Transmission Control Protocol. Internet Protocol.

The deployment of TCP was the birth of the modern Internet — it was the same protocol still in use today. But before TCP, IP networks still had a standard way to communicate: NCP, Network Control Program. It was warty and problematic and limited, but by all accounts it mostly worked.

NCP/IP dates back to 1969, and was unrestricted. TCP just marks the start of the protocol we use today.

The specification;
https://datatracker.ietf.org/doc/html/rfc791?fbclid=IwY2xjawHj5_FleHRuA2FlbQIxMQABHaUUYNRzvN3YgPe4JZW_xulrjuJk6f4ywYU1EvLMJ4lO4fLh40M_Rbw2pA_aem_Dejta7U6dR9J2u5_JV44WQ

Source:
https://www.facebook.com/share/wRPNhcC9PBWK7enQ/

Finnish authorities board a ship in the Baltic Sea that the West suspects is linked to Russia, a day after an underwater Finland-Estonia electricity cable was cut and several telecom fiber optic cables were damaged.

Lloyd’s List on-line magazine claims that Russia-linked cable-cutting tanker seized by Finland ‘was loaded with spying equipment’

The incident has intensified fears in Europe over a Russian hybrid war targeting critical infrastructure in the Baltic and beyond. Estonia navy to protect undersea power link after main cable damaged.

Sources:
https://www.lloydslist.com/LL1151955/Russia-linked-cable-cutting-tanker-seized-by-Finland-was-loaded-with-spying-equipment
https://www.nytimes.com/2024/12/26/world/europe/finland-estonia-cables-russia.html
https://www.theguardian.com/world/2024/dec/25/finland-estonia-power-cable-hit-in-latest-baltic-sea-incident
https://yle.fi/a/74-20133531
https://www.bbc.com/news/articles/c1elq7lx9qdo
https://www.aljazeera.com/news/2024/12/27/did-a-russian-shadow-ship-cut-the-finland-estonia-undersea-baltic-cable

iFi-Audio has released the LAN iSilencer, an audiophile accessory which aims to “quiet your network.” According to the Ethernet dongle designers in Japan, this product removes digital signal interference, and thus protects your audio signals from noise. The device supports 1000BASE-T /100BASE-T /10BASE-T transmission speeds, has a shielded case, weighs 17 grams, and measures 73.5 x 19 x 16mm.

Manufacturer claims “a zero jitter memory buffer and galvanically isolated inputs.”
Based on what I saw in article, the galvanic isolation seems to be there.
But the “zero jitter memory buffer” sounds like hifi marketing bullshit (especially when this is a passive device that is not powered).

The key design features that are claimed to be of benefit to your digital audio’s 0s and 1s are “a zero jitter memory buffer and galvanically isolated inputs.” I don’t buy those zero jitter buffer claims.

On the topic of galvanic isolation, iFi-Audio says that audio signals passing through won’t suffer due to the interference of ground potential differences and AC power transients. Keep in mind that twisted pair Ethernet has already transformer isolation in the network interface and in the Ethernet switch. So with normal twisted pair Ethernet wiring is already transformer isolated on the both ends of connection, so I don’t think that adding an extra isolation transformer in on one end would do a big difference. Only application where there is a valid technical reason to add isolation transformer in the middle of cable are some medical networking applications, where the extra transformer provides safety isolation (guarantees higher isolation voltage than built in transformers around 1.5 kV)

You can get ground loop issues with Ethernet wiring only if you use shielded cable. The cable shield is normally connected straight through from connector shield to another connector shield (which are typically connected to equipment metal case). Shielded Ethernet wiring can create ground loop issues (that generally don’t affect data but but can sometimes cause other issues).
In this case the isolation device could possibly help in this problem somewhat if the IFi LAN isolator does not connect the shield on input to output. If shielded cable has ground loop issues, then a cheap proven way is to replacing the cable with unshielded will solve the Ethernet related ground loop problem immediately.

The jury is still out on whether it does anything useful. The LAN iSilencer boasts premium galvanic isolation technology, but looking at what is inside it I do not see any premium technology or claimed magical “zero-jitter memory buffer”

But that does not stop some companies trying to sell “magic boxes”. It doesn’t really matter whether if it technically works, or not. The over-riding question is that if the device makes an improvement to perceptible sound quality. Even if it did affect the Ethernet signal at all, which it can’t, by the time it makes it through the PHY, MAC, and TCP IP stack, there is not only no measurable effect there is definitively no effect. Zero. Just because of digital error correction. TCP has checksums on every packet.

From Let’s Make Fun Of The Audiophools Facebook group:

Chris Ripoll there seems to be just Ethernet transformers module and some capacitors in there. They will pass Ethernet signal and provide isolation without need for any external power (just like similar components built into the device and ethernet switch ports do).

The pics that Tomi linked show that it’s pure snake oil.

Image source: https://ifi-audio.com/products/lan-isilencer/

Ethernet is galvanically isolated by design. This iFi isolator had two TVS diodes, 12 ceramic capacitors, one Pulse Electronics Ethernet transformer. No “zero jitter memory buffers” of any kind. It’s totally not needed in normal usage cases because every Ethernet device is already going to have a transformer like this onboard.

Same type of signals isolation transformer module as found in pretty much every modern Ethernet port made to devices and switches. Does not look nothing special, made by company named PULSE, looks like from some of their commonly used series. Other parts are typical components used around it.

Based on pictures I can’t be sure if this device cuts shielded cable shield or does it go straight through from connector to another. If it cuts the ground between input and output, it could help to solve some ground loop problems (but has not so good external noise rejection as if the ground goes through).

After some research on some product information pages and Wikipedia Network Isolator page I found out that there are some special cases where there are sensible reasons to use such extra isolation device on Ethernet network. After some more searching, I also found products designed for industrial applications and audio applications.

PATIENT PROTECTION
Galvanic isolation of the Ethernet interfaces on medical electrical equipment or systems
for which patients must be protected from harmful leakage currents in line with standards.

APPLIANCE PROTECTION
Protection of particularly valuable devices from ripple voltages and surges from the edge of the network.

MEASUREMENT TECHNOLOGY
Protection of electrical measurement and monitoring equipment from external voltages and interference voltages from the
Ethernet cabling.

POTENTIAL DIFFERENCES (BUILDING TECHNOLOGY)
Potential equalisation currents are prevented in computer systems connected via an Ethernet
cabling over greater distances.

AUDIO
Reduction of low-frequency AC voltages (mains ripples), which are caused by the network connection, to an imperceptible level.

Medical applications

Network isolators are used in the medical industry to protect patients against leakage currents. IEC standard IEC 60601-1 (3rd edition) specifically deals with medical electronic and electrical equipment and systems, and classifies non-medical devices as potential hazard sources. Network isolators work to remove this hazard, by electrically disconnecting medical devices from a network. They are often installed in the medical field in conjunction with isolation transformers, which serve to protect the patient from electrical faults. The international standard IEC 60601-1 Medical Electrical Equipment (3rd edition) specifies stringent criteria on the safety and isolation of medical devices. Very many medical institutions use Ethernet isolators for electrical safety and to keep equipment interference free. Medical-grade Ethernet isolators must follow strict regulations concerning the isolation level that an Ethernet isolator provides. Isolators marketed to meet European Medical Device Directive (EN6060-1) typically have isolation level of 4kV or higher.

Industrial applications

Network isolators have industrial applications in overcoming the problems of differing ground potentials across networks, or between network components for example to stop shield currents on shielded Ethernet cable (ground loop currents) and on electrical testing facilities where higher that normal office environment electrical disturbances are present. There are also uses in electronics testing  systems where dangerous voltages are present.

Ethernet Isolator combines intrinsically safe energy limitation and galvanic isolation page tells that the FieldConnex® Ethernet Isolator combines intrinsically safe energy limitation and galvanic isolation into one product. Now Ethernet connections are plug and play in Ex-Zone 1. Intrinsically safe Ethernet Isolator EI-0D2-10Y-10B product provides galvanic isolation according to EN50020 for 10 BASE-T/100 BASE-TX. It contains active electronics and needs a power source to operate.

Audio applications

Ground loops and high frequency noise have known to cause all kinds of issues with sensitive audio systems. Especially people tuning their HiFi systems are interested could Ethernet connection be improved in some way. Because almost all the audiophiles would have experienced of tuning their own audio system with variety of cables or accessories in order to enhance the music sound from their treasured audio systems, some special HiFi equipment manufacturers have seen market for expensive Ethernet isolators for HiFi applications. So called ‘audiophile’ grade ethernet cables have made inroads into specialist audio dealers.

Audio Stream Ethernet Accessories and Cables page has information on several special (expensive) accessories that are claimed to provide improvement when used with HiFi equipment. In Ethernet isolation sector the page lists SOtM iSO-CAT6 Ethernet isolator. SOtM iSO-CAT6 Ethernet isolator product page claims that noise interference created by LAN port has enormous effect to system sound and SOtM iSO-CAT6 may offer certain varying sound improvement (for other views check reviews at 6moons and avrev). SOtM iSO-CAT6 manual says that this product provides isolation 1500Vrms, 0.5mA, 60sec (same level as normal Ethernet cards).

Are the isolators really needed in audio system? Maybe not in most cases (but there can be some special cases where extra isolation can have some effect). By default the ethernet ports are isolated with transformers. However – ground loops from shielding still can exist if you use shielded cables. If you are worried on ground loops on audio system, I recommend to use unshielded Ethernet cables, so you get no ground loop. If you are really paranoid on isolation, isolate the audio with a fiber optic cable. Some people who have written on their experiences have found out no difference on copper, isolated copper or fiber on sound quality. This no difference will also apply to special Ethernet cables: The use of solid core verses stranded or gold verses silver for the conductors for this link in particular is just putting lipstick on a pig. Again, this is digital side… The likelihood of there being a genuine difference rather than a psychoacoustic cause for the described difference is much, much lower given known physics.

How Ethernet Isolators Work

An Ethernet isolator separates the electrical currents of multiple devices: it allows the Ethernet data signals to pass without allowing the two circuits to physically contact each other. The Ethernet isolator is basically just several 1:1 Ethernet transformers put between the RJ-45 connections (two needed for 10/100 Mbit/s Ethernet, four needed for 1 Gbit/s Ethernet). Typically all those transformers are built into one transformer module similar to ones used in Ethernet cards and switches. Such isolator consists of a small PCB at the back panel with two RJ45 connectors and a LAN transformer in between. This would provide an additional 1500V to 4000V of isolation depending on the transformer chosen.

Network isolators are commercially available in various designs. Medical-grade Ethernet isolators must follow much stricter regulations concerning the isolation level that Ethernet isolators for industrial uses.

Ethernet isolators are typically constructed using the same technique as normal Ethernet port. Ethernet specification needs magnetic transformer coupling between RJ45 connector and electronics. Most modern Ethernet ports with MDIX functionality (auto-detect direct or cross-connect) use 1:1 transformers optimized for Ethernet frequencies (frequency range depends on line speed) and impedance (100 ohms)  for all used signal pairs.

Transformers offer a very good common mode rejection: A transformer only “sees” the voltage accross its windings, not the common voltage both ends of the winding are driven to simultaneously. You get a differential front end without a deliberate circuit, just basic physics.

An Ethernet isolator could be basically built using one such transformer module (contains 2 or 4 transformers in one case) that is just wired between two RJ45 connectors. Standard Ethernet transformers provide typically 1500Vrms isolation. If higher isolation level is needed, a suitable special transformer with improved isolation specification needs to be manufactured. For example medical isolator can isolate the data AND the shield up to 5.000V. The nic transformers only isolate the data up to 1.500V. Here is picture of MI 1005 E Medical Built In Isolator showing that there is just transformers (inside black box in the center) and two RJ45 connectors.

Isolation is a very good idea on communications systems that are linking lots of different hardware over a wide area: You don’t want fault current/voltages in the mains wiring or devices to spread onto your communications wiring.

Ethernet transformer links:
http://www.haloelectronics.com/products/lan/ethernet/
http://www.mouser.fi/new/molex/molexRJ45jacks/
http://www.mouser.fi/new/halo-electronics/halo-ethernet-transformers/
https://www.eeweb.com/company-blog/microchip/migrating-from-the-lan9115-to-the-lan9210/

Links to more information:
http://www.diyaudio.com/forums/pc-based/154048-ethernet-galvanic-isolation.html
http://www.bb-elec.com/Learning-Center/All-White-Papers/Ethernet/Power-over-Ethernet-PoE.aspx
http://hackaday.com/2010/10/26/ethernet-connection-using-capacitive-coupling/
http://www.youritronics.com/magnetic-less-ethernet/

Some product links:

I have found those with Google search. I have not used any of those or recommend them.
http://industrialcomponent.com/baaske/2006633.html
http://industrialcomponent.com/baaske/ethernet-isolation.html
Ethernet Data Isolator – 10BASE-T/100BASE-TX
http://industrialcomponent.com/baaske/2006633.html
L-com 10/100/1000 Ethernet Data Isolator (EN60601-1 Compliant) provides isolation up to 4 kV
Bourns 360 V dc 3kA 1500 Isolated Ethernet Protector, Wall Mount Mounting is an Ethernet surge protector product that also promises to provide 5 kV isolation for 10/100/1000 Mbit/s Ethernet.
EMO EN-100C :: Network isolator for PCB mounting is intended for integration on the PCB of the device being protected. The devices in the EN-100-series meet the requirements of IEC 60601-1 (3rd edition) and IEC 60601-1-2 for medical settings
Phoenix Contact Network isolator – FL ISOLATOR 100-RJ/RJ – 2313931 is a passive passive network isolator for electrical isolation in Ethernet networks up to 4 kV and speeds of up to 100 Mbps.
https://www.mtl-inst.com/images/uploads/datasheets/is_ethernet/9468-ET.pdf
http://www.mmcchina.com/Upload/whitepaper/MMC_Whitepaper12EN.pdf
http://industrialcomponent.com/baaske/ethernet-isolation.html
http://industrialcomponent.com/baaske/2006633.html
http://www.baaske-medical.de/media/content/Datasheet_MI1005_MI1005E.pdf
http://industrialcomponent.com/baaske/2006633.html
https://www.dustinhome.fi/product/5011222413/rj45-network-isolator-6kv
https://www.dxengineering.com/parts/dxe-iso-plus-2
https://www.phoenixcontact.com/en-pc/products/network-isolator-fl-isolator-1000-rj-rj-2313915

Sources:
http://www.tech-faq.com/ethernet-isolator.html
http://electronics.stackexchange.com/questions/180415/ethernet-3000v-isolation
http://www.mouser.fi/new/halo-electronics/halo-ethernet-transformers/
http://www.diyaudio.com/forums/pc-based/154048-ethernet-galvanic-isolation.html
http://www.6moons.com/audioreviews2/sotm2/1.html
http://www.avrev.com/home-theater-accessories/acoustics-eq-room-tuning/sotm-iso-cat6-lan-filter-and-tx-usbhub-review-3.html
http://www.computeraudiophile.com/f22-networking-networked-audio-and-streaming/audiophile-ethernet-cables-13798/
http://www.computeraudiophile.com/f22-networking-networked-audio-and-streaming/ethernet-cables-audiostream-test-17713/
http://electronics.stackexchange.com/questions/27756/why-are-ethernet-rj45-sockets-magnetically-coupled/27762
http://www.diyaudio.com/forums/pc-based/154048-ethernet-galvanic-isolation.html

For most fiber optic applications single mode and multi mode fiber optic cable made of glass is most suitable. Single mode and multi mode are the two transmission methods for fiber optics- having to do with how they get the signal to the other end of the glass. They are not interchangeable, so it’s important to know which you have. Single-mode fibers provide a single pathway for light to travel and are defined by their small core size of approximately 8.3 µm. Multimode fibers, on the other hand, have various paths, or modes, in which light can travel through optical fiber. These core sizes are larger, ranging from 50 µm to 62.5 µm.

Single Mode Fiber Optic Cable
Core Diameter: Approximately 8-10 micrometers.
Light Propagation: Uses a single light path (mode) to transmit data.
Wavelengths: Typically operates at 1310 nm and 1550 nm.
Distance: Ideal for long-distance communication (up to 100 km or more).
Bandwidth: Higher bandwidth and lower attenuation, providing high data transfer rates over long distances.
Applications: Long-haul telecommunications, cable television, and Internet backbones.

Multi Mode Fiber Optic Cable
Core Diameter: Approximately 50-62.5 micrometers.
Light Propagation: Uses multiple light paths (modes) to transmit data.
Wavelengths: Typically operates at 850 nm and 1300 nm.
Distance: Suitable for shorter distances (up to 2 km for slower speeds and up to 550 meters for high-speed networks).
Bandwidth: Lower bandwidth compared to single mode, with higher attenuation over long distances.
Applications: Local area networks (LANs), data centers, and intra-building networks.

Single mode fiber has very thin center core. You need a laser source that is very accurately shooting signal to it and all cable splices need to be very accurate. In typical telecommunications fiber, single mode operation is obtained with core diameters of 2–10 microns with a standard outer diameter of 125 microns. Once you get signal to single mode fiber, it will go through it with very little loss and other signal quality issues. Single-mode fibre are used almost universally in telecommunications over 1 km or so and are generally used at the 1300 nm and 1550 nm wavelengths. (Below 1100 nm, the Rayleigh-scattering dominates, while above 1600 nm the infrared absorption dominates). Single-mode fibers used in telecommunications typically operate at 1310 or 1550 nm and require laser sources (that some were expensive and many are still are expensive). OS1 and OS2 are standard single-mode optical fiber used with wavelengths 1310 nm and 1550 nm (size 9/125 μm) with a maximum attenuation of 1 dB/km (OS1) and 0.4 dB/km (OS2). Single-mode fibres are capable of wide bandwidths (e.g. >40 GHz) and are, therefore, ideally suited for long-haul and high capacity circuits.

Multimode fiber has core diameters considerably larger, typically 50, 62.5, 85, and 110 microns, again with a cladded diameter of 125 microns. Because of their larger core size, multi-mode fibers have higher numerical apertures which means they are better at collecting light than single-mode fibers. Multi mode fiber has thicker core, so sending light to it is easier (cheaper led technology will work and does not necessarily need laser transmitter). Multi-mode fiber has higher “light-gathering” capacity than single-mode optical fiber. In practical terms, the larger core size simplifies connections and also allows the use of lower-cost electronics such as light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) which operate at the 850 nm and 1300 nm wavelength. Also cable splices do not need to be micrometer accurate to work OK. Multi mode is easier to work with and hardware for it is cheaper. As the name implies, multimode fibres are capable of propagating more than one mode at a time and they are ideally sited for high bandwidth (i.e. a few GHz) and medium haul applications. The disadvantages are much higher signal loss and more signal distortion – meaning supports less distance and less data bandwidth compared to single mode. Multimode fibers tend to have higher attenuation than single-mode fibers since the intrinsic loss of the multimode fiber is higher due to the natural loss of the fiber in the operating wavelengths of 850 nm and 1300 nm. The LED light sources sometimes used with multi-mode fiber produce a range of wavelengths and these each propagate at different speeds, which limits the available bandwidth over distance.

When transporting data over fiber optic cable, the transceivers have to match the cable type used. This means that the connector type in the transceiver and fiber optic type need to match. LC is the connector type tat is pretty common to find those when using SFP’s in network gear. Other connectors you may run into would be LC, SC, ST, and FC.

You need to select the transceivers that are designed to work with fiber type you have. Generally if you try to use multi mode transceivers with single mode cable, it will not work. Also trying to use single mode transceivers with multi mode cable does not give good results or work at all. Mixing different cable types on one fiber optic link is a recipe for a disaster.

Jacket color is sometimes used to distinguish multi-mode cables from single-mode, but it cannot always be relied upon to distinguish types of cable. The standard TIA-598C recommends, for civilian applications, the use of a yellow jacket for single-mode fiber, and orange for 50/125 µm (OM2) and 62.5/125 µm (OM1) multi-mode fiber.[3] Aqua is recommended for 50/125 µm “laser optimized” OM3 fiber.

Can you mix and match single mode and multi mode components / fiber? In some rare cases yes.

There are some special adapters that allow some mixing:
“The mode conditioning cables have allowed us to succesfully run Gb ehternet over our multimode cable using Single mode transcievers, but only at distances that would have worked using multimode transcievers. It did not work where we were exceeding the distance spec for multimode, must have been too much loss in the cable…”
“we just successfully ran from a SM Finisar FTLF1323P1BTR over a 400’ run of MM fiber to a media converter and it worked. I was trying to research this at this site so I posted our results.”
“I’m using 1000Base-LX/LH singlemode transceivers over 62.5 multimode fiber in several places, including a link over 1000’ long between two buildings. I do use mode-conditioning patch cables.”
Mode Conditioning Cable Selector: Launching a single-mode laser into the center of a multimode fiber can cause multiple signals to be generated that confuse the receiver at the other end of the fiber. A mode conditioning patch cord eliminates these multiple signals by allowing the single-mode launch to be offset away from the center of a multimode fiber. This offset point creates a launch that is similar to typical multimode LED launches. “The launch of the light coming out of the equipment begins on a Singlemode fiber. The Singlemode fiber is precision fusion spliced to the multimode fiber to a precise core alignment”

In a research laboratory environment I have run setup where a single mode transmitter sense signal to single or multi mode cable, and the signal was received with multi mode receiver. Also setup where single mode transmitter, single mode fiber, multimode fiber and multimode receiver has worked. Generally the direction that light goes from single mode to multi mode cable works somewhat OK, while the direction from multi mode to single mode causes a very high attenuation.

This article provides an overview of the most promising network technologies and innovations, such as time-sensitive networking, and looks at how they’re revolutionizing industrial communications.

Here are some links to some other related articles:

https://www.electronicdesign.com/blogs/altembedded/article/21240842/electronic-design-the-evolution-of-ethernet

Time for Time-Sensitive Networking (TSN)
Synchronization of clocks across the network is being standardized
https://www.electronicdesign.com/magazine/51099?utm_source=EG+ED+Auto+Electronics&utm_medium=email&utm_campaign=CPS220627006&o_eid=7211D2691390C9R&rdx.ident%5Bpull%5D=omeda%7C7211D2691390C9R&oly_enc_id=7211D2691390C9R

https://www.electronicdesign.com/industrial-automation/article/21241056/electronic-design-nxp-upgrades-industrialgrade-mcu-with-tsn-ethernet

https://www.electronicdesign.com/industrial-automation/article/21154669/electronic-design-switch-chips-bring-timesensitive-networking-to-factory-floors

What’s the Difference: Serial Communications 101
June 1, 2021
Communication is the hallmark of IoT and computer systems in general. Here are some of the basics.
https://www.electronicdesign.com/technologies/communications/whitepaper/21127800/whats-the-difference-serial-communications-101?utm_source=EG+ED+Auto+Electronics&utm_medium=email&utm_campaign=CPS220627012&o_eid=7211D2691390C9R&rdx.ident%5Bpull%5D=omeda%7C7211D2691390C9R&oly_enc_id=7211D2691390C9R

What is the bandwidth of your snax? How fast is your internet in bananas?
It is a common way to measure and MEME almost anything with a banana scale. There is now a banana scale for Internet speed: bananas transmit at about 53mbps on vdsl btw. VDSL over Banana is real – the tester got 53680/12658 kbps connection speed on a short run from in-house exchange/DSLAM, through banana, to a VDSL2 modem.
Here is a tweet from https://twitter.com/lauriewired/status/1735348312684020069 (also tweted at https://twitter.com/Evil_Mog/status/1709671970957386230)

It’s official, ADSL works over wet string Engineers at a small British internet service provider have successfully made a broadband connection work over 2m (6ft 7in) of wet string. The connection reached speeds of 3.5 Mbps (megabits per second). ADSL itself is something of an ingenious hack, carrying data over decades-old telephone wires designed only for voice. Some employees of Andrews & Arnold (a UK network provider) applied this mentality towards connecting their ADSL test equipment to some unlikely materials. The verdict of experiment: yes, ADSL works over wet string.

Here is picture of the experiment from https://www.revk.uk/2017/12/its-official-adsl-works-over-wet-string.html article.

According to those experiments it seems that you can use anything that is electrically conductive to transmit data signals in a way or another. In other news, materials that conduct electricity can be used to transmit signal. Marvelous finding lads!

Could you do that even without strings attached?
Can You Send The Internet Through Water Instead of Cables? The Literal Web Streaming Experiment!
https://www.youtube.com/watch?v=nEg9R7kcrIo

A lot of data goes through water, but using fiber optic cables instead of using the water itself as medium. There is a lot of data going under the sea. What’s more, 98% of the world’s internet cables are located undersea. This includes around 400 underwater cables around the world.

How The Internet Travels Under Sea
https://www.youtube.com/watch?v=LEM_I3HbIU8

How about telecommunications or fast data over barbed wire? Yes this has been done also.

Barbed wire fences were an early DIY telephone network. In some early years of telecommunication, even over 100 years ago, fences became phones: The unexpected use of barbed wire. A party line (multiparty line, shared service line, party wire) is a local loop telephone circuit that is shared by multiple telephone service subscribers. Party line systems were widely used to provide telephone service, starting with the first commercial switchboards in 1878. Barbed wire telephone lines were local networks created in rural America around the turn of the 20th century. In some isolated farming communities, it was not cost-effective for corporations to invest in the telephone infrastructure. Instead, the existing extent of barbed wire fences could be used to transmit electric signals and connect telephones in neighboring farms. Nowadays VDSL can be done over a farm fence if you want internet access or a security camera somewhere inconvenient.

But can you run Ethernet over barbed wire? In 1995 Broadcom showed it’s implementation of a subset of Fast Ethernet called 100BASE-T4 (different from the 100BASE-TX version that ultimately prevailed in the market). The value of the Broadcom T4 design was its ability to work at high speeds on horrible cables, so Broadcom wanted to demonstrate its operation using the world’s worst cable.

At Interop that year, Broadcom set up a 2×4-ft glass case containing eight parallel strands of barbed wire configured as four differential pairs, each running straight from side to side, suspended in air. The wires were ugly and rusty and had nasty little barbs all over them. A transmitter and a reel of Category 3 data cabling were on one side of the case. The data cabling led to the glass case where it coupled onto the four barbed-wire pairs. The other side of the case coupled through more Category 3 cabling to a receiver. They showed that 100 Mbit/s Ethernet can run over this kind of poor looking wiring sing their technology. During the show, lo and behold, Broadcom’s demonstration flawlessly conveyed 100 Mbps of data through the barbed wire. “Buy our parts” was the message the Broadcom marketing folks wanted to impress on their audience. There was also a display of this in action at COMDEX in Vegas (2000).

In year 2002 WideBand Gigabit Ethernet Over Barbed Wire was on display. WideBand Corporation has been showing its Gigabit Ethernet Without Rewiring by using barbed wire to make the point at trade shows from coast to coast this spring. WideBand has used its barbed wire demo as a way to underscore the robust transmission capability of its Ethernet products.

So how is it possible to use this kind of poor looking wiring for high speed data?
Only four properties really affect the performance of most digital transmission structures. The “big four” transmission-line properties are impedance, delay, high-frequency loss, and crosstalk. Crosstalk in a barbed-wire configuration is controlled by enforcing a large spacing between the pairs. The T4 system divides its data among the four pairs, so that each pair operates at only 25 Mbps. At that low frequency the skin-effect resistance of 4 ft of barbed wire is insignificant, and the overall high-frequency loss in the glass case at 25 Mbps was practically nil. The signal delay is less on barbed wire than on an equivalent length of PVC-insulated Category 3 wiring, due to the use of an air dielectric between the barbed strands. You can intentionally set the spacing to create almost any impedance you want. Inside the glass case, the spacing between barbed strands was set to create an impedance of 100 Ω.

In summary, the barbed wire had zero impact on signal quality. The signals went through perfectly undistorted. The only thing the barbed wire did was impress the heck out of Broadcom’s customers.

Besides Ethernet running over many barbed wires, the are also demos that run high speed data over one pair of barbed wires. Westermo has demonstrated Ethernet extension based on SHDSL technology running over a pair of barbed wire. The wire pair doesn’t have to be barbed wire, but it does look rather cool for this demo. If you need to run data over barbed wire over some real distance, this might be the practical way to do it. SHDSL technology allows running quite high data speeds over quite long distance old wiring.
Westermo Ethernet extender demo over barbed wire!
https://www.youtube.com/watch?v=LP3amXkjvPg

Links to more information on ADSL over wet strings:

https://www.revk.uk/2017/12/its-official-adsl-works-over-wet-string.html
https://hackaday.com/2017/12/14/adsl-robustness-verified-by-running-over-wet-string/
https://www.zdnet.com/article/fact-broadband-really-does-work-over-a-piece-of-wet-string
https://www.techpowerup.com/forums/threads/dsl-broadband-over-wet-string.239701/

Barbed wire Ethernet links:
https://www.sigcon.com/Pubs/edn/SoGoodBarbedWire.htm
https://www.wband.com/2002/05/wideband-gigabit-ethernet-over-barbed-wire-catches-fancy-of-national-magazine/
https://www.reddit.com/r/networking/comments/17g0b4/ethernet_over_barbed_wire/
https://www.quora.com/Is-it-true-that-someone-ran-Ethernet-over-barbed-wire-and-if-so-WHY
https://news.ycombinator.com/item?id=15910263
https://forums.tomshardware.com/threads/gigabit-over-barbed-wire.958476/

Barbed wire telephone links:

Phones, modems and barbed wire!
https://www.wanderingaustralia.com.au/the-phones-are-driving-me-mad/

Barbed Wire Telephone Lines Brought Isolated Homesteaders Together
And then let them snoop on each other
https://www.atlasobscura.com/articles/barbed-wire-telephone-lines-homesteaders-prairie-america-history

When fences became phones: The unexpected use of barbed wire
https://www.kttn.com/when-fences-became-phones-the-unexpected-use-of-barbed-wire/

Atrocious but efficient: How ranchers used barbed wire to make phone calls
A barbed wire telephone call didn’t sound great but could quickly warn others about something such as a wildfire.

https://www.texasstandard.org/stories/atrocious-but-efficient-how-ranchers-used-barbed-wire-to-make-phone-calls/

https://en.wikipedia.org/wiki/Barbed_wire_telephone_lines

https://www.agriculture.com/podcast/successful-farming-podcast/barbed-wire-telephones-connected-the-old-frontier

Barbed Wire Fences Were An Early DIY Telephone Network
https://gizmodo.com/barbed-wire-fences-were-an-early-diy-telephone-network-1493157700

The Daily Herald
Delphos, OH, United States, Thursday, April 19, 1900
vol. 6, no. 266, p. 3, col. 5-6
BARB-WIRE TELEPHONE LINE.
Three Towns in Indiana Connected by Using Ordinary Fence Wires.
https://reference.insulators.info/publications/view/?id=5740

TEXAS HISTORY
Wired for Sound
Between you, me and the fence post, barbed-wire telephone systems kept rural folks hanging on every word
https://texascooppower.com/wired-for-sound/

Video
BARBED WIRE TELEPHONE LINE
https://www.youtube.com/watch?v=koEkQ3EqyNk

The use of public telephones was common at the time and phone cards were seen as the cutting edge of development. Those were first launched on a large scale in 1986 in Germany by Deutsche Bundespost after three years of testing, and in France by France Télécom. Many other countries followed suit, including Ireland in 1990 and the UK circa 1994–1995. Tele (nowadays known with name Sonera) was the first to use phone card machines in Finland. Tele and several local telephone companies switched coin-operated telephones in telephone booths to card-operated telephone models in the early 1990s.

The cards had a certain amount of balance loaded at the time of purchase using chip technology. The first phase technology was technically quite simple and not very secure. But by the mid-to-late 1990s, highly secure technology aided the spread of chip phonecards worldwide.

The whole phone card technology was somewhat short-lived (especially in Finland) because in the late in the 1990′s they became unnecessary as cell phones became more common (thank’s to Nokia), which led to situation that the the previously common telephone booths disappeared from the street scene. Here are pictures of one 30 years old not so smart telephone booth calling cards used in Finland.

This type of telephone cards are the simplest type of “smart card”. The cards had a certain amount of balance loaded at the time of purchase, and this amount was stored to the card. Those telephone cards (as used in Finland and France) were technically simple memory card with smart card connector. This kind of memory cards only have some amount of memory inside the card and this memory can be normally read and written. There is normally nothing really intelligent inside those cards. There is a memory chip that has a small amount of card information it followed by memory are that contains the information of balance in the card.

A stored-value phone card stores the available balance in digital memory physically embedded in the card. This balance can be read by a public payphone when the card is inserted into the card reader. The stored-value system used in Finland write data to an embedded chip to reflect the new balance after a call. Used primarily for payphones, stored-value systems avoid the time lag and expense of communication with a central database, which would have been technically complex before the 1990s. In Finland the card had a memory area, where there was one memory bit for each token (30 mk card had 30 tokens) value in card. The tokens could be freely read, and one by one written to “used” state after use (but could not be turned back to not used state).

The technology worked, but it was not the most secure as a href=”https://en.wikipedia.org/wiki/Telephone_card”>the initial microchips were easy to hack. Some users found out that some cards could be hacked by scratching off the programming-voltage contact on the card, which rendered the phone unable to reduce the card’s value after a call. Also some people have built their own cards that looked like phone card to the phone, but they did not decrease the stored amount during use or were automatically reset back to card balance full state when removed from card. This kind of hack cards could be built at the time using a small thin circuit board and a small micro-controller soldered to it running a small program that emulates phone card operation.

I was interested in how those cards worked in the early 1990′s. I looked the technical information related to them and built my own hardware+software that allowed my PC to communicate with them.

Hacker magazine PHRACK issue 48 (September 1, 1996) published a two part article on electronic telephone cards technology. That article also mentions some of my work on the field (I improved some of the card communications software published in the article). The software enables you to dumb the memory of electronics phonecards to see the information in them. The software also allowed to write to cards (write out some bits to lower the balance).

You can find the article parts here:
Electronic Telephone Cards: How to make your own! (part 1)
Electronic Telephone Cards: How to make your own! (part 2)

Here are some picks from those articles:

{*****************************************************************************}
{ T E L E C A R D . PAS }
{*****************************************************************************}
{ This program enable you to dumb the memory of electronics phonecards }
{ from all over the world, so that you will be able to see which country }
{ the card is from how many units are left and so on …. }
{*****************************************************************************}
{ }
{ Written by Stephane BAUSSON (1993) }
{ }
{ Email: sbausson@ensem.u-nancy.fr }
{ }
{ Snail Mail Address: 4, Rue de Grand }
{ F-88630 CHERMISEY }
{ France }
{ }
{*****************************************************************************}
{* Thanks to: Tomi Engdahl (Tomi.Engdahl@hut.fi) *}
{*****************************************************************************}

After the information was more widely on-line, more and more people figured out how to hack those phone card to get free calls. People hacked those card and sold fake cards in Finland to the point that phone companies had to start to try to catch the users of fake phone cards and magazines started to write about the problem.

Here is one article from 1996 on the phone card hacking problems in Finland:
Puhelinkorttien jäljitelmillä huijattu ilmaisia puheluita Tele joutui korjaamaan tuhansien yleisöpuhelimien suojausta
” Poliisi tutkii Suomessa ensi kertaa paljastuneita puhelinhuijauksia, joissa on puhelinkorttien jäljitelmien avulla huijattu ilmaista soittoaikaa. Simulaatiokorteiksi kutsuttujen jäljitelmien avulla huijari on voinut soittaa ilmaiseksi kuinka kauan tahansa.”

Just few years later the system started to shut down because in addition to free calls problems the increasing owning of of mobile phones started to make phone booths not as profitable anymore as it once was.

Sources:
https://en.wikipedia.org/wiki/Telephone_card
https://www.epanorama.net/links/smartcards.html#memorycard
https://www.turku.fi/blogit/kukkuu-kokoelmista/kokoelmanosto-kuvat-kortilla-yleisopuhelimien-lahihistoriaa
Electronic Telephone Cards: How to make your own! (part 1)
Electronic Telephone Cards: How to make your own! (part 2)
https://groups.google.com/g/sfnet.harrastus.elektroniikka/c/k2yqfJVb_aA/m/fqmm4nNa4MwJ
https://www.hs.fi/kotimaa/art-2000003536142.html
https://www.antikvariaatti.net/kerailyesineet/puhelinkortit

Exactly which day Cerf and Kahn’s manuscript was received by the IEEE editors is not clear (it was either November 4th or 5th, 1973).

Cerf and Kahn’s paper was published in the May 1974 edition of IEEE Transactions on Communications, Vol Com-22, No 5 May 1974 [1].

Happy 50th birthday TCP/IP!

#internet #tcpip

References:
[1] “A Protocol for Packet Network Intercommunication”, https://www.cs.princeton.edu/courses/archive/fall06/cos561/papers/cerf74.pdf

Modems are commonly used for connecting computers and other devices to the internet or other remote networks. They come in various types and technologies, including: Dial-Up Modems, Fixed-line Modems, DSL Modems, Cable Modems, and Wireless Modems.

Dial-Up Modems are the traditional modems used for connecting to the internet over telephone lines. They work by dialing a phone number and establishing a connection with an internet service provider (ISP). Dial-up modems are relatively slow compared to modern broadband technologies. This article concentrates on the dial-up modems that were widely used from 1980′s to early 2000′s.

A modem transmits data by modulating one or more carrier wave signals to encode digital information, while the receiver demodulates the signal to recreate the original digital information. Modems communicating over telephone line operate with one functioning as an originate unit and the other as an answer unit. Three modulation techniques in common use to send data over communications line are amplitude, frequency and phase modulation. In a frequency modulation system, digital signals are connected to one of the two frequencies corresponding to the 0 and 1 values of the data. The simplest modulation of this form is known as Frequency Shift Keying (FSK). FSK is a commonly used technique for low speed transmission (typically 0 to 600 bits/s). Phase modulation or phase modulation together with amplitude modulation is widely utilized in high speed systems.

The public telephone network was the most commonly used transmission system for modems. A dial-up modem transmits computer data over an ordinary switched telephone line that has not been designed for data use. This is a very limited media with only around 3 kHz of useful bandwidth. The early dial-up modems generally operated at 110 or 300 bits per second (bit/s), and the connection between devices was normally manual, using an attached telephone handset. Those connected to the computer or terminal using RS-232 serial port interface. By the 1980s, less expensive 1,200 and 2,400 bit/s dialup modems were being released. Those modems were available as separate boxes (connected with RS-232 cable) and as PC expansion cards. I started my modem journey with those in the late 1980′s. Dial-up Internet has been around since the 1980s using those modems.

Once it was thought that dial-up lines having bandwidths of 3 kHz was suitable for transmission rates of up to 4800 bits per second, but modem standards with much faster maximum speeds were developed. As device sophistication grew rapidly in the late 1990s, telephone-based modems quickly exhausted the available bandwidth, reaching 56 kbit/s. Dial-up modems were once a widely known technology, since it was mass-marketed to consumers in many countries for dial-up internet access.

Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone line. Dial-up connections use modems to decode audio signals into data to send to a router or computer, and to encode signals from the latter two devices to send to another modem at the ISP. The beayty of dial-up connections to the Internet that it required no additional infrastructure other than the telephone network and the modems and servers needed to make and answer the calls. This made telephone dial-up access widely available.

The rise of public use of the internet during the late 1990s led to demands for much higher performance, leading to the move away from audio-based dial-up modem systems to entirely. The replacements were DSL, cable modems and wireless mobile communications that could supports speeds of megabytes per per second. Dial-up service has since been largely supplanted by broadband internet. Broadband Internet access via cable, digital subscriber line, wireless broadband, mobile broadband, satellite and FTTx has replaced dial-up access in many parts of the world.

Let’s get back to the dial-up modems technology. Pairs of modems are used at opposite ends of a telephone connection, each with a transmitter and a receiver to achieve bidirectional (called full duplex) communication. Once such modems are in place, and once they have been connected via the telephone network, then they function as a bidirectional “bit pipe.” That bit pipe is then usable by other systems.

Sending different sounds to telephone line through telephone interface is not technically very complicated. But it requires quite a sophisticated device, with some very elaborate signal processing, to extract a bit sequence from such a sound. That is the modem receiver, and it is indeed quite a sophisticated device.

Block diagram of V.90 system (ISPs) are already using digital connection at their end. There is only one analog portion on the downstream transmission path (from ISP to DTE) and the upstream data conforms to the V.34 standard.

The dial up modems were controlled by the computer using AT commands. AT commands are essentially modem instructions. Originally developed by the modem maker Hayes as means to operate their dial-up landline products, AT commands — the ‘AT’ stands for ‘come to ATtention’ — are now used by all modems, of all types. AT commands are primarily used to configure a modem and establish its network connection. AT commands are sent to the modem as plain text over a serial (UART). Even modern developers that use cellular modem will have to make use of what are called ‘AT commands’ at some point to control their communications device.

Here are some interesting videos on dial-up modems:

Dial Up Modem Sounds, from 300 bps to 56K
https://www.youtube.com/watch?v=xalTFH5ht-k

The sound of dial-up at some of the most common speeds, including 300, 1200, 2400, 9600, 14,400, 33,600, and 56K. As noted in the video, the sound of a V.34 connection at either 28,800 and 33,600 will be the same, and both were common around the same time, so I’ve only included the 33,600 connection.

0:00 Intro
0:04 300 bps Bell 103
0:19 1200 bps V.22
0:31 2400 bps V.22bis
0:46 9600 bps V.32
1:02 14,400 bps V.32bis
1:19 33,600 bps V.34
1:36 56 Kbps V.90

Why Does Dial Up Sound The Way It Does? (An Explanation)
https://www.youtube.com/watch?v=xp47x1EabqI

V.90 Dial-up Modem Handshake – Transactional Analysis
https://www.youtube.com/watch?v=VaWpi9o_hHI

Check also related article The sound of the dialup, pictured at https://www.windytan.com/2012/11/the-sound-of-dialup-pictured.html with this drawing:

Dialup modem connecting
https://www.youtube.com/watch?v=jpMrTxMV6E4

Dial Up Modem Handshake Sound – Spectrogram
https://www.youtube.com/watch?v=vvr9AMWEU-c

How 90s dial-up Internet worked, and let’s make our own ISP.
https://www.youtube.com/watch?v=Je8lwcUPBys

Up until home broad band came into existence the only way to access the internet at home was to get your modem to call the ISP’s phone number and listen to the unpleasant sound that would happen. In this video we look at the history and technology of dial-up ISPs and build one our self.

0:00 – Introduction
1:02 – A word from our sponsors
1:45 – Let normal service resume
3:07 – Bell 101 Modem
3:51 – Hayes Smart Modem
7:38 – Building an ISP
8:34 – Telephone line simulator
11:05 – Building a Linux Dialup Server
14:28 – Client setup
15:34 – First test
16:00 – Comparing our setup to a commercial one
19:36 – 56k modems & ISDN
25:50 – Radius
27:20 – Testing over the real phone network
29:59 – Free serve
34:50 – The coming of broad band
35:43 – Emergence service after the POTS switch off
37:27 – Thanks

Sources:

https://www.eeeguide.com/modem-definition/
https://en.wikipedia.org/wiki/Modem
https://ptolemy.berkeley.edu/eecs20/week2/modems.html
https://ptolemy.berkeley.edu/eecs20/week2/modems.html
https://www.researchgate.net/figure/Block-diagram-of-V90-system-ISPs-are-already-using-digital-connection-at-their-end_fig1_287206229
https://www.twilio.com/docs/iot/supersim/introduction-to-modem-at-commands
https://en.wikipedia.org/wiki/Dial-up_Internet_access
SERIES V: DATA COMMUNICATION OVER THE TELEPHONE NETWORK at
https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-V.8bis-199608-S%21%21PDF-E&type=items