J series configuration questions

[Adam1]

Having some difficulties with maintaining sync/consistent communication between 3 remotes and an AP. These are 900mHz j series radios at pump stations At various distances. Closest one being 150 feet from AP. Other 2 are 1-2 miles away. The closest one is set to Tx @ lowest setting of 10db at 256k. Other 2 sites are set to Tx @ 30 at 256. What should ideal TX strength of the AP be? 
I think we are having some issues due to less than ideal configuration settings from what I have gathered on this forum. For example: AP- PTMP, 256k, re transmit= 3, hop interval is 100, radio retries= 10, back off time= light, radio Tx power= 27, radio trusted remotes= all 3 remotes set as trusted, Rid Eth filtering= uniarp, net conn= static. 
The 3 remotes are using laird yagi antennas AP has a FG8966 Omni base antenna. 
any suggestions are appreciated. Thank You!

[Joel_Weder]

Hi Adam, 

Sounds more like a question for our Tech Support team, but I can make a few comments:

- There's no "ideal" signal level, but as your radios are configured for 256 kbps the sensitivity is -102 dBm. Industry standard minimum fade margin is 20 dB, so that means you want all sites to hear the Access Point at better (less negative) than -82 dBm. From what you've written, it doesn't sound like signal level is an issue.

- Check the VSWR reported by each radio. This is an indication of antenna system health. Power reflected by an imperfect match between coaxial cable, connectors, surge arrestor, antenna can affect reliability. VSWR above 3:1 is bad and means something needs to be fixed. Between 2:1 and 3:1 is a cautionary level, where you might look when you get a chance. Below 2:1 is OK.

- Another common issue isn't related to the radios themselves. If any device on the network is generating too much traffic, the connected radio could be suffering a transmit buffer overflow and consequent loss of data. Make sure all devices are generating only necessary traffic, at reasonable levels for a 256 kbps system.

- Interference might be a concern. The attached simple document discusses use of the built-in spectrum analyzer tool. You could run that at the Access Point to look for any potential interference sources. If you run it at a remote, make sure to disable the AP or you'll be confused as to who's generating signals you're seeing.

- Not likely a cause of your issue, but... Most customers don't bother with the Trusted Remotes/Trusted Access Point tool, unless there's some specific concern from management about enhanced security. You'll have to remember that if any radio fails and is replaced, the new radio's serial number must be added to the Access Point.

If none of these suggestions helps, or if you need further guidance to implement them, contact our Tech Support team. To find contact info for your region, go to se.com, select Support menu, then Contact Support. Navigate to your region and you'll see appropriate contact information. They'll want to see config files for all the radios, and preferably also whatever information you've gathered. E.g. screen capture of spectrum analyzer scan after 30 sec & 2 minutes, and screen captures of diagnostic information.

[Peter_Mioni]

Hi Adam,

To Add to Joel’s comments and information you can also run in background our free Tview+ Diagnostics software on the J Series network.

Trio TView+ Software (Version V3.31.0 build183)

https://www.se.com/au/en/product-range-download/61419-trio-licensed-radios/#/software-firmware-tab

With this you can log the statistical performance of your system over time and see if there is antenna issues, fading on any path or if remote units are losing synchronisation to the AP etc.

On the AP radio configuration the

 “Data Retransmissions” should be left at “1”.

“No Acknowledge Retry Limit” can stay at “10”

Peter Mioni

Radio Technical Support Specialist

Schneider Electric

[Adam1]

Thanks for your replies. I spent several hours on this one today, spoke with tech support followed the recommendations and we are still having the same issues (with slight improvement). I used T View diagnostics, VSWR was all under 2 (1:1 on AP, 1:5 on remotes), also used spectrum analyzer via telnet,  locked out some channels, and I’m still losing sync -5-10x a minute some staying down for up to 2 minutes. One thing I did notice while watching AP summary on Telnet is that my RSSI will fluctuate between -51 to -91 in seconds, it’s very erratic jumps all over the place. Another was corrupted packets and tokens, lots of those on remotes. The most baffling part of this is that this particular segment has been stable for 3 years and  started to do this for reasons unknown. While remainder of our APs, Bridges and remotes have very reliable comms. It’s an interesting one. I will follow up with tech support tomorrow. And hope to post the culprit when it’s found! Cheers!

[Peter_Mioni]

Hi Adam,

In TView diagnostics the AP will have Rx signals going up and down from the different remote signal strengths.  Are the remote diagnostics also showing weak signals at the furthest remotes? 

In the AP you could turn on "Force Retransmissions Across Separate Hops" and still leave "Data Retransmissions" set to 1.  This might help if there is local interference on the spectrum.

If this has not helped then by lowering the over the air speed to 128 or 64kbps will give the receiver better selectivity and sensitivity.  Is the protocol Modbus or DNP3 like?

[Joel_Weder]

I'll reiterate Peter's comment that watching the RSSI in the Access Point won't be all that helpful, as it hears signals from all the other radios at different levels. Checking RSSI in the remotes is the way to go, and TView Diagnostics can help by limiting travel time. 

This sort of sounds like a new interference source may have arrived. Did you do screen captures of the spectrum analyzer scans & send to Tech Support? I wouldn't lock out channels unless you're sure those specific channels will be constantly interfered with. E.g. some devices might use a range of 10 consecutive channels constantly, so you could block those 10 in a row. But if the interference source is another frequency-hopping radio you can't use channel lock-out as they'll be using ALL the channels. That's where "Force across Separate Hops" can help as can increasing retries a bit.

Another possibility, presuming all sites are being affected, is that the AP radio has been damaged. Try swapping that radio with another that seems reliable. Or maybe all radios downstream of one repeater are having trouble, in which case you try swapping out that repeater radio.

[Adam1]

Thanks Joel.  Using t view at remote sites RSSI is -71, -59, -74. VSWR is great as well. Tried swapping out AP radio as well as remotes. Small PTMP network that has no bridges. I even tried turning off all but 1 remote and setting up as a PTP network between master and 1 remote with the best signal. It continued to behave the same as every other configuration which is flawless communication for almost exactly 5 minutes  (on startup) before it drops in and out continuously.. 

[Joel_Weder · Accepted solution]

Adam, you really should keep working with our Tech Support team on this, as they can focus more on it. But a couple more things:

- I've suggested a possible interference source that comes every few minutes. Spectrum analyzer running throughout that timeframe and longer might see something.  (send screen captures to Tech Support)

- Or more likely I'm thinking a device somewhere on the network may be intermittently generating a massive burst of traffic that bogs the system down. You need to ensure all radio filters are set to ARP & Unicast mode, but also watch each device that can generate traffic for high levels. Especially any computers. Each radio has statistics for the LAN ports you can look at, and Wireshark is an excellent tool for traffic monitoring.

[Adam1 · Accepted solution]

Problem identified. This had nothing to do with the radios themselves. In order to figure that out I physically disconnected AP from the servers network switch and was only plugged into laptop running TView and using a handheld spectrum analyzer (RF explorer). After cycling power to AP I could see the noise floor jump a bit as radio found its channel. Once it did, that noise settled, all remotes connected and surpassed the 5 minute mark where it was previously losing sync. After this AP’s Ethernet was connected to a different switch on the rack it maintained steady communications and we have not had an issue since. Quite the experience in radio troubleshooting. I learned quite a bit throughout this process and appreciate all the troubleshooting tips and explanations you guys provided. Have a nice day!

[Joel_Weder]

I'm glad to hear it's turned out well for you Adam. Good work !!

[kanyemerch61]

Regards, Joel. The RSSI using t view at distant sites is -71, -59, and -74. VSWR is also excellent. I tried replacing the AP radio and remotes. Small, without bridges, PTMP network. I even tried shutting off every remote except for the one with the best signal and setting up a PTP network between the master and that one remote. Upon startup, it behaved like every previous setup, which is flawless communication for almost exactly 5 minutes, before it started dropping in and out again.

[John_Snopek]

On behalf of Joel during his absence

Are the radios running the latest release firmware? If not, I have provided a link below:

https://www.se.com/au/en/product-range/61420-trio-licensefree-radios/#software-and-firmware

What is the nature and volume of the traffic?

Would it be possible to share your configuration file’s even the PTP configuration between the master and one remote that exhibited the issue after 5 minutes.

Also, could you share any TView diagnostics logs you may have collected during your testing.

John Snopek
Remote Operations Specialist
Schneider Electric

Please share any content with me directly on my Email rather than here on the forum.

john.snopek@se.com

[Adam1]

This issue turned out to be a problem with a switch/server and had nothing to do with our radios afterall.