We have a wide area network of Mikrotik RB411 and RB433 with Ubiquiti SR5 radio cards. We are monitoring the RF signal levels with an external SCADA package and Mikrotik MIB that interrogates and records the RF signal levels over time. The idea being to alarm when the signal level drops beyone a threshold level to indicate a failing link.
The links are performing well with good throughput and CCQ’s but the SNMP interrogated RF levels vary considerably when interrogated with SNMP. I am asurprised at the number of RF alarms we generate due to low signal strength. These are fleeting and very short duration, the next poll clears the alarm. Am seeing this across all our links, for example 9km link, 40 dB fade margin, rural, good LOS, no interfering signals. Links are simple point to point bridges configured in the 5.8GHz band with 10MHz channel bandwidths. Getting up to 16 dB fades.
How is the sampling done to determine sig level within the Mikrotik OS, is there any averaging and can this sampling rate be configured.
We can adjust SCADA with a delay to filter the fleeting variation in reported signal strength thereby removing the alarms but this is not preferred.
This may of course just be atmospheric effects but any insight into the RF Monitor or suggestions appreciated.
What sort of RF stability are others seeing with similar configurations.
Example
Date Time Signal Fade
16/10/2011 20:21:18 -69.00 -14 Signal Strength LO
16/10/2011 20:21:38 -55.00 0 Signal Strength OK
19/10/2011 19:49:54 -66.00 -11 Signal Strength LO
19/10/2011 19:50:14 -55.00 0 Signal Strength OK
22/10/2011 06:38:46 -68.00 -13 Signal Strength LO
22/10/2011 06:39:06 -55.00 0 Signal Strength OK
24/10/2011 02:21:27 -67.00 -12 Signal Strength LO
24/10/2011 02:21:47 -54.00 1 Signal Strength OK
25/10/2011 05:33:47 -67.00 -12 Signal Strength LO
25/10/2011 05:34:07 -56.00 -1 Signal Strength OK
5/11/2011 20:25:14 -68.00 -13 Signal Strength LO
5/11/2011 20:25:34 -55.00 0 Signal Strength OK
6/11/2011 13:26:15 -57.00 -2 Signal Strength OK
6/11/2011 13:25:55 -71.00 -16 Signal Strength LO