I've got an area in Colombia where we're seeing an elevated noise floor. It seems to happen in area either where power lines cross the tracks or we're near transformers; so our first suspicion is that power equipment is the source of our problems. It seems to be fairly consistent and lasts over a long period of time, so I don't think its power surges. It could be a rusty bolt effect (https://en.wikipedia.org/wiki/Rusty_bolt_effect), especially since people tap into the power lines. Is there anything else that could break or be installed improperly in a power line or transformer that would cause it to generate such a large electrical field that it would interfere with radio?
(For those of you playing along at home; in radio communication "Noise" is the incidental undesired signal. The noise floor is the sum of all the sources of undesired noise, usually it's excusively thermal noise (https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise) at the UHF frequencies we're operating at. Noise is undesirable because it deteriorates the quality of the desired signal. I mentioned a power surge because an "Impulse" broadcasts (briefly) across a wide frequency range (which is why you can hear lightning strikes on your AM radio.))
"over a long period of time"? So it is periodic? Does it occur consistent with anything like time of day? Does it occur every time the power lines cross the tracks or are near transformers?
Booooring!
Quote from: Valmy on January 27, 2020, 05:01:29 PM
"over a long period of time"? So it is periodic? Does it occur consistent with anything like time of day? Does it occur every time the power lines cross the tracks or are near transformers?
Does it happen with a goat?
Does it happen on a boat?
Does it happen here or there?
Does it happen anywhere?
Engage the manual override then redirect the photon torpedo drive to the flim flam array.
Quote from: Valmy on January 27, 2020, 05:01:29 PM
"over a long period of time"? So it is periodic? Does it occur consistent with anything like time of day? Does it occur every time the power lines cross the tracks or are near transformers?
It doesn't seem to be correlate with time of day. We don't monitor noise power constantly; but in some of the qualifying train runs the radio supplier did. We monitor drop packets on the radio system; that is when the data has become so corrupted the radio fails the cyclic redundancy check (CRC) and asks for a retransmission. The areas of packet drops correlate directly with the area of elevated noise power from the qualifying runs; which tells me that the elevated noise floor is still present. By "Long period of time" I mean that as long as trains are in these areas they continue to drop packages (that is, it's not an impulse or a series of impulses.) These areas are near transformers or places where the power lines cross the track. It isn't everywhere the power lines cross the tracks or the trains run near transformers; just in north where there's a greater population density (and more people stealing power.) In the south of the line (which is mostly range land) we don't see this problem.
Quote from: Admiral Yi on January 27, 2020, 05:11:15 PM
Engage the manual override then redirect the photon torpedo drive to the flim flam array.
Nah, Sav should just reverse the polarity of the neutron flow.
I thought this was going to be hot and exciting, like the girls Valmy had in his engineering classes at Texas - not awful and boring like the girls in the engineering classes at UWyo.
Quote from: PDH on January 27, 2020, 06:00:03 PM
I thought this was going to be hot and exciting, like the girls Valmy had in his engineering classes at Texas - not awful and boring like the girls in the engineering classes at UWyo.
What about the Californian girls? :P
Hey, whilst there are some engineers in this thread I've got a sexy question, with cellphones that have no sim installed, do they use less power or are they still polling the cell towers anyway.
I ask as I want to use some for long term non-telephonic non-data uses and need to cut battery usage to a minimum.
Though I do wonder if it's possible to use them for a call to the emergency services, does that mean the devices are maintaining a normal cell connection.
Another option is to use flight mode, but that often knocks out other audio functions and I'm not sure if the cell connect activity is really 'put to bed' ?
Thanks in advance.
They still poll. In Canada, they connect.
Quote from: Grey Fox on January 27, 2020, 10:03:38 PM
They still poll. In Canada, they connect.
Thanks, that was my suspicion.
Airplane mode would completely cut off the cellular network.
Is this a GSM phone, or do you use SIM cards for 3G/4G in Europe?
Quote from: PDH on January 27, 2020, 06:00:03 PM
I thought this was going to be hot and exciting, like the girls Valmy had in his engineering classes at Texas - not awful and boring like the girls in the engineering classes at UWyo.
Edison said that "invention is one percent inspiration and ninety-nine percent perspiration." He didn't add the obvious corollary that "that's why engineers smell so bad."
You can't use "hot and exciting" in the same sentence as "engineering."
Quote from: grumbler on January 28, 2020, 10:27:41 AM
You can't use "hot and exciting" in the same sentence as "engineering."
I've had a few hot and exciting moments in my career. It's usually not a good thing, though. :ph34r:
Quote from: Savonarola on January 28, 2020, 10:22:57 AM
Airplane mode would completely cut off the cellular network.
Is this a GSM phone, or do you use SIM cards for 3G/4G in Europe?
Thanks, OK that means airplane mode shouild kill polling etc.
I can use older 2G phone for most of this, though now 3G/4G is the norm for nearly all handsets/sims.
Quote from: Savonarola on January 27, 2020, 05:35:04 PM
Quote from: Valmy on January 27, 2020, 05:01:29 PM
"over a long period of time"? So it is periodic? Does it occur consistent with anything like time of day? Does it occur every time the power lines cross the tracks or are near transformers?
It doesn't seem to be correlate with time of day. We don't monitor noise power constantly; but in some of the qualifying train runs the radio supplier did. We monitor drop packets on the radio system; that is when the data has become so corrupted the radio fails the cyclic redundancy check (CRC) and asks for a retransmission. The areas of packet drops correlate directly with the area of elevated noise power from the qualifying runs; which tells me that the elevated noise floor is still present. By "Long period of time" I mean that as long as trains are in these areas they continue to drop packages (that is, it's not an impulse or a series of impulses.) These areas are near transformers or places where the power lines cross the track. It isn't everywhere the power lines cross the tracks or the trains run near transformers; just in north where there's a greater population density (and more people stealing power.) In the south of the line (which is mostly range land) we don't see this problem.
Ok so I have thought about it and chatted with my colleagues about this and I think it is related to the illegal tapping going on, probably due to poor grounding. Would the Rusty Bolt Effect be an issue unless they just happened to be tapping right on that particular line? Because I suspect they are tapping into distribution lines not transmission lines unless they have a few transformers handy.
Quote from: Valmy on January 28, 2020, 02:47:36 PM
Ok so I have thought about it and chatted with my colleagues about this and I think it is related to the illegal tapping going on, probably due to poor grounding. Would the Rusty Bolt Effect be an issue unless they just happened to be tapping right on that particular line? Because I suspect they are tapping into distribution lines not transmission lines unless they have a few transformers handy.
Thanks, Valmy
Distribution lines seem like they'd be too low power unless, maybe, they cut the perfect length and created an antenna for our frequency. This being Colombia it's possible the transmission towers or the transformers themselves are poorly maintained and poorly grounded.
On a totally unrelated topic; did you see this article in The Spectrum:
A Plug-and-Play Microgrid for Rooftop Solar
(https://spectrum.ieee.org/green-tech/solar/a-plugandplay-microgrid-for-rooftop-solar)
I think you'll enjoy it since it involves both solar power and Austin. :alberta: