Re: DSP-X for AM?
> Kevin
> Your wish is my command.
> We will start with the AM mini and work up from there. I
> will try and get an alpha software version done in the next
> couple of weeks. If anyone wants to beta hardware/software
> over xmas period contact me off list.
*raises hand*
> The most time consuming thing is getting revised xover
> structure and distortion filtering right for AM. Actually
> implementing the filtering is easy peasy but what filter
> arrangements sound best, which is subjective, is the hard
> part.
Yes, and with the "brick-wall" filter, there is a trade-off between brightness, distortion/ringing, and overshoot control which needs to be fine-tuned, especially at lower frequencies (like the horribly low 4.5 kHz bandwidth that the ITU requires in Europe). Plus there is no point to having four or six bands of processing when the upper half of those bands will never be heard on the air! Thus, adjustable crossover frequencies between each band is a really nice thing to have, at least for users who are stuck with narrowband AM audio. For example, on the Omnia 5-EX, the highest band's crossover is at 4.8 kHz -- so if you're only transmitting 4.5 or 5 kHz's worth of audio, that processing band is rendered useless.
> I will try and digest the C-quam and implement it. Is there
> anyone else who wants it apart from Kevin?
As long as companies like
Harris are still manufacturing C-Quam AM Stereo equipment, then there is definitely a market for C-Quam-compatible audio processing. Companies like <a target="_blank" href=http://www.bdcast.com/products/am_trans/am_idx.html>Broadcast Electronics</a> are also building AM transmitters with built-in AM Stereo capability.
> Also, how important is a transmitter compensation (tilt)
> function nowadays?
For stations still using tube-type transmitters, it definitely is a useful feature. It isn't needed with solid-state transmitters, but there are still many tube-type transmitters in use, especially in backup service or at small-market stations.
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