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Jeff Liebermann <jeffl@cruzio.com>: May 29 09:57AM -0700 >and I think a few, very few, variable. The wider bandwidth results >in much lower distortion. However then there is more noise and >you need a stronger signal.   What little I've done with broadcast FM was at various radio stations and designing some low end receivers. That was also long ago, so I'm fairly well behind on the technology. However, if "high end" means "high price", I've fixed a few of these systems: <http://www.elanhomesystems.com>   If you've ever swept a decent analog FM receiver, you may have noticed that the IF bandwidth is much wider than the occupied bandwidth (200KHz) of the signal. In order to keep the group delay fairly constant within the IF bandwidth, this was necessary. That meant that while the audio was very good quality, the receiver would pickup junk from adjacent channels. Sensitivity is limited by the receiver front end and is unaffected by the wider bandwidth.   Roll forward a few decades and we are now blessed with all digital receivers. The best example is the Sony XDR-F1HD tuner: <http://ham-radio.com/k6sti/xdr-f1hd.htm> <http://www.amazon.com/Sony-XDR-F1HD-Radio-Discontinued-Manufacturer/dp/B00168Q248> These typically sell on eBay for $150 to $250 or $500 with some necessary modifications. Seems to be a demand: <http://www.ebay.com/sch/i.html?_from=R40&_nkw=XDR-F1HD&LH_Complete=1&LH_Sold=1> The difference is that this receiver has a "brick wall" digital IF filter that doesn't need to be excessively wide in order to get low group delay and low distortion. The narrower bandwidth is also good for reducing much of the alternate channel noise produced by IBOC (HD Radio) signals.   Meanwhile, the lower end FM receivers are also deriving benefits from digital IF and demodulators. The Sony tuner uses an NXP/Philips SAF7730 chip while most of the low end stuff uses various Silicon Labs AM/FM chips: <http://www.silabs.com/products/audio/fm-am-receiver/> <http://www.silabs.com/products/audio/fmreceivers/> Basically, it's almost an SDR (software defined radio) with most everything in a single chip. Tecsun uses these chips in their various radios. Plugged into a proper audio amp and speakers, they sound very good, with little IBOC junk from the adjacent channels. (Note: Not all Tecsun radios use digital receiver chips).   >Actually it is all going digital soon, a couple of countries are in >the process of that right now.   No, it's not, at least in the USA. The FCC, in its infinite wisdom, has endorse exactly one proprietary and expensive standard (IBOC) totally owned and licensed by iBiquity. As usual, half measures don't work. In this case, the broadcast industry wasn't quite sure if they were going to commit to doing IBOC, so instead of 100% digital FM, iBiquity was forced to provide the half ass analog/digital compatible system that we're cursed with today. Incidentally, the failed AM stereo system following a similar life cycle demonstrating that the FCC and the industry doesn't learn from their expensive mistakes.   In 2012, a made a graph of the number of HD Radio stations in the SF Bay area and in the USA. <http://802.11junk.com/jeffl/crud/hd-radio-stations-calif.jpg> <http://802.11junk.com/jeffl/crud/hd_radio_stations.jpg> <http://www.stateofthemedia.org/2013/audio-digital-drives-listener-experience/9-number-of-stations-dropping-hd-outnumber-those-adopting-in-2012/> There's actually been a decrease in stations, that have unplugged their HD Radio equipment since 2012 but I don't have numbers handy.   I know little (or nothing) of what's going on with DAB (digital audio broadcasting) as it's not used in the USA: <https://en.wikipedia.org/wiki/Digital_audio_broadcasting>   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

dplatt@coop.radagast.org (Dave Platt): May 29 11:13AM -0700 In article <f8dd99f8-b2a4-4800-8fd2-de2d449496e1@googlegroups.com>,   >I saw a modification for it and surprising to me is it was not something to cut the IF bandwidth, it was >strictly in the ratio detector. It seems the newer quadrature detectors don't have much of a problem with >this, so far I saw.   The digital noise is commonly a problem as the result of the way stereo demultiplexing works. The higher-frequency components of the FM detector's output are mixed against the 38 kHz local oscillator, thus doing an AM demodulation of the L-R subcarrier band which lies on either side of 38 kHz.   Many MPX decoders use a simple switching-mixer architecture, and these will end up detecting both the signal around 38 kHz, but also whatever is present in the neighborhood of the third and fifth harmonic of 38 kHz. Since that's where the digital subcarriers often line, the digital signal ends up as sideband noise in the L-R difference signal, and (unless you switch the tuner to "mono") ends up in the left and right channel audio.   There are a number of ways to fix this. One is to filter the FM detector output signal before it goes to the MPX chip... either a low-pass filter (knee somewhere about 60 kHz), or notch filters centered on the odd harmonics of 38 kHz, or both.   Another approach is to demodulate the MPX signal using a design which is inherently not sensitive to the 38 kHz harmonic regions... e.g. a true multiplying mixer using a 38 kHz sinewave local oscillator (rather than a square wave or switching design), or a Walsh-function decoder using a stepped wave which has no 3rd or 5th harmonic content (some Sansui tuners do this).   Modern DSP-based MPX decoders could do any of these.   http://ham-radio.com/k6sti/hdrsn.htm has a nice overview of the problem and solutions.

Jeff Liebermann <jeffl@cruzio.com>: May 29 12:58PM -0700 On Sun, 29 May 2016 11:13:09 -0700, dplatt@coop.radagast.org (Dave Platt) wrote:   >http://ham-radio.com/k6sti/hdrsn.htm has a nice overview of the >problem and solutions.   That article is on HD Radio (IBOC, iBiquity, dismal radio, etc) and not about conventional FM stereo. While the mechanism for generating the noise that you don't want to hear is similar, the technology, solutions, and sources of noise are quite different. For example, there's no mixing required for the excessive occupied bandwidth of IBOC to ruin your day.   Incidentally, Brian Beezley has written several other articles on HD Radio and tuners: <http://ham-radio.com/k6sti/> See "HD Radio" section at lower right and various equipment reviews at the upper right.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

isw <isw@witzend.com>: May 29 10:38PM -0700 In article <f8dd99f8-b2a4-4800-8fd2-de2d449496e1@googlegroups.com>,   > But bear in mind there were adverse implications. When it was simple "store > cast allocation" it was at 76 KHz, locked to the 19 KHz stereo pilot. The > deviation was very low and did not produce much in the way of sidebands.   SCA usage predates FM stereo. Originally there were two subcarrier frequencies: 43 kHz and 76 kHz. As stereo broadcasting became popular, the 43 kHz channel was abandoned due to interference. While some broadcasters may have synchronized the 76 kHz frequency with the 19 kHz stereo pilot, this was not required. Plus, since the SCA signal itself is frequency modulated, locking it to the pilot would not accomplish much in any case.   Isaac

jurb6006@gmail.com: May 30 09:43AM -0700 Interesting, in fact everybody, interesting.   Next we need a thread on what all they crammed into the NTSC TV signal. Like PRO audio which was another SAP essentially, the VITS or VIR, closed captioning, ghost cancelling reference and who knows what else.   Man's innate lust to cram as much as possible into any given bandwidth.   With TV, they wasted it. They went digital because NTSC takes too much bandwidth and has limited resolution. The problem is they cannot come up with any decent programming anymore.   In other words, the resolution doesn't matter if there's nothing to watch. I don't need 2,000 line resolution to watch Gunsmoke. Just like I don't need 24 bit/96 KHz sampling to listen to music from the 1960s.

thekmanrocks@gmail.com: May 29 11:43AM -0700 This resistor is very simple. It will have stereo RCA in and out, and 1/8" mini in and out.   All it will do is attenuate 2.5khz by 3 dB, with a Q wide enough to modestly affect frequencies from 1kHz up to 4kHz.   Essentially to mildly scoop out those audio frequencies humans most readily hear. One could plug a line source or phone into it, and RCA out, IE, to a stereo amp. One could use the built- in tone controls('Bass', 'Treble'), to tailor the ends of the bandwidth to taste.   Result? A smoother, less intrusive sound at background or concert- hall levels.   What materials do I need?

Rasta Robert <rr@dds.nl.ReMoVe_ThIs.invalid>: May 30 03:20PM > sound at background or concert- > hall levels.   > What materials do I need?   So not a resistor, but a filter, a notch or band stop filter to be precise. You will at least need resistors and capacitors, possibly one or two coils.   <https://en.wikipedia.org/wiki/Band-stop_filter> <http://www.radio-electronics.com/info/circuits/rc_notch_filter/twin_t_notch_filter.php> <http://www.hobby-circuits.com/circuits/audio/audio-filter/590/rc-notch-filter-twin-t> <http://www.instructables.com/id/Passive-Filter-Circuits/>   Making it a passive circuit will also attenuate the signal level, so you might need some active amplification in it to recover that.   <http://www.circuitsstream.com/2013/06/simple-notch-filter-uses-operational.html> <http://www.radio-electronics.com/info/circuits/opamp_notch_filter/opamp_notch_filter.php>

M Philbrook <jamie_ka1lpa@charter.net>: May 30 11:38AM -0400 In article <4ce17090-787d-4c15-8515-4d09abacc6f5@googlegroups.com>, thekmanrocks@gmail.com says... > sound at background or concert- > hall levels.   > What materials do I need?   a Graphic EQ.   Jamie

hrhofmann@att.net: May 29 02:08PM -0700 Sorry, but your post doesn't make any sense.   If it is a mechanical timer, when you set the time, it starts a clockworks mechanism that closes contacts for the length of time set, and then opens the contacts, to shut of the bathroom fan, for example. If it is a purely electrical type of timer, a motorized clock does the timing for opening a set of contacts and shutting off the ventilating fan.

dplatt@coop.radagast.org (Dave Platt): May 29 10:58AM -0700 In article <edc77ec8-cedd-4e17-b1f8-7c0c9da95b93@googlegroups.com>, >My car's CD player reports Check CD and ejects many CDs. I've managed to get the radio out of the car, and >opened it until I can now see the laser lens.   >I plan to clean with Qtip and isopropyl alcohol 91%.   Use a photographer's "puffer brush" first (a rubber squeeze-bulb with a soft-bristle brush on the end). Brush the lens very lightly and then puff it gently with air. This will dislodge and remove the worst of the dust.   I would recommend getting electronics-grade isopropyl rather than using 91% commercial type... you really want something as pure as possible so that it won't leave a residue.   >Is there anything else I can clean? Or lube with white lithium?   The only other thing I see which you might address, is the metal rail on which the optical sled moves in and out. If I'm seeing what I think I'm seeing, it's the silver metal rod, which has something that looks like a helical spring wound around it.   If this rail is dirty, or if it has old lubricant which has gotten gummy, the sled would be unable to move smoothly and the laser/photodiode mechanism would have trouble following the spiral track on the CD's data layer.   You might be able to clean it (very carefully) using a small brush with a suitable solvent (electronics-grade isopropyl, or "white spirit" (naptha), and then relubricate (a *small* amount of sewing machine or watchmaker's oil... "light machine oil"). Do *not* use 3-in-1 or WD-40! Be very careful not to get either the solvent or the oil on other parts of the mechanism, or force or bend anything.   Due to the presence of that helical spring or coil (whatever it is I think I'm seeing) this is likely to be a tricky process. Don't try it at all unless you're willing to take the risk of destroying the whole thing.   If you can get a long disc (70-80 minutes) to play all the way to the end, and then cut the power without pressing "STOP", you'll probably find that the laser sled has moved all the way to the outer diameter of the CD. This may leave the "rail" exposed, and easier to access and clean.   You might find that some gunk has built up near the inner diameter of the rail. This could "bind" the optical sled when it tried to read the disc's table of contents, which is written right at the inner diameter of the CD data area.   >the CDs have trouble and will eject with Check CD repeatedly. Then on one of the re-inserts, they'll read. >The CDs are books on CD from the library. I've washed most of them, and they look good (not scratched or >dirty).   Books-on-CD are commonly "burned" CD-Rs, rather than "pressed" CDs. The reflectivity contrast of their data patterns is about half that of pressed CDs, which means that the laser/photodiode has a weaker signal to follow. It's fairly common for failing CD players to start rejecting CD-Rs, while they can still track commercial "pressed" CDs.   This sometimes (often?) means that the laser diode is approaching its end of life - the laser output is declining, and the photodiode system is getting a weaker and weaker signal from the disc.   The only real cure for this is to replace the laser diode (often the whole optical assembly), and then recalibrate the laser drive and the tracking. This is definitely possible but may not be economically worthwhile. There are probably YouTube videos which show the procedure.   It's sometimes possible to turn up the laser drive current, but this is a *very* temporary hack... the higher current just makes the diode fail all that much sooner.

Jeff Liebermann <jeffl@cruzio.com>: May 29 01:19PM -0700 On Sun, 29 May 2016 08:53:43 -0700 (PDT), curls <borskyc@yahoo.com> wrote:   >My car's CD player reports Check CD and ejects many CDs.   Does the CD player have a maker and model number? Your photos kinda look like the player is part of the vehicle console and not a seperate unit. Perhaps the vehicle maker and model might help.   This might help: <http://www.repairfaq.org/sam/cdfaq.htm>   With CD lasers, I like to use my digital camera to "see" the IR output of the laser. To determine if it's lacking in brightness, compare it with what the digital camera can see from another CD player.   Most common problem I've seen on vehicle CD players is "smoke" on the lenses and mirrors.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

"Snuffy \"Hub Cap\" McKinney" <Snuffy-Hub-Cap@Livebait-McKinney.com>: May 29 10:27AM -0700 > It can be something as simple as a slipping belt. I'd tighten or > replace it before rebuilding the alternator. Yes, I've seen it happen > more than once. . ---   Thanks for all the help. Still trying to find the time to spend TS...   Last night I was able to catch it cycling just now. No time to check at the alternator tonight, but here's some voltages at the battery terminal.... Turn signals seems to cause the cycling tonight, although I have seen it cycling with just the lights on.   Battery with engine off - 13.6 Turned engine on Idling with no lights - 15.0 steady Turned on parking lights - 15.0 steady Turned on headlights - 15.0 steady Turned on headlights and turn signal - 15.2-15.8 cycling No lights, turn signal on - 15.2-15.8 cycling

Sjouke Burry <burrynulnulfour@ppllaanneett.nnll>: May 29 08:49PM +0200 On 29.05.16 19:27, Snuffy "Hub Cap" McKinney wrote: > Turned on headlights - 15.0 steady > Turned on headlights and turn signal - 15.2-15.8 cycling > No lights, turn signal on - 15.2-15.8 cycling   That sounds like a defective regulator or generator going on/off. Which would suggest the two voltages. Bad wiring would produce a different pattern.

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