You can try the parameter ''Air Delay'' from the SNMP with the OID .1.3.6.1.4.1.161.19.3.1.4.1.24 this feature displays the distance of the SM/BHS from the AP/BHM.

This can also be found in the radio GUI under Home >> Session Status >> Session

Here is what I did to convert and find the link distance on the Canopy PMP100 series. I suspect that it may be the same for the PTP450. I was really just searching and hunting through the forums for a clue on how to do this. Didn't find anything close however. So I did some digging further and unfortunately had to put on my 'thinking cap' for what we have at hand.

We use Mikrotik Dude to monitor and display information for the Canopy PMP100 series since it does SNMP v2c. So I'll give you the complete formula here in Dude format/syntax and then briefly explain how I arrived at the formula.

m.whispSmStatus.airDelay.0")*147.4453125)/5280),0,5)," mi")" <---use everything inside the outer quotes

Here is I derived at that formula (function in Dude). So I take the SNMP value for airDelay which is in units. The SNMP OID for Air Delay is "1.3.6.1.4.1.161.19.3.2.2.4.0" (remember this is for the PMP100 series). Then I found that multiplying by 147.4453125 converts it to a distance (feet) and finally, dividing by 5280 converts it to miles. You will notice on the GUI it shows the AirDelay along with miles and in brackets feet. That is how I derived the formula and confirmed my results.

The picture above shows how I display the results in Mikrotik Dude (using Appearance).