External Filters Delay...??? What is it..?? How to set it..

I am running external filters on my 900 APs and I know there is some phase shifting going on with these passive filters; however, I have NOT been able to find anything regarding the “External Filters Delay” setting on the radio config tab of the AP.

Can anyone enlighten me as to what are common settings in this field…??


My best guess is it’s a delay before the network protocol filters are put into place after the SM becomes operational.

Thanks for the response.

I think the External Filter Delay has to do with the phase shifting that goes on with a passive filter. Since the moto encoding mechanism is a time division multiplexed (TDM) encoding scheme, I would think that the the filter delay is to align the signal with AP’s clock as tightly as possible. The passive filter phase shifts the signal slightly to the delay side things… I would imagine that if this shift is significant enough, you could be putting out tons of power, but have your timing off so that you have SM flapping problems and so on.

I am using the Canopy 900 integrated filters out to an external antenna.

The AP config page shows a valid range of 0 - 2000 nSec. That’s quite a bit of range. I was hoping that someone on the forum had some experience with this config param. and might be able to shed some light on the subject.