On 19/11/17 10:04, Martin Brown wrote: [...]
You should know better. Yes, there will be beats at df, but the combined signal contains no energy at df. Low pass filtering will leave nothing.
Jeroen Belleman
gotta nonlinearise it first. Which isn't much of a challenge.
NT
Wow, are there still tape recorders?
That's another technology that I don't miss. Wow and flutter will turn FM into AM. AM would have more noise, and wow and flutter would make time shifts.
I wonder how many cubic feet (and dollars) of tape reels or casettes does it take to equal a 2 terabyte hard drive.
I was musing the other day on various butterfly effects, small things that had gigantic consequences. Dolby's B circuit was one of those.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Or use two channels at the same frequency and phase, one AM-modulated signal and one a constant reference for a synchronous demodulator.
Anybody who plays with electronics and hasn't had a formal Signals+Systems course should get this:
-- John Larkin Highland Technology, Inc lunatic fringe electronics
On a sunny day (Sun, 19 Nov 2017 10:17:28 -0800) it happened John Larkin wrote in :
You are dreaming:
Don't use a soundcard at all. Use an ADC and then you will know what's there. You can buy USB ones.
That's not a reel, nor a casette.
I wonder what one of those Sony cartriges costs. Looks like roughly $4/tB for the current gen ones.
The problem with tape backup is that the drives get obsolete and die. USB, for hard drives, will probably be around for a while.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
On a sunny day (Sun, 19 Nov 2017 11:45:40 -0800) it happened John Larkin wrote in :
So try getting a 1 TB harddrive for 4$.
I don't think so, tape read/ write is simpler than optical r/w systems.
As long as the protocol is known it can be reproduced, and even if not it is not that hard to crack.
I still have audio cassettes and players, and those still work. Magnetic storage is very very reliable, in a way better than most DVD bluray etc.
USB is a disaster, we are now at USB version 3? I avoid it if I can. It is a ratmond widows invention and it shows.
Most USB harddisks need 2 or more ports for power, I have 1 TB on my TV that takes up 2 USB ports, because USB is limited to what was it 600 mA? Also have a 1 TB Seagate on the PC that is powered from a separate wallwart...
Try dropping a [USB] harddisk, I did, total loss, data gone.
State-o-de-art is LTO-8 Ultrium at 12TB per cartridge. Planned are O-9 at 26TB and LTO-10 at 48TB per cart.
LTO-8 was just recently announced and I can't seem to find any pricing. LTO-7 at 6TB per cart varites but seems to average around $80/cart or $13.33/TB. LTO-6 and 7 drives are typically about $4,000 ea. I don't want to think about the cost of an LTO-7 juke box.
Data rates are around 2.5TB/hour (with compression).
The typical LTO cartridge weighs about 200g or 0.44lbs.
In the sci-fi story, it took a few million years (Mesozoic) for stomping on the butterfly to change the political climate of the future. We are living in an age where everything is accellerating, so we won't have to wait as long to see the effects of little things. I'm not sure if this is a good or bad thing.
I don't believe that Dobly B has done much good. Todays music is so heavily compressed and lacking in dynamic range, that if there was any low level noise to reduce under the loud music, we wouldn't hear it.
Drivel: What I want are hearing protectors for the movie theater. The volume is deafening and according to my Android SLP (sound level pressure) meter, can be dangerous. The problem is that ordinary hearing protectors and ear muffs are more effective at high audio frequencies than low, resulting in a skewed frequency response. What I want is a hearing attenuator with a flat frequency bandpass.
-- 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
Probably not; if you couldn't get line-of-sight to a radio receiver, though, they were common in the 1980's (Mt. St. Helens eruption was the only reason I had contact with 'em).
Solved problems; multitrack analog, there was a timing track as well as the signal tracks (multiple-axis sensors). The motor was slow, a big spool of tape lasted a month or two, then you had to visit to swap batteries anyhow.
Seven DLT-S4 tapes (2004 introduction) would do it. You don't see those record/playback decks outside of server rooms, though; fiber channel or SCSI/SAS are typically required.
Dolby made casettes much more popular than they would have been. I remember people sneering at casette quality, then loving Dolby.
Casettes fueled the fall of the USSR and the fall of the Shah in Iran.
I haven't been to a movie theater in a decade or so. Who needs parking hassles and $7 popcorn?
This will probebly continue down. Especially with the horrible movies being made lately.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Adding to Xmas wish list. GH
Parking hassles? No one needs $7 popcorn. We haven't been to the theater in a year or so. Hollywood isn't making anything we want to see.
+1
I don't recall ever owning a cassette plays that had Dolby. I just lived with the crappy quality because the available alternatives (Fidelipac, 4-track, 8-track, reel to reel, vinyl) were either equally disgusting or far more expensive. If I had to listen to every possible noise and distortion, I might was well listen to it on the cheapest player available.
During the mid 1960's, I worked in a hi-fi and camera repair shop in Santa Monica. Mostly, we did warranty repairs on the minor brands of music players. Concord, which sold tape recorders, was nearby, so we ended up doing their warranty repairs. I got a fairly good picture of how the company operated and what drove the technical decisions. I don't want to get into yet another audiophile discussion, but lets just say that cassette player were not sold on the basis of quality. The best of the breed, Nakamichi, didn't sound much better than a cassette player 1/10th its cost. I participated in a listen test and found that I couldn't tell the difference.
"How Rock and Roll Brought the Soviet Union Down"
It's an interesting theory and probably has some validity. However, my relatives and friends from the former Soviet Union told me it was more likely caused by much of the Russian economy going underground to the black market. The ruble was rapidly losing value (unofficially since it was not on the international monetary exchange). Workers were either not being paid, or being paid in worthless rubles. Yet, the people were not starving or wearing rags. Where did the goods come from? They came from the black market, where barter based on theft of factory goods, farm produce, and foreign currency, was the common currency. When the Baltic states of Latvia, Estonia, and Lithuania quietly revolted and decided to bail out of the Soviet Union and nothing happened: it was a signal for the other states to do the same. At the same time, the Soviet Union was not making itself very popular dealing with the effects from the reactor meltdown in Chernobyl. If there were cassette tapes or rock and roll in there somewhere, I must have missed them.
$7 will get you a small popcorn. Add $5 for a small drink: Ouch.
My last three visits to the local movie theater was to help manage a herd of kids celebrating someone's birthday. I think the movies were all Pixar creations, which I thought were rather well made and entertaining. Except for the high volume, a good time was had by all. However, I suspect that something addictive had been added to the popcorn.
-- 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
snip
Tape quality improved dramatically at the same time dolby b became popular. IME tape quality had far more effect, 1980s cassettes were ok without dolby.
Had they not existed, 8 tracks or bones recordings would have done. They were the media not the message.
NT
My IEEE dictionary defines Extreme Low Frequency as 3Hz to 30Hz. Linx App Note AN-00100 [1] defines ELF as 100Hz - 10kHz. The app note doesn't spell out what its ELF acronym stands for. (Epi Low Frequency?)
Note.
Thank you,
-- Don Kuenz, KB7RPU
There are some things better left buried and forgotten. This is one.
The ITU says ELF is 3 - 30Hz in V.431-8 See Table 2 on Pg 2 which divides this into 4 sub-bands. Band Symbol Freq sub-division Metric Abrev -1 0.03-0.3 Hz Gigametric waves B.Gm 0 ELF 0.3-3 Hz Hectomegametric waves B.hMm 1 3-30 Hz Decamegametric B.daMm 2 30-300 Hz Megametric B.Mm
More:
Wikipedia offers yet another alternative as 3Hz - 3KHz. "In atmospheric science, an alternative definition is usually given, from 3 Hz to 3 kHz.[4][5] In the related magnetosphere science, the lower frequency electromagnetic oscillations (pulsations occurring below ~3 Hz) are considered to lie in the ULF range, which is thus also defined differently from the ITU radio bands." I tried to find these numbers in footnotes [4] and [5] but ran into the usual paywall.
Blundering further down the page, I find 0 to 300Hz: "The World Health Organization (WHO) have used ELF to refer to the concept of "extremely low frequency (ELF) electric and magnetic fields (EMF)"[17] The WHO also stated that at frequencies between 0 and 300 Hz..."
So, we have at least 4 different frequency ranges that claim to be called ELF. I think I'm getting a headache. Could you please pound the nails back into the coffin and quietly bury this monster?
-- 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
On a sunny day (Sun, 19 Nov 2017 13:25:35 -0800) it happened Jeff Liebermann wrote in :
An old school mate of mine who had company making audio power amps once took me to a disco where he just installed his latest power model. I REALLY wanted to get out of there because of the pressure level on my ears. People did not seem to care...
Movie theaters do those still exist ?;-) Everybody (including me) has a big screen at home it seems these days. OK, the popcorn.... oh well... we now have 'marsepein' (marzipan' in English in this time of the year
On a sunny day (Sun, 19 Nov 2017 16:53:06 -0800) it happened Jeff Liebermann wrote in :
At the end of the sixties I worked in the national TV studio and movie / audio synchronization (perfotape) we had very nice tape recorders, Telefunken, Studer, PER525 tape was the norm.
On a sunny day (Sun, 19 Nov 2017 15:13:59 -0800 (PST)) it happened whit3rd wrote in :
Hey, 'timecode' used for editing, also on video tape.
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