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[linux-dvb] Re: DVB-T and zigzag scans question



Andrew de Quincey wrote:
With DVB-T, the zigzag scanning code chooses a step size as follows:

stepsize = fe->info->frequency_stepsize * 2;

frequency_stepsize for OFDM frontends seems to be set to 166667 usually, which means it zigzags using a stepsize of 333334.

Thing is, in my experience, frequency bending doesn't work for DVB-T either. Using a stepsize of 166667 for trying to lock on to a slightly displaced signal is way too large, let alone 333334.

My guess for the problems with the tda100045h is that it loses the lock, kicks off a zigzag scan, then never manages to tune again because the steps are so large.

Does zigzag scanning/frequency bending work for anyone with DVB-T cards? Or is it some quirk here in the UK that means it achieves nothing useful?

I notice for DVB-C cards, zigzag scanning is disabled: stepsize is hardcoded to 0.
Just add FE_CAN_RECOVER to the capabilities flags if your frontend does not needs to zigzag...

Holger



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