Hello
I use a lot of RICs with RB 532 and RB 333 with the standard 65mw card for short p2p links etc.
Some of the shortest links have more power than they need (snr 60-70).
What is the best way to adjust this?
Is there a way to make this autoadjust, so that it uses more power in snow/rain etc, and less when it`s not needed?
When you say SNR of 60-70 do you mean you are running like -30 to -40 db rx level? If so, yes, you need to turn them WAY down… 64-72 is where you will see about the best performance with the least overdrive and you won’t run into issues with destroying sensitivity of your cards. Easiest way to go about it would be to set your TX Power tab to custom and then adjust the top two or three bitrates down until you get to levels you are comfortable with. Add 1 db per fall back rate and that should allow the radios to fall back with rain or weather issues and turn the power up to compensate. Set your highest bitrate to whatever power setting gives you a RX level around -65 and then increase power on the other bitrates by 1-2 db.
And when the CPE is that close to the AP that even the lowest power setting (5dBm, 4 will drop the unit of air in my case, rb133c) still gives too much signal at the AP I turn the CPE just a little away from the tower. That brings the signal a lot down in the AP.
rgds.
Agreed. If possible, try to aim the antenna a bit above the other. Keeps the noise down if the extra signal goes up rather than bounces around.
What about using an attenuator when the output power can’t be further reduced?
In the case of a P2P link, would it be better to place the attenuator on the sending or receiving end?
(Assuming 90% of traffic flows in one direction)
Well, both radio’s do both do sending and receiving function. On the AP though you don’t want to reduce power too much because you might loose more distant stations. The power levels in the ros will do.
So if you want you should use this device on the client end.
But is this not a bit superfluous to spend money on an extra little device to put in your antenna cable while the same could be achieved by setting the antenna a bit off line?
rgds.
The problem is that setting the receiving antenna a bit “off target” causes a higher amount of gain from the wrong direction. In order words, doing so not only reduces the signal (good) but also increases noise/interference (bad). An attenuator will only decrease the signal.
Correct, you don’t want to aim the antennas in the wrong direction. It will cause far more problems than it solves.
You could always just use smaller gain antennas… I’d do that before putting other junk into the mix.
But then I pick up more noise (because the antenna is less directional on the RX) and on the TX, send out more noise.
Is that really a problem? If your signal is so strong that you’re worried about overdriving the other side, then a tiny bit more noise is probably the least of your concerns. What do you mean by “send out more noise”? It won’t send out any more “noise” but your signal being received by someone else could be considered noise to them.
Right. I won’t literally be sending out noise, but that’s what it will be to another receiver (be it one of my own on the same tower or someone elses across the street). I think an attenuator is the only reasonable solution (or someone fixing the driver for SR/XR to allow lower output power).
I can’t see where overshooting the AP would really cause a problem. If you’re aiming high, signal goes to space. A lower gain antenna will see more noise and create more noise with reflections. I’ve got a few I’d have to cut down to dipole and I really don’t want to do that.
You could use a lower power card such as the CM9 or CM6
Yes, but that doesn’t help with the receive side. The client was running at -39 with the antenna pointed directly at the tower. We pointed it higher until it got around -50.
Well, consider that you have a more distant client antenna almost behind (like in a street) the close one. If the close one has a stong signal, while the distant one is much weaker the AP sometimes just doesn¡t ´see´ the distant one. The moment I reduced power, or pointed a bit away from the tower, of the close one, the distant one connected fine to the AP.
I’m working with RIC unit of MT so changing radio cards to weaker ones, or changing into lower dB antenna’s, is not really an option.
I just put the close CPE as low in power as possible and if the signal at the tower is still too strong I point the CPE a bit off line. That this might create more noise for other AP’s is not an issue, all AP’s work with clients at short range = high signal levels = high signal to noise level.
When I am having to hook up a real distant client to an AP that has lots of short distant client I either set up a special AP for it or this distant client has to be in a sector of the AP where not a lot of close range units are present.
Rudy
That part I understand. I was responding to jwcn saying to buy a lower powered card or lower gain antenna. I’m using Crossroads for as many CPE’s as I can, and I’ve got a few on that receive too strong with a 15dBi Rootenna.