Ubiquity link

Gotta watch those Fresnel zones!
oldradioguy
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Ubiquity link

Post by oldradioguy » Mon May 23, 2016 11:37 am

Any of you barix via Rocket guys got any suggestions for me. about a 1 mile link from a 950 4 foot dish at the transmit end and a paraflector at the receive end. A couple hundred feet of half inch line at each end probably negate any antenna gain I guess but it's a one mile shot total line of sight and I wanted to use antennas already on the towers.

Getting -66 to -68 signal. The noise floor is -104 db so still plenty of s/n. I have throttled the bandwidth down to 5 mhz and cut the max speed way down. I can do no better than 99% CCQ with airmax quality of about 70%. Showing TX/RX rate about 5 mbps.

When running the Barix boxes at 256K mp3 I get a one second or more silence about every 10-15 seconds. Running a Shoutcast server at 128K stereo into WInamp on a computer at the receive end, there is an occasional hiccup but only maybe one silence sense per hour or so...probably because of all the buffering in Shoutcast.

The viewer program shows no interference anywhere and the signal level is fairly stable on all frequencies in the band.

I see all these guys showing their 100% CCQ, but I just can't get there. Any ideas on that last little tweak, or am I just not going to get it -68 db?

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kkiddkkidd
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Re: Ubiquity link

Post by kkiddkkidd » Mon May 23, 2016 12:22 pm

Several questions:

Are there other 900mhz STL's in operation at either end?

Do you have the unused RF port terminated with 50 ohms?

Set for MCS 0 thru 7 (which supposedly equals single port)? Or edited the setup file manually to enable only 1 chain?

You might also try turning off AirMax.

I would have to think that a 950 link that short should net a lot better signal than that with the hardware described.
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oldradioguy
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Re: Ubiquity link

Post by oldradioguy » Mon May 23, 2016 12:40 pm

Thanks Kevin. Yes Chan 1 is terminated with a resistive plug. Chan0 has the little pigtail to the type N for the dish.

There is a 950 STL in the building. The antennas are a couple of feet apart at the top and the cables go up together. But the airviewer shows no interference, not that that means anything. I am currently running MCS2 showing just under 5 MHZ.

I will turn off the STL temporarily and see if that enhances anything.

oldradioguy
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Re: Ubiquity link

Post by oldradioguy » Mon May 23, 2016 12:44 pm

Actually the access point won't let me turn off Airmax. It has a greyed out check mark and I can't change it.

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kkiddkkidd
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Re: Ubiquity link

Post by kkiddkkidd » Mon May 23, 2016 12:51 pm

Hmmm... It may already be turned off since you have throttled it back via the Max TX Rate...
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oldradioguy
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Re: Ubiquity link

Post by oldradioguy » Mon May 23, 2016 1:07 pm

Turned off the 950 STL and made no difference.

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Re: Ubiquity link

Post by NECRAT » Mon May 23, 2016 4:20 pm

Do you have a single Barix at each end?
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oldradioguy
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Re: Ubiquity link

Post by oldradioguy » Mon May 23, 2016 5:28 pm

Yes, a 100 at each end> I have also tried a shoutcast stream to both Winamp and the Barix receiver. A little more forgiving, but definitely not air quality.

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Re: Ubiquity link

Post by Slab Bulkhead » Tue May 24, 2016 8:25 am

For comparison, I have a link at 5 MHz BW doing -69 dBm or so over a -102 noise floor for a 2.3 mile path using paraflectors at both ends. This one's probably got less cable loss but is diplexed with a Starlink so there's some loss in those filters.

I'm only using it for backup but it seemed like I could push a 160kbps mp3 stream through it fairly reliably.

oldradioguy
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Re: Ubiquity link

Post by oldradioguy » Tue May 24, 2016 12:33 pm

I assumed I could handle that as well. The link is more than adequate for surfing the web. I may go two hours without a dropout and then get 2 or 3 within a couple of minutes. Each time you hear a hiccup where some packets are dropped and then it disconnects for a couple of secionds then picks back up. The CCQ never goes below about 98.5 but I have yet to ever see it top 99.1 even when it's going well for a couple of hours. I've got it in WDM mode, nothing else using the link. It's very frustrating indeed.

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Re: Ubiquity link

Post by sallen » Tue May 24, 2016 1:33 pm

Are you using the Barix in the STL mode or firmware? I have two links using the Barix in STL mode and was able to reliably run PCM. But due to hardware updates one pair would do 44.1 the other 48Khz. Running MP3 was no problem. However I had the LPFM that uses the link, buy a pair of the Deva encoder Decoder to run it in place of the Barix stuck at 48khz PCM (uncompressed is so nice). The Deva seems to handle buffering better than the Barix did using the STL firmware. Also the Deva was able to switch to AAC V2 pretty quick. There is alot of latency in the audio but ACC sounds good and the bit rate of 36kbps or lower is real easy to pass.

I also have played and have a 900mkz unit. But I have opted for the Rocket radio and the 30db dish using 5ghz band. I have four links for an LPFM and use Spanning tree to keep a seperate audio and data path unless there is a radio failure then spanning tree tries to heal the bad path. I'm able to run uncompressed 44.1Khz sample rate on two links no real noticable drop outs. On a good day I only lose 2-6 frames a day.

If your able to switch to ACC try that.

Steven

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kkiddkkidd
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Re: Ubiquity link

Post by kkiddkkidd » Tue May 24, 2016 1:40 pm

I am out of logical suggestions and am suspecting some type of interference. 900mhz cordless phones, WISPS, Ham radio and a bizillion other devices share that same 26mhz bandwidth. If you have line of sight, going to 5.8 may be your best bet if it is a high priority. It only takes a few miliseconds of interference to make a Barix buffer.
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Re: Ubiquity link

Post by NECRAT » Tue May 24, 2016 5:04 pm

This may seem a little far fetched on this, but swap out the wall-wart on both Barix. One of my clients had a box that was doing some strange things for the first few weeks we had it. Barix receiver at the transmitter. Dropping randomly, buffering, etc. This was on a fixed circuit (Comcast Business) with a big pipe. Suddenly one day, in the middle of programming, it started reading out it's IP over the programming. Swapped out the wall wart with a replacement after market unit. All the issues went away.
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sallen
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Re: Ubiquity link

Post by sallen » Tue May 24, 2016 6:48 pm

Some other thoughts. Over the period of two weeks I ran several of my ubiquiti STL radio's in different modes to see where it ran best. First of all make sure your firmware is up to date. v5.6.5 is available but my radio's are on v5.6.3 and I have a mix of NSM5 5.8ghz and rocket radios with the 30db dish.

Things did work better overall with Airmax on and you get the pretty bar graph displays.

Enable installer EIRP on Advanced page. This allows you to set your power and takes it out of Auto mode which is good.
10Mhz seemed to be the sweet spot for bandwidth. I could run 20 but I would want rocket radios with the 30db dish for that. MP3 should work fine with 5mhz

Max TX rate can be adjusted but you need to remember that if you need to set it at the MCS1 or MCS0 level your already are on the edge. I have found that it is better to leave the auto mode on for this setting. I have good paths all around but have the radios set at MCS 14 and in auto mode. The radio's would bump up to MCS 15 but would, several times within ten minutes switch to MCS 14. So I set all the radio's to MCS 14 but left them in auto mode because some times they need to drop down and they do it less between MCS 14 and 13 than 15 to 14. It very rarely needs to switch lower but if it does it does not seem to upset the barix and never upset it in MP3 mode. So if you set your Max TX Rate at MCS2 and not in auto mode it may drop because it can't drop to the next lower level. Like I said this setting works better with it in auto. Whatever Max TX rate you set, it's a good rule to allow at least one or two levels it can drop and still keep the STL equipment happy.

It sounds like you are using rocket radios feeding a shared antenna system is that correct?

Steven

oldradioguy
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Re: Ubiquity link

Post by oldradioguy » Wed May 25, 2016 7:32 am

Still same issue. I don't think this is a Barix issue because it will still drop out when the Barix isn't streaming. Plus it does it with the Shoutcast server and winamp. The antennas aren't shared. This is a translator at the site where the FM was before it was moved to bigger city. Just using the old STL dishes left by the FM.

One possibility I want to explore is the 447 mhz ham repeater a few feet away. It's very inactive but if it gets keyed up every couple hours a couple of times that could explain the dropouts but not the 99% figure. Unfortunately the guy who owns the repeater is out of town and I have no way of keying it to check it out. So maybe that will provide part of the answer when he gets back.

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