361
QSLs Received / Re: Radio Illuminati 08 Dec 2019 Broadcast eQSL
« on: December 12, 2019, 0309 UTC »
Got one too. Thanks AC!
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Shortwave Pirate Radio In North America And Around The World, And Other Signals That Go Bump In The Night
We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations.
Always consult with the appropriate authorities if you have questions concerning what is permissible in your locale.
Its not usually that simple. Any digital mode requires a reasonably flat group delay response across the occupied bandwidth. older AM directional systems often had very poor bandwidth and need a complete overhaul to pass the digital signals of ANY type. We first started learning about group delay problems in existing arrays during the AM stereo rollout of the early 80's. HD/DRM is best implemented on simple, non-directional antenna systems.
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It always has been. The music industry is a headless laviathan, and this new ruling probably means that a lot of small operators are going to have to shut down. Everyone else will just make their streaming servers private and remove them from any public directory services like shoutcast or dir.xiph.org. In an era where the only version of a song you can buy is a watermarked MP3, it serves the music industry right to sink with their own ship. Piracy is going to come back with a vengeance.
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362
General Radio Discussion / Re: HD FM Audio Drives Me Nuts
« on: December 11, 2019, 0924 UTC »
Yes. The main HD channel is encoded with the same PPM data and passes through the same enhancement (voltair) chain in most cases.
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363
General Radio Discussion / Re: HD FM Audio Drives Me Nuts
« on: December 11, 2019, 0219 UTC »
If what your hearing exists only in the digital portion, then it is most likely a codec issue. It could also be caused by sample rate conversion happening somewhere in the airchain.
PPM encoding happens mostly in the midrange frequencies, from about 1.5-4 KHz. The exact mechanism is a trade secret.
Usually that decision is made farther up the chain either in the management or programming end. Engineering has little to do with it, outside of implementation. Further, the majority of HD installations these days are being done to support feeding translators.
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PPM encoding happens mostly in the midrange frequencies, from about 1.5-4 KHz. The exact mechanism is a trade secret.
Quote
am glad to see its not just me. I find it appalling that any broadcast engineer would accept such degradation in audio.
Have they not heard good audio??
Usually that decision is made farther up the chain either in the management or programming end. Engineering has little to do with it, outside of implementation. Further, the majority of HD installations these days are being done to support feeding translators.
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364
North American Shortwave Pirate / Re: Unid 4065 AM 2337 UTC 10 Dec 2019
« on: December 10, 2019, 2340 UTC »
12/10/2019 4065 KHz AM 2337z First noticed with B52's 'Channel Z' About S9 on peaks, but very high noise floor here.
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365
Huh? / Re: ACLU reads holiday greets
« on: December 10, 2019, 2126 UTC »
Amusing in many ways 
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366
General Radio Discussion / Re: HD FM Audio Drives Me Nuts
« on: December 10, 2019, 2115 UTC »
The HD and analog paths are processed very differently. Any lossy codec as a rule does not like clipped audio, as it contains more harmonic energy that it must process, with varying success. Instead, look-ahead limiting is used, but as a consequence, produces some intermodulation distortion. The analog path is processed conventionally. The codec for HD also makes use of spectral band replication, which can cause all sorts of wierd artifacts on its own. It all depends on what data rate the station has set their importer/exporter up for, and this is largely determined by how many HD sub channels they have.
There is a long standing theory that American DAB (HD) has a self-noising property. Some more detail can be found here http://ham-radio.com/k6sti/hdrsn.htm
Also within the last few years, the Arbitron PPM system has been toyed with by several manufacturers in an attempt to boost the host stations' ratings. They do this by making the PPM signal louder, and in many cases unmasking the tones. It seems to be most noticeable on dry voice, and makes the announcer sound as if they are in a broom closet, or talking through a paper towel tube. The device responsible for this is made by Telos, called the voltair. https://www.telosalliance.com/25-Seven/Voltair
It's a race to the bottom. The voltairs running on large corporate stations here have made the stations unlistenable for me. My favorite station here switched on HD about 18 months ago, and I immediately noticed their audio quality drop. Everything got sort of fuzzy sounding.
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There is a long standing theory that American DAB (HD) has a self-noising property. Some more detail can be found here http://ham-radio.com/k6sti/hdrsn.htm
Also within the last few years, the Arbitron PPM system has been toyed with by several manufacturers in an attempt to boost the host stations' ratings. They do this by making the PPM signal louder, and in many cases unmasking the tones. It seems to be most noticeable on dry voice, and makes the announcer sound as if they are in a broom closet, or talking through a paper towel tube. The device responsible for this is made by Telos, called the voltair. https://www.telosalliance.com/25-Seven/Voltair
It's a race to the bottom. The voltairs running on large corporate stations here have made the stations unlistenable for me. My favorite station here switched on HD about 18 months ago, and I immediately noticed their audio quality drop. Everything got sort of fuzzy sounding.
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367
The RF Workbench / High level SSB transmitter; and old dream come true.
« on: December 10, 2019, 0459 UTC »
Some guys finally figured out how to do this with modern parts. They claim 80+% efficiency @ 500W PEP out, 160-10 meters.
https://www.polex-tech.com/
A white paper covering the fundamentals of operation is here
www.arrl.org/files/file/QEX_Next_Issue/Mar-Apr2017/MBF.pdf
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https://www.polex-tech.com/
A white paper covering the fundamentals of operation is here
www.arrl.org/files/file/QEX_Next_Issue/Mar-Apr2017/MBF.pdf
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368
The RF Workbench / Re: AD9833_SPI
« on: December 08, 2019, 2314 UTC »
I hate programming as well, but have warmed up to the Arduino IDE. I like it much more than the PIC stuff we had in college a decade ago. The AVR's seem to be more robust as well. I've had a number of PIC devices randomly fail over the years, yet only one of the AVR's...who knows.
As far as the AD9833, I suspect cost was a determining factor, not performance.
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As far as the AD9833, I suspect cost was a determining factor, not performance.
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369
Bacon, BBQ, Beef, And More / Re: Kielbasa
« on: December 06, 2019, 0102 UTC »
Gentlemen, please stop...your making me hungry. Hungry enough to brave traffic and empty the bank account at the local shrine to all things Polish.
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370
General Radio Discussion / Re: FCC approves all digital AM
« on: December 04, 2019, 2002 UTC »...in fact, I drove by a station I used to engineer not long ago, and ALL THREE 367' towers had not a single working beacon, and only the middle tower had the 75' obstruction lamps lit... nothing above those were lit, and it's in the direct approach to the airport! In fact, it's listed on the FAA maps as a LANDMARK for VFR. How does Cumulus get away with this crap? And that is only ONE of their tower lighting issues in this market.
I'm all for minding my own business, but that is a life safety issue. Call the FAA.
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371
General Radio Discussion / Re: FCC approves all digital AM
« on: December 03, 2019, 1956 UTC »
New adaptive precorrection can deal with minor problems to some degree, but large equalization shifts require more transmitter headroom which may not be available depending on required TPO and transmitter rating. Also keep in mind with directionals especially, the radiated response in the nulls may be cause loss of receive due to group delay and amplitude response issues. In the analog days, the nulls may just sound funny, but still be listenable.
A friend of mine used to care for a 3 tower array built in the late 40's. The transmission line to the towers was open wire coax (5 wire). The array was so narrow, they had to cut the audio down to 6 KHz to keep the new transmitter from tripping off on VSWR. The array has since been overhauled with new transmission line and ATU's.
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A friend of mine used to care for a 3 tower array built in the late 40's. The transmission line to the towers was open wire coax (5 wire). The array was so narrow, they had to cut the audio down to 6 KHz to keep the new transmitter from tripping off on VSWR. The array has since been overhauled with new transmission line and ATU's.
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372
General Radio Discussion / Re: FCC approves all digital AM
« on: December 03, 2019, 0338 UTC »Take a cue from India and China. The car radios already exist:
https://www.radioworld.com/news-and-business/india-drm-receivers-find-place-in-cars
DRM30 works with existing feedline and antennas, and with relatively modern existing transmitters, so no need to retool the entire RF chain.
Its not usually that simple. Any digital mode requires a reasonably flat group delay response across the occupied bandwidth. older AM directional systems often had very poor bandwidth and need a complete overhaul to pass the digital signals of ANY type. We first started learning about group delay problems in existing arrays during the AM stereo rollout of the early 80's. HD/DRM is best implemented on simple, non-directional antenna systems.
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373
The RF Workbench / Re: A 25W experimental transmitter for medium wave (AM)
« on: December 02, 2019, 0706 UTC »
Work continues on this little guy. I was having some problems with the audio IC, I couldn't get it to work above 15V supply, the audio would cut out on peaks. I used some junkbox cores for the filter inductors, and the IC doesnt like them. I built another modulator card with different inductors, and after a few wiring snafu's were corrected its working happily up to 31V input. The datasheet says it should work up to 36V, but TI has been know to lie before. I hooked this test modulator up to the remainder of the transmitter and all seems to be well. The finger scorch factor implies something around 20W carrier balls-out...that's all she wrote. Still, not bad for a proto build. Proper scematics coming later in the week if all goes well.
Re the Harris exciter... Most of the AM stereo exciters aside from BE's were setup for a single frequency and it was a job to move them somewhere else. That said, I've never seen the docs for the STX-1.
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Re the Harris exciter... Most of the AM stereo exciters aside from BE's were setup for a single frequency and it was a job to move them somewhere else. That said, I've never seen the docs for the STX-1.
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374
MW Loggings / Re: WHO 1040 AM 0418 UTC 23 Nov 2019
« on: December 01, 2019, 1948 UTC »
I went sniffing around MW last night. Using the TX-11A on the workbench and a Belar shielded loop in the backyard. Had good copy on WHO around 1000z, heard top of the hour news, mentions of a plane crash in SD killing 9 and injuring 3.
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375
General Radio Discussion / Re: The Demise of Radionomy Marks the End of Free Streaming for Internet Radio?
« on: December 01, 2019, 0713 UTC »It's all about greed and control, http://www.radiosurvivor.com/2019/11/27/the-demise-of-radionomy-marks-the-end-of-free-streaming-for-internet-radio-broadcasters/
It always has been. The music industry is a headless laviathan, and this new ruling probably means that a lot of small operators are going to have to shut down. Everyone else will just make their streaming servers private and remove them from any public directory services like shoutcast or dir.xiph.org. In an era where the only version of a song you can buy is a watermarked MP3, it serves the music industry right to sink with their own ship. Piracy is going to come back with a vengeance.
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