IntraLink
Premium,MVM
join:2002-08-14
Utah Valley | So, client on PTMP can be EIRP 36. Right or wrong?
I want to know the final word on the FCC eirp limit for PTMP.
The base station can do up to 30.
The clients (more than one) can do up to 36.
Is this correct? |
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dongato17
VIP
join:2000-07-28
Atlanta, GA | »www.telex.com/Wireless/faq.nsf/C···art%2015 |
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IntraLink
Premium,MVM
join:2002-08-14
Utah Valley
| reply to IntraLink
That artical contradicts itself I think.
At one point I get that a PTP (or client of PtMP) can be up to 43dBm.
But their chart starts at 36dBm (4W) and goes to 52dBm (158W). That sounds like WAY too much power...
According to their artical the AP of PtMP can be 36dBm and the CPE can be 52dBm.
So why do the Smartbridges AP's and CPE's have 30dBm as a "limit" on their power meters? Are they wrong? |
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Antennaguy
join:2001-08-06
Lincoln, NE
| reply to IntraLink
Stations that are PtMP are limited to +36 dBm (e.g. +30 dBm radio and 6 dBi antenna). This is just the AP in normal infrastructure mode.
The clients are always in PtP mode, as they ONLY talk with the AP unit. Therefore they follow the PtP rules, which allow more transmit power as long as the antenna is directive. Follow the link to FCC Part 15.247 and read the rules for PtP.
Mesh systems must use PtMP rules (+36 dBm eirp max). |
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magnushsi
join:2002-11-06
Cedar Springs, MI | reply to IntraLink
The specs on the new Telex all in ones are
41dmb eirp and it's FCC certified. So they must have gotten the FCC to interpret the rules somehow. |
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Antennaguy
join:2001-08-06
Lincoln, NE | reply to IntraLink
Telex wasn't the first. YDI has had the Etherant & Etherant II & Etherant LR out for more than a year. Tranzeo & Alvarian also have similar offerings that are FCC Certified. |
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IntraLink
Premium,MVM
join:2002-08-14
Utah Valley
| reply to IntraLink
So what CPE device currently has the highest FCC certified eirp?
And can that device possibly reach the 52dBm eirp mark as hinted at by Telex's interpretation of FCC Part 15.247?
And does Smartbridges just interpret the Part 15.247 rule differently for their embedded eirp calculator? |
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BSDish
join:2002-02-20
Lakeland, FL
| At 2.4GHz you can have:
1. Up to 30dBi coming out of the radio for PtMP
2. Up to 36dBi once antenna gain is figured for PtMP
3. Up to 30dBi coming out of the radio for PtP
4. Up to 36dBi once antenna gain is figured in for PtMP IF the radio outputs 30dBi. If the radio outputs less, antenna gain can be increased by 3x the difference. So with a 20dBi radio, you could have up to 36dBi of antenna gain.
Matt |
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magnushsi
join:2002-11-06
Cedar Springs, MI
| reply to Antennaguy
Telex wasn't the first to what? YDI uses Lucent radios in the Etherants, I have several and have taken them apart. Those radios are only 12db plus the 18db antenna giving it 30db eirp...
As far as I know, this new Telex has the highest eirp rating I have seen in an all in one. I will have one tomorrow and will be happy to let anyone know my testing results. |
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jarosoup
join:2003-01-14
| reply to IntraLink
WRT the paragraph from the link above titled "Is the Customer or Client (CPE) system considered PtMP or PtP?"
quote:
If the CPE system (or Subscriber Unit - SU) only talks with the POP/AP and is at a fixed location, then it is considered to be PtP and can use power and antenna gain associated with PtP systems, as shown below. (This has been verified by FCC Certified systems...
I stumbled across this very same explaination on another website a few months ago. I was very curious about this as it's not really spelled out this way in 15.247 of the FCC reg. It would also allow me to rework some links at our POP. So, I called the FCC. After a week and multiple failures of them calling me back and getting zero info from anyone at the FCC, I reached an engineer there named "Bob" (seriously, that was his name). I restated this statement from above and asked if this was really true. Well, he put me on hold for a minute or so, and I could hear him mumbling to someone else while waiting. "They" came to the conclusion that this statement was not correct. He stated that if multiple clients are connected to a fixed AP, even if directionals were used on both sides and fixed locations, that it's considered PtMP.
I'm still confused as to why they (the FCC) can't deal with such a question, and if it is legal, why it's not stated as such in their rules? Since I made that call, I was under the impression that they knew what they were talking about and the website was in the wrong. I have since had to rethink some links based on what they had told me (which were using the 1:3 rule as a PtP link). What gives? |
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ikarus1
Premium
join:2002-10-23
Urbanna, VA
| reply to magnushsi
Methinks...
The AP is a PtMP unit. The client is a PtP unit. This means the client can run one heck of a lot of eirp towards the tower and the FCC is going to give a "ratz hinderst parts".
Look guyz it's simple really, PtMP = YOUR TOWER if and only IF you are running multiple links into your AP. PtP = YOUR CLIENTS, period. I mean your clients only talk to your AP, right? Therefore your clients are PtP links and your AP is PtMP, IF AND ONLY IF it hosts more than one client.
So no, 36 dBi eirp is not the max allowed for a client. The client is governed by the PtP limits. I have a client ONE client on ONE PtP to the tower running 26+24 = 50 dBi eirp. I am going to remove the 24 dBi dish on the tower this year and replace it with a 12-16 dBi panel so that I can have multiple clients on that unit. Thus the AP will be kept to around 20 or so dBm so that I am LEGALLY allowed to run the tower at PtMP levels.
I have no fear that I will be troubled by the FCC because I can read what they have specified.
Oh... and I too called the FCC (18 mo. ago) and spoke with the engineer who WROTE the pertinent parts of the specification. I suppose I could dig out the information on his name and telephone number but at this point, the desire does not rise to the requirement. The end user to an AP is a PtP unit and can be physically PROVEN to be such.
-m-
--
FAVORITE ANSWERED QUESION
Q: I want to add an antenna to my wireless device, any suggestions?
A: »www.freeantennas.com
[text was edited by author 2003-10-09 21:16:58] |
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Antennaguy
join:2001-08-06
Lincoln, NE
| reply to IntraLink
The "client is PtP" issue was discussed to death about 2 years ago over on the ISP-Wireless List. It was their conclusion (and the FCC's) that if the client only talks to one AP, then it can follow the PtP rules. Mesh clients and repeaters are totally different.
The YDI Etherant II-LR has a built-in bi-directional amplifier, has an eirp of 16 watts and is FCC Certified also for PtP (and client use). There are also lots more certifications for YDI, Lucent/Agere & Cisco systems that use a 24 dBi grid and 100mW radios (or 250mW amps)for PtP client applications.
The FCC currently has an NPRM to allow AP's that use narrow sector antennas to use the same power rules as a PtP station. I would suggest that anyone who is interested in this to read the entire NPRM and submit your comments to the FCC.
[text was edited by author 2003-10-10 11:10:21] |
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DSLbyAir
Premium,MVM
join:2003-04-10
Ocean Springs, MS
 ·AT&T DSL Service
| reply to IntraLink
Well guys, I don't know about the rest of you but I've read everything in this thread about PTP eirp and I'm just as confused now more than ever. I've read every FCC link that I could find and still can't find the answer to this question. Can someone explain it to me as if I was 12 years old? I think that everyone here would just like to know the magic number eirp that can be used at the clients location.
Thanks for all the input everyone has put into this thread....
--
If you can't fit, force it, and if it breaks, it needed replaced anyway! |
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BSDish
join:2002-02-20
Lakeland, FL
| Does this make more sense?
code:
maxRadioOutput = 30dBi;
if ptp; then
maxeirp = radioOutput + 6 + 3(30 - radioOutput);
else
maxeirp = 36dBi;
|
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DSLbyAir
Premium,MVM
join:2003-04-10
Ocean Springs, MS
·AT&T DSL Service
| reply to IntraLink
BSDish, finally a simple answer to a simple question...YOU ROCK!!! That makes sense. BTW, I work for a vending company and currently dealing with a company in your neck of the woods, Protel...there web site is www dot protelinc dot com.
Again thanks for the information...Joe
--
If you can't fit, force it, and if it breaks, it needed replaced anyway! |
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hextex
Premium
join:2003-10-01
Wallace, NC
| reply to IntraLink
ikarus has explained it in very good detail and I can't understand why anyone can't understand it to start with. Let me try to break it down kitty style.
The "AP" Unit is the "Point To MultiPoint" part your wireless setup...it is going from your tower and connecting to multiple customers.
The SU(CPE,IBRIDGE...whatever your customer uses to connected to your AP) is NOT a "Point to MultiPoint" unit. It is "Point to Point"...it is going from your roof straight to your tower, not trying to connect to anything else...it is bound to that one AP.
The "AP" unit is what the FCC says cannot exceed 36dBi coming out of your antenna becuase it is covering a lot larger area then your SU.
The "SU" normally uses a panel antenna or a yagi...something with a much tighter beamwidth. This again is NOT a Point to MultiPoint unit...its Point to Point so the same rules that PTMP has to apply to do NOT apply to your "SU". The power can be much higher.
Hope this helps |
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DSLbyAir
Premium,MVM
join:2003-04-10
Ocean Springs, MS
·AT&T DSL Service
| reply to IntraLink
I know the concept of PTP and PTMP, and from installing licensed microwave sites for the last 20 years, I know the limitations on the eirp. What I didn't know was the eirp on a PTP setup in the ISM band. Thank you for clearing that up...
--
If you can't fit, force it, and if it breaks, it needed replaced anyway! |
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hextex
Premium
join:2003-10-01
Wallace, NC | reply to IntraLink
Point to Point falls under the 3 to 1 rule...so you can use over 64 watts (48dBi) if you can afford that. However you can only apply the 3 to 1 rule to 2.4ghz. 5.8 would be 16watt |
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cmaenginsb
Premium
join:2001-03-19
Palmdale, CA | reply to IntraLink
Actually your power limit in 5.8 depends on whether you are operating an ISM or UNII radio. ISM point to point allows a 1 watt emitter with no power reduction for additional antenna gain. |
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drdabbles
join:2002-06-28
Bedford, NH
| reply to IntraLink
Hello all,
Do not just think of the matter as CPE and POP. A point to point connection is created with directional antennas. A point to multipoint connection is created with omni-directional antennas. This is important, because ANY device using an omni. antenna must be considered Point to MultiPoint...even if it is a "client" device.
Additionally, I would suggest that if anybody is confused or has doubts, PLEASE read the FCC documents. They are all available for free on the FCC website. It is ALWAYS better to get the information from the source, than someone's interpretation.
Also keep in mind that anything one of us does has the potential to affect the rest of us, as the FCC could decide to clamp down on WISPs, and others using the 2.5GHz spectrum. I would be angry. :-P |
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