Re: Time Domain Reflectometer (was Re: internet outages)

[rhkramer]

I (John Hasler) wrote:
> As to TDRs, if you can get by without actually seeing pictures of all
> the impedence bumps 

> you can get by with a fast counter, a high risetime
> pulse generator, and a couple of fast comparators.  Maybe $20 at
> Digikey.

You (Randy Kramer) wrote:
> Can you elaborate a little on how that would work?  

Apply the pulse to the cable under test.  The rising edge triggers the
counter and enables the comparators.  One comparator triggers on the
first rising edge on a return pulse, latching the count and disabling
itself.  The other comparator triggers on the first falling edge on a
return pulse, latching the count in a different register and also
disables itself.

The count latched by the positive comparator represents the distance to
first positive impedance bump encountered by the pulse. An open will
double the applied voltage.  The other will represent the distance to
the first negative bump.  A short will invert the voltage.

You'll want to make the thresholds adjustable, of course, and you will
also want to add range gating so that you can ignore all but a selected
section of the cable.

There are some time to distance converter chips that would be ideal for
this.  You'll want to put the whole thing under the control of a micro,
of course.  It could scan the range gates up and down the cable and
report impedance as a function of distance.
-- 
John Hasler 
jhas...@newsguy.com
Elmwood, WI USA

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 15:22:07 Ric Moore wrote:

> On 12/24/18 1:27 PM, Gene Heskett wrote:
> > On Monday 24 December 2018 12:29:53 rhkra...@gmail.com wrote:
> >> On Monday, December 24, 2018 08:39:18 AM Gene Heskett wrote:
> >>> On Monday 24 December 2018 08:18:27 Carl Fink wrote:
>  On 12/24/18 7:37 AM, Gene Heskett wrote:
> > I have a firmware update file kit for it, but it requires a dos
> > box with a usb port. When was the last time you saw one of them?
> > Short answer is never.
> 
>  Doesn't freeDOS support USB? I know they recommend booting off a
>  USB drive.
> 
>  There's a commercial DOS driver, DOSUSB, but it's very expensive.
> >>>
> >>> I'll have to check that FreeDOS out. Unforch this old Asus board
> >>> won't boot from usb.
> >>
> >> There is (are?) dos emulator(s?) for Linux -- do any of those
> >> support a usb port?
> >
> > No clue, thats another round tuit I've misslaid someplace. And ATM.
> > I have 2 milling machines broken and am having to buy a third to fix
> > the 1st one. But the ball screw I need to fix the 2nd one seems to
> > be made from pure unobtainium, an 8mm by 500mm. The best I can do is
> > only 130mm long. :(
>
> Just so you know, they are republishing Carl and Jerry from Popular
> Electronics. I just received the first year collection, sold over at
> lulu.com :) Ric

That was tongue in cheek at its finest.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 14:10:44 rhkra...@gmail.com wrote:

> Hmm, intended to send this to the list, sent to John Hasler, only, who
> did respond -- I hope he will copy his reply to the ist (or tell me it
> is ok to do so).
>
> On Monday, December 24, 2018 08:21:57 AM John Hasler wrote:
> > As to TDRs, if you can get by without actually seeing pictures of
> > all the impedence bumps
> >
> >
> > you can get by with a fast counter, a high risetime
> > pulse generator, and a couple of fast comparators.  Maybe $20 at
> > Digikey.
>
> Can you elaborate a little on how that would work?
I can imagine the first fast comparator would enable the counter, 
previously held in reset and the second comparator is then enabled, and 
its threshhold adjusted for a stable stop of the counter, giving the 
number of input cycles between the start and the stop. Decent calculator 
math would then give you the distance to the major impedance disturbance 
that caused the echo.

You need a GHz (at least) signal source to count, the higher, the more 
accurate. The delay of course is 2 way, out to the fault and back, so 
convert that to distance one way with a /2.000 after using the usual 
hambooks 984/frequency derivation to get the wavelength in feet IIRC. 
Ideally the frequency should be a wavelength short enough to give decent 
accuracy because this method will only give you the number of cycles as 
an integer. You send the pulse and wait for the echo to come back and 
stop the counter. Multiply the wavelength by the counter to get how far 
away the fault is, multiply that by the PV of the line being tested and 
divide by 2 to get the one way distance.

Clear as mud, right? 2000 feet of 6.125" inch line can be fun due to 
losses weakening the return signal. Specially a fast one like a tunnel 
diode might make. And no bets at all for a broadcast antenna because the 
pulse is not frequency shaped to match the antenna's operating 
frequency, so from the fine matcher on into the element array, its a 
broadband mess that splatters all over the TDR screen. Seeing that on a 
real TDR with trained eyeballs seems to be the only way to tell that, 
from a cracked and burned up elbow 50 feet below it at the tower top to 
antenna feed connections.  And that 50 feet might be a weeks work for a 
tower crew with some antenna styles. And of course it always happens in 
bad weather, making the high steel work dangerous because there may be a 
6" thick layer of ice on everything 2000 feet up. 

That broken elbow might be the starting point, but the fire then moves 
down the line towards the power source and may burn up 600 feet of line 
before the transmitters VSWR protection circuits can shut it down. Been 
there, done that, several times at what was once NETV's KXNE transmitter 
on UHF channel 19. Rosemounts rime ice detectors buried on the antenna 
structure had an average lifetime of a year. They cost quite a bit, but 
their failure mode was always safe mode, so you didn't know a thing 
until the main beam power breaker opened in response to the rising VSWR. 
By then you were out 10 to 50 grand and several days to get a crew 
rounded up to work on it, to get it back on the air. More than once in 
that decade we had to let them sit around, or go do another job while 
the ice went away. One time litterally tons of it had formed a flag 
about 8 feet long on the downwind side of that storm.  Cleaning 600 feet 
of that line and rebuilding it took time, rags by the pickup load of 
bags, alcohol in several 5 gallon buckets, and teflon parts aren't free 
either. I'm glad I'm retired now.

Now, back to the asinine arguments about boobs. Is this our regularly 
scheduled programming for this week? :)

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[Ric Moore]

On 12/24/18 1:27 PM, Gene Heskett wrote:

On Monday 24 December 2018 12:29:53 rhkra...@gmail.com wrote:


On Monday, December 24, 2018 08:39:18 AM Gene Heskett wrote:

On Monday 24 December 2018 08:18:27 Carl Fink wrote:

On 12/24/18 7:37 AM, Gene Heskett wrote:

I have a firmware update file kit for it, but it requires a dos
box with a usb port. When was the last time you saw one of them?
Short answer is never.


Doesn't freeDOS support USB? I know they recommend booting off a
USB drive.

There's a commercial DOS driver, DOSUSB, but it's very expensive.


I'll have to check that FreeDOS out. Unforch this old Asus board
won't boot from usb.


There is (are?) dos emulator(s?) for Linux -- do any of those support
a usb port?


No clue, thats another round tuit I've misslaid someplace. And ATM. I
have 2 milling machines broken and am having to buy a third to fix the
1st one. But the ball screw I need to fix the 2nd one seems to be made
from pure unobtainium, an 8mm by 500mm. The best I can do is only 130mm
long. :(




Just so you know, they are republishing Carl and Jerry from Popular 
Electronics. I just received the first year collection, sold over at 
lulu.com :) Ric

Re: Time Domain Reflectometer (was Re: internet outages)

[John Hasler]

rhkramer writes:
> Hmm, intended to send this to the list, sent to John Hasler, only, who
> did respond -- I hope he will copy his reply to the ist (or tell me it
> is ok to do so).

Go ahead.
-- 
John Hasler 
jhas...@newsguy.com
Elmwood, WI USA

Re: Time Domain Reflectometer (was Re: internet outages)

[rhkramer]

Hmm, intended to send this to the list, sent to John Hasler, only, who did 
respond -- I hope he will copy his reply to the ist (or tell me it is ok to do 
so).

On Monday, December 24, 2018 08:21:57 AM John Hasler wrote:
> As to TDRs, if you can get by without actually seeing pictures of all
> the impedence bumps 


> you can get by with a fast counter, a high risetime
> pulse generator, and a couple of fast comparators.  Maybe $20 at
> Digikey.

Can you elaborate a little on how that would work?  

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 12:29:53 rhkra...@gmail.com wrote:

> On Monday, December 24, 2018 08:39:18 AM Gene Heskett wrote:
> > On Monday 24 December 2018 08:18:27 Carl Fink wrote:
> > > On 12/24/18 7:37 AM, Gene Heskett wrote:
> > > > I have a firmware update file kit for it, but it requires a dos
> > > > box with a usb port. When was the last time you saw one of them?
> > > > Short answer is never.
> > >
> > > Doesn't freeDOS support USB? I know they recommend booting off a
> > > USB drive.
> > >
> > > There's a commercial DOS driver, DOSUSB, but it's very expensive.
> >
> > I'll have to check that FreeDOS out. Unforch this old Asus board
> > won't boot from usb.
>
> There is (are?) dos emulator(s?) for Linux -- do any of those support
> a usb port?

No clue, thats another round tuit I've misslaid someplace. And ATM. I 
have 2 milling machines broken and am having to buy a third to fix the 
1st one. But the ball screw I need to fix the 2nd one seems to be made 
from pure unobtainium, an 8mm by 500mm. The best I can do is only 130mm 
long. :(

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[rhkramer]

On Monday, December 24, 2018 08:39:18 AM Gene Heskett wrote:
> On Monday 24 December 2018 08:18:27 Carl Fink wrote:
> > On 12/24/18 7:37 AM, Gene Heskett wrote:
> > > I have a firmware update file kit for it, but it requires a dos box
> > > with a usb port. When was the last time you saw one of them? Short
> > > answer is never.
> > 
> > Doesn't freeDOS support USB? I know they recommend booting off a USB
> > drive.
> > 
> > There's a commercial DOS driver, DOSUSB, but it's very expensive.
> 
> I'll have to check that FreeDOS out. Unforch this old Asus board won't
> boot from usb.

There is (are?) dos emulator(s?) for Linux -- do any of those support a usb 
port?

Re: Time Domain Reflectometer (was Re: internet outages)

[Dan Ritter]

Gene Heskett wrote: 
> On Sunday 23 December 2018 20:27:37 rhkra...@gmail.com wrote:
> 
> > On Sunday, December 23, 2018 07:33:38 PM Doug wrote:
> > > RE: Time Domain Reflectometer:
> > >
> > > Theoretically, you can build your own with a fast pulse generator
> > > and an oscilloscope. The trick is, you need a REALLY FAST
> > > oscilloscope!  The pulse generator is easy, just a couple of
> > > transistors, maybe a diode. The  circuit is probably in every
> > > edition of the Radio Amateur's Handbook. The scope is expensive. If
> > > you don't have at least a 1GHz digital sampling scope, don't bother!
> > >
> > > --doug, WA2SAY, retired RF engineer
> >
> > Hmm, with CPU clocks hitting 4 GHz, I wonder how expensive an ADC
> > converter to work at corresponding speeds would be?  (Just an idle
> > question ;-)
> 
> If you have to ask, you can't afford it. Bring outrageous sums of money
> This is typically done by every trick tek knows about fast analogue 
> circuitry, in the best units with long vertical deflection plates in a 
> custom made crt with teeny delay lines between the sections of the 
> plates so the signal is virtually traveling toward the screen at the 
> same speed as the electron beam is traveling. And its moving fast enough 
> at 22,000 volts, relativity can and does get in the way. Such scopes put 
> the plates so close to the beam that the beam is intercepted by striking 
> the plates at just a hair over 4 cm high, 2cm from the horizontal center 
> line. The only one of those I ever saw was in the early 1980's or so at 
> the NAB show in Vegas, and it was well into a 5 digit asking price then.

We're almost in 2019, which means:

https://www.mouser.com/ProductDetail/Analog-Devices/HMCAD1511?qs=sGAEpiMZZMvTvDTV69d2Qnrp4UY3MFmsfo%252bIC8KWhPQ%3d

Analog Devices HMCAD1511 
1 GS/s, 8 bits, 1 channel: quantity 1 from Mouser: $64.76.

That's the cheapest GHz+ ADC they have; you can still go up to
much heftier prices for more channels, more bit depth, even
higher sampling rates.

-dsr-

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 08:57:27 Joe wrote:

> On Mon, 24 Dec 2018 08:09:11 -0500
>
> Gene Heskett  wrote:
> > On Monday 24 December 2018 04:26:05 Joe wrote:
> > > There is normally a real Nyquist bandwidth quoted somewhere in the
> > > small print. I used to repair and calibrate Hitachi scopes for a
> > > while, until everyone stopped using them.
> >
> > I wonder why, Joe. My V-1065 still works well enough to measure
> > frequency at a 1% accuracy, and its now pushing 35yo. In a pinch
> > I've looked at the output sample of an old analogue tv transmitter
> > to adjust the modulation depth when the monitor was bonkers, it was
> > actually usable at 180 mhz.
>
> I used to see about three or four of the 665/1065 series a week,
> mostly ten years old with mains switcher problems. Mostly routine
> fixing, after the initial pain of troubleshooting a mains switcher.
> Capacitors, mostly. Even the high-ripple ones will only run so long
> before they dry up.
>
> Then over about six months, it dropped off to nothing, and we never
> saw any more. I assume oscilloscope use had dropped off enough that
> people could just put a dead one in a cupboard wand say 'we'll get it
> fixed if we ever need it'. Fortunately, oscilloscopes were a minor
> sideline, so I didn't run out of work. The company still has a 1085,
> which I use occasionally. At home, I have a 35-yo Kikusui, and a
> temperamental Tek 465B of uncertain age, but older than that.

465B's were temperamental allright, and way the hell out of calibration 
due to drifting R's on the custom made ceramic input attenuator, and tek 
has had no service parts for that for nearly 40 years now, and wanted 
nearly $400 for one then.  Then they merged with GVG, and it all went to 
hell. I needed the custom ceramic plate they made a video op-amp on in 
about 1995 as we had bought KTLA's old 300-3A/B complete with a digital 
effects unit. They had just one, $1500, as is, where is! I said no, 
I don't think so, and started looking in the chip books, finding a 
single ended one from TI for just under $2. Should bought 2 sticks of 
them, it was enough faster that it threw the color phase out more than 
there was adjustments for. There was about 8 of them in each channel, 
and 6 paths thru that switcher. I should have shotgunned them all, but 
since the packaging was different, each one would have taken around an 
hour to do neatly. And I was thinking of retireing by then so it never 
got done. If I'd have done them all, the video bandwidth would have been 
at least trippled. Way ahead of its time in what it could do, I think 
that was close to GVG's last hurrah. But the controls were about shot 
too. GVG had an accessory E-Disk so the tech directors could program 
their own bag of tricks, gvg wanted 20 thou for it. But when we got the 
first copy of that switcher from the Penny's production house in NYC, it 
came with the edisk manual and the com protocol specs. I looked at that, 
said I can do that on a trs-80 color computer, took an old coco2 and 
added "the Forgitten Chip" to give it a hardware rs232, wrote the 
utility in basic09, which ran on the after market *nix imitation, called 
os9, and sold it and two disk drives to the tv station for $245. Later I 
found out mine was 4x faster than theirs! Not to mention it gave the 
operators english names for their bags of tricks. And because that gave 
me a comm path into the switchers innards, I wrote some more utils that 
could reach into its control logic and identify which logic chip had 
died. Handier than bottled beer in the long haul.

Oh, and I lied about the year in a previous msg this morning, I was 16 so 
that was 1950, and the scope was a Hickock 505.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[Joe]

On Mon, 24 Dec 2018 08:09:11 -0500
Gene Heskett  wrote:

> On Monday 24 December 2018 04:26:05 Joe wrote:
> 

> >
> > There is normally a real Nyquist bandwidth quoted somewhere in the
> > small print. I used to repair and calibrate Hitachi scopes for a
> > while, until everyone stopped using them.  
> 
> I wonder why, Joe. My V-1065 still works well enough to measure
> frequency at a 1% accuracy, and its now pushing 35yo. In a pinch I've
> looked at the output sample of an old analogue tv transmitter to
> adjust the modulation depth when the monitor was bonkers, it was
> actually usable at 180 mhz. 

I used to see about three or four of the 665/1065 series a week, mostly
ten years old with mains switcher problems. Mostly routine fixing, after
the initial pain of troubleshooting a mains switcher. Capacitors,
mostly. Even the high-ripple ones will only run so long before they dry
up.

Then over about six months, it dropped off to nothing, and we never
saw any more. I assume oscilloscope use had dropped off enough that
people could just put a dead one in a cupboard wand say 'we'll get it
fixed if we ever need it'. Fortunately, oscilloscopes were a minor
sideline, so I didn't run out of work. The company still has a 1085,
which I use occasionally. At home, I have a 35-yo Kikusui, and a
temperamental Tek 465B of uncertain age, but older than that.

-- 
Joe

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 08:21:57 John Hasler wrote:

> Gene writes:
> > In a cnc machine running on stepper motors, the current regulating
> > of the drivers if the grounding is not truly single point, can
> > crosstalk at the regulating frequency, usually well above 20
> > kilohertz, at peak voltages well over what it takes to destroy an
> > fpga gate as the ringing in that event often peaks at over 100 MHz
> > and 30
> > volts. Trivial to see on the samplers display, but turn off the room
> > lights and really study what you see on a 100+ megahertz analogue
> > scope.
>
> For that sort of thing you want a storage scope.  Old Nicolets are
> readily available for prices that even I can almost justify.
>
> I used Tektronix analog storage scopes when doing motor control design
> in the seventies but the digital ones are orders of magnitude better.
> Being able to trigger on things that already happened is cool.
>
> Before that it was cameras.
>
> As to TDRs, if you can get by without actually seeing pictures of all
> the impedence bumps you can get by with a fast counter, a high
> risetime pulse generator, and a couple of fast comparators.  Maybe $20
> at Digikey.

I dunno if I could tolerate losing the pix, this old f--- has had a scope 
probe in one hand since 1951.


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 08:18:27 Carl Fink wrote:

> On 12/24/18 7:37 AM, Gene Heskett wrote:
> > I have a firmware update file kit for it, but it requires a dos box
> > with a usb port. When was the last time you saw one of them? Short
> > answer is never.
>
> Doesn't freeDOS support USB? I know they recommend booting off a USB
> drive.
>
> There's a commercial DOS driver, DOSUSB, but it's very expensive.
I'll have to check that FreeDOS out. Unforch this old Asus board won't 
boot from usb.

Thanks Carl.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[John Hasler]

Gene writes:
> In a cnc machine running on stepper motors, the current regulating of
> the drivers if the grounding is not truly single point, can crosstalk
> at the regulating frequency, usually well above 20 kilohertz, at peak
> voltages well over what it takes to destroy an fpga gate as the
> ringing in that event often peaks at over 100 MHz and 30
> volts. Trivial to see on the samplers display, but turn off the room
> lights and really study what you see on a 100+ megahertz analogue
> scope.

For that sort of thing you want a storage scope.  Old Nicolets are
readily available for prices that even I can almost justify.

I used Tektronix analog storage scopes when doing motor control design
in the seventies but the digital ones are orders of magnitude better.
Being able to trigger on things that already happened is cool.

Before that it was cameras.

As to TDRs, if you can get by without actually seeing pictures of all
the impedence bumps you can get by with a fast counter, a high risetime
pulse generator, and a couple of fast comparators.  Maybe $20 at
Digikey.
-- 
John Hasler 
jhas...@newsguy.com
Elmwood, WI USA

Re: Time Domain Reflectometer (was Re: internet outages)

[Carl Fink]

On 12/24/18 7:37 AM, Gene Heskett wrote:

I have a firmware update file kit for it, but it requires a dos box with
a usb port. When was the last time you saw one of them? Short answer is
never.


Doesn't freeDOS support USB? I know they recommend booting off a USB
drive.

There's a commercial DOS driver, DOSUSB, but it's very expensive.

--
Carl Fink  c...@finknetwork.com
Thinking and logic and stuff at Reasonably Literate
http://reasonablyliterate.com

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 04:26:05 Joe wrote:

> On Sun, 23 Dec 2018 22:54:20 -0600
>
> John Hasler  wrote:
> > rhkramer writes:
> > > Yeah, but I wasn't thinking about actually using a CRT to display
> > > the signal in real time, but, instead, collect samples (at maybe 4
> > > GHz??), store them, and then display them as a static display.
> >
> > At that sort of frequency sampling scopes (including the old crt
> > ones) sample at far below the signal repitition rate.
>
> Yes, they rely on the signal being repetitive. To see a single
> transient, you want at least five samples in the relevant period,
> preferably more.
>
> There is normally a real Nyquist bandwidth quoted somewhere in the
> small print. I used to repair and calibrate Hitachi scopes for a
> while, until everyone stopped using them.

I wonder why, Joe. My V-1065 still works well enough to measure frequency 
at a 1% accuracy, and its now pushing 35yo. In a pinch I've looked at 
the output sample of an old analogue tv transmitter to adjust the 
modulation depth when the monitor was bonkers, it was actually usable at 
180 mhz. 

Their absolute top of the line V-1085, 200 mhz had a totally duff 
triggering circuit in it so I sent 2 of it back, but its baby brother, a 
4 trace 100 mhz was an absolute doll, and the only analogue scope that 
would let you do the final calibration after replacing the head wheel on 
a Panasonic DVC-PRO broadcast vtr. At $1500-2000+ a copy, I've done that 
about 100,000 dollars worth of that. That and replaceing the tiny 
electrolytic caps by the 3 lb coffee can full. 3 of those IIRC before I 
retired in 2002. Failure rate on those in the dvc-pro's was near 100% in 
2 or 3 years. Had to buy 'em from Pan., because all the others were 
physically too big. Glad those are now history and I've retired, bending 
over to see thru a big magnifying light 6-7 hours a day for a week or 
more at a time is half of whats wrong with my back today.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Monday 24 December 2018 04:20:45 Joe wrote:

> On Sun, 23 Dec 2018 23:11:35 -0500
>
> Gene Heskett  wrote:
> > Thats essentially what our high bandwidth scopes do today, $400 gets
> > you a 1ghz sampler with an effective bandwidth of 200 mhz. I've got
> > one, the nice thing is that because it is digital, a once a second
> > glitch in a 42 megabaud seriel data train stands out like a sore
> > thumb because its not limited to the screen writing speed of an
> > analogue scope. So its just as bright as the main signal that
> > doesn't have the glitch. The operating software is buggier than a 10
> > day old road kill in August though.
>
> Ah, Hantek (or one of its aliases). Yes. I have the bottom-end one,
> mainly for DC and audio. The triggering is worthless.

I think mine is a Gratten, and the triggering is fine once you hit the 
magic twanger, but the firmware that controls it is buggier than a 10 
day old road kill in August.

I have a firmware update file kit for it, but it requires a dos box with 
a usb port. When was the last time you saw one of them?  Short answer is 
never. 

dfu on linux won't talk to it. And I've never seen a dos with usb 
drivers, not even the last drdos. If anyone knows how to get past that, 
I'd be a happy camper indeed. Or maybe they charge for the access key, I 
see the unpacked firmware dir has an empty "key" directory. If anyone 
knows how to get past that... The manual, ADS1000*.pdf 
does very carefully NOT mention it.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Sunday 23 December 2018 23:54:20 John Hasler wrote:

> rhkramer writes:
> > Yeah, but I wasn't thinking about actually using a CRT to display
> > the signal in real time, but, instead, collect samples (at maybe 4
> > GHz??), store them, and then display them as a static display.
>
> At that sort of frequency sampling scopes (including the old crt ones)
> sample at far below the signal repitition rate.

And depend on being out of synch with a repetitive signal, so they in 
effect build up an image that covers enough time samples to assemble the 
waveform.  So you do not see it in real time. But the glitch is still 
caught, and you will see a full brightness dot or pulse thats out of 
place.  In a cnc machine running on stepper motors, the current 
regulating of the drivers if the grounding is not truly single point, 
can crosstalk at the regulating frequency, usually well above 20 
kilohertz, at peak voltages well over what it takes to destroy an fpga 
gate as the ringing in that event often peaks at over 100 MHz and 30 
volts. Trivial to see on the samplers display, but turn off the room 
lights and really study what you see on a 100+ megahertz analogue scope.
Probably also true of servo-motors today since they are often driven at 
full power with pwm signals.  Much more efficient to make the motors 
inductance work for you instead of against you. The drivers will heat at 
1% or less compared to an analogue drive with the same effective gain 
and power. They heat only during the transition, with very little heat 
when on, and no heat when off. So the faster you can make that 
transition, the cooler it stays. I use such an amplifier thats not much 
bigger than a pack of camel cigarettes, to run a 1hp at 90 volts at 9.7 
amps rated spindle motor on a 127 volt, 20+ amp capable supply, so it 
can do in a short 1/2 second surge, around 2 hp. I've never scanned the 
heat sink with an IR thermometer and found it above 85F in a 75F room.  
The only time I hear it is when this amplifier regulates the current, 
which I've set at 17 amps, makeing the motor iron "chirp". I figure 
thats enough considering that the gear train its driving is plastic.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[Joe]

On Sun, 23 Dec 2018 22:54:20 -0600
John Hasler  wrote:

> rhkramer writes:
> > Yeah, but I wasn't thinking about actually using a CRT to display
> > the signal in real time, but, instead, collect samples (at maybe 4
> > GHz??), store them, and then display them as a static display.  
> 
> At that sort of frequency sampling scopes (including the old crt ones)
> sample at far below the signal repitition rate.

Yes, they rely on the signal being repetitive. To see a single
transient, you want at least five samples in the relevant period,
preferably more.

There is normally a real Nyquist bandwidth quoted somewhere in the
small print. I used to repair and calibrate Hitachi scopes for a while,
until everyone stopped using them.

-- 
Joe

Re: Time Domain Reflectometer (was Re: internet outages)

[Joe]

On Sun, 23 Dec 2018 23:11:35 -0500
Gene Heskett  wrote:

> Thats essentially what our high bandwidth scopes do today, $400 gets
> you a 1ghz sampler with an effective bandwidth of 200 mhz. I've got
> one, the nice thing is that because it is digital, a once a second
> glitch in a 42 megabaud seriel data train stands out like a sore
> thumb because its not limited to the screen writing speed of an
> analogue scope. So its just as bright as the main signal that doesn't
> have the glitch. The operating software is buggier than a 10 day old
> road kill in August though. 

Ah, Hantek (or one of its aliases). Yes. I have the bottom-end one,
mainly for DC and audio. The triggering is worthless.

-- 
Joe

Re: Time Domain Reflectometer (was Re: internet outages)

[John Hasler]

rhkramer writes:
> Yeah, but I wasn't thinking about actually using a CRT to display the
> signal in real time, but, instead, collect samples (at maybe 4 GHz??),
> store them, and then display them as a static display.

At that sort of frequency sampling scopes (including the old crt ones)
sample at far below the signal repitition rate.
-- 
John Hasler 
jhas...@newsguy.com
Elmwood, WI USA

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Sunday 23 December 2018 22:20:30 rhkra...@gmail.com wrote:

> On Sunday, December 23, 2018 09:03:15 PM Gene Heskett wrote:
> > On Sunday 23 December 2018 20:27:37 rhkra...@gmail.com wrote:
> > > On Sunday, December 23, 2018 07:33:38 PM Doug wrote:
> > > > RE: Time Domain Reflectometer:
> > > >
> > > > Theoretically, you can build your own with a fast pulse
> > > > generator and an oscilloscope. The trick is, you need a REALLY
> > > > FAST oscilloscope!  The pulse generator is easy, just a couple
> > > > of transistors, maybe a diode. The  circuit is probably in every
> > > > edition of the Radio Amateur's Handbook. The scope is expensive.
> > > > If you don't have at least a 1GHz digital sampling scope, don't
> > > > bother!
> > > >
> > > > --doug, WA2SAY, retired RF engineer
> > >
> > > Hmm, with CPU clocks hitting 4 GHz, I wonder how expensive an ADC
> > > converter to work at corresponding speeds would be?  (Just an idle
> > > question ;-)
> >
> > If you have to ask, you can't afford it. Bring outrageous sums of
> > money This is typically done by every trick tek knows about fast
> > analogue circuitry, in the best units with long vertical deflection
> > plates in a custom made crt with teeny delay lines between the
> > sections of the plates so the signal is virtually traveling toward
> > the screen at the same speed as the electron beam is traveling. And
> > its moving fast enough at 22,000 volts, relativity can and does get
> > in the way. Such scopes put the plates so close to the beam that the
> > beam is intercepted by striking the plates at just a hair over 4 cm
> > high, 2cm from the horizontal center line. The only one of those I
> > ever saw was in the early 1980's or so at the NAB show in Vegas, and
> > it was well into a 5 digit asking price then.
>
> Yeah, but I wasn't thinking about actually using a CRT to display the
> signal in real time, but, instead, collect samples (at maybe 4 GHz??),
> store them, and then display them as a static display.
>
> ???

Thats essentially what our high bandwidth scopes do today, $400 gets you 
a 1ghz sampler with an effective bandwidth of 200 mhz. I've got one, the 
nice thing is that because it is digital, a once a second glitch in a 42 
megabaud seriel data train stands out like a sore thumb because its not 
limited to the screen writing speed of an analogue scope. So its just as 
bright as the main signal that doesn't have the glitch. The operating 
software is buggier than a 10 day old road kill in August though. I have 
both. My analogue Hitachi is actually good to around 200 mhz.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: Time Domain Reflectometer (was Re: internet outages)

[rhkramer]

On Sunday, December 23, 2018 09:03:15 PM Gene Heskett wrote:
> On Sunday 23 December 2018 20:27:37 rhkra...@gmail.com wrote:
> > On Sunday, December 23, 2018 07:33:38 PM Doug wrote:
> > > RE: Time Domain Reflectometer:
> > > 
> > > Theoretically, you can build your own with a fast pulse generator
> > > and an oscilloscope. The trick is, you need a REALLY FAST
> > > oscilloscope!  The pulse generator is easy, just a couple of
> > > transistors, maybe a diode. The  circuit is probably in every
> > > edition of the Radio Amateur's Handbook. The scope is expensive. If
> > > you don't have at least a 1GHz digital sampling scope, don't bother!
> > > 
> > > --doug, WA2SAY, retired RF engineer
> > 
> > Hmm, with CPU clocks hitting 4 GHz, I wonder how expensive an ADC
> > converter to work at corresponding speeds would be?  (Just an idle
> > question ;-)
> 
> If you have to ask, you can't afford it. Bring outrageous sums of money
> This is typically done by every trick tek knows about fast analogue
> circuitry, in the best units with long vertical deflection plates in a
> custom made crt with teeny delay lines between the sections of the
> plates so the signal is virtually traveling toward the screen at the
> same speed as the electron beam is traveling. And its moving fast enough
> at 22,000 volts, relativity can and does get in the way. Such scopes put
> the plates so close to the beam that the beam is intercepted by striking
> the plates at just a hair over 4 cm high, 2cm from the horizontal center
> line. The only one of those I ever saw was in the early 1980's or so at
> the NAB show in Vegas, and it was well into a 5 digit asking price then.

Yeah, but I wasn't thinking about actually using a CRT to display the signal 
in real time, but, instead, collect samples (at maybe 4 GHz??), store them, 
and then display them as a static display.

???

Re: Time Domain Reflectometer (was Re: internet outages)

[Gene Heskett]

On Sunday 23 December 2018 20:27:37 rhkra...@gmail.com wrote:

> On Sunday, December 23, 2018 07:33:38 PM Doug wrote:
> > RE: Time Domain Reflectometer:
> >
> > Theoretically, you can build your own with a fast pulse generator
> > and an oscilloscope. The trick is, you need a REALLY FAST
> > oscilloscope!  The pulse generator is easy, just a couple of
> > transistors, maybe a diode. The  circuit is probably in every
> > edition of the Radio Amateur's Handbook. The scope is expensive. If
> > you don't have at least a 1GHz digital sampling scope, don't bother!
> >
> > --doug, WA2SAY, retired RF engineer
>
> Hmm, with CPU clocks hitting 4 GHz, I wonder how expensive an ADC
> converter to work at corresponding speeds would be?  (Just an idle
> question ;-)

If you have to ask, you can't afford it. Bring outrageous sums of money
This is typically done by every trick tek knows about fast analogue 
circuitry, in the best units with long vertical deflection plates in a 
custom made crt with teeny delay lines between the sections of the 
plates so the signal is virtually traveling toward the screen at the 
same speed as the electron beam is traveling. And its moving fast enough 
at 22,000 volts, relativity can and does get in the way. Such scopes put 
the plates so close to the beam that the beam is intercepted by striking 
the plates at just a hair over 4 cm high, 2cm from the horizontal center 
line. The only one of those I ever saw was in the early 1980's or so at 
the NAB show in Vegas, and it was well into a 5 digit asking price then.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Time Domain Reflectometer (was Re: internet outages)

[rhkramer]

On Sunday, December 23, 2018 07:33:38 PM Doug wrote:
> RE: Time Domain Reflectometer:
> 
> Theoretically, you can build your own with a fast pulse generator and an
> oscilloscope. The trick is, you need a REALLY FAST oscilloscope!  The
> pulse generator is easy, just a couple of transistors, maybe a diode.
> The  circuit is probably in every edition of the Radio Amateur's
> Handbook. The scope is expensive. If you don't have at least a 1GHz
> digital sampling scope, don't bother!
> 
> --doug, WA2SAY, retired RF engineer

Hmm, with CPU clocks hitting 4 GHz, I wonder how expensive an ADC converter to 
work at corresponding speeds would be?  (Just an idle question ;-)

Re: internet outages

[Gene Heskett]

On Sunday 23 December 2018 19:33:38 Doug wrote:

> On 12/23/2018 04:24 PM, David Christensen wrote:
> > On 12/23/18 12:11 PM, rhkra...@gmail.com wrote:
> >> On Sunday, December 23, 2018 02:50:34 PM David Christensen wrote:
> >>> On 12/23/18 2:02 AM, Curt wrote:
>  On 2018-12-22, David Christensen  
wrote:
> > 1.  Test and verify your network cables:
> >
> > https://www.idealnetworks.net/us/en/products/cable-testing/coppe
> >r-testin
> >
> > g/cable-verifiers-linkmaster.aspx
> 
>  I think in my particular home situation I'd rather just replace
>  my 10 dollar ethernet cable with a new one (or swap in a new one
>  to see if it
>  makes some appreciable difference) than purchase an $80 device to
>  test whether it's failing or not (in which former case I'd then
>  be out $90, which is a real nice load of money).
> >>>
> >>> If you own a continuity tester or multimeter, you could build a
> >>> pair of RJ-45 jacks with pigtails for a few dollars and use those
> >>> to test your cables.
> >>
> >> Wow, for $80 I would have expected something that would measure dB
> >> loss and
> >> maybe even a time domain reflectometer (well, maybe not that).
> >
> > Please provide a URL for such test instrument(s).
> >
> >
> > One other point -- MRSP is not the same a street price:
> >
> > https://www.homedepot.com/p/Ideal-LinkMaster-UTP-STP-Wiremapper-and-
> >Tester-62-200/100091453
> >
> >> I have seen those continuity type testers on ebay for under $10
> >> (the test sets
> >> with two devices, both with RJ-45 jacks, you plug the ends of the
> >> cable into
> >> those (one at each end of the cable), and then the "master device"
> >> tells you
> >> whether the pairs are connected properly and there is continuity).
> >
> > I am sure there are cheap clones and/or counterfeits of the
> > LinkMaster available.  I prefer genuine, reputable brands.
> >
> >
> > David
>
> RE: Time Domain Reflectometer:
>
> Theoretically, you can build your own with a fast pulse generator and
> an oscilloscope. The trick is, you need a REALLY FAST oscilloscope! 
> The pulse generator is easy, just a couple of transistors, maybe a
> diode. The  circuit is probably in every edition of the Radio
> Amateur's Handbook. The scope is expensive. If you don't have at least
> a 1GHz digital sampling scope, don't bother!
>
> --doug, WA2SAY, retired RF engineer

Doug, another retired tv CE here. And I won't make the statement that its 
not worth the bother.  In a pinch I've made one from a radio shack ttl 
pulse generator and a 100 mhz scope, and was close enough that when I 
sent a tower crew up to dis the transmission line & find a burnout, they 
found the first fried teflon disk, and a bad bullet cobbled up 
with "whisky cups" at the first joint they opened up. Plenty close 
enough for the girls I go with.  Part of the secret is of course the 
teflon disked 3.125" line has a prop speed just above 98% of C, while 
the sterate versions are only about 97.25. You see EVERTTHING with that, 
even bullet dents from some kid with a Christmas 22. Still, I wasn't 
able to count the 20' joints with that slow ttl signal and scope. That 
takes the real thing, and even then you might have to wait till the 
middle of the night to get rid of the local daytime AMers that can sure 
screw up your display. The tek version uses a tunnel diode, which has a 
femtosecond switch time, but is only about a half volt switch.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

Re: internet outages

[Doug]

On 12/23/2018 04:24 PM, David Christensen wrote:

On 12/23/18 12:11 PM, rhkra...@gmail.com wrote:

On Sunday, December 23, 2018 02:50:34 PM David Christensen wrote:

On 12/23/18 2:02 AM, Curt wrote:

On 2018-12-22, David Christensen  wrote:

1.  Test and verify your network cables:

https://www.idealnetworks.net/us/en/products/cable-testing/copper-testin 


g/cable-verifiers-linkmaster.aspx


I think in my particular home situation I'd rather just replace my 10
dollar ethernet cable with a new one (or swap in a new one to see 
if it

makes some appreciable difference) than purchase an $80 device to test
whether it's failing or not (in which former case I'd then be out $90,
which is a real nice load of money).


If you own a continuity tester or multimeter, you could build a pair of
RJ-45 jacks with pigtails for a few dollars and use those to test your
cables.


Wow, for $80 I would have expected something that would measure dB 
loss and

maybe even a time domain reflectometer (well, maybe not that).


Please provide a URL for such test instrument(s).


One other point -- MRSP is not the same a street price:

https://www.homedepot.com/p/Ideal-LinkMaster-UTP-STP-Wiremapper-and-Tester-62-200/100091453 




I have seen those continuity type testers on ebay for under $10 (the 
test sets
with two devices, both with RJ-45 jacks, you plug the ends of the 
cable into
those (one at each end of the cable), and then the "master device" 
tells you

whether the pairs are connected properly and there is continuity).


I am sure there are cheap clones and/or counterfeits of the LinkMaster 
available.  I prefer genuine, reputable brands.



David



RE: Time Domain Reflectometer:

Theoretically, you can build your own with a fast pulse generator and an 
oscilloscope. The trick is, you need a REALLY FAST oscilloscope!  The 
pulse generator is easy, just a couple of transistors, maybe a diode.
The  circuit is probably in every edition of the Radio Amateur's 
Handbook. The scope is expensive. If you don't have at least a 1GHz 
digital sampling scope, don't bother!


--doug, WA2SAY, retired RF engineer

Re: internet outages

[Joe]

On Sun, 23 Dec 2018 16:46:43 -0500
rhkra...@gmail.com wrote:


> 
> Oh, I misread that, I thought you wanted a URL for the under $10
> device.  Try googling for time domain reflectometer, I don't think
> you'll find one for even near $80 (but I'd love to be wrong) -- maybe
> a cable loss tester at that price.
> 
> Some URLs for under $10 testers (prices have changed ;-)  (Prices are
> a little over $3)
> 
>*
> [[https://www.ebay.com/itm/Pocket-LED-Ethernet-4-Port-RJ45-RJ11-Cat5-
> Network-LAN-Cable-Tester-Keychain-
> G6Z5/253214577684?epid=675204148&hash=item3af4c3d414:g:EIsAAOSwuLZY3IhA:rk:1:pf:0]]
> 
> From a review of that one:
> 
> 
> Excellent cable tester!
> 
> Plug in both ends and watch for the lights. It's as easy as that.
> Great for testing Ethernet cables to rule them out as the issue.
> Requires 1x 9v battery.
> 

I have one, but they're not great at testing for intermittents while
you wiggle the cable. But one with lights constantly illuminated isn't
good for spotting incorrect wiring or shorts, so I'm currently making
one with switchable light cycle speed, which doesn't seem to be
commercially available.

-- 
Joe

Re: internet outages

[rhkramer]

On Sunday, December 23, 2018 04:24:58 PM David Christensen wrote:
> > Wow, for $80 I would have expected something that would measure dB loss
> > and maybe even a time domain reflectometer (well, maybe not that).
> 
> Please provide a URL for such test instrument(s).

Oh, I misread that, I thought you wanted a URL for the under $10 device.  Try 
googling for time domain reflectometer, I don't think you'll find one for even 
near $80 (but I'd love to be wrong) -- maybe a cable loss tester at that 
price.

Some URLs for under $10 testers (prices have changed ;-)  (Prices are a little 
over $3)

   * [[https://www.ebay.com/itm/Pocket-LED-Ethernet-4-Port-RJ45-RJ11-Cat5-
Network-LAN-Cable-Tester-Keychain-
G6Z5/253214577684?epid=675204148&hash=item3af4c3d414:g:EIsAAOSwuLZY3IhA:rk:1:pf:0]]

From a review of that one:


Excellent cable tester!

Plug in both ends and watch for the lights. It's as easy as that. Great for 
testing Ethernet cables to rule them out as the issue.
Requires 1x 9v battery.


   * [[https://www.ebay.com/itm/WZ-468-RJ45-Ethernet-Network-RJ11-Cable-
Tester-Crimper-Punch-Down-Tool-Kit-
red/183476025283?epid=20024613296&hash=item2ab805f7c3:g:n0IAAOSw2JxboQgU:rk:2:pf:0]]




> 
> 
> One other point -- MRSP is not the same a street price:
> 
> https://www.homedepot.com/p/Ideal-LinkMaster-UTP-STP-Wiremapper-and-Tester-
> 62-200/100091453
> 
> > I have seen those continuity type testers on ebay for under $10 (the test
> > sets with two devices, both with RJ-45 jacks, you plug the ends of the
> > cable into those (one at each end of the cable), and then the "master
> > device" tells you whether the pairs are connected properly and there is
> > continuity).
> 
> I am sure there are cheap clones and/or counterfeits of the LinkMaster
> available.  I prefer genuine, reputable brands.
> 
> 
> David

Re: internet outages

[David Christensen]

On 12/23/18 12:11 PM, rhkra...@gmail.com wrote:

On Sunday, December 23, 2018 02:50:34 PM David Christensen wrote:

On 12/23/18 2:02 AM, Curt wrote:

On 2018-12-22, David Christensen  wrote:

1.  Test and verify your network cables:

https://www.idealnetworks.net/us/en/products/cable-testing/copper-testin
g/cable-verifiers-linkmaster.aspx


I think in my particular home situation I'd rather just replace my 10
dollar ethernet cable with a new one (or swap in a new one to see if it
makes some appreciable difference) than purchase an $80 device to test
whether it's failing or not (in which former case I'd then be out $90,
which is a real nice load of money).


If you own a continuity tester or multimeter, you could build a pair of
RJ-45 jacks with pigtails for a few dollars and use those to test your
cables.


Wow, for $80 I would have expected something that would measure dB loss and
maybe even a time domain reflectometer (well, maybe not that).


Please provide a URL for such test instrument(s).


One other point -- MRSP is not the same a street price:

https://www.homedepot.com/p/Ideal-LinkMaster-UTP-STP-Wiremapper-and-Tester-62-200/100091453



I have seen those continuity type testers on ebay for under $10 (the test sets
with two devices, both with RJ-45 jacks, you plug the ends of the cable into
those (one at each end of the cable), and then the "master device" tells you
whether the pairs are connected properly and there is continuity).


I am sure there are cheap clones and/or counterfeits of the LinkMaster 
available.  I prefer genuine, reputable brands.



David

Re: internet outages

[rhkramer]

On Sunday, December 23, 2018 02:50:34 PM David Christensen wrote:
> On 12/23/18 2:02 AM, Curt wrote:
> > On 2018-12-22, David Christensen  wrote:
> >> 1.  Test and verify your network cables:
> >> 
> >> https://www.idealnetworks.net/us/en/products/cable-testing/copper-testin
> >> g/cable-verifiers-linkmaster.aspx
> > 
> > I think in my particular home situation I'd rather just replace my 10
> > dollar ethernet cable with a new one (or swap in a new one to see if it
> > makes some appreciable difference) than purchase an $80 device to test
> > whether it's failing or not (in which former case I'd then be out $90,
> > which is a real nice load of money).
> 
> If you own a continuity tester or multimeter, you could build a pair of
> RJ-45 jacks with pigtails for a few dollars and use those to test your
> cables.

Wow, for $80 I would have expected something that would measure dB loss and 
maybe even a time domain reflectometer (well, maybe not that).

I have seen those continuity type testers on ebay for under $10 (the test sets 
with two devices, both with RJ-45 jacks, you plug the ends of the cable into  
those (one at each end of the cable), and then the "master device" tells you 
whether the pairs are connected properly and there is continuity).

Re: internet outages

[David Christensen]

On 12/23/18 2:02 AM, Curt wrote:

On 2018-12-22, David Christensen  wrote:

On 12/22/18 7:16 AM, Jude DaShiell wrote:

Has Linux got tools that can run while a computer runs that can poll
several sites and log internet outages?  I figure a minute down time is a
failure and have experienced several of these where my wifi connection had
to be deactivated and reactivated to have the internet connection
restored.  This is a new wifi router too.  The log would be sent into
comcast along with payment requesting credits for the down times.


I suggest:

1.  Test and verify your network cables:

https://www.idealnetworks.net/us/en/products/cable-testing/copper-testing/cable-verifiers-linkmaster.aspx


I think in my particular home situation I'd rather just replace my 10
dollar ethernet cable with a new one (or swap in a new one to see if it
makes some appreciable difference) than purchase an $80 device to test
whether it's failing or not (in which former case I'd then be out $90,
which is a real nice load of money).


If you own a continuity tester or multimeter, you could build a pair of 
RJ-45 jacks with pigtails for a few dollars and use those to test your 
cables.



David

Re: internet outages

[Curt]

On 2018-12-22, David Christensen  wrote:
> On 12/22/18 7:16 AM, Jude DaShiell wrote:
>> Has Linux got tools that can run while a computer runs that can poll
>> several sites and log internet outages?  I figure a minute down time is a
>> failure and have experienced several of these where my wifi connection had
>> to be deactivated and reactivated to have the internet connection
>> restored.  This is a new wifi router too.  The log would be sent into
>> comcast along with payment requesting credits for the down times.
>
> I suggest:
>
> 1.  Test and verify your network cables:
>
> https://www.idealnetworks.net/us/en/products/cable-testing/copper-testing/cable-verifiers-linkmaster.aspx

I think in my particular home situation I'd rather just replace my 10
dollar ethernet cable with a new one (or swap in a new one to see if it
makes some appreciable difference) than purchase an $80 device to test
whether it's failing or not (in which former case I'd then be out $90,
which is a real nice load of money).

Re: internet outages

[David Christensen]

On 12/22/18 10:00 PM, john doe wrote:

On 12/22/2018 9:15 PM, David Christensen wrote:

On 12/22/18 7:16 AM, Jude DaShiell wrote:

Has Linux got tools that can run while a computer runs that can poll
several sites and log internet outages?  I figure a minute down time is a
failure and have experienced several of these where my wifi connection
had
to be deactivated and reactivated to have the internet connection
restored.  This is a new wifi router too.  The log would be sent into
comcast along with payment requesting credits for the down times.


I suggest:

1.  Test and verify your network cables:

https://www.idealnetworks.net/us/en/products/cable-testing/copper-testing/cable-verifiers-linkmaster.aspx


2.  Buy and read "Networking for System Administrators" by Lucas:

 https://mwl.io/nonfiction/networking#n4sa

3.  Write a shell script that invokes some standard utility (ping(8),
wget(1), etc.), appends a timestamp and the utility output to a log
file, sleeps for 60 seconds, and then repeats.  >


Along with redirecting the output to a file, the logger(1) utility can
also be used (1) to make entry in the system log.

http://man7.org/linux/man-pages/man1/logger.1.html


Yes -- that would be a possible follow-on exercise to #3.  Also see 
rsyslog(8) and rsyslog.conf(5).



David

Re: internet outages

[john doe]

On 12/22/2018 9:15 PM, David Christensen wrote:
> On 12/22/18 7:16 AM, Jude DaShiell wrote:
>> Has Linux got tools that can run while a computer runs that can poll
>> several sites and log internet outages?  I figure a minute down time is a
>> failure and have experienced several of these where my wifi connection
>> had
>> to be deactivated and reactivated to have the internet connection
>> restored.  This is a new wifi router too.  The log would be sent into
>> comcast along with payment requesting credits for the down times.
> 
> I suggest:
> 
> 1.  Test and verify your network cables:
> 
> https://www.idealnetworks.net/us/en/products/cable-testing/copper-testing/cable-verifiers-linkmaster.aspx
> 
> 
> 2.  Buy and read "Networking for System Administrators" by Lucas:
> 
> https://mwl.io/nonfiction/networking#n4sa
> 
> 3.  Write a shell script that invokes some standard utility (ping(8),
> wget(1), etc.), appends a timestamp and the utility output to a log
> file, sleeps for 60 seconds, and then repeats.  >

Along with redirecting the output to a file, the logger(1) utility can
also be used (1) to make entry in the system log.

http://man7.org/linux/man-pages/man1/logger.1.html

-- 
John Doe

Re: internet outages

[David Christensen]

On 12/22/18 7:16 AM, Jude DaShiell wrote:

Has Linux got tools that can run while a computer runs that can poll
several sites and log internet outages?  I figure a minute down time is a
failure and have experienced several of these where my wifi connection had
to be deactivated and reactivated to have the internet connection
restored.  This is a new wifi router too.  The log would be sent into
comcast along with payment requesting credits for the down times.


I suggest:

1.  Test and verify your network cables:

https://www.idealnetworks.net/us/en/products/cable-testing/copper-testing/cable-verifiers-linkmaster.aspx

2.  Buy and read "Networking for System Administrators" by Lucas:

https://mwl.io/nonfiction/networking#n4sa

3.  Write a shell script that invokes some standard utility (ping(8), 
wget(1), etc.), appends a timestamp and the utility output to a log 
file, sleeps for 60 seconds, and then repeats.  Put the script on two 
hosts on opposite sides of the router, configure the router so that the 
hosts can see each other, and have the hosts monitor each other.


4.  Keep a plain text log file of all your host and network 
administration activities.  Timestamp your entries so that you can 
correlate them to the monitoring logs.



David

Re: internet outages

[Jude DaShiell]

On Sat, 22 Dec 2018, john doe wrote:

> Date: Sat, 22 Dec 2018 13:32:57
> From: john doe 
> To: debian-user@lists.debian.org
> Subject: Re: internet outages
> Resent-Date: Sat, 22 Dec 2018 18:33:16 + (UTC)
> Resent-From: debian-user@lists.debian.org
>
> On 12/22/2018 6:21 PM, John Hasler wrote:
> > mark writes:
> >> From your description of the problem, it sounds like it is the router
> >> that is not doing its job properly.
> >
> > This is a Comcast-supplied combination router-modem-ap?  From everything
> > I've read and been told by people who know from experience the firmware
> > in those is always buggy and insecure (the supplier always has a
> > backdoor, for example).  In my experience even simple DSL modems with no
> > wifi are unstable when you let them try to be routers. Comcast may be
> > willing to swap it for a different one (probably one they got back from
> > another unhappy customer but never tested) but it's not likely to be
> > better.  Put the thing in bridge mode and put a real router behind it.
> > Otherwise you are entrusting the security of your LAN to Comcast.
> >
>
> Or if you can get a modem only and use your own router (1).
>
>
> One easy way to determine if the wifi is at fault would be to be wiredly
> connected to the router.
>
>
> https://20somethingfinance.com/how-to-replace-a-comcast-modem-with-your-own/
>
>
Ah, direct ethernet connection.  That's doable temporarily.  Thanks for
the url too.


--

Re: internet outages

[Mark Neidorff]

On Saturday, December 22, 2018 11:34:27 AM EST Jude DaShiell wrote:
> Thanks for the script and the tool recommendation.
> Has Linux got a tool to check up on the router and find out if the
> router is doing its job?
> Before I mail logs into comcast, I want to make sure I've  done all due
> dilligence on this end so if comcast isn't having a problem they don't
> catch any undeserved heat.  A router replacement can be done if that's
> the source of these problems.  On more than one of these outage
> occassions I have used a stylus and rebooted the router to clear any
> potential malware just in case.

Rebooting the router will not clear any malware that is in NVRAM.  That is 
Comcast's job to 
diagnose and fix.

IMO, your due dilligence consists of testing things from the router to your 
PCs.  So, the list 
of suspects is:  router, inside network wiring,  insdie the building electrical 
wiring and the 
pc.  Most likely point of failure is the router in this case.  You can also try 
jiggling ethernet 
wires to see if you can find a problem there. 

Mark

Re: internet outages

[Nate Bargmann]

This.

I have been very pleased with OpenWRT over the past several years.  The
WISP wanted to setup their Ubiquity Nanobridge CPE as a router and were
willing to configure it as a bridge instead.  That allows me remote SSH
access through my OpenWRT router.  This really is the way to do it to
give yourself the most control.

- Nate

-- 

"The optimist proclaims that we live in the best of all
possible worlds.  The pessimist fears this is true."

Web: http://www.n0nb.us  GPG key: D55A8819  GitHub: N0NB


signature.asc
Description: PGP signature

Re: internet outages

[john doe]

On 12/22/2018 6:21 PM, John Hasler wrote:
> mark writes:
>> From your description of the problem, it sounds like it is the router
>> that is not doing its job properly.
> 
> This is a Comcast-supplied combination router-modem-ap?  From everything
> I've read and been told by people who know from experience the firmware
> in those is always buggy and insecure (the supplier always has a
> backdoor, for example).  In my experience even simple DSL modems with no
> wifi are unstable when you let them try to be routers. Comcast may be
> willing to swap it for a different one (probably one they got back from
> another unhappy customer but never tested) but it's not likely to be
> better.  Put the thing in bridge mode and put a real router behind it.
> Otherwise you are entrusting the security of your LAN to Comcast.
> 

Or if you can get a modem only and use your own router (1).


One easy way to determine if the wifi is at fault would be to be wiredly
connected to the router.


https://20somethingfinance.com/how-to-replace-a-comcast-modem-with-your-own/

-- 
John Doe

Re: internet outages

[John Hasler]

mark writes:
> From your description of the problem, it sounds like it is the router
> that is not doing its job properly.

This is a Comcast-supplied combination router-modem-ap?  From everything
I've read and been told by people who know from experience the firmware
in those is always buggy and insecure (the supplier always has a
backdoor, for example).  In my experience even simple DSL modems with no
wifi are unstable when you let them try to be routers. Comcast may be
willing to swap it for a different one (probably one they got back from
another unhappy customer but never tested) but it's not likely to be
better.  Put the thing in bridge mode and put a real router behind it.
Otherwise you are entrusting the security of your LAN to Comcast.
-- 
John Hasler 
jhas...@newsguy.com
Elmwood, WI USA

Re: internet outages

[Jude DaShiell]

On Sat, 22 Dec 2018, m...@neidorff.com wrote:

> Date: Sat, 22 Dec 2018 10:54:06
> From: m...@neidorff.com
> To: debian-user@lists.debian.org
> Subject: Re: internet outages
> Resent-Date: Sat, 22 Dec 2018 15:54:23 + (UTC)
> Resent-From: debian-user@lists.debian.org
>
> On Saturday, December 22, 2018 10:16:58 AM EST Jude DaShiell wrote:
> > Has Linux got tools that can run while a computer runs that can poll
> > several sites and log internet outages?  I figure a minute down time is a
> > failure and have experienced several of these where my wifi connection had
> > to be deactivated and reactivated to have the internet connection
> > restored.  This is a new wifi router too.  The log would be sent into
> > comcast along with payment requesting credits for the down times.
> >
> >
> >
> > --
>
> >From your description of the problem, it sounds like it is the router that 
> >is not doing its job
> properly.  Before you send your request for credit, make sure that it is a 
> Comcast problem.
>
> But, if you want to jost test when the net is down:
>
> Here is a script that you can run from a cron job which will log Internet 
> status and store
> the results into a file  in your home folder called net-test.txt:
>
> #! /bin/bash
>
> date >> ~/net-test.txt
> ping -c 1 google.com >> ~/net-test.txt
>
> #end of file
>
>

Thanks for the script and the tool recommendation.
Has Linux got a tool to check up on the router and find out if the
router is doing its job?
Before I mail logs into comcast, I want to make sure I've  done all due
dilligence on this end so if comcast isn't having a problem they don't
catch any undeserved heat.  A router replacement can be done if that's
the source of these problems.  On more than one of these outage
occassions I have used a stylus and rebooted the router to clear any
potential malware just in case.

--

Re: internet outages

[Dominik George]

>
>Here is a script that you can run from a cron job which will log
>Internet status and store 
>the results into a file  in your home folder called net-test.txt:
>
>#! /bin/bash
>
>date >> ~/net-test.txt
>ping -c 1 google.com >> ~/net-test.txt
>
>#end of file

smokeping is a tool made for this.

-nik

Re: internet outages

[mark]

On Saturday, December 22, 2018 10:16:58 AM EST Jude DaShiell wrote:
> Has Linux got tools that can run while a computer runs that can poll
> several sites and log internet outages?  I figure a minute down time is a
> failure and have experienced several of these where my wifi connection had
> to be deactivated and reactivated to have the internet connection
> restored.  This is a new wifi router too.  The log would be sent into
> comcast along with payment requesting credits for the down times.
> 
> 
> 
> --

>From your description of the problem, it sounds like it is the router that is 
>not doing its job 
properly.  Before you send your request for credit, make sure that it is a 
Comcast problem.

But, if you want to jost test when the net is down:

Here is a script that you can run from a cron job which will log Internet 
status and store 
the results into a file  in your home folder called net-test.txt:

#! /bin/bash

date >> ~/net-test.txt
ping -c 1 google.com >> ~/net-test.txt

#end of file

internet outages

[Jude DaShiell]

Has Linux got tools that can run while a computer runs that can poll
several sites and log internet outages?  I figure a minute down time is a
failure and have experienced several of these where my wifi connection had
to be deactivated and reactivated to have the internet connection
restored.  This is a new wifi router too.  The log would be sent into
comcast along with payment requesting credits for the down times.



--