinion) is at a site where you have a 
bunch of customers within 1-2 miles.  Unfortunately I don't have sites like 
that.

-Adam

 

 

On 11/21/2019 11:31 AM, Ken Hohhof wrote:

We mostly avoid DFS frequencies on APs because of the impact if we get false 
radar detects.  Also we are mostly a Cambium shop.  So I’m a bit confused about 
DFS on other vendor equipment like Ubiquiti as well as home routers.

 

Quest

Re: [AFMUG] dumb DFS questions

[chuck]

Those radars sweep the sky pretty slowly.  Like 60 rpm.  It would be 
theoretically possible to be on their frequency and just blank TX when it is 
looking your way.  You could extract timing sync from the radar sweep and 
figure out when to blank.  Their gain is such that you would only have to blank 
for perhaps 50 mS.  

If I had more ambition I would ask for an experimental license to play with the 
idea.  

From: Ken Hohhof 
Sent: Thursday, November 21, 2019 11:11 AM
To: 'AnimalFarm Microwave Users Group' 
Subject: Re: [AFMUG] dumb DFS questions

Only the APs, at least under FCC rules, I’m not sure about the rest of the 
world.

 

That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
themselves.  If I have a sector pointed away from some government radar, it 
won’t detect the radar, but the SMs are pointed back at the radar and are not 
required to have a detection mechanism.  Probably a good point that it would be 
too complicated for one SM to detect radar and then communicate with the AP to 
request a channel change.  But you really need something like a SAS for this 
spectrum sharing idea to work.

 

 

From: AF  On Behalf Of Kurt Fankhauser
Sent: Thursday, November 21, 2019 12:04 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] dumb DFS questions

 

one thing i have always wondered is do the SM's actually look for RADAR or only 
the AP's?

 

On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof  wrote:

  Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt.  And SMàAP is the direction you may actually need a better signal because 
the AP likely has a sector antenna and is mounted higher so it sees more 
interference.

   

  It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi 
antenna at the SM.  The antenna gain would help the rcv signal at the SM, but 
it would probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit.

   

  In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits).

   

  From: AF  On Behalf Of Adam Moffett
  Sent: Thursday, November 21, 2019 11:27 AM
  To: af@af.afmug.com
  Subject: Re: [AFMUG] dumb DFS questions

   

  There might be something I don't understand, but I thought you had flat EIRP 
limit of +30dbm whether it's an SM or an AP.

  On 11/21/2019 12:11 PM, castarritt . wrote:

6 dBm loss for the AP transmit isn't the end of the world.  It's the up to 
23 dBm loss on the SM transmit power that destroys the usefulness of DFS for 
PTMP past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in the air 
just can't hear those SMs over all the noise they are picking up.  What we need 
is the ability to run downlink on DFS and uplink on 5.2 or 5.8.

 

 

On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett  wrote:

  Yeah I think on most equipment you can set alternate channels that are 
just shifted over 5mhz from where you were.  And yeah I think the channel needs 
to be clear for a few minutes before you can go back to it.

  Assuming you don't really have a TDWR near you, I don't think DFS events 
are that big of a deal.  My understanding is that DFS events are more likely if 
you lie to the software about antenna gain to cheat the EIRP limit.  False 
detects happen, but I don't think it's a daily event.  Disclaimer: I've mostly 
used it on Point to point with dishes.  I'm not sure if you'd pick up more 
anomolies on a sector antenna.

  The biggest bummer is the EIRP limit.  When you're trying to get that 32 
SNR for the 256QAM then losing 6db kind of hurts.  Or when you've already got 
someone hooked up 10 miles away and lowering the power ruins them.  

  Where you really want to use DFS (In my opinion) is at a site where you 
have a bunch of customers within 1-2 miles.  Unfortunately I don't have sites 
like that.

  -Adam

   

   

  On 11/21/2019 11:31 AM, Ken Hohhof wrote:

We mostly avoid DFS frequencies on APs because of the impact if we get 
false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit confused 
about DFS on other vendor equipment like Ubiquiti as well as home routers.

 

Question 1 – what happens when there’s a DFS detection?  On the Cambium 
gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I 
don’t see this.  When there’s a DFS hit, does it jump to another random 
frequency?  Does it rescan the current frequency until it tests clear and only 
then resume transmission?  Is the answer right in front of me and I’m being 
stupid?  Maybe in the case of routers they are exempt because of low EIRP?

 

Question 2 – what about 40/80/160 MHz channels?  We have a competitor 
using Ubiquiti gear and advertising residential subscriber speed plans up to 
100x100.  Clearly they must be using at least 40 MHz channels if not 80

Re: [AFMUG] dumb DFS questions

[Ken Hohhof]

Only the APs, at least under FCC rules, I’m not sure about the rest of the 
world.

 

That alone IMHO says DFS is a joke, or regulatory “experts” deluding 
themselves.  If I have a sector pointed away from some government radar, it 
won’t detect the radar, but the SMs are pointed back at the radar and are not 
required to have a detection mechanism.  Probably a good point that it would be 
too complicated for one SM to detect radar and then communicate with the AP to 
request a channel change.  But you really need something like a SAS for this 
spectrum sharing idea to work.

 

 

From: AF  On Behalf Of Kurt Fankhauser
Sent: Thursday, November 21, 2019 12:04 PM
To: AnimalFarm Microwave Users Group 
Subject: Re: [AFMUG] dumb DFS questions

 

one thing i have always wondered is do the SM's actually look for RADAR or only 
the AP's?

 

On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof mailto:af...@kwisp.com> > wrote:

Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt.  And SM-->AP is the direction you may actually need a better signal 
because the AP likely has a sector antenna and is mounted higher so it sees 
more interference.

 

It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi antenna 
at the SM.  The antenna gain would help the rcv signal at the SM, but it would 
probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit.

 

In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits).

 

From: AF mailto:af-boun...@af.afmug.com> > On Behalf 
Of Adam Moffett
Sent: Thursday, November 21, 2019 11:27 AM
To: af@af.afmug.com <mailto:af@af.afmug.com> 
Subject: Re: [AFMUG] dumb DFS questions

 

There might be something I don't understand, but I thought you had flat EIRP 
limit of +30dbm whether it's an SM or an AP.

On 11/21/2019 12:11 PM, castarritt . wrote:

6 dBm loss for the AP transmit isn't the end of the world.  It's the up to 23 
dBm loss on the SM transmit power that destroys the usefulness of DFS for PTMP 
past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in the air just 
can't hear those SMs over all the noise they are picking up.  What we need is 
the ability to run downlink on DFS and uplink on 5.2 or 5.8.

 

 

On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett mailto:dmmoff...@gmail.com> > wrote:

Yeah I think on most equipment you can set alternate channels that are just 
shifted over 5mhz from where you were.  And yeah I think the channel needs to 
be clear for a few minutes before you can go back to it.

Assuming you don't really have a TDWR near you, I don't think DFS events are 
that big of a deal.  My understanding is that DFS events are more likely if you 
lie to the software about antenna gain to cheat the EIRP limit.  False detects 
happen, but I don't think it's a daily event.  Disclaimer: I've mostly used it 
on Point to point with dishes.  I'm not sure if you'd pick up more anomolies on 
a sector antenna.

The biggest bummer is the EIRP limit.  When you're trying to get that 32 SNR 
for the 256QAM then losing 6db kind of hurts.  Or when you've already got 
someone hooked up 10 miles away and lowering the power ruins them.  

Where you really want to use DFS (In my opinion) is at a site where you have a 
bunch of customers within 1-2 miles.  Unfortunately I don't have sites like 
that.

-Adam

 

 

On 11/21/2019 11:31 AM, Ken Hohhof wrote:

We mostly avoid DFS frequencies on APs because of the impact if we get false 
radar detects.  Also we are mostly a Cambium shop.  So I’m a bit confused about 
DFS on other vendor equipment like Ubiquiti as well as home routers.

 

Question 1 – what happens when there’s a DFS detection?  On the Cambium gear, 
we have to select 1 or 2 alternate frequencies.  But on other gear, I don’t see 
this.  When there’s a DFS hit, does it jump to another random frequency?  Does 
it rescan the current frequency until it tests clear and only then resume 
transmission?  Is the answer right in front of me and I’m being stupid?  Maybe 
in the case of routers they are exempt because of low EIRP?

 

Question 2 – what about 40/80/160 MHz channels?  We have a competitor using 
Ubiquiti gear and advertising residential subscriber speed plans up to 100x100. 
 Clearly they must be using at least 40 MHz channels if not 80 MHz, or else 
their marketing people have burning pants and long noses.  And I don’t see how 
a WISP, especially one surrounded by other WISPs, could use wide channels other 
than in DFS bands.  We have some PTP links using 40 MHz but only 10 and 20 MHz 
channels on our APs.  So assuming you are using 40 or 80 MHz in DFS, what 
happens when there’s a DFS detect?  Does the whole 40 or 80 MHz have to find a 
new home?  Can it slide over 2.5 or 5 MHz and substantially overlap the 
previous occupied spectrum?  DFS bands come with enough spe

Re: [AFMUG] dumb DFS questions

[Kurt Fankhauser]

I wonder if the FCC would be open to a discussion about allowing higher TX
power on SM's considering that that are usually way lower to the ground
then AP's tend to be mounted.

On Thu, Nov 21, 2019 at 1:06 PM Adam Moffett  wrote:

> Only AP
> On 11/21/2019 1:04 PM, Kurt Fankhauser wrote:
>
> one thing i have always wondered is do the SM's actually look for RADAR or
> only the AP's?
>
> On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof  wrote:
>
>> Yes, that’s true, but a higher gain antenna at the SM end helps rcv but
>> not xmt.  And SMàAP is the direction you may actually need a better
>> signal because the AP likely has a sector antenna and is mounted higher so
>> it sees more interference.
>>
>>
>>
>> It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi
>> antenna at the SM.  The antenna gain would help the rcv signal at the SM,
>> but it would probably have to lower its conducted power by 9 dB to stay
>> within the regulatory EIRP limit.
>>
>>
>>
>> In contrast, in U-NII-3 the CPE end is treated as point-to-point and can
>> use antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE
>> limits).
>>
>>
>>
>> *From:* AF  *On Behalf Of *Adam Moffett
>> *Sent:* Thursday, November 21, 2019 11:27 AM
>> *To:* af@af.afmug.com
>> *Subject:* Re: [AFMUG] dumb DFS questions
>>
>>
>>
>> There might be something I don't understand, but I thought you had flat
>> EIRP limit of +30dbm whether it's an SM or an AP.
>>
>> On 11/21/2019 12:11 PM, castarritt . wrote:
>>
>> 6 dBm loss for the AP transmit isn't the end of the world.  It's the up
>> to 23 dBm loss on the SM transmit power that destroys the usefulness of DFS
>> for PTMP past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in
>> the air just can't hear those SMs over all the noise they are picking up.
>> What we need is the ability to run downlink on DFS and uplink on 5.2 or 5.8.
>>
>>
>>
>>
>>
>> On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett 
>> wrote:
>>
>> Yeah I think on most equipment you can set alternate channels that are
>> just shifted over 5mhz from where you were.  And yeah I think the channel
>> needs to be clear for a few minutes before you can go back to it.
>>
>> Assuming you don't really have a TDWR near you, I don't think DFS events
>> are that big of a deal.  My understanding is that DFS events are more
>> likely if you lie to the software about antenna gain to cheat the EIRP
>> limit.  False detects happen, but I don't think it's a daily event.
>> Disclaimer: I've mostly used it on Point to point with dishes.  I'm not
>> sure if you'd pick up more anomolies on a sector antenna.
>>
>> The biggest bummer is the EIRP limit.  When you're trying to get that 32
>> SNR for the 256QAM then losing 6db kind of hurts.  Or when you've already
>> got someone hooked up 10 miles away and lowering the power ruins them.
>>
>> Where you really want to use DFS (In my opinion) is at a site where you
>> have a bunch of customers within 1-2 miles.  Unfortunately I don't have
>> sites like that.
>>
>> -Adam
>>
>>
>>
>>
>>
>> On 11/21/2019 11:31 AM, Ken Hohhof wrote:
>>
>> We mostly avoid DFS frequencies on APs because of the impact if we get
>> false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit
>> confused about DFS on other vendor equipment like Ubiquiti as well as home
>> routers.
>>
>>
>>
>> Question 1 – what happens when there’s a DFS detection?  On the Cambium
>> gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I
>> don’t see this.  When there’s a DFS hit, does it jump to another random
>> frequency?  Does it rescan the current frequency until it tests clear and
>> only then resume transmission?  Is the answer right in front of me and I’m
>> being stupid?  Maybe in the case of routers they are exempt because of low
>> EIRP?
>>
>>
>>
>> Question 2 – what about 40/80/160 MHz channels?  We have a competitor
>> using Ubiquiti gear and advertising residential subscriber speed plans up
>> to 100x100.  Clearly they must be using at least 40 MHz channels if not 80
>> MHz, or else their marketing people have burning pants and long noses.  And
>> I don’t see how a WISP, especially one surrounded by other WISPs, could use
>> wide channels other than in DFS bands.  We have some PTP links using 40 MHz
>> but only 10 and 20 MHz channels on our APs.  So assuming you are using 40
>> or 80 MHz in DFS, wh

Re: [AFMUG] dumb DFS questions

[Adam Moffett]

Only AP

On 11/21/2019 1:04 PM, Kurt Fankhauser wrote:
one thing i have always wondered is do the SM's actually look for 
RADAR or only the AP's?


On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof <mailto:af...@kwisp.com>> wrote:


Yes, that’s true, but a higher gain antenna at the SM end helps
rcv but not xmt.  And SMàAP is the direction you may actually need
a better signal because the AP likely has a sector antenna and is
mounted higher so it sees more interference.

It would not be unusual to have a 16 dBi antenna at the AP but a
25 dBi antenna at the SM. The antenna gain would help the rcv
signal at the SM, but it would probably have to lower its
conducted power by 9 dB to stay within the regulatory EIRP limit.

In contrast, in U-NII-3 the CPE end is treated as point-to-point
and can use antenna gain to exceed the AP limit of 36 dBm EIRP
(subject to OOBE limits).

*From:* AF mailto:af-boun...@af.afmug.com>> *On Behalf Of *Adam Moffett
*Sent:* Thursday, November 21, 2019 11:27 AM
*To:* af@af.afmug.com <mailto:af@af.afmug.com>
*Subject:* Re: [AFMUG] dumb DFS questions

There might be something I don't understand, but I thought you had
flat EIRP limit of +30dbm whether it's an SM or an AP.

On 11/21/2019 12:11 PM, castarritt . wrote:

6 dBm loss for the AP transmit isn't the end of the world. 
It's the up to 23 dBm loss on the SM transmit power that
destroys the usefulness of DFS for PTMP past a couple miles.
The ~16 dBi gain 90° sectors 2-300' up in the air just can't
hear those SMs over all the noise they are picking up.  What
we need is the ability to run downlink on DFS and uplink on
5.2 or 5.8.

On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett
mailto:dmmoff...@gmail.com>> wrote:

Yeah I think on most equipment you can set alternate
channels that are just shifted over 5mhz from where you
were.  And yeah I think the channel needs to be clear for
a few minutes before you can go back to it.

Assuming you don't really have a TDWR near you, I don't
think DFS events are that big of a deal.  My understanding
is that DFS events are more likely if you lie to the
software about antenna gain to cheat the EIRP limit. False
detects happen, but I don't think it's a daily event. 
Disclaimer: I've mostly used it on Point to point with
dishes.  I'm not sure if you'd pick up more anomolies on a
sector antenna.

The biggest bummer is the EIRP limit.  When you're trying
to get that 32 SNR for the 256QAM then losing 6db kind of
hurts.  Or when you've already got someone hooked up 10
miles away and lowering the power ruins them.

Where you really want to use DFS (In my opinion) is at a
site where you have a bunch of customers within 1-2
miles.  Unfortunately I don't have sites like that.

-Adam

On 11/21/2019 11:31 AM, Ken Hohhof wrote:

We mostly avoid DFS frequencies on APs because of the
impact if we get false radar detects.  Also we are
mostly a Cambium shop.  So I’m a bit confused about
DFS on other vendor equipment like Ubiquiti as well as
home routers.

Question 1 – what happens when there’s a DFS
detection?  On the Cambium gear, we have to select 1
or 2 alternate frequencies.  But on other gear, I
don’t see this.  When there’s a DFS hit, does it jump
to another random frequency? Does it rescan the
current frequency until it tests clear and only then
resume transmission?  Is the answer right in front of
me and I’m being stupid?  Maybe in the case of routers
they are exempt because of low EIRP?

Question 2 – what about 40/80/160 MHz channels?  We
have a competitor using Ubiquiti gear and advertising
residential subscriber speed plans up to 100x100. 
Clearly they must be using at least 40 MHz channels if
not 80 MHz, or else their marketing people have
burning pants and long noses.  And I don’t see how a
WISP, especially one surrounded by other WISPs, could
use wide channels other than in DFS bands.  We have
some PTP links using 40 MHz but only 10 and 20 MHz
channels on our APs.  So assuming you are using 40 or
80 MHz in DFS, what happens when there’s a DFS
detect?  Does the whole 40 or 80 MHz have to find a
new home?  Can it slide over 2.5 or 5 MHz and
substantially ov

Re: [AFMUG] dumb DFS questions

[Kurt Fankhauser]

one thing i have always wondered is do the SM's actually look for RADAR or
only the AP's?

On Thu, Nov 21, 2019 at 12:55 PM Ken Hohhof  wrote:

> Yes, that’s true, but a higher gain antenna at the SM end helps rcv but
> not xmt.  And SMàAP is the direction you may actually need a better
> signal because the AP likely has a sector antenna and is mounted higher so
> it sees more interference.
>
>
>
> It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi
> antenna at the SM.  The antenna gain would help the rcv signal at the SM,
> but it would probably have to lower its conducted power by 9 dB to stay
> within the regulatory EIRP limit.
>
>
>
> In contrast, in U-NII-3 the CPE end is treated as point-to-point and can
> use antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE
> limits).
>
>
>
> *From:* AF  *On Behalf Of *Adam Moffett
> *Sent:* Thursday, November 21, 2019 11:27 AM
> *To:* af@af.afmug.com
> *Subject:* Re: [AFMUG] dumb DFS questions
>
>
>
> There might be something I don't understand, but I thought you had flat
> EIRP limit of +30dbm whether it's an SM or an AP.
>
> On 11/21/2019 12:11 PM, castarritt . wrote:
>
> 6 dBm loss for the AP transmit isn't the end of the world.  It's the up to
> 23 dBm loss on the SM transmit power that destroys the usefulness of DFS
> for PTMP past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in
> the air just can't hear those SMs over all the noise they are picking up.
> What we need is the ability to run downlink on DFS and uplink on 5.2 or 5.8.
>
>
>
>
>
> On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett  wrote:
>
> Yeah I think on most equipment you can set alternate channels that are
> just shifted over 5mhz from where you were.  And yeah I think the channel
> needs to be clear for a few minutes before you can go back to it.
>
> Assuming you don't really have a TDWR near you, I don't think DFS events
> are that big of a deal.  My understanding is that DFS events are more
> likely if you lie to the software about antenna gain to cheat the EIRP
> limit.  False detects happen, but I don't think it's a daily event.
> Disclaimer: I've mostly used it on Point to point with dishes.  I'm not
> sure if you'd pick up more anomolies on a sector antenna.
>
> The biggest bummer is the EIRP limit.  When you're trying to get that 32
> SNR for the 256QAM then losing 6db kind of hurts.  Or when you've already
> got someone hooked up 10 miles away and lowering the power ruins them.
>
> Where you really want to use DFS (In my opinion) is at a site where you
> have a bunch of customers within 1-2 miles.  Unfortunately I don't have
> sites like that.
>
> -Adam
>
>
>
>
>
> On 11/21/2019 11:31 AM, Ken Hohhof wrote:
>
> We mostly avoid DFS frequencies on APs because of the impact if we get
> false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit
> confused about DFS on other vendor equipment like Ubiquiti as well as home
> routers.
>
>
>
> Question 1 – what happens when there’s a DFS detection?  On the Cambium
> gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I
> don’t see this.  When there’s a DFS hit, does it jump to another random
> frequency?  Does it rescan the current frequency until it tests clear and
> only then resume transmission?  Is the answer right in front of me and I’m
> being stupid?  Maybe in the case of routers they are exempt because of low
> EIRP?
>
>
>
> Question 2 – what about 40/80/160 MHz channels?  We have a competitor
> using Ubiquiti gear and advertising residential subscriber speed plans up
> to 100x100.  Clearly they must be using at least 40 MHz channels if not 80
> MHz, or else their marketing people have burning pants and long noses.  And
> I don’t see how a WISP, especially one surrounded by other WISPs, could use
> wide channels other than in DFS bands.  We have some PTP links using 40 MHz
> but only 10 and 20 MHz channels on our APs.  So assuming you are using 40
> or 80 MHz in DFS, what happens when there’s a DFS detect?  Does the whole
> 40 or 80 MHz have to find a new home?  Can it slide over 2.5 or 5 MHz and
> substantially overlap the previous occupied spectrum?  DFS bands come with
> enough spectrum to use wide channels, but is there enough to jump around
> when you take a DFS hit?
>
>
>
> --
> AF mailing list
> AF@af.afmug.com
> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
>
>
>
> --
> AF mailing list
> AF@af.afmug.com
> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
>
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Re: [AFMUG] dumb DFS questions

[castarritt .]

What Ken said.  Also, the upper band isn't a flat 36 dBm; the SM gets to
transmit at up to 53 dBm under the PTP rules.

On Thu, Nov 21, 2019 at 11:55 AM Ken Hohhof  wrote:

> Yes, that’s true, but a higher gain antenna at the SM end helps rcv but
> not xmt.  And SMàAP is the direction you may actually need a better
> signal because the AP likely has a sector antenna and is mounted higher so
> it sees more interference.
>
>
>
> It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi
> antenna at the SM.  The antenna gain would help the rcv signal at the SM,
> but it would probably have to lower its conducted power by 9 dB to stay
> within the regulatory EIRP limit.
>
>
>
> In contrast, in U-NII-3 the CPE end is treated as point-to-point and can
> use antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE
> limits).
>
>
>
> *From:* AF  *On Behalf Of *Adam Moffett
> *Sent:* Thursday, November 21, 2019 11:27 AM
> *To:* af@af.afmug.com
> *Subject:* Re: [AFMUG] dumb DFS questions
>
>
>
> There might be something I don't understand, but I thought you had flat
> EIRP limit of +30dbm whether it's an SM or an AP.
>
> On 11/21/2019 12:11 PM, castarritt . wrote:
>
> 6 dBm loss for the AP transmit isn't the end of the world.  It's the up to
> 23 dBm loss on the SM transmit power that destroys the usefulness of DFS
> for PTMP past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in
> the air just can't hear those SMs over all the noise they are picking up.
> What we need is the ability to run downlink on DFS and uplink on 5.2 or 5.8.
>
>
>
>
>
> On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett  wrote:
>
> Yeah I think on most equipment you can set alternate channels that are
> just shifted over 5mhz from where you were.  And yeah I think the channel
> needs to be clear for a few minutes before you can go back to it.
>
> Assuming you don't really have a TDWR near you, I don't think DFS events
> are that big of a deal.  My understanding is that DFS events are more
> likely if you lie to the software about antenna gain to cheat the EIRP
> limit.  False detects happen, but I don't think it's a daily event.
> Disclaimer: I've mostly used it on Point to point with dishes.  I'm not
> sure if you'd pick up more anomolies on a sector antenna.
>
> The biggest bummer is the EIRP limit.  When you're trying to get that 32
> SNR for the 256QAM then losing 6db kind of hurts.  Or when you've already
> got someone hooked up 10 miles away and lowering the power ruins them.
>
> Where you really want to use DFS (In my opinion) is at a site where you
> have a bunch of customers within 1-2 miles.  Unfortunately I don't have
> sites like that.
>
> -Adam
>
>
>
>
>
> On 11/21/2019 11:31 AM, Ken Hohhof wrote:
>
> We mostly avoid DFS frequencies on APs because of the impact if we get
> false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit
> confused about DFS on other vendor equipment like Ubiquiti as well as home
> routers.
>
>
>
> Question 1 – what happens when there’s a DFS detection?  On the Cambium
> gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I
> don’t see this.  When there’s a DFS hit, does it jump to another random
> frequency?  Does it rescan the current frequency until it tests clear and
> only then resume transmission?  Is the answer right in front of me and I’m
> being stupid?  Maybe in the case of routers they are exempt because of low
> EIRP?
>
>
>
> Question 2 – what about 40/80/160 MHz channels?  We have a competitor
> using Ubiquiti gear and advertising residential subscriber speed plans up
> to 100x100.  Clearly they must be using at least 40 MHz channels if not 80
> MHz, or else their marketing people have burning pants and long noses.  And
> I don’t see how a WISP, especially one surrounded by other WISPs, could use
> wide channels other than in DFS bands.  We have some PTP links using 40 MHz
> but only 10 and 20 MHz channels on our APs.  So assuming you are using 40
> or 80 MHz in DFS, what happens when there’s a DFS detect?  Does the whole
> 40 or 80 MHz have to find a new home?  Can it slide over 2.5 or 5 MHz and
> substantially overlap the previous occupied spectrum?  DFS bands come with
> enough spectrum to use wide channels, but is there enough to jump around
> when you take a DFS hit?
>
>
>
> --
> AF mailing list
> AF@af.afmug.com
> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
>
>
>
> --
> AF mailing list
> AF@af.afmug.com
> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
>
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Re: [AFMUG] dumb DFS questions

[Ken Hohhof]

Yes, that’s true, but a higher gain antenna at the SM end helps rcv but not 
xmt.  And SM-->AP is the direction you may actually need a better signal 
because the AP likely has a sector antenna and is mounted higher so it sees 
more interference.

 

It would not be unusual to have a 16 dBi antenna at the AP but a 25 dBi antenna 
at the SM.  The antenna gain would help the rcv signal at the SM, but it would 
probably have to lower its conducted power by 9 dB to stay within the 
regulatory EIRP limit.

 

In contrast, in U-NII-3 the CPE end is treated as point-to-point and can use 
antenna gain to exceed the AP limit of 36 dBm EIRP (subject to OOBE limits).

 

From: AF  On Behalf Of Adam Moffett
Sent: Thursday, November 21, 2019 11:27 AM
To: af@af.afmug.com
Subject: Re: [AFMUG] dumb DFS questions

 

There might be something I don't understand, but I thought you had flat EIRP 
limit of +30dbm whether it's an SM or an AP.

On 11/21/2019 12:11 PM, castarritt . wrote:

6 dBm loss for the AP transmit isn't the end of the world.  It's the up to 23 
dBm loss on the SM transmit power that destroys the usefulness of DFS for PTMP 
past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in the air just 
can't hear those SMs over all the noise they are picking up.  What we need is 
the ability to run downlink on DFS and uplink on 5.2 or 5.8.

 

 

On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett mailto:dmmoff...@gmail.com> > wrote:

Yeah I think on most equipment you can set alternate channels that are just 
shifted over 5mhz from where you were.  And yeah I think the channel needs to 
be clear for a few minutes before you can go back to it.

Assuming you don't really have a TDWR near you, I don't think DFS events are 
that big of a deal.  My understanding is that DFS events are more likely if you 
lie to the software about antenna gain to cheat the EIRP limit.  False detects 
happen, but I don't think it's a daily event.  Disclaimer: I've mostly used it 
on Point to point with dishes.  I'm not sure if you'd pick up more anomolies on 
a sector antenna.

The biggest bummer is the EIRP limit.  When you're trying to get that 32 SNR 
for the 256QAM then losing 6db kind of hurts.  Or when you've already got 
someone hooked up 10 miles away and lowering the power ruins them.  

Where you really want to use DFS (In my opinion) is at a site where you have a 
bunch of customers within 1-2 miles.  Unfortunately I don't have sites like 
that.

-Adam

 

 

On 11/21/2019 11:31 AM, Ken Hohhof wrote:

We mostly avoid DFS frequencies on APs because of the impact if we get false 
radar detects.  Also we are mostly a Cambium shop.  So I’m a bit confused about 
DFS on other vendor equipment like Ubiquiti as well as home routers.

 

Question 1 – what happens when there’s a DFS detection?  On the Cambium gear, 
we have to select 1 or 2 alternate frequencies.  But on other gear, I don’t see 
this.  When there’s a DFS hit, does it jump to another random frequency?  Does 
it rescan the current frequency until it tests clear and only then resume 
transmission?  Is the answer right in front of me and I’m being stupid?  Maybe 
in the case of routers they are exempt because of low EIRP?

 

Question 2 – what about 40/80/160 MHz channels?  We have a competitor using 
Ubiquiti gear and advertising residential subscriber speed plans up to 100x100. 
 Clearly they must be using at least 40 MHz channels if not 80 MHz, or else 
their marketing people have burning pants and long noses.  And I don’t see how 
a WISP, especially one surrounded by other WISPs, could use wide channels other 
than in DFS bands.  We have some PTP links using 40 MHz but only 10 and 20 MHz 
channels on our APs.  So assuming you are using 40 or 80 MHz in DFS, what 
happens when there’s a DFS detect?  Does the whole 40 or 80 MHz have to find a 
new home?  Can it slide over 2.5 or 5 MHz and substantially overlap the 
previous occupied spectrum?  DFS bands come with enough spectrum to use wide 
channels, but is there enough to jump around when you take a DFS hit?





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Re: [AFMUG] dumb DFS questions

[Kurt Fankhauser]

We are using DFS on PMP450 for customer access and AF5XHD for backhauls. It
works surprisingly well. On both the PMP450 and AF5XHD's you can set an
alternative freq and a secondary alternative for the radios to immediately
jump to if they detect RADAR. Radios will try the first alt freq and if
they get a hit on that will then go to the second freq. It should happen
instantly without taking the link down. If you do not set the alt freqs the
radios will shutdown for 30 minutes and then attempt to use that freq
again. I have noticed that the wider the channels you use the more
"susceptible" you are yo getting a radar event. Try running on 20mhz
channels and you wont get as many hits if any. We have some AP's that have
been running for 6 months+ without any radar hits. We are also not anywhere
near any airports so that may be helping us as well.

On Thu, Nov 21, 2019 at 12:42 PM Matt Hoppes <
mattli...@rivervalleyinternet.net> wrote:

> You do.
>
> On 11/21/19 12:27 PM, Adam Moffett wrote:
> > There might be something I don't understand, but I thought you had flat
> > EIRP limit of +30dbm whether it's an SM or an AP.
> >
> > On 11/21/2019 12:11 PM, castarritt . wrote:
> >> 6 dBm loss for the AP transmit isn't the end of the world. It's the up
> >> to 23 dBm loss on the SM transmit power that destroys the
> >> usefulness of DFS for PTMP past a couple miles. The ~16 dBi gain 90°
> >> sectors 2-300' up in the air just can't hear those SMs over all the
> >> noise they are picking up.  What we need is the ability to run
> >> downlink on DFS and uplink on 5.2 or 5.8.
> >>
> >>
> >> On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett  >> > wrote:
> >>
> >> Yeah I think on most equipment you can set alternate channels that
> >> are just shifted over 5mhz from where you were.  And yeah I think
> >> the channel needs to be clear for a few minutes before you can go
> >> back to it.
> >>
> >> Assuming you don't really have a TDWR near you, I don't think DFS
> >> events are that big of a deal.  My understanding is that DFS
> >> events are more likely if you lie to the software about antenna
> >> gain to cheat the EIRP limit.  False detects happen, but I don't
> >> think it's a daily event.  Disclaimer: I've mostly used it on
> >> Point to point with dishes.  I'm not sure if you'd pick up more
> >> anomolies on a sector antenna.
> >>
> >> The biggest bummer is the EIRP limit.  When you're trying to get
> >> that 32 SNR for the 256QAM then losing 6db kind of hurts.  Or when
> >> you've already got someone hooked up 10 miles away and lowering
> >> the power ruins them.
> >>
> >> Where you really want to use DFS (In my opinion) is at a site
> >> where you have a bunch of customers within 1-2 miles.
> >> Unfortunately I don't have sites like that.
> >>
> >> -Adam
> >>
> >>
> >>
> >> On 11/21/2019 11:31 AM, Ken Hohhof wrote:
> >>>
> >>> We mostly avoid DFS frequencies on APs because of the impact if
> >>> we get false radar detects.  Also we are mostly a Cambium shop.
> >>> So I’m a bit confused about DFS on other vendor equipment like
> >>> Ubiquiti as well as home routers.
> >>>
> >>> Question 1 – what happens when there’s a DFS detection?  On the
> >>> Cambium gear, we have to select 1 or 2 alternate frequencies.
> >>> But on other gear, I don’t see this.  When there’s a DFS hit,
> >>> does it jump to another random frequency?  Does it rescan the
> >>> current frequency until it tests clear and only then resume
> >>> transmission?  Is the answer right in front of me and I’m being
> >>> stupid?  Maybe in the case of routers they are exempt because of
> >>> low EIRP?
> >>>
> >>> Question 2 – what about 40/80/160 MHz channels?  We have a
> >>> competitor using Ubiquiti gear and advertising residential
> >>> subscriber speed plans up to 100x100.  Clearly they must be using
> >>> at least 40 MHz channels if not 80 MHz, or else their marketing
> >>> people have burning pants and long noses. And I don’t see how a
> >>> WISP, especially one surrounded by other WISPs, could use wide
> >>> channels other than in DFS bands.  We have some PTP links using
> >>> 40 MHz but only 10 and 20 MHz channels on our APs.  So assuming
> >>> you are using 40 or 80 MHz in DFS, what happens when there’s a
> >>> DFS detect?  Does the whole 40 or 80 MHz have to find a new
> >>> home?  Can it slide over 2.5 or 5 MHz and substantially overlap
> >>> the previous occupied spectrum?  DFS bands come with enough
> >>> spectrum to use wide channels, but is there enough to jump around
> >>> when you take a DFS hit?
> >>>
> >>>
> >> --
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> >> AF@af.afmug.com 
> >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
> >>
> >>
> >
>
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> 

Re: [AFMUG] dumb DFS questions

[Ken Hohhof]

The idea that DFS detects must be from TDWR or military radar, or from
cheating on the antenna gain setting (which wouldn't even be possible with
integral sector antennas), is just not true.

 

Maybe some equipment has detection algorithms that are less susceptible to
false positives than others, but I still say there are false positives.
Sometimes I think just a reflection of another WISP radio off a moving
vehicle might cause it, who knows?  But it's not radar.  Unless it's being
tripped by something like speed trap guns, but Wikipedia says those mostly
use X, K and Ka bands which are all above 10 GHz.

 

 

From: AF  On Behalf Of ch...@wbmfg.com
Sent: Thursday, November 21, 2019 11:02 AM
To: af@af.afmug.com
Subject: Re: [AFMUG] dumb DFS questions

 

I would think you can do a frequency search on radar in the area and simply
shut off those frequencies.  I have never used anything on DFS but a an
armchair QB would that not be the proactive solution?  Those big TDWR don't
change positions.  Not sure if the change their frequencies around, but even
if they did, I am sure they are re-using the same frequencies and not just
sliding around in a band.  Maybe the are?

 

From: Adam Moffett 

Sent: Thursday, November 21, 2019 9:55 AM

To: af@af.afmug.com <mailto:af@af.afmug.com>  

Subject: Re: [AFMUG] dumb DFS questions

 

Yeah I think on most equipment you can set alternate channels that are just
shifted over 5mhz from where you were.  And yeah I think the channel needs
to be clear for a few minutes before you can go back to it.

Assuming you don't really have a TDWR near you, I don't think DFS events are
that big of a deal.  My understanding is that DFS events are more likely if
you lie to the software about antenna gain to cheat the EIRP limit.  False
detects happen, but I don't think it's a daily event.  Disclaimer: I've
mostly used it on Point to point with dishes.  I'm not sure if you'd pick up
more anomolies on a sector antenna.

The biggest bummer is the EIRP limit.  When you're trying to get that 32 SNR
for the 256QAM then losing 6db kind of hurts.  Or when you've already got
someone hooked up 10 miles away and lowering the power ruins them.  

Where you really want to use DFS (In my opinion) is at a site where you have
a bunch of customers within 1-2 miles.  Unfortunately I don't have sites
like that.

-Adam

 

 

On 11/21/2019 11:31 AM, Ken Hohhof wrote:

We mostly avoid DFS frequencies on APs because of the impact if we get false
radar detects.  Also we are mostly a Cambium shop.  So I'm a bit confused
about DFS on other vendor equipment like Ubiquiti as well as home routers.

 

Question 1 - what happens when there's a DFS detection?  On the Cambium
gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I
don't see this.  When there's a DFS hit, does it jump to another random
frequency?  Does it rescan the current frequency until it tests clear and
only then resume transmission?  Is the answer right in front of me and I'm
being stupid?  Maybe in the case of routers they are exempt because of low
EIRP?

 

Question 2 - what about 40/80/160 MHz channels?  We have a competitor using
Ubiquiti gear and advertising residential subscriber speed plans up to
100x100.  Clearly they must be using at least 40 MHz channels if not 80 MHz,
or else their marketing people have burning pants and long noses.  And I
don't see how a WISP, especially one surrounded by other WISPs, could use
wide channels other than in DFS bands.  We have some PTP links using 40 MHz
but only 10 and 20 MHz channels on our APs.  So assuming you are using 40 or
80 MHz in DFS, what happens when there's a DFS detect?  Does the whole 40 or
80 MHz have to find a new home?  Can it slide over 2.5 or 5 MHz and
substantially overlap the previous occupied spectrum?  DFS bands come with
enough spectrum to use wide channels, but is there enough to jump around
when you take a DFS hit?





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Re: [AFMUG] dumb DFS questions

[Matt Hoppes]

You do.

On 11/21/19 12:27 PM, Adam Moffett wrote:
There might be something I don't understand, but I thought you had flat 
EIRP limit of +30dbm whether it's an SM or an AP.


On 11/21/2019 12:11 PM, castarritt . wrote:
6 dBm loss for the AP transmit isn't the end of the world. It's the up 
to 23 dBm loss on the SM transmit power that destroys the 
usefulness of DFS for PTMP past a couple miles. The ~16 dBi gain 90° 
sectors 2-300' up in the air just can't hear those SMs over all the 
noise they are picking up.  What we need is the ability to run 
downlink on DFS and uplink on 5.2 or 5.8.



On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett > wrote:


Yeah I think on most equipment you can set alternate channels that
are just shifted over 5mhz from where you were.  And yeah I think
the channel needs to be clear for a few minutes before you can go
back to it.

Assuming you don't really have a TDWR near you, I don't think DFS
events are that big of a deal.  My understanding is that DFS
events are more likely if you lie to the software about antenna
gain to cheat the EIRP limit.  False detects happen, but I don't
think it's a daily event.  Disclaimer: I've mostly used it on
Point to point with dishes.  I'm not sure if you'd pick up more
anomolies on a sector antenna.

The biggest bummer is the EIRP limit.  When you're trying to get
that 32 SNR for the 256QAM then losing 6db kind of hurts.  Or when
you've already got someone hooked up 10 miles away and lowering
the power ruins them.

Where you really want to use DFS (In my opinion) is at a site
where you have a bunch of customers within 1-2 miles. 
Unfortunately I don't have sites like that.


-Adam



On 11/21/2019 11:31 AM, Ken Hohhof wrote:


We mostly avoid DFS frequencies on APs because of the impact if
we get false radar detects.  Also we are mostly a Cambium shop. 
So I’m a bit confused about DFS on other vendor equipment like

Ubiquiti as well as home routers.

Question 1 – what happens when there’s a DFS detection?  On the
Cambium gear, we have to select 1 or 2 alternate frequencies. 
But on other gear, I don’t see this.  When there’s a DFS hit,

does it jump to another random frequency?  Does it rescan the
current frequency until it tests clear and only then resume
transmission?  Is the answer right in front of me and I’m being
stupid?  Maybe in the case of routers they are exempt because of
low EIRP?

Question 2 – what about 40/80/160 MHz channels?  We have a
competitor using Ubiquiti gear and advertising residential
subscriber speed plans up to 100x100.  Clearly they must be using
at least 40 MHz channels if not 80 MHz, or else their marketing
people have burning pants and long noses. And I don’t see how a
WISP, especially one surrounded by other WISPs, could use wide
channels other than in DFS bands.  We have some PTP links using
40 MHz but only 10 and 20 MHz channels on our APs.  So assuming
you are using 40 or 80 MHz in DFS, what happens when there’s a
DFS detect?  Does the whole 40 or 80 MHz have to find a new
home?  Can it slide over 2.5 or 5 MHz and substantially overlap
the previous occupied spectrum?  DFS bands come with enough
spectrum to use wide channels, but is there enough to jump around
when you take a DFS hit?


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Re: [AFMUG] dumb DFS questions

[Matt Hoppes]

We don't like our APs jumping channels, and we have too tight of a 
channel plan to have "extra" channels available.  We lock our APs to the 
DFS frequency.


If a detection happens (true or false) the AP shuts down for 30 minutes 
and then will sense and fire back up if the source is gone.  Almost 
never a false positive hit on Ubiquiti gear when run properly.


On 11/21/19 11:41 AM, Steve Jones wrote:
180 second wait on a detect, i believe. so it waits the 180 before 
transmitting initially, then if there is a detection it waits to hop. 
the 4.4.2 firmware is really sticky on your alternate channels, it wont 
let you save them if you dont have the required separation (no to 2.5 or 
5mhz) DFS is really only a 2 mile pmp solution on a good day with your 
leg cocked back. but you can do massive speeds in that 2 miles. youre 
"supposed" to spread your DFS use across the whole band across your 
network but i doubt anybody does. consumer stuff i wonder if it has the 
same requirements for detection since its "indoor" only.


On Thu, Nov 21, 2019 at 10:32 AM Ken Hohhof > wrote:


We mostly avoid DFS frequencies on APs because of the impact if we
get false radar detects.  Also we are mostly a Cambium shop.  So I’m
a bit confused about DFS on other vendor equipment like Ubiquiti as
well as home routers.

__ __

Question 1 – what happens when there’s a DFS detection?  On the
Cambium gear, we have to select 1 or 2 alternate frequencies.  But
on other gear, I don’t see this.  When there’s a DFS hit, does it
jump to another random frequency?  Does it rescan the current
frequency until it tests clear and only then resume transmission? 
Is the answer right in front of me and I’m being stupid?  Maybe in

the case of routers they are exempt because of low EIRP?

__ __

Question 2 – what about 40/80/160 MHz channels?  We have a
competitor using Ubiquiti gear and advertising residential
subscriber speed plans up to 100x100.  Clearly they must be using at
least 40 MHz channels if not 80 MHz, or else their marketing people
have burning pants and long noses.  And I don’t see how a WISP,
especially one surrounded by other WISPs, could use wide channels
other than in DFS bands.  We have some PTP links using 40 MHz but
only 10 and 20 MHz channels on our APs.  So assuming you are using
40 or 80 MHz in DFS, what happens when there’s a DFS detect?  Does
the whole 40 or 80 MHz have to find a new home?  Can it slide over
2.5 or 5 MHz and substantially overlap the previous occupied
spectrum?  DFS bands come with enough spectrum to use wide channels,
but is there enough to jump around when you take a DFS hit?

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Re: [AFMUG] dumb DFS questions

[Adam Moffett]

There might be something I don't understand, but I thought you had flat 
EIRP limit of +30dbm whether it's an SM or an AP.


On 11/21/2019 12:11 PM, castarritt . wrote:
6 dBm loss for the AP transmit isn't the end of the world. It's the up 
to 23 dBm loss on the SM transmit power that destroys the 
usefulness of DFS for PTMP past a couple miles. The ~16 dBi gain 90° 
sectors 2-300' up in the air just can't hear those SMs over all the 
noise they are picking up.  What we need is the ability to run 
downlink on DFS and uplink on 5.2 or 5.8.



On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett > wrote:


Yeah I think on most equipment you can set alternate channels that
are just shifted over 5mhz from where you were.  And yeah I think
the channel needs to be clear for a few minutes before you can go
back to it.

Assuming you don't really have a TDWR near you, I don't think DFS
events are that big of a deal.  My understanding is that DFS
events are more likely if you lie to the software about antenna
gain to cheat the EIRP limit.  False detects happen, but I don't
think it's a daily event.  Disclaimer: I've mostly used it on
Point to point with dishes.  I'm not sure if you'd pick up more
anomolies on a sector antenna.

The biggest bummer is the EIRP limit.  When you're trying to get
that 32 SNR for the 256QAM then losing 6db kind of hurts.  Or when
you've already got someone hooked up 10 miles away and lowering
the power ruins them.

Where you really want to use DFS (In my opinion) is at a site
where you have a bunch of customers within 1-2 miles. 
Unfortunately I don't have sites like that.

-Adam



On 11/21/2019 11:31 AM, Ken Hohhof wrote:


We mostly avoid DFS frequencies on APs because of the impact if
we get false radar detects.  Also we are mostly a Cambium shop. 
So I’m a bit confused about DFS on other vendor equipment like
Ubiquiti as well as home routers.

Question 1 – what happens when there’s a DFS detection?  On the
Cambium gear, we have to select 1 or 2 alternate frequencies. 
But on other gear, I don’t see this.  When there’s a DFS hit,
does it jump to another random frequency?  Does it rescan the
current frequency until it tests clear and only then resume
transmission?  Is the answer right in front of me and I’m being
stupid?  Maybe in the case of routers they are exempt because of
low EIRP?

Question 2 – what about 40/80/160 MHz channels?  We have a
competitor using Ubiquiti gear and advertising residential
subscriber speed plans up to 100x100.  Clearly they must be using
at least 40 MHz channels if not 80 MHz, or else their marketing
people have burning pants and long noses. And I don’t see how a
WISP, especially one surrounded by other WISPs, could use wide
channels other than in DFS bands.  We have some PTP links using
40 MHz but only 10 and 20 MHz channels on our APs.  So assuming
you are using 40 or 80 MHz in DFS, what happens when there’s a
DFS detect?  Does the whole 40 or 80 MHz have to find a new
home?  Can it slide over 2.5 or 5 MHz and substantially overlap
the previous occupied spectrum?  DFS bands come with enough
spectrum to use wide channels, but is there enough to jump around
when you take a DFS hit?


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Re: [AFMUG] dumb DFS questions

[castarritt .]

6 dBm loss for the AP transmit isn't the end of the world.  It's the up to
23 dBm loss on the SM transmit power that destroys the usefulness of DFS
for PTMP past a couple miles.  The ~16 dBi gain 90° sectors 2-300' up in
the air just can't hear those SMs over all the noise they are picking up.
What we need is the ability to run downlink on DFS and uplink on 5.2 or 5.8.


On Thu, Nov 21, 2019 at 10:56 AM Adam Moffett  wrote:

> Yeah I think on most equipment you can set alternate channels that are
> just shifted over 5mhz from where you were.  And yeah I think the channel
> needs to be clear for a few minutes before you can go back to it.
>
> Assuming you don't really have a TDWR near you, I don't think DFS events
> are that big of a deal.  My understanding is that DFS events are more
> likely if you lie to the software about antenna gain to cheat the EIRP
> limit.  False detects happen, but I don't think it's a daily event.
> Disclaimer: I've mostly used it on Point to point with dishes.  I'm not
> sure if you'd pick up more anomolies on a sector antenna.
>
> The biggest bummer is the EIRP limit.  When you're trying to get that 32
> SNR for the 256QAM then losing 6db kind of hurts.  Or when you've already
> got someone hooked up 10 miles away and lowering the power ruins them.
>
> Where you really want to use DFS (In my opinion) is at a site where you
> have a bunch of customers within 1-2 miles.  Unfortunately I don't have
> sites like that.
>
> -Adam
>
>
>
> On 11/21/2019 11:31 AM, Ken Hohhof wrote:
>
> We mostly avoid DFS frequencies on APs because of the impact if we get
> false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit
> confused about DFS on other vendor equipment like Ubiquiti as well as home
> routers.
>
>
>
> Question 1 – what happens when there’s a DFS detection?  On the Cambium
> gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I
> don’t see this.  When there’s a DFS hit, does it jump to another random
> frequency?  Does it rescan the current frequency until it tests clear and
> only then resume transmission?  Is the answer right in front of me and I’m
> being stupid?  Maybe in the case of routers they are exempt because of low
> EIRP?
>
>
>
> Question 2 – what about 40/80/160 MHz channels?  We have a competitor
> using Ubiquiti gear and advertising residential subscriber speed plans up
> to 100x100.  Clearly they must be using at least 40 MHz channels if not 80
> MHz, or else their marketing people have burning pants and long noses.  And
> I don’t see how a WISP, especially one surrounded by other WISPs, could use
> wide channels other than in DFS bands.  We have some PTP links using 40 MHz
> but only 10 and 20 MHz channels on our APs.  So assuming you are using 40
> or 80 MHz in DFS, what happens when there’s a DFS detect?  Does the whole
> 40 or 80 MHz have to find a new home?  Can it slide over 2.5 or 5 MHz and
> substantially overlap the previous occupied spectrum?  DFS bands come with
> enough spectrum to use wide channels, but is there enough to jump around
> when you take a DFS hit?
>
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Re: [AFMUG] dumb DFS questions

[chuck]

I would think you can do a frequency search on radar in the area and simply 
shut off those frequencies.  I have never used anything on DFS but a an 
armchair QB would that not be the proactive solution?  Those big TDWR don’t 
change positions.  Not sure if the change their frequencies around, but even if 
they did, I am sure they are re-using the same frequencies and not just sliding 
around in a band.  Maybe the are?

From: Adam Moffett 
Sent: Thursday, November 21, 2019 9:55 AM
To: af@af.afmug.com 
Subject: Re: [AFMUG] dumb DFS questions

Yeah I think on most equipment you can set alternate channels that are just 
shifted over 5mhz from where you were.  And yeah I think the channel needs to 
be clear for a few minutes before you can go back to it.


Assuming you don't really have a TDWR near you, I don't think DFS events are 
that big of a deal.  My understanding is that DFS events are more likely if you 
lie to the software about antenna gain to cheat the EIRP limit.  False detects 
happen, but I don't think it's a daily event.  Disclaimer: I've mostly used it 
on Point to point with dishes.  I'm not sure if you'd pick up more anomolies on 
a sector antenna.


The biggest bummer is the EIRP limit.  When you're trying to get that 32 SNR 
for the 256QAM then losing 6db kind of hurts.  Or when you've already got 
someone hooked up 10 miles away and lowering the power ruins them.  


Where you really want to use DFS (In my opinion) is at a site where you have a 
bunch of customers within 1-2 miles.  Unfortunately I don't have sites like 
that.

-Adam





On 11/21/2019 11:31 AM, Ken Hohhof wrote:

  We mostly avoid DFS frequencies on APs because of the impact if we get false 
radar detects.  Also we are mostly a Cambium shop.  So I’m a bit confused about 
DFS on other vendor equipment like Ubiquiti as well as home routers.

   

  Question 1 – what happens when there’s a DFS detection?  On the Cambium gear, 
we have to select 1 or 2 alternate frequencies.  But on other gear, I don’t see 
this.  When there’s a DFS hit, does it jump to another random frequency?  Does 
it rescan the current frequency until it tests clear and only then resume 
transmission?  Is the answer right in front of me and I’m being stupid?  Maybe 
in the case of routers they are exempt because of low EIRP?

   

  Question 2 – what about 40/80/160 MHz channels?  We have a competitor using 
Ubiquiti gear and advertising residential subscriber speed plans up to 100x100. 
 Clearly they must be using at least 40 MHz channels if not 80 MHz, or else 
their marketing people have burning pants and long noses.  And I don’t see how 
a WISP, especially one surrounded by other WISPs, could use wide channels other 
than in DFS bands.  We have some PTP links using 40 MHz but only 10 and 20 MHz 
channels on our APs.  So assuming you are using 40 or 80 MHz in DFS, what 
happens when there’s a DFS detect?  Does the whole 40 or 80 MHz have to find a 
new home?  Can it slide over 2.5 or 5 MHz and substantially overlap the 
previous occupied spectrum?  DFS bands come with enough spectrum to use wide 
channels, but is there enough to jump around when you take a DFS hit?


   



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Re: [AFMUG] dumb DFS questions

[Adam Moffett]

...and if Belkin did it wrong, who would know or care?

On 11/21/2019 11:41 AM, Steve Jones wrote:
180 second wait on a detect, i believe. so it waits the 180 before 
transmitting initially, then if there is a detection it waits to hop. 
the 4.4.2 firmware is really sticky on your alternate channels, it 
wont let you save them if you dont have the required separation (no to 
2.5 or 5mhz) DFS is really only a 2 mile pmp solution on a good day 
with your leg cocked back. but you can do massive speeds in that 2 
miles. youre "supposed" to spread your DFS use across the whole band 
across your network but i doubt anybody does. consumer stuff i wonder 
if it has the same requirements for detection since its "indoor" only.


On Thu, Nov 21, 2019 at 10:32 AM Ken Hohhof > wrote:


We mostly avoid DFS frequencies on APs because of the impact if we
get false radar detects.  Also we are mostly a Cambium shop.  So
I’m a bit confused about DFS on other vendor equipment like
Ubiquiti as well as home routers.

Question 1 – what happens when there’s a DFS detection?  On the
Cambium gear, we have to select 1 or 2 alternate frequencies.  But
on other gear, I don’t see this.  When there’s a DFS hit, does it
jump to another random frequency?  Does it rescan the current
frequency until it tests clear and only then resume transmission? 
Is the answer right in front of me and I’m being stupid?  Maybe in
the case of routers they are exempt because of low EIRP?

Question 2 – what about 40/80/160 MHz channels?  We have a
competitor using Ubiquiti gear and advertising residential
subscriber speed plans up to 100x100.  Clearly they must be using
at least 40 MHz channels if not 80 MHz, or else their marketing
people have burning pants and long noses.  And I don’t see how a
WISP, especially one surrounded by other WISPs, could use wide
channels other than in DFS bands.  We have some PTP links using 40
MHz but only 10 and 20 MHz channels on our APs.  So assuming you
are using 40 or 80 MHz in DFS, what happens when there’s a DFS
detect?  Does the whole 40 or 80 MHz have to find a new home?  Can
it slide over 2.5 or 5 MHz and substantially overlap the previous
occupied spectrum?  DFS bands come with enough spectrum to use
wide channels, but is there enough to jump around when you take a
DFS hit?

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Re: [AFMUG] dumb DFS questions

[Adam Moffett]

Yeah I think on most equipment you can set alternate channels that are 
just shifted over 5mhz from where you were.  And yeah I think the 
channel needs to be clear for a few minutes before you can go back to it.


Assuming you don't really have a TDWR near you, I don't think DFS events 
are that big of a deal.  My understanding is that DFS events are more 
likely if you lie to the software about antenna gain to cheat the EIRP 
limit.  False detects happen, but I don't think it's a daily event.  
Disclaimer: I've mostly used it on Point to point with dishes.  I'm not 
sure if you'd pick up more anomolies on a sector antenna.


The biggest bummer is the EIRP limit.  When you're trying to get that 32 
SNR for the 256QAM then losing 6db kind of hurts.  Or when you've 
already got someone hooked up 10 miles away and lowering the power ruins 
them.


Where you really want to use DFS (In my opinion) is at a site where you 
have a bunch of customers within 1-2 miles. Unfortunately I don't have 
sites like that.


-Adam



On 11/21/2019 11:31 AM, Ken Hohhof wrote:


We mostly avoid DFS frequencies on APs because of the impact if we get 
false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit 
confused about DFS on other vendor equipment like Ubiquiti as well as 
home routers.


Question 1 – what happens when there’s a DFS detection?  On the 
Cambium gear, we have to select 1 or 2 alternate frequencies.  But on 
other gear, I don’t see this. When there’s a DFS hit, does it jump to 
another random frequency?  Does it rescan the current frequency until 
it tests clear and only then resume transmission?  Is the answer right 
in front of me and I’m being stupid?  Maybe in the case of routers 
they are exempt because of low EIRP?


Question 2 – what about 40/80/160 MHz channels?  We have a competitor 
using Ubiquiti gear and advertising residential subscriber speed plans 
up to 100x100. Clearly they must be using at least 40 MHz channels if 
not 80 MHz, or else their marketing people have burning pants and long 
noses.  And I don’t see how a WISP, especially one surrounded by other 
WISPs, could use wide channels other than in DFS bands.  We have some 
PTP links using 40 MHz but only 10 and 20 MHz channels on our APs.  So 
assuming you are using 40 or 80 MHz in DFS, what happens when there’s 
a DFS detect? Does the whole 40 or 80 MHz have to find a new home?  
Can it slide over 2.5 or 5 MHz and substantially overlap the previous 
occupied spectrum?  DFS bands come with enough spectrum to use wide 
channels, but is there enough to jump around when you take a DFS hit?



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Re: [AFMUG] dumb DFS questions

[Steve Jones]

180 second wait on a detect, i believe. so it waits the 180 before
transmitting initially, then if there is a detection it waits to hop. the
4.4.2 firmware is really sticky on your alternate channels, it wont let you
save them if you dont have the required separation (no to 2.5 or 5mhz) DFS
is really only a 2 mile pmp solution on a good day with your leg cocked
back. but you can do massive speeds in that 2 miles. youre "supposed" to
spread your DFS use across the whole band across your network but i doubt
anybody does. consumer stuff i wonder if it has the same requirements for
detection since its "indoor" only.

On Thu, Nov 21, 2019 at 10:32 AM Ken Hohhof  wrote:

> We mostly avoid DFS frequencies on APs because of the impact if we get
> false radar detects.  Also we are mostly a Cambium shop.  So I’m a bit
> confused about DFS on other vendor equipment like Ubiquiti as well as home
> routers.
>
>
>
> Question 1 – what happens when there’s a DFS detection?  On the Cambium
> gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I
> don’t see this.  When there’s a DFS hit, does it jump to another random
> frequency?  Does it rescan the current frequency until it tests clear and
> only then resume transmission?  Is the answer right in front of me and I’m
> being stupid?  Maybe in the case of routers they are exempt because of low
> EIRP?
>
>
>
> Question 2 – what about 40/80/160 MHz channels?  We have a competitor
> using Ubiquiti gear and advertising residential subscriber speed plans up
> to 100x100.  Clearly they must be using at least 40 MHz channels if not 80
> MHz, or else their marketing people have burning pants and long noses.  And
> I don’t see how a WISP, especially one surrounded by other WISPs, could use
> wide channels other than in DFS bands.  We have some PTP links using 40 MHz
> but only 10 and 20 MHz channels on our APs.  So assuming you are using 40
> or 80 MHz in DFS, what happens when there’s a DFS detect?  Does the whole
> 40 or 80 MHz have to find a new home?  Can it slide over 2.5 or 5 MHz and
> substantially overlap the previous occupied spectrum?  DFS bands come with
> enough spectrum to use wide channels, but is there enough to jump around
> when you take a DFS hit?
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> AF@af.afmug.com
> http://af.afmug.com/mailman/listinfo/af_af.afmug.com
>
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[AFMUG] dumb DFS questions

[Ken Hohhof]

We mostly avoid DFS frequencies on APs because of the impact if we get false
radar detects.  Also we are mostly a Cambium shop.  So I'm a bit confused
about DFS on other vendor equipment like Ubiquiti as well as home routers.

 

Question 1 - what happens when there's a DFS detection?  On the Cambium
gear, we have to select 1 or 2 alternate frequencies.  But on other gear, I
don't see this.  When there's a DFS hit, does it jump to another random
frequency?  Does it rescan the current frequency until it tests clear and
only then resume transmission?  Is the answer right in front of me and I'm
being stupid?  Maybe in the case of routers they are exempt because of low
EIRP?

 

Question 2 - what about 40/80/160 MHz channels?  We have a competitor using
Ubiquiti gear and advertising residential subscriber speed plans up to
100x100.  Clearly they must be using at least 40 MHz channels if not 80 MHz,
or else their marketing people have burning pants and long noses.  And I
don't see how a WISP, especially one surrounded by other WISPs, could use
wide channels other than in DFS bands.  We have some PTP links using 40 MHz
but only 10 and 20 MHz channels on our APs.  So assuming you are using 40 or
80 MHz in DFS, what happens when there's a DFS detect?  Does the whole 40 or
80 MHz have to find a new home?  Can it slide over 2.5 or 5 MHz and
substantially overlap the previous occupied spectrum?  DFS bands come with
enough spectrum to use wide channels, but is there enough to jump around
when you take a DFS hit?

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