Women Hearing Distorsion on Station After STL realign

Gotta watch those Fresnel zones!
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Re: Women Hearing Distorsion


Looks like I started a diversion. Well, time for a war story.

Back in the 70's sometime the wife and I went shopping in like a Sears/Pennys/Boston Store place on the far Wes side of Milwaukee. We were only a few minutes in the store and it felt like someone put a clamp on my head. Asked the wife if she noticed the same thing, but no, she didn't. After a very brief pause, 'I started moving around to see if it was something I heard and discovered I had zeroed into a small area. Looked up on the ceiling and saw some round thingys. Got it figured out.....they used an ultrasonic motion detector alarm system and it was still turned on. That was extremely annoying and I never understood how a woman could work in that environment.

Needless to say, we exited the store quickly and I never went back.

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Re: Women Hearing Distorsion on Station After STL realign

Post by kb4mdz »

Dale H. Cook wrote:
Sat Nov 18, 2017 11:44 am
Sat Nov 18, 2017 9:39 am
Could the loss of hearing in men be the result of constant nagging, or is it "selective hearing loss", which is what I have?
Fossil -

It's just that men turn into old farts faster than women do.
Well, yes, we do, I'll agree to that.

I don't want to hijack the thread, it's good to keep it going, but I'll throw in a couple other true stories.

My Dad lived in Vermont with my Mom from maybe 1951 to about 1954; did a lot of work in sawmills. Back then, the concept of hearing protection just wasn't 'manly' and such. So, a couple years of high-pitched saws, motors and such. By the time I was along in the 60's & 70's his hearing was really starting to fade, esp. in the upper registers. (Gee, maybe about where those saws produced sound??? Maybe???) If you graphed his hearing against frequency, it was OK on lower registers, but really started to fall off right where women's voices were the fullest. And if he asked someone to repeat themselves, most people will raise their VOLUME and also the PITCH! So women's voices would just disappear into the range where his hearing loss became most extreme. Flapping lips, no hearing, and EVERYone is frustrated. :evil:

Mom, sister & I all learned quickly to raise the volume, but LOWER the PITCH to talk to him. :(

FWIW, sending this off in a tangent, did you guys know that one of the biggest reasons that older people stop going to church is their hearing loss?? They start to feel disconnected from the service and the community.

Same daughter as above can not stand the sound of some of my cordless tool-chargers. Too audible and irritating. She'll move it into the other room if she has too.

I keep looking for tween girls in my church to groom for soundboard mixing work. They have better discrimination and tend not to ram the controls up to max like a lot of boys. :-)
Last edited by kb4mdz on Sun Nov 19, 2017 2:39 pm, edited 1 time in total.

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Re: Women Hearing Distorsion on Station After STL realign

Post by Shane »

...really started to fall off right where women's voices were the fullest.
This COULD be advantageous. (Probably shouldn’t have put that in writing!)
Mike Shane, CBRE
— — Omaha — —

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Re: Women Hearing Distorsion on Station After STL realign

Post by kb4mdz »

Shane wrote:
Sun Nov 19, 2017 1:36 pm
...really started to fall off right where women's voices were the fullest.
This COULD be advantageous. (Probably shouldn’t have put that in writing!)
No, you shouldn't have put it in writing. I'll by alerting your XYL to your post. :-D

Trust me, it was a damn pain in the patoot for all of us. Most of all Dad.

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Re: Women Hearing Distorsion on Station After STL realign

Post by KPJL FM »

I can remember hearing the horizontal oscillator in TV sets. Way back when. At least I still can remember. What were we talking about?
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Re: Women Hearing Distorsion on Station After STL realign

Post by BigRed »

And back to the STL issue, 'cause it sure looks like you have one.

Let's start with your path study/link budget. You do have one of those? If not please feel free to post the coordinates for the TX and the RX ends here along with antenna types/gains, antenna heights on each end, and transmission line lengths/types. If the tower supporting the receive antenna is "hot" then also need to know how you're getting the signal across the base insulator and the loss from that device. And what polarity is the link licensed for?

And speaking of licensing, you also mentioned that you moved the transmit (studio) end? Depending on how far the move, doing so to either end will probably require frequency coordination and a re-licensing of the link with the FCC. Has THAT been done?

As to what you're seeing . . . if the RSL on the receiver is indicating around 10-dBuV that equates to around -97-dBm (sorry I work in dB/dBm, it's just easier to run the path budget numbers). Not familiar with the brand of equipment that you're using but the stuff that I'm most familiar with (like Moseley for radio STL's and M/A-Com for the TV folks) gives up the ghost when the RSL in dBm drops below the mid -80's. (If I remember correctly the Moseley Starlink recveiver poops out at somewhere between -86-dBm and -93-dBm, depending on the traffic its carrying.)
{And now that I've re-read the three postings I see that I used the wrong RSL level of 10-dBuV when it should have been 26-dBuV. But that level is still a very low -81-dBm when it should be closer to -50-dBm. The link needs work; my suggestions stand!}

Until you have the numbers from a real path study/link budget we can use a back-of-the-napkin guesstimate as a starting point. (A well-done path study/link budget should get you to within a dB of the actual signal level that you will see "in the field".) I come up with a conservative RSL at the receiver input of around -50-dBm, or around 57-dBuV with that guesstimate (which should give you an easy 40 to 45-dB fade margin). [Your transmitter says that it's putting out 10-watts (+40-dBm) and I assumed 250-feet of 7/8" Heliax at each end, a path length of 10-miles and 16-dB gain antennas at each end.]

Given that there appears to be almost 50-dB unexplained loss something serious is wrong with the "path". (That's a far greater discrepancy than can be explained by a cross-pol antenna situation if path alignment is correct.)

So either one, or both antennas are pointing in the wrong direction(s) or are severely damaged, or one or both of the transmission lines is damaged or excessively lossy (Maybe RG-8 instead of Heliax? and that 0.1-watt of reflected power makes me nervous, but that may be due to poor power detection in the radio?). Or perhaps one of the radios is in trouble in some way? There may even be some major obstruction in the path that you're not considering? There could even be a combination of several, or all of those issues.

Some things to look for . . .
You can do a rough check of antenna alignment with Google Earth and a compass. Just draw a line using their "ruler" function between the two sites and make note of the azimuths from each to the other. You can zoom in on each end to get an idea of the approximate direction that the respective antenna should be pointing. And then take your compass and go have a look at each end. That obviously won't tell you if the antennas are "peaked", but if one, or both happens to be off by some ridiculous amount, say by 90-degrees, that will be rather obvious. (And don't take the tower crew's word for it being right, most are OK when it comes to aligning two holes with a spud or even tightening bolts, but that's about it.)

If there's a device getting the signal across a base insulator on a "hot" tower you can always bypass that as a test (after taking the station off-the-air, of course) to see if the signal dramatically improves. (Don't forget to "normal" it up after the test though.)

You can also check the coaxial connectors that are accessible from the ground. Make sure that nothing is broken or recessed too far. (The center pins in male "N" connectors should be almost flush with the end of the inside "outer" part of the connector; you can always get a cheap and dirty digital caliper from everyone's favorite Chinese tool store (Harbor Freight) and actually measure both the male and female pin depths, values are available on-line). I also usually give the outer of the connector a gentle "twist" (keeping in mind that part of it is supposed to turn). If it's tight and won't twist it's probably OK. If it does "twist" back and forth then chances are that the connector is either built incorrectly or the shield has separated from the connector, either of which is bad.

If you have access to a Bird wattmeter with a 10-watt "slug" good at 950-mHz you can verify that the transmitter is actually outputting the 10-watts that it claims to be (the Bird probably won't be accurate, they never are, but it will be close enough for government work). If you have a 1-watt "slug" available you can look at the reflected power too.

And if you're feeling real brave you can test the radios "back-to-back" with a "path-loss simulator". I use a 10-dB "pad" on the output of the transmitter that can handle the power level, followed by a 60-dB pad that can handle the 1-watt coming out of that 10-dB pad and then either a 30-dB pad and/or a variable attenuator. The 10-dB + 60-dB + 30-dB of padding should give you about -60-dBm into the receiver from a +40-dBm (10-watt) transmitter (about 47-dBuV) and that's roughly the level that the receiver's RSL indicator should show.

Anyhow, good luck with troubleshooting the issue. Please keep the group updated on how this turns out or if you need any further help (like that path study/link budget) or a recommendation for a decent engineering firm in your area.

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