Vela Navega Forum

Due to a Lowrance/Navionics bugs I have to block DBT sequence completely (leaving DPT untouched).
How should filter string look like?
According to manual it should be something like n-R-DBT but what value has to be used in place of 'n'?

Hello,

I would put 0. Meaning no skipping of filtering. So all the DBT sequences will be blocked.

Regards Luis

PS - I need to check. I am confused. Please wait for me to confirm if it is 0 or 1. Will come here later today.

Hello,

I am here to correct my previous post this morning. I was just reading the source code. So when the filtering sentence is n-R-DBT, the following happens:

- if n=0 (no matter what follows) filtering is totally ignored. The CPU will not lose any time to check the arriving sentence for filtering. The sequence is read, received and routed as per the other settings.

- if n=9 (no matter what follows) the CPU ignores that entry port. No time is taken in reading.

- if n is between 1 and 8, then filtering is ignored (n-1) times in every n times. I am sorry if my English is not clear. Say n=4. In that case filtered is ignored 3 times and checked 1 time every 4 arrivals.

Therefore if you want to reject DBT every time it appears at a given input you should use 1-R-DBT

Regards, Luis

Thanks. I will try using "1-R-DBT".

Reason for this is that Lowrance sounder sends both DBT (depth below transucer) and DPT (depth from surface).
DBT sequence should have keel/surface offset included and sum of DBT and offset should give DPT.
But it is not. Navionics Boating app shows depth alternating every second by half meter (transducer offset) which leads to conclusion that it reads both DPT and DBT but ignores transducer offset.
Or maybe Lowrance sends DBT sequence with zero offset - I did not check who is to blame.
The simplest solutions seems to be to block DBT completely - I did not need this sequence anyway.
Turning off DBT in Lowrance sounder works only until power off - settings are not remembered by Lowrance.
Bugs everywhere