micky <NONONOmisc07@fmguy.com>: Dec 25 01:34PM -0500
Technical qustion about wave valleys and troughs and if two radio
playing the same station will be in phase wrt all frequencies, or if
some will cancel out?
And why is it low frequencies are famous for cancelling out when out of
phase when high frequencies are just as likely, 0.5, I think, to cancel
each other out?
Can I just turn off one radio and turn it on again so that the total
odds over both times have increased that by the second time the radios
will be in phase?
I have a radio and tv in one bathroom but neither in the other, which is
smaller and adjoins the bedroom. Sometimes I want to hear the radio
which only gets 'loud' if you are in the same room. I can hear it from
the bathroom but not enough to understand what is said.
I have another table radio, KLM, expensive, that I had for about 33
years when the speaker switch started to fail**, and I turn that one on
too, to the same station, also at maximum volume, and I can hear in the
bathroom just fine, but I wonder if some frequencies are out of phase
from one radio to the other, cancelling each other, and I'm not hearing
them.
It seems to me, if one radio is farther from the transmitting antenna,
by 1/2 wave length, the speakers in the two radios will always be going
in the opposite direction from each other. Maybe.
In my case, the radios are one above the other, so the distance from the
xmtr is very similar. But what about within the radio, when the
heterodyning frequency starts. What if it starts have a cycle after the
first radio?
**So I bought the second radio. The first one has a pushbutton switch
meant to connect/disconnect a wooden-cabinet stereo speaker, which I
have no room for, and unless I get the switch just right, no sound comes
out at all. (even the on/off momementary contact switch no longer works
well, after only 33 years, maybe using it at most 6 times a day, so that
6x365x33=66,000 times. Aren't switches supposed to last into the
millions of times? --- It's failing isn't nearly as bad, because I just
keep pushing until it works. The speaker switch OTOH has a spring that
pushes it out, past its sweet spot, so now it's hard to get to connect
at all.
|
micky <NONONOmisc07@fmguy.com>: Dec 25 04:12PM -0500
sci.electronics.design added.
Technical qustion about wave valleys and troughs and if two radio
playing the same station will be in phase wrt all frequencies, or if
some will cancel out?
And why is it low frequencies are famous for cancelling out when out of
phase when high frequencies are just as likely, 0.5, I think, to cancel
each other out?
Can I just turn off one radio for a few seconds and turn it on again so
that the total odds over both times have increased that by the second
time the radios will be in phase?
I have a radio and tv in one bathroom but neither in the other, which is
smaller and adjoins the bedroom. Sometimes I want to hear the radio
which only gets 'loud' if you are in the same room. I can hear it from
the bathroom but not enough to understand what is said.
I have another table radio, KLM, expensive, that I had for about 33
years when the speaker switch started to fail**, and I turn that one on
too, to the same station, also at maximum volume, and I can hear in the
bathroom just fine, but I wonder if some frequencies are out of phase
from one radio to the other, cancelling each other, and I'm not hearing
them.
It seems to me, if one radio is farther from the transmitting antenna,
by 1/2 wave length, the speakers in the two radios will always be going
in the opposite direction from each other. Maybe.
In my case, the radios are one above the other, so the distance from the
xmtr is very similar. But what about within the radio, when the
heterodyning frequency starts. What if it starts have a cycle after the
first radio?
**So I bought the second radio. The first one has a pushbutton switch
meant to connect/disconnect a wooden-cabinet stereo speaker, which I
have no room for, and unless I get the switch just right, no sound comes
out at all. (even the on/off momementary contact switch no longer works
well, after only 33 years, maybe using it at most 6 times a day, so that
6x365x33=66,000 times. Aren't switches supposed to last into the
millions of times? --- It's failing isn't nearly as bad, because I just
keep pushing until it works. The speaker switch OTOH has a spring that
pushes it out, past its sweet spot, so now it's hard to get to connect
at all.
|
Ed Cryer <ed@somewhere.in.the.uk>: Dec 25 09:13PM
micky wrote:
> keep pushing until it works. The speaker switch OTOH has a spring that
> pushes it out, past its sweet spot, so now it's hard to get to connect
> at all.
Let's rule out Hertzian waves from Net speeds to begin with. If you have
an FM radio and a Wifi radio in the same room, there'll be a very
noticeable discrepancy.
This phenomenon is so well known that I don't need linger on the cause.
Added to that, you may have two wifi radios together, but processed by
different hardware/ software. And here again the cause needs no explanation.
Your second radio with the dodgy on/off button doesn't even contribute
to the mix; and it won't do so until it produces some output sound. A
faulty switch is a different problem from an echoing, out-of-sync
cacophony of sound.
Ed
|
Ed Cryer <ed@somewhere.in.the.uk>: Dec 25 09:29PM
Ed Cryer wrote:
> faulty switch is a different problem from an echoing, out-of-sync
> cacophony of sound.
> Ed
My best radio is in my bathroom. I didn't put it there; it was in place
when I moved in; it comes through the vent fan which switches on with
the room switch.
I've been trying to figure out for years which station it's tuned to.
Mostly it seems classical, like a choir singing, but now and again it
has a bom-da-da-bom rhythm of rock music. I once heard it playing
Werewolves of London.
If you solve your problem, let me know. I'd love to find out which
station my bathroom is tuned into.
Ed
|
John Larkin <jlarkin@highlandSNIPMEtechnology.com>: Dec 25 01:31PM -0800
On Sun, 25 Dec 2022 16:12:19 -0500, micky <NONONOmisc07@fmguy.com>
wrote:
>Can I just turn off one radio for a few seconds and turn it on again so
>that the total odds over both times have increased that by the second
>time the radios will be in phase?
Phase is probably constant for each radio, but random between
different types.
Measure it.
Sound waves are short so you'd have to be equidistant from both
speakers, without wall reflections, to have phasing mean much.
>keep pushing until it works. The speaker switch OTOH has a spring that
>pushes it out, past its sweet spot, so now it's hard to get to connect
>at all.
Try some contact cleaner.
|
micky <NONONOmisc07@fmguy.com>: Dec 25 05:55PM -0500
In alt.home.repair, on Sun, 25 Dec 2022 16:56:38 -0500, Rachelle
>> some will cancel out?
>Are the radios powered by the same 120v phase or on opposite legs (180
>degree out-of-phase)?
Yes, plugged into the same outlet.
Both are traditional over-the-air AM-FM radios, usually using FM. (One
has bluetooth but it's not in use. )
(To other poster, The radio with the bad speaker switch works well if
the switch stops in the right spot, and sometimes it will stay that way
for days. No access for contact cleaner at the moment.
|
rbowman <bowman@montana.com>: Dec 26 12:12AM
On Sun, 25 Dec 2022 21:29:49 +0000, Ed Cryer wrote:
> If you solve your problem, let me know. I'd love to find out which
> station my bathroom is tuned into.
Don't you have another radio? It would be trivial to scan the frequencies
until you get a match. Doesn't the UK require broadcast stations to
periodically identify themselves?
https://www.transmissionzero.co.uk/radio/london-pirate-radio/
Perhaps it's a pirate with eclectic taste. The local university has a low
power FM station that's all over the map depending on who the DJ is for
the slot.
|
dplatt@coop.radagast.org (Dave Platt): Dec 25 09:54PM -0800
In article <m3fhqhpa8r1b700ol2pk2j6ru33aol4r47@4ax.com>,
>Technical qustion about wave valleys and troughs and if two radio
>playing the same station will be in phase wrt all frequencies, or if
>some will cancel out?
To a very close approximation, the movement of their speaker cones
will be in phase (assuming that the radios are of identical design).
The speed of light (and radio) is fast enough that you need a lot of
separation between two identical radios, before the outputs will
develop a perceptible phase shift.
The in-phase-vs-out-of-phase behavior at the actual listening location,
and its effect on specific frequencies, is dominated by the distance
from each speaker cone to the listener's ear. Since sound moves at only
about 1 foot per millisecond, changing the distances by an inch or two can
make a big difference in which frequencies cancel and which ones reinforce.
>And why is it low frequencies are famous for cancelling out when out of
>phase when high frequencies are just as likely, 0.5, I think, to cancel
>each other out?
They do. However, you're less likely to notice it, for a number of
reasons.
At the higher frequencies, our ears (and brains) are constantly
dealing with the reinforcement and cancellation of different
frequencies, as the sound waves bounce off of floors and ceilings and
create all sorts of "multipath" interference which changes every time
we move a few inches. This happens even for a single sound source
(mono radio, person speaking, etc.). Our brains have evolved to
perceive sound sources even in the face of this sort of multipath
interference and the resulting "comb filter" effect. So, we just
don't notice it consciously when it's happening. You can see the
effect on a spectrogram (pick up the REW software and a good
microphone if you want to experiment).
>Can I just turn off one radio for a few seconds and turn it on again so
>that the total odds over both times have increased that by the second
>time the radios will be in phase?
"In phase" where and at what frequencies? At the speaker cones? At
your current listening position? At the position you'll be in ten
seconds, after you move your head a bit?
>bathroom just fine, but I wonder if some frequencies are out of phase
>from one radio to the other, cancelling each other, and I'm not hearing
>them.
Look at it this way. At a frequency of 1000 Hz (roughly in the middle
of the speech-frequency range), a full wave of the sound is about a
foot long (in air). If you stand between the two radios, and then
move three inches one way or the other, you'll increase one path
length by a quarter-wavelength and reduce the other by a
quarter-wavelength, and thus change the timing difference by half
a wavelength. You'll go from "reinforcement" to "cancellation" (or
vice versa) at this one frequency, just by making this simple little
movement of your head.
At higher frequencies, moving as little as an inch has this same
effect. At lower frequencies, yoh have to move further to change
cancellation into reinforcement.
As you move, you're probably also going to be changing the collection of
reflective paths from each radio to your head, and these changes will
also alter the cancellations and reinforcements. "Multipath" can be
extremely complicated.
>It seems to me, if one radio is farther from the transmitting antenna,
>by 1/2 wave length, the speakers in the two radios will always be going
>in the opposite direction from each other. Maybe.
No, that's too simple a model of how the sound-in-air is related to the
signal-by-radio. It doesn't really work that way.
In FM radio, the position of the speaker cone (pushed towards you or
pulled back to you) depends on the frequency of the RF (above or below
the nominal FM carrier frequency), *not* on the phase of the RF at any
given instant. Delaying the RF by a few cycles will result in only a
negligible delay in the phase of the speaker cone
motion... approximately 1 nanosecond of timing change per foot.
AM detection works somewhat similarly, in that the amplitude of the
signal fed to the speaker is proportional to the _envelope_ of the
RF signal, and not to its instantaneous value or phase.
So, in both AM and FM, the amount of phase shift in the speaker-cone
output caused by moving the radio towards, or away from the transmitter
is tiny. The effect of changing the length of the sound path (in air)
between radio and listener are far, far larger.
(Move the radio 1 foot closer to the transmitter, and you change the
speaker-cone timing by at most a nanosecond or so. At the same time,
you change the speaker-cone-to-ear sound travel timing by as much as
a millisecond. That's a million-to-one difference! Radio fast, sound
slow.)
>xmtr is very similar. But what about within the radio, when the
>heterodyning frequency starts. What if it starts have a cycle after the
>first radio?
Essentially irrelevant, once the heterodyned IF signal hits the
detector (FM detector such as a ratio or quadrature detector, or an AM
envelope or product detector). At this point, the heterodyned IF
signal per se ceases to exist, and we start looking at an audio signal
which is based on a longer-term "measurement" of the IF (its envelope,
or its frequency deviation from nominal center) which doesn't depend
significantly on the phase of the IF or the original RF.
>well, after only 33 years, maybe using it at most 6 times a day, so that
>6x365x33=66,000 times. Aren't switches supposed to last into the
>millions of times?
Switches and relays are (in my experience) often the weakest point in
radios and etc. The contacts wear out or bend, the contacts get dirty or
contaminated (tobacco and cannabis smoke leave a nasty, insulating tar),
the plastic switch body wears out, etc.
Yes, they may be "supposed to" last for hundreds of thousands, or even
millions of cycles, *if* the manufacturer chose a really good switch
and if it's been kept clean. Often, neither of these is the case.
OEMs often "economize" on such things to save a few cents per unit.
If it lasts until after the warranty expires... for many brands,
that's plenty good enough.
I've gotten quite a few radios and so forth "back from the dead" by giving
switches a good cleaning, or (when necessary) replacing them.
|
Martin Brown <'''newspam'''@nonad.co.uk>: Dec 26 09:30AM
On 25/12/2022 22:55, micky wrote:
>> Are the radios powered by the same 120v phase or on opposite legs (180
>> degree out-of-phase)?
> Yes, plugged into the same outlet.
The radio will convert it to DC anyway so that doesn't matter.
> Both are traditional over-the-air AM-FM radios, usually using FM. (One
> has bluetooth but it's not in use. )
Chances are one will be a few hundred ns time shifted relative to the
other since the amplifiers in each stage of detection are unlikely to
have exactly the same delay or frequency phase response.
Propagation of sound waves in the room will have a much larger effect on
what you hear. Positioning of the speakers relative to hard surfaces.
> (To other poster, The radio with the bad speaker switch works well if
> the switch stops in the right spot, and sometimes it will stay that way
> for days. No access for contact cleaner at the moment.
If you really want massive flanging effects try two different digital
radios or SDR decoders within earshot. The difference in delays then can
be fractions of a second or seconds when compared to an FM radio.
DAB is completely useless in an emergency situation unless you have a
shed load of batteries. Uses a set every 8 hours of run time. A decent
FM radio will run for a week or more on just one set of batteries.
--
Regards,
Martin Brown
|
Clive Arthur <clive@nowaytoday.co.uk>: Dec 26 10:48AM
On 25/12/2022 22:55, micky wrote:
> (To other poster, The radio with the bad speaker switch works well if
> the switch stops in the right spot, and sometimes it will stay that way
> for days. No access for contact cleaner at the moment.
I would expect two radios of the same make and model to be in phase, but
different radios will have different amplifier designs and speaker
arrangements which will likely give phase differences at different
frequencies. Plus it is possible that the two loudspeakers are simply
connected in opposite polarity anyway.
--
Cheers
Clive
|
upsidedown@downunder.com: Dec 26 02:49PM +0200
On Sun, 25 Dec 2022 17:55:35 -0500, micky <NONONOmisc07@fmguy.com>
wrote:
>Both are traditional over-the-air AM-FM radios, usually using FM.
Even if two radios produce in phase audio on AM (with equal number of
audio inverting stages) the radio may produce opposite phase audio on
FM. One might have the local oscillator (LO) below the received
frequency (RF), while in the other the LO is above the RF frequency.
|
Ken Blake <Ken@invalid.news.com>: Dec 25 09:41AM -0700
On Sun, 25 Dec 2022 14:04:49 +0000, Andy Burns <usenet@andyburns.uk>
wrote:
>> because of inexpert handling - don't blame yourself, it happens to all of us!
>When it happens, chop the lead in two with a vengeance and discard it, so you're
>not tempted to re-use it later "just temporarily" ...
Better than using a vengeance would be using wire cutter pliers.
|
micky <NONONOmisc07@fmguy.com>: Dec 25 01:13PM -0500
In alt.home.repair, on Sun, 25 Dec 2022 03:40:40 +0100, "Carlos E.R."
>secure the circuits when temps are out of range. Rather, nothing has
>been calculated beyond the design range, and anything could happen. It
>might even work perfectly outside of range. Or catch fire. Anything goes.
Okay, thanks. I won't assume those things. Now I have to think about
it all some more.
|
Char Jackson <none@none.invalid>: Dec 25 04:15PM -0600
On Sun, 25 Dec 2022 14:04:49 +0000, Andy Burns <usenet@andyburns.uk>
wrote:
>> because of inexpert handling - don't blame yourself, it happens to all of us!
>When it happens, chop the lead in two with a vengeance and discard it, so you're
>not tempted to re-use it later "just temporarily" ...
That seems drastic. I've successfully used Ethernet cables where the
barb has fallen off, including one cable that has been barbless for a
number of years. I could lop off the connector and re-terminate it, and
I probably should, but it works fine as it is and I'm too lazy to fix
things that work, so here we are.
|
Paul <nospam@needed.invalid>: Dec 25 08:24PM -0500
On 12/25/2022 9:04 AM, Andy Burns wrote:
> Graham J wrote:
>> the barbs on RJ45 plugs do break off, rendering them useless. They break because of inexpert handling - don't blame yourself, it happens to all of us!
> When it happens, chop the lead in two with a vengeance and discard it, so you're not tempted to re-use it later "just temporarily" ...
You can chop the head off with a vengeance, then put another head on.
Just like that Frankenstein movie.
https://www.amazon.ca/Shahe-Ethernet-Network-Tester-Crimping/dp/B08LQ8QF4Q
One of the images is a video (on the left), and shows "crimping on a new head".
It's just the first thing that showed up in a search, and has
no particular merits.
I've never done one of those, so can't say how easy it is to
get a good termination.
Paul
|
micky <NONONOmisc07@fmguy.com>: Dec 25 09:02PM -0500
In alt.home.repair, on Sun, 25 Dec 2022 20:24:06 -0500, Paul
>You can chop the head off with a vengeance, then put another head on.
>Just like that Frankenstein movie.
> https://www.amazon.ca/Shahe-Ethernet-Network-Tester-Crimping/dp/B08LQ8QF4Q
Char, Paul, I was going to ask about this. I have one of these tools
that I bought for phone cords, but the place that holds the plug is wide
enough ethernet. I just need some connectors.
Mine is just plastic but it worked well. I think I have a professional
model I got at a hamfest or yard sale.
The comments are mostly positive, but this is one star:
>this sucks, the blade doesn't trim wires properly and damages crystals, not worth the money. Wasted so much time on
installs just trying to trim a crystal properly
What is a crystal. The plastic end? Why is he trimming it?
---
Thhis is 4 stars but negative. It implies you should write down the
order of the wires before cutting off the original end.
Will probably work well…. but don't buy
Reviewed in the United States on September 13, 2021
Model: 4in1 Tool KitVerified Purchase
That is, if you've never done this before. Instead, get a pass-through
crimper and plug set and your life will be easier. See, the cable wires
[What's that?]
you want to splice must be unraveled into the 8 individual data wires
and put into a specific color order to be inserted into the modular plug
and then crimped. (By the way, the video on the page shows the order for
only the rare, 568A configuration. Most systems call for the 568B
configuration which orders the wires differently. Be sure you know what
configuration you are working with before you order the wire colors. A
568B wire-order diagram is on the product page.) It's not too difficult
to separate, smooth the wires, and get them into the right color order
when you're working with two inches of the cable wires. But holding that
order in your fingers right next to the plastic cable sheathing,
clipping the wires down to a half inch and then inserting all of them
all into the plug at the same time is very difficult for a first timer
and takes a lot of practice (I assume). The problem is that the wires
terminate at the end of the plug. You can't hold one wire in that
position while you mess with other wires that are misbehaving; and they
[I know. It was pretty easy for 4 wires, haven't tried more.]
will misbehave. The pass-through plugs help solve this by letting the
wires go in the back of the plug into their proper channel and then
extend out through the front end of the plug. This way you don't have to
clip the wires before inserting them. You can actually insert one wire
at a time and when it passes through the front bend it so that it stays
put while you insert the next wire in the order (a procedure that
probably infuriates the purists). Once all the wires are inserted
through in the right order the special pass-through crimper not only
locks down the wires and sheathing, but also clips the excess wires in
front of the plug. You just have to be careful when inserting the wires
that you don't skip a hole and end up one or two wires with no home.
You'll also want to twist the end of the loose wires together after
their all in to get them through the crimping hole cleanly. Finally,
remember to slip the plug cover on the cable before you start working
[shoudln't be "finally". Should be first.]
with the wire. You can find the pass-through crimpers here on Amazon by
searching for them specifically. It will still be a tedious process but
at least doable for a novice. Good luck.
One person found this helpful
Report abuse
--
Here is one that is called pass-through. I don't know why it would be
easier.
https://www.amazon.com/CHZHLM-Through-Connector-Connectors-Stripper/dp/B0B73Y5RS4/ref=sr_1_1_sspa
>no particular merits.
>I've never done one of those, so can't say how easy it is to
>get a good termination.
Phone line was easy.
|
Bob F <bobnospam@gmail.com>: Dec 25 08:13PM -0800
On 12/25/2022 6:02 PM, micky wrote:
> --
> Here is one that is called pass-through. I don't know why it would be
> easier.
I would imagine you can cut the wires much longer, push them through,
then pull them each tight to pull the wire casing tight into the
connector. then cut off the extra wire ends. That may be easier than
trying to cut them to the final length, get them ordered correctly in a
TIGHT flat pattern, then push them all the way into their appropriate holes.
|
Char Jackson <none@none.invalid>: Dec 25 11:30PM -0600
>no particular merits.
>I've never done one of those, so can't say how easy it is to
>get a good termination.
The crimper linked above is essentially what I use and it works well. It
probably helps that I've done a crap ton of them. If I was asked to make
a recommendation to someone who doesn't have much experience, I would
very definitely recommend the pass-thru type of connector. They're quite
a bit easier, especially for someone who's just getting started.
Someone else mentioned TIA 568B (vs 568A). If a diagram isn't handy, you
can use the other end of the cable that you're working on. Put the two
connectors side by side, not end to end, and just match the colors.
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whit3rd <whit3rd@gmail.com>: Dec 25 09:50PM -0800
On Monday, December 19, 2022 at 9:09:44 AM UTC-8, micky wrote:
> PC, or maybe something that connected straight to the PC.
> But all I see for sale are cameras meant to clip to the monitor, not be
> screwed to the wall.
Oh, they're available four outdoor install. This one, for instance <at temu.com search for LY02238>
The POE (power-over-ethernet) type don't require house current directly (you'll
need a switch or POE power injector in addition to ethernet interfaces).
|
Andy Burns <usenet@andyburns.uk>: Dec 26 06:29AM
Char Jackson wrote:
> That seems drastic. I've successfully used Ethernet cables where the
> barb has fallen off, including one cable that has been barbless for a
> number of years.
And then one day, someone is doing the hoovering, or kicks a desk, or a pet gets
round the back, and something stops working ... if you can retuerminate it with
a new plug, sure but patch cables are cheap, stuff not working is frequently
expensive ...
|
Andy Burns <usenet@andyburns.uk>: Dec 26 06:32AM
micky wrote:
> I have one of these tools
> that I bought for phone cords, but the place that holds the plug is wide
> enough ethernet. I just need some connectors.
Most plugs are for 'solid' cable, to repair patch cables you need to get the
type of plugs for 'stranded' cable, I think there is also a type of plug that
copes with both ...
|
Piet <www.godfatherof.nl/@opt-in.invalid>: Dec 26 10:40AM +0100
Ken Blake wrote:
>> A plastic lunch box, silicone sealant and a bit of home work would
>> do the job in a cheap way. I
> But if a hungry thief sees the lunch box...
Then (s)he would be disappointed by the not exactly nutritious content. ;-)
-p
|
Paul <nospam@needed.invalid>: Dec 26 05:05AM -0500
On 12/25/2022 9:02 PM, micky wrote:
>> I've never done one of those, so can't say how easy it is to
>> get a good termination.
> Phone line was easy.
It just means you can stuff the wires one at a time into
the connector and it won't pop out of place.
The T368A and T368B thing is for rolled or straight-thru cabling.
I can tell this, by noting the reversal of 1,2 3,6 on the two connectors
in the depiction.
1,2 to 1,2 Straight-thru (most all of my cables are like this)
3,6 to 3,6
1,2 to 3,6 Rolled cable (only one spare is like this, haven't used in some time)
3,6 to 1,2 (Could have blue boot on one end, red boot on other end of cable)
Any more info than that, you'll have to look up. A rolled cable
might be used between a broadband modem and a router. Straight cables
tend to be used from router to PC or switch to PC. Doing direct PC to PC,
uses a rolled cable (only if both ends are limited to 10/100BT NICs).
GbE equipment has MDI/MDIX which can deal with either straight or
rolled cabling.
Paul
|
