[Imported] New to Radios - RSSI Help!


[Imported] New to Radios - RSSI Help!

>>Message imported from previous forum - Category:Trio Data Radios<<
User: joelw, originally posted: 2018-10-17 18:32:51 Id:73
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.


Hi there, new user to this site as well as radio use. Can you help me please with some general, basic questions?
We are trying out using radios to eliminate some leased lines in our system. Currently running Bell 202 modems direct to each site. We want to install a master radio (J-Type) at one station (a booster station for water) and the two wells that supply it with remotes. The radios and antennae have been installed. (Omni at the master, a panel mount omni at one slave and a yagi at the other). Everything is being done in house, no studies or training has been provided to us on how it would/should all work.
Just starting to power things up, and after the basic configuration I am showing a RSSI at the master of -70.4dB, Remote 1 RSSI -56.3dB and Remote 2 RSSI of -63.5dB. Now to the questions:
1) The only number I see as a 'guideline' for a good RSSI is 90dB is about 2.5 V from the quickstart manual. Are my numbers better or worse with respect to radio systems? ie: is -120dB better or is -20dB better?
2) Once configured and good signals are confirmed, the radios are essentially being used as modems, correct? The master station will have an e-net link from the 357 to a switch, then to the radio, the slaves are both SCADAPacks with serial connection to the radios. Are there any programming examples out there that can be used to help guide me along? Any comments would be greatly appreciated.


Hi Mike,

You haven't noted the radio data rate you've configured your J Series radios to operate at. If the default 256 kbps the radio's sensitivity spec is -102 dBm. (for 1x10-6 Bit Error Rate) Or if you're using the optional fast speed of 512 kbps the sensitivity is -92 dBm. Your radios are replacing a 1200 baud system so I'd presume you went with the slower speed.

We always design a system for a fade margin of at least 20 dB on all paths to the Access Point. For the 256 kbps speed this would be -82 dBm or better (less negative -towards zero- is better) while for the 512 kbps speed this would be -72 dBm or better.

Fade margin is a term used to describe receive signal strength over and above the bare minimum needed. It ensures the radio will keep working even if there are hardware faults (eg bad antenna or cable) or new sources of degredation (eg trees growing in the path) that might reduce the receive level. Also it can help keep a path reliable if noise or interference from another radio system exists.

The table in the user manual comparing voltage and RSSI is only approximate. The voltmeter measurement technique is really only good for aiming your remote site yagi antennas. Rotate it a bit then take a reading. Rotate again and take another reading. Look for the strongest voltage. If you want a more exact value you can log on to the radio and go to the Diagnostics Summary page.

The RSSI value reported in the Access Point will be for the last-heard remote. You won't know which that is, so it's not very useful. But an RSSI taken in a Remote will show the strength of the signal from its Access Point.

The RSSI values you've reported are good for either a 256 kbps or 512 kbps system. No worries there. Yes the radios do act as modems, just wireless ones.

I think you're asking for programming examples for the SCADAPack to perform polling. That's outside my realm but please do contact Tech Support for assistance with this. Their phone number is 1-888-226-6876. Or you can email them at SupportTRSS[at]schneider-electric.com


I am new to radios and am currently configuring a SCADAWave 5907 and I just got the Trio TView+ software but I can't figure out what series this model is?


You have a Freewave radio which is attached toa 5907 adapter board to power up the radio. You can use hyper terminal or EZ config to configure the freewave radio.