Hello
I have a NLOS link utilizing the 450 900MHz PTP gear running 14.1.1
Currently using the Cambium 12dBi yagi antennas.
Due to obstructions the signal strength is very weak.
-82.0 dBm ( -85.0 dBm B / -85.0 dBm A )
After running LINKPlanner it would appear that two things would help.
1. More Height - I am maxed out at the SM side and can raise the AP only 10’ more.
2. Higher Gain Yagi - Cambium only has 12dBi yagis. Another company makes a 17.5 dBi yagi.
I have contacted that company as well as two of their resellers and have been told that they only sell in packs of five.
Questions
1. Is anyone using the higher gain yagis?
2. If so what improvement are you seeing?
3. Does anyone have 1 or 2 to sell?
Thanks for your time.
Have a great day.
We have recently stated using the long yagis from KPP. I haven't personally installed any, but today is the day. 2 upgrades planned. I'll let you know how they go.
Thanks for the fast reply.
If you have any before and after data that would be great.
Also if you have a couple for sale please let me know.
I'll let you know this afternoon.
For sale, absolutely. But, we're in Canada, so shipping may be more than you want to pay. haha
Hello,
I have recently swapped two 12db yagi antennas to the 17.5db from KPP. Both were around -79 to -81 with a link test of 6 down and 1 up at 8x/1x and after the swap they were -72 to -74 and link test of 16 down and 2 up at 8x/2x. That site has 2 60 degree sectors running 10Mhz channels. I am not a fan of how they have to be assembled but they do what they will be at least 5 to 7db better than the Cambium ones.
What size channel width are you running? The lower the channel width, the better your link SnR wll be... of course at the expense of bandwidth :-)
Hi David.
Great to hear the signal improvement.
What sort of obstructions are you dealing with?
You didn’t mention the radio you are using. Are you using the dual slant 17.5 on a 450 900MHz SM or are you using a single polarity 17.5 on a different radio?
How difficult was it aiming and did you find it difficult to install?
Thanks for the information.
@LostInTheTrees wrote:
Hi David.
You didn't mention the radio you are using. Are you using the dual slant 17.5 on a 450 900MHz SM or are you using a single polarity 17.5 on a different radio?
He's using a PMP450 radio, and he's using the new dual polarity, dual-slant KP performance antennas.
Hi Eric
I started at 5MHz Channel Width & 2.5 ms frame period the receive signal was fairly close to what it is now.
My best results have come from enableing pager filtering, moved to 10MHz Channel Width & 5 ms frame period.
From my experience with this link going back to 5MHz I do not see it improving the robustness of the link and it would as you said cut the throughput significantly.
Noise floor is very quiet around here with the exception of a repeater way up on the other end of the spectrum and a smart meter that goes off a little after 9 am.
Hi
Would love to be up your way and out of this heat.
Shipping would be a little much I am sure but the way it is looking I may need to take you up on it.
Look forward to hearing your results.
Can you post screen shots of the SA on both sides? I have a completely non-LOS link, at just under 1.5 miles, and the noise floor is horrific. In all my testing, I found that turning the paging filter on did more harm then good.
You can see my post here.
Eric
Sent you a PM
Below are Spectrum Analysis via the onboard tools for both the AP and the SM.
The analysis were run for 1 minute each. I have run them longer in the past with results being similar.
This one is for the SM
This one is for the AP
A few other screen grabs from the SM and the AP
SM first
AP Screen Grabs
Wow, the noise floor appears to be incredibly low for 900MHz, the distance is pretty short too at just over 3 miles. Are you shooting through a huge, dense forest of trees? ALSO, just noticed this, but your slave is showing a huge mismatch in SnR on the chains... 21 on B and 7 on A. This is unusual.
I can only dream of noise floors that low. Ours are generally around -70 to -80. So much oil and gas SCADA using 900 MHz gear - Freewaves, Microhards, TransNets, etc. I was super excited for this new PM450i 900 MHz equipment, but it's ability to handle this interference is less than the FSK radios was - with the FSK radios, we could stay registered at or around the noise floor, even if it was with only a few hundred kbps each way. With the new stuff, we need 10+ dB above the noise floor to stay registered. Super frustrating to try to do direct "upgrades" when we can't keep them registered. Many places we end up leaving in place what they had originally and saying "sorry, we'll try something else".
Sorry, got a bit off topic there.
@acherman wrote:With the new stuff, we need 10+ dB above the noise floor to stay registered. Super frustrating to try to do direct "upgrades" when we can't keep them registered. Many places we end up leaving in place what they had originally and saying "sorry, we'll try something else".
Sorry, got a bit off topic there.
I've heard this complaint from a number of WISP's, and once you start investigating, I've typically found that they had the power cranked up (FSK radios allow the user to specify a higher TX power then the 450i), and they were using 17dBi yagi's... so basically way over the EIRP. We've done tests in extremely noisy urban environments, and assuming you're using the legal EIRP on the FSK system, we've found that the 450i beats it every time.
We are staying within the legal EIRP limits. And that's what hurts. I can't say that the instrumentation guys that do some of the gas and oilfield stuff in this area are doing the same. They think that license free stuff gives them the right to do whatever they want. We are one of the only companies in the area with tower crews, so we see a lot of silly stuff they have done and we have to fix afterward.
The path is 3.12 miles via Google Earth.
The path elevation is fairly even.
The mid portion of the path is obstructed by 1.2 miles or is it 1.4 miles of trees with estimated average height of 55 feet.
Regarding the A & B chain I have a few questions.
1. Is this referring to horizontal and vertical?
2. Which is horizontal and which is vertical?
3. On the radio looking from the back side or from the top which RF port is A chain and which is B chain?
Forgive the newbie questions but could not locate in the user guide.
Regarding the difference in SnR what could cause that?
@acherman wrote:I can only dream of noise floors that low. ...
...Sorry, got a bit off topic there.
Be careful what you dream of. A noise floor this low comes at price. : (
Now that's off topic. : )
Getting back on topic.
Did you have a chance to install the KPP 17.5 ds yagis? If so what improvement did you see?
@LostInTheTrees wrote:
Regarding the A & B chain I have a few questions.
1. Is this referring to horizontal and vertical?
2. Which is horizontal and which is vertical?
3. On the radio looking from the back side or from the top which RF port is A chain and which is B chain?
Forgive the newbie questions but could not locate in the user guide.
Regarding the difference in SnR what could cause that?
1. There is no H or V chain, it's +-45 dual-slant
2. Unfortunatly there are no labels as to which port is which
3. Unless a Cambium employee can chime in and tell us which one is which, the easiest way to check is to just disconnnect one of the chains briefly and watch the radios GUI for changes.
There are multiple possibilities for the chain SnR difference, could be a loose RF connector, a bad RF cable, bad antenna, bad radio port, or lots of interference on just one of the polarities.