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Scanning failure for ATSC channels using Happauge 950Q


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Hello all,


I am a newbie to DVBViewer and TransEdit. I am trying to scan local off-the-air ATSC channels (Wakefield, Quebec, Canada) on my Happauge 950Q tuner using either the DVBViewer demo scanner or TransEdit, but no channels whatsoever are being found. I am using the provided ATSC_America list of transponders.


My Happauge tuner is working OK with Win-TV: some 20 different stations are being found.


Guidance or suggestions would be greatly appreciated.



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I am using the provided ATSC_America list of transponders.


Try to shift the frequencies up by 1.75 MHz in TransEdit: Select a frequency on the right side -> change the frequency (e.g. 533 to 534.75 MHz) -> click apply -> try to scan,


1.75 MHz is the difference between the NTSC video carrier frequency and digital center frequency, and it is unknown how it is handled by the Hauppauge driver. For ATSC / Clear QAM the Windows BDA system uses the NTSC video carrier frequency, so many ATSC device drivers convert it into the digital center frequency needed by the hardware by adding 1.75 MHz. However, the ATSC transponder list shipped with DVBViewer contains digital center frequencies, so TransEdit / DVBViewer subtract 1.75 MHz from the frequencies before passing them to the driver in order to compensate for the subsequent addition - may be wrong in this case (?).

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Thanks a lot for your input, Griga!


I tried adding 1.75MHz to all ATSC frequencies as you suggested, but unfortunately that did not help: I am still unable to get any station whatsoever.


Can you think of any other possible fix?


Thanks again,



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