Carrier 42 HQX Manual de usuario descargar pdf (Pagina 39)

The image above is a portion of the main configuration screen and you can see that my

sound card is exhibiting a sample rate error of 1.0006 for the input and .9997 for the output.

Those figures seem reasonably common and do not represent large errors, but should be

corrected (as they are since Enable Automatic RX/TX Sample Rate Correction is enabled).

When JT65-HF first begins you will notice, if you have the configuration screen open, that

both sample rate indicators will undergo a substantial and reasonably quick change until the

figures settle on stable values. This is normal as the overall sample rate figures are an

average. If after 5 minutes the values continue to show large changes then you most likely

have a problem. You will normally see (taking the numbers shown above) some small

fluctuations say from 1.003 to 1.009 for the RX and this is not a problem, but, if you saw the

SR numbers moving from .990 to 1.380 and never settle that is a problem.

Unfortunately some sound devices simply can not provide a stable 11025 sample rate and

there is little to nothing I can do to address this. In the case where you have unstable figures

I would suggest that you make sure your sound device driver is the most recent version from

the manufacturer of your sound card (or computer/motherboard for integrated sound devices)

as some of the default drives supplied by Microsoft have been shown to be suboptimal. If

after exhausting this option you still have an erratic SR indication you should not use JT65-

HF and consider purchasing a different sound device. Running JT65-HF with a sound device

that is erratic will lead to nothing but problems both for your decoding of signals and for those

attempting to decode yours.

While I have no specific suggestions I have seen USB sound devices for under $20 that offer

good performance and stable SR figures.

I will likely add code to versions beginning at 1.0.8 to warn of unstable sample rate errors and, in extreme

conditions, disable TX with very bad hardware.

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Carrier 42 HQX Manual de usuario Pagina 39