Filter width on DSP radios


Gary Kinsman
 

Hello all,

I noticed that on my PL-380, I can detune up to one filter width and still get good sound quality. For example, if I'm listening to 1070 kHz with the 2 kHz filter, I can tune as low as 1068 kHz or as high as 1072 kHz.

In the past, I've always used the rule that you can detune up to one half the filter width. This is how is works with my Satellit 800 and Icom R75 for example. With the 4 kHz filter selected on the Sat 800, I can detune by 2 kHz.

This leads me to believe that on the Tecsun DSP radios, the specified filter width is half as wide as it is on my other radios. For example, the 2 kHz DSP filter is equivalent to a 4 kHz filter on my other radios.

On most of my radios the filter width is specified using both sidebands; on the DSP radio it appears to be specified using just one sideband. I always thought the former was the standard way of measuring filters. Is this not the case?

Regards,
Gary

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