Hi,
Im the customer of a WISP using the Motorla Canopy system. I have a 900MHz connectorized SM unit with a directional Yagi antenna (http://i29.tinypic.com/2vvqexe.jpg). Since I have been hooked up I have had frequent drop outs to my connection (every 10-15 mins) which I have not been able to resolve. The installers have come out again and said they tried everything but they could not fix it and they won’t be able to. They claim there is interference somewhere along the path and there are no other users in my area experiencing the same issues.
Personally I have attemped to move the antenna along the roof and raise the antenna height an additional 5-6 metres with no positive effects. Is it possible that this issue can be resolved, and if not - what the problem is? Below is some information taken from the web interface of the SM.
Device type 900MHz - Multipoint - Subscriber Modem - 0a-00-3e-92-30-1c
Software Version CANOPY 7.2.9 Jul 23 2005 01:49:03 SM-DES
Software Boot Version CANOPYBOOT 3.0
FPGA Version 070605 (DES Sched)
Uptime 1d, 07:51:44
System Time 07:51:44 01/02/2001
Ethernet Interface 10Base-T Full Duplex
Subscriber Modem Stats
Session Status REGISTERED
Registered AP 0a-00-3e-90-28-df
RSSI 1259 (-79 dBm)
Jitter 2
Air Delay 291 (approximately 8.10 miles (42777 feet))
Stats for LUID: 45 Test Duration: 2 Pkt Length: 1522
Downlink RATE: 1632256 bps
Uplink RATE: 233472 bps
Downlink Efficiency: 100 Percent
Max Downlink Index: 100
Actual Downlink Index: 100
Expected Frag Count: 6376
Actual Frag Count: 6376
Uplink Efficiency: 48 Percent
Max Uplink Index: 100
Actual Uplink Index: 48
Expected Frag Count: 912
Actual Frag Count: 1871
sometimes there could be allot of noise in the path to the tower that may only be affecting you. i have seen it before.
1 guy gets great signal then right down the road someone can get anything because of noise.
interferance can affect only one customer for sure.
do you have any baby monitors, landline cordless phones?
being 8 miles away is REALLY pushing it
It could be interference or just trees or something else infringing on the LOS path. And at 8+ miles even a few trees could cause problems.
Hop up on the roof and take a look at the path back to the tower, see if there are any trees or buildings in the path.
-79db at 8+ miles 
sounds like your WISP has no standards for installs.
The uplink efficiency is definitely showing signs of something wrong. Is this link running in 1x or 2x? If the latter, dropping it to 1x might help.
My personal experience with uplink problems has either been interference or some kind of reflection. Unless there is something in the path I would guess the first scenario is more likely, especially since you’ve raised the antenna and seen no improvement.
-79 is it going to get it. Elevate the radio and antenna 25’ above your roof or above the roofline. Easiest way is to use a telescoping tv antenna mast and guy wires. Don’t try to do it by yourself.
Alternately a tree install might be in order. look for mattman’s posts on tee installs.
Jerry Richardson wrote:
Alternately a tree install might be in order. look for mattman's posts on tee installs.
We would never install a -79. Also since it shows 100% downlink and 48% uplink there is likely a problem at the AP side from interference or poor signal level. Without knowing the signal level at the AP its hard to make a good suggestion.
That looks like a 17dbi yagi. With the 8.1 mile short I do not recommend an installation in any sort of tree. At that distance + tree sway its very hard to maintain a consistent signal.
I would go with what Jerry said about height if you cannot see (with a telescope) the tower. If you can see the tower then its most likely a gain problem. I would suggest using a stacked yagi setup from M2inc.You take 2x 17yagi with a 917ISPCX2 combiner and you get about 21 db of gain. This should hopefully stabilize the connection.
The one other option is to move the setup a few hundred feet to the side of the building. This could help mitigate interference if that is the issue. I personally would start by doing this.
- Matt
I’m not sure who all manufactures 17db antennas but it actually looks to me more like a Hyperlink 13db yagi. If that is the case jumping up to a 17db would be the first step before attempting the stacking kit.
wifiguy wrote: I'm not sure who all manufactures 17db antennas but it actually looks to me more like a Hyperlink 13db yagi. If that is the case jumping up to a 17db would be the first step before attempting the stacking kit.
I just assumed by the length that it was a 17. I have never actually used any of the hyperlinktech's antennas.
It is either a Hyperlinktech or Pacwireless antenna.
The -79 on the client side is fine. The AP is probably hearing the SM at far less.
I’ve had some issues lately where the SM hears the AP at -72 but the AP only hears the SM at -80.
jwcn wrote: It is either a Hyperlinktech or Pacwireless antenna.
The -79 on the client side is fine. The AP is probably hearing the SM at far less.
I've had some issues lately where the SM hears the AP at -72 but the AP only hears the SM at -80.
we had something similar where the SM saw a -68 and the AP saw a -84
turns out the sm was just WAY off calibration
Interesting, how do you calibrate a SM?
jwcn wrote: Interesting, how do you calibrate a SM?
i dont think you can. your just stuck with how it comes
So the SM you mentioned you just replaced?
jwcn wrote: So the SM you mentioned you just replaced?
nope. had to deinstall the customer. wasnt able to get solid stats with a good radio. we dont install anything higher then -78 to many problems
we see many cases where the SM receives much less than the AP.
sometimes as much as 8 db off. as long as the noise level at the SM is much less than that of the AP (which is almost always the case) it doesn’t seem to complain…
the AP is so much higher usually it hears things…well…everywhere
i have also wondered what causes this - but it sounds like i’m seeing the opposite of what ya’ll see?
Correct, that has been my experience. The AP (Omni) usually hears the SM better than the SM hears the AP. In this case it is the opposite. The only difference is this is a repeater on top of someone’s house instead of a tower…
Thanks for all your feedback people - much appreciated!
Most of the comments make sense and unfortunately Im not in a position to find out any sort of information from the AP.
An interesting point to make is that the WISP have told me they installed a higher gain Yagi (which would make sense as they replaced a 5 element with a 15 element) however my RSSI is less than before, it was average -78dBm with the smaller Yagi, now receiving -80dBm however with slightly less dropouts. Im a bit weary of the quality of the antenna they have replaced.
I have tried to shift the position of the antenna all over our roof however the results are consistent with the original install that the best RSSI and jitter is obtained from the present location.
I’m in the process of obtaining a 17dBi Yagi as my next move. Any recommendations for quality antennas for use with the Canopy system?
i dont know if a 17 db yagi is a relevant solution. we use some for a time and were always out performed by there 13db brothers. maybe its because the 17s we used were two piece and had to be assembled. dunno. but we dont use them any more.
We’ve had a few installs that could only be made with 17dBi yagi’s…