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Bandwidth limiting, why bother?




 
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Author Topic: Bandwidth limiting, why bother?  (Read 2229 times)
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N1BCG
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« Reply #25 on: March 02, 2017, 10:04:40 PM »

What do you do?

If two QSOs start at the same common time, such as UTC, then it would need to be worked out in a gentlemanly way at the time when propagation causes them to conflict.

If the coincidental beginning at the same common time happens nightly, then a longer term solution should be worked out in a gentlemanly way.

If a QSO begins at 2230Z and a net begins at 2330Z on the same frequency at a time of year when both groups can hear each other, then the solution is obvious. The harder question arises when the 2330Z net refuses to QSY and says they have priority because:

A) "we are an established net"
B) "our frequencies are published on our website"

That brings us back to "What would you do?" The attached MP3 gives a real-world example...



* 151125_WE5TXS&W1LLY.mp3 (879.18 KB - downloaded 47 times.)
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Steve - K4HX
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« Reply #26 on: March 02, 2017, 10:37:12 PM »

What would you do?

You should take this conversation to the QSO section. It's no longer a Technical one.
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flintstone mop
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« Reply #27 on: March 03, 2017, 10:50:31 AM »

What if:
Stations start up a QSO on a "clear" x frequency.
At the same time, stations 1500 miles away start up a QSO on the same "clear" or close to same x frequency.
Bandwidth of both sets of QSO's might vary from 3 to 8 KHz depending on mode.
Roughly 20 to 30 minutes into the QSO's  on this "clear" frequency area, propagation changes.
Now both sets of QSO's can hear each other causing interference to each others QSO.
What do you do?
Do you:
all just piss and moan about the interference;
your QSO moves;
they move or you ask them to move or they ask you to move;
each claim the other is causing intentional interference and no one moves;
piss and moan about each others bad operating habits and no one moves;
threaten recording tapes and notification to the FCC or to anyone who will listen to each others piss and moan;
What do you do?


1500 mi away and causing interference would tell me that SOMEONE is on the air with 10KW of power!!
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Fred KC4MOP
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« Reply #28 on: March 05, 2017, 12:51:42 AM »

What would you do?

You should take this conversation to the QSO section. It's no longer a Technical one.
Indeed, but to bring it back, testing my latest killer transmitter, an AT-1 with a cathode modulator that is  only -3 dB at 5 kHz  and -6db at 8 kHz, but with a D-104 with its falls-off-a-cliff high frequency response yielded essentially nothing past 5 kHz out. This test wasn't terribly scientific. I was just watching my signal on a WebSDR waterfall display during an on the air test QSO, but that's the way it looked. A buddy was listening and could not hear anything out there either. I was driving a linear, 100 watts carrier. My signal was strong at the SDR. Unfortunately, I didn't note the S meter reading which would have made the test a touch more scientific. Not in the mud anyway.

Maybe it's my foggy voice but there you have it.

Compare the response curve of the D104 (and Shure 444) with my usual microphone, a Heil PR-40. With the D-104, I can get away with very little bandwidth limiting in the audio chain.  The PR-40 is a different story. It actually has a peak at 10 kHz.


* D104.png (32.66 KB, 599x450 - viewed 48 times.)

* PR-40.png (43.55 KB, 650x220 - viewed 41 times.)
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MikeKE0ZUinkcmo
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« Reply #29 on: March 05, 2017, 07:53:09 AM »

The station mic here is an Astatic D-104 crystal element, which as seen in the curves is 12db off the peak at 5kc, and more than 30db down at 10kc.   So long as all is kept linear at voice peaks, all is well in my book.

As for Pete's scenario, If I felt "I was there first" I'd ask the "new" guy to move over a little, but if he thinks it's HIS fire hydrant, I'd just move, not happy, but life's too short to whine about such inconsequential things.   

Now if the other guy is obviously over modulating, or has other significant distortion products, I'd probably let him know, but beyond that, there's lots of room on most the bands.       
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Patrick J. / KD5OEI
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« Reply #30 on: March 07, 2017, 12:19:34 AM »

I always have a bandwidth limiting arrangement with a pretty sharp cutoff at 3.8KHz or so, and as clean a modulator as it can be run.

The reports always indicate no buckshot or splatter. I can't stand to cause noise outside my intended bandwidth. I feel like it is shameful to transmit distortion outside one's chosen bandwidth and I hope others feel the same way.
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #31 on: March 07, 2017, 12:35:03 AM »

I always have a bandwidth limiting arrangement with a pretty sharp cutoff at 3.8KHz or so, and as clean a modulator as it can be run.

The reports always indicate no buckshot or splatter. I can't stand to cause noise outside my intended bandwidth. I feel like it is shameful to transmit distortion outside one's chosen bandwidth and I hope others feel the same way.

I totally agree -- stay clean and use brick wall filters, definitely. Sometimes, of course, my chosen bandwidth is +/- 7.5 kHz -- fairly often, actually. At other times it might be less or more -- though I much prefer operating when and where it can be fairly wide. When the AM passband gets significantly narrower than +/- 5 kHz, I feel like the quality is so low that I might as well be running filter-type SSB.

73,

Kevin.
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N1BCG
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« Reply #32 on: March 07, 2017, 10:39:16 AM »

It depends on how you want to be perceived. This would work much better in an open lot...



* Bandwidth06.jpg (523.08 KB, 2398x1227 - viewed 245 times.)
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WB4AIO
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« Reply #33 on: March 07, 2017, 10:55:07 AM »

It depends on how you want to be perceived. This would work much better in an open lot...




Great illustration.

Yes, the "three kHz audio is always best" and "every three kHz" channelized mentality is a plague on amateur radio (in addition to being very questionable from a best intelligibility point of view), and should never have been instituted or taught.

Just like those narrow parking spaces -- so ridiculously narrow that even compact cars' doors can't fully open without striking other cars! -- should never have been designed that way.

73,

Kevin, WB4AIO.
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WD5JKO
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« Reply #34 on: March 07, 2017, 12:59:46 PM »

This happens too.... Tongue

The guy in the Ferrari picked a place away from everyone, and occupied two spaces (channels).

Than some person decides to park right next to him, and, and occupies one space (channel).

This happens on the radio as well as in the parking lot.

I recall once as a young man, doing the same thing with my 73 Dodge. I was within inches of a diagonally parked Corvette. My entire care was within the lines of 1 parking spot. The Vette driver was trapped, and was waiting for me.... Embarrassed

Jim
Wd5JKO


* ferrari-vs-truck.jpg (14.55 KB, 400x300 - viewed 44 times.)
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Patrick J. / KD5OEI
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« Reply #35 on: March 07, 2017, 03:30:05 PM »

It depends on how you want to be perceived. This would work much better in an open lot...


Around here the red car would be more likely than the others to be accidentally damaged. Someone with a truck might be confused about which parking slot it was in and try to pull in to the perceived empty slot.

As for narrow slots, unless it is marked 'compact car only' (which is ignored..) the state requires the slot to be minimum 96" wide (502.2 Vehicle Spaces).

The only 'narrow slots' or slots of any kind? on the ham bands are those 60 meter SSB channels.
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #36 on: March 08, 2017, 12:17:38 AM »

At least the red and blue cars are clean, (see K1JJ's post). Some of the signals I encounter on the band are more like this:


* Ugly signal.jpg (818.61 KB, 2247x1264 - viewed 62 times.)
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w8khk
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« Reply #37 on: March 08, 2017, 12:31:32 AM »

At least the red and blue cars are clean, (see K1JJ's post). Some of the signals I encounter on the band are more like this:

Is that a plate modulated rig or PWM?  After studying the photo, from the looks of the front end alignment, that might be Tim's (WA1HLR) SBE (Slop bucket eliminator).
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Rick / W8KHK  ex WB2HKX, WB4GNR
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« Reply #38 on: March 08, 2017, 08:22:05 PM »

At least the red and blue cars are clean, (see K1JJ's post). Some of the signals I encounter on the band are more like this:

That jalopy there is what's known as a rat.
https://en.wikipedia.org/wiki/Rat_rod

truck version: (equivalent to CB with 5KW leen yar)
https://encrypted.google.com/search?q=rat+truck&tbm=isch&imgil=GpJntqLozaYTaM%253A%253Bq2y-Jdz5KPLgQM%253Bhttps%25253A%25252F%25252Fwww.pinterest.com%25252Fpin%25252F546131892287351022%25252F&source=iu&pf=m&fir=GpJntqLozaYTaM%253A%252Cq2y-Jdz5KPLgQM%252C_&usg=__n2S6m6tLhllOrFZw9amYhDGOSZg%3D&biw=1440&bih=698&ved=0ahUKEwjWo9-BocjSAhVDeCYKHXnjDaIQyjcIJA&ei=E67AWJbOOcPwmQH5xreQCg#imgrc=GpJntqLozaYTaM:


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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #39 on: March 09, 2017, 11:01:22 AM »

You have to admire the creativity and rebelliousness.  Still I wouldn't want to be driving next to one, especially that first truck,  5K linear, over driven, no filter network at all:


* Spiked truck.jpg (94.28 KB, 736x490 - viewed 36 times.)
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K1JJ
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« Reply #40 on: March 09, 2017, 01:18:47 PM »

Ah, yes, gotta love the Rat Rods!  Check out the one below... how does the guy see the street? Imagine how loud those open headers are.

I've got my heart set on a blue '67 GTO with an off-chassis restoration, 4-speed, black interior and even some pro-stock mods. Used to own two '64 GTOs in high school, but a '67 was always my favorite dream car.  

My second choice is a marina blue '66 Chevelle SS-396.

T


* Rat Rod Primo.jpg (219.02 KB, 1200x900 - viewed 43 times.)

* '67 GTO Dream.jpg (171.36 KB, 1024x571 - viewed 41 times.)

* '66 SS-396 Chevelle.jpg (102.09 KB, 780x448 - viewed 34 times.)
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« Reply #41 on: March 09, 2017, 01:23:46 PM »



                                                                            ?
Looks like the "Mystery Date" game.


klc
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What? Me worry?
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