HFU HF Underground
Technical Topics => Part 15 AM and FM Station Operation => Topic started by: ThaDood on May 14, 2024, 1823 UTC
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https://www.schlockwood.com/ Look under Products for the audio processor and AM Monitor. Then, check out under Projects.
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We actually use the audio processor in our studio and it really makes a big difference in audio quality.
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The Phase Buster project looks pretty cool.
(https://previews.dropbox.com/p/thumb/ACX9XqDfu8d1AD33hKYkBnuGBvTHUav083jDg7Tc8uB-9iopfWjq7ens3WbVCZ2DRh_FUoCo0268T4ArbgW546wlQvG8Fx7ajHF2_FyoE_fQA7C49DPKimdhyp4eNBSnvA-4jo8jNgKkkkJxKNI-rZwlnpfzSDbYMHBeXRR2gktSqtNpJNho2CnlZm-Rj4XuY5tR5ucuUcjRvPcvfEJOtT9jjxJfxLKFQ8wY-0pg5svyEF0m5_rb3ZKQYFmTJiuIoucBm-Fx7KmNxU-2eTe25k9a8L22tJS7neUbFDoaNmS5G-6pAD_-THj1wa9XJl6hVTUnLY-Ck1aOBxSywe5yui2V/p.png?is_prewarmed=true)
"PROJECT GOALS
1. To create a monaural mix from stereo
without losing audible components that
end-up out of phase, either accidentally or
by design.
2. To process a stereo program for better
mono compatibility; that is, a program
that will sum to L+R mono without pro-
gram component loss.
3. To create a pseudo-stereo program from a
monaural source.
4. To ‘spatialize’ a stereo source, increasing
the apparent soundstage width.
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Just a quick FYI. Note similar phasing configurations can be accomplished with StereoTool as well; including the free version. :)
Check the Stereo Image config for the Image phase amplifier and Image width amplifier settings.
https://www.thimeo.com/documentation/stereo.html
0 is VERY useful for converting to MONO, the resulting sound can be downmixed to mono without any distortion or loss of sounds, which occur in normal stereo to mono conversion. This creates a much fuller and undistorted mono sound. Note that "0" does not mean that the output signal is mono, because the instrument locations are not affected by the phase slider. To get mono sound, also set Image width amplifier to 0.
The Azimuth correction and Single instrument phase errors features might be of related interest, too.
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Check the Stereo Image config for the Image phase amplifier and Image width amplifier settings.
https://www.thimeo.com/documentation/stereo.html
0 is VERY useful for converting to MONO, the resulting sound can be downmixed to mono without any distortion or loss of sounds, which occur in normal stereo to mono conversion. This creates a much fuller and undistorted mono sound. Note that "0" does not mean that the output signal is mono, because the instrument locations are not affected by the phase slider. To get mono sound, also set Image width amplifier to 0.
However, they follow that, that paragraph with a warning which they emphasize in red print:
"This filter creates artifacts, mainly for values above 1.00. When playing compressed audio, especially lower (< 192 kbit/s) bandwidth MP3 files, setting phase to a high value will also very strongly amplify the already present MP3 encoding artifacts, which results in a very poor sound quality."
Regardless if Stereo Tool or the hardware version is used, I suppose the same issue applies.
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Note that is for values above 1 trying to add phase and/or width. ;)
Set phase to 0 and leave width at 1 (or perhaps slightly lower) to "fuller" sounding mono alongside stereo.
Set both phase and width to 0 for complete stereo to mono conversion, which works quite nicely in my experience.
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I was lucky enough to be an early adopter of the Schlockwood SW200 LPAM Broadcast Processor, owning serial #002, from the first production run. It's a great little processor. The manual does a very effective job of explaining how it works, as well as how to set it up and adjust it, for folk like me who hadn't used a broadcast processor before. I consider it to be something of a classic, and will never sell mine.
The SW300 is now beginning to look mighty tempting. It would be great to be able to read the modulation depth of my station, as well as being able to take it portable and get a reasonably accurate reading of the field strength at various points in the coverage area. It might seem a bit pricey - and for most of us Part 15'ers, it's not a minor budget item by any means. However, considering that a really accurate field strength meter, such as the Potomac, costs thousands of dollars, the price of the SW300 looks very attractive. Plus, Jim Wood is a really good guy.
I think I'm trying to talk myself into buying the SW300. My wallet is getting nervous......... ;D
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At antiqueradios.com forum a couple of years ago, someone was considering purchasing the REA Modulation Monitor ($234.95), but he was having difficulty measuring the waveform because it didnt properly display overmodulation or distortion.
I suggested he give the SW300 a look (I didnt realize it cost $790).
He responded:
That one does more than the other one and it's just one box and antenna versus the other which requires two boxes and a PC and doesn't do as much.
At the time Schockwood was offering a pre-production models for half price, s0 he bought one.. He said he was "well 0leased with it" however, went on to say "Now had the one I got been full price I would have gone with the REA".. And then later went on to Express "The modulation monitor just proved its usefulness....."
https://antiqueradios.com/forums/viewtopic.php?p=3584601#p3584601
I
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That's an interesting thread Rich. Thanks for that. At half the current price, I'd consider the SW300 to be a no-brainer and jump on it. I'm not questioning it's value at ~$790. It's just that for me, it takes quite a lot to justify spending that kind of money all in one go, on a hobby. If I continue to want it badly enough though, I suspect that I will get there! There's an extra advantage for me, being a licensed amateur, in that it also works on the 160M amateur band.
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A bit off-topic, but with you being a licensed ham and a tinker, maybe this curiosity I came across last night might interest you:
https://www.notebookcheck.net/New-open-source-project-transforms-Android-phones-into-ham-radio-transceivers.902140.0.html
It's a android phone hack transmitter that cost $35 to build that can broadcast text and voice long distances. It does require a license to transmit with it though.
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A bit off-topic, but with you being a licensed ham and a tinker, maybe this curiosity I came across last night might interest you:
https://www.notebookcheck.net/New-open-source-project-transforms-Android-phones-into-ham-radio-transceivers.902140.0.html
It's a android phone hack transmitter that cost $35 to build that can broadcast text and voice long distances. It does require a license to transmit with it though.
I saw that somewhere else tybee. I'm mainly an HF (and CW) kind of a guy, so it's of limited interest to me.
By the way, back on the subject of Schlockwood Labs, I just took delivery of an SW300 AM Field Strength and Modulation Monitor. I stumbled across a very reasonable deal on one and couldn't turn it down. I've had it for a week now, and it's great. I appreciate the ability to hear what my AM signal really sounds like on a wide open receiver. It has much better fidelity than I realized - it almost sounds like an FM signal. The SW300 also has the ability to switch in various degrees of audio cut-off, to get an idea of what your signal sounds like on different AM receivers. Monitoring the licensed signals in my local market was quite educational too. A couple of the stations were pushing their positive peaks way, way beyond the 125% that is allowed to licensed stations by the FCC. Interesting........! A couple of other stations seemed to be under-modulating a bit.
It's good to know that my little Part 15 station is behaving well. Quite frankly, with the combination of an SW200 feeding a Rangemaster, and an SW300 to keep the whole operation in check, I feel like a very lucky Part 15 op indeed!
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You are, but you earned it.
You know I wouldn't even know what to do with a modulation monitor, I'm that tech unsavory. Though I didnt use to be, I had quite the aptitude when I was 20, could read and diagnose the potential problems using only a schematic on trainer jets. By far the top of my class in tech school (USAF). But after that short stint in the service I never really delved into electrical circuitry again. Cant even remember what a diode does.. but I knew it inside out when I was a kid. Guess it's true that if you dont use it you lose it.
But damn on e upon a time I was obsessed with it, and talented.
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By the way, for the life of me I don't know what the hell influenced me to call myself "Tybee" here. I've never used that handle anywhere else before. I've been going by End80 online for about 25 years, either that or simply Rich.
It felt so weird when you called me Tybee in the last post! What ever got into me to do that? I wonder if I can change it without having to re-register.
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I think of you as Rich, and secondly as End80. I was going to call you Rich, but wanted to make sure it was OK to do so first!
And yes, use it or lose it is definitely a thing. I used to be a lot better at solving math problems in my head, but I tend to reach for the calculator for even simple calculations these days. I'm turning into an underachiever in my latter years!