The original author was Fred Archibald, VE1FA, and this article is a translation and rewrite of his work.
The radio on the Titanic
I. A Brief History of Early Radio Development
| Do you have any power amplifiers? | Transmitter type | Application period |
|---|
| None | Spark Gap Transmitter | From 1886 to the early 1920s |
| None | RF signal generator | From 1902 to the 1920s, some were used in the 1950s. |
| There are | Arc discharge generator | From 1905 to the 1940s |
| There are | Vacuum tube transmitter | From 1906 to the 1970s, it still has some applications currently. |
| There are | Semiconductor Transistor | From 1947 to present |
A simple spark generator, which works by creating an LC oscillation through high-voltage discharge to release a damped wave.
200kW Александerson RF AC generator, using an electric motor to drive the generator at high speed to produce RF AC power.
1MW American Navy Arc Radio. The arc radio was one of the earliest transmitters capable of producing a continuous sine wave, and it was also one of the first technologies used to transmit sound (amplitude modulation) wirelessly. It quickly replaced the spark radios, which occupied a very wide spectrum. In 1922, approximately 80% of wireless devices used arc radios.
You can refer to the introduction of the Arc discharge generator for reference. Arc Welding Wireless Transmitter - Electronics Engineering Special Issue
Two. The Titanic's antenna.
The photo shows the Titanic: 53,310 tons; length 883 feet (269.1 meters), width 92 feet (28 meters), 46,000 horsepower, with a capacity for 2,224 passengers and two wireless sets on board.
The diagram shows the Marconi double-T antenna structure for the Titanic. It consists of two pairs of horizontal wires and two pairs of feed lines connecting to the radio equipment.
The horizontal antenna group consists of two masts, one extending from the bow and the other from the stern, with a total length of 450 feet (137.2 meters). The height above the deck/sea level is 190 feet (57.9 meters) for the forward mast and 250 feet (76.2 meters) for the aft mast. The two ends are connected and fixed using asphalt-coated hemp rope and 20-foot (6.1 meter) white cedar poles. The intermediate wires consist of two pairs of parallel wires, with a spacing of 6 feet (1.8 meters) between them, and there are also four downward-pointing wires. The feed point for the antenna is located at the center of the "T", with an approximate natural resonant frequency of 930 kHz (325 meters wavelength).
It is indeed a positive gain antenna on the long axis.
Three. Titanic's radio equipment
1. Summary parameters
The Titanic had two sets of sending and receiving equipment: one for primary use and another for secondary use.
Main transmitterThis was the most advanced spark-gap transmitter of its time, designed for a 5kW synchronous rotary system. Operated by radio operators Jack Philips (25) and Harold Bride (21), it was installed, tested, commissioned, and operated at the Harland + Wolff shipyard in Belfast, and went into full operation on April 2, 1912.Call signForMGY。Input DC powerFor 100-110 VDC at 60A.Transmitting wavelengthThe signals were transmitted on two frequencies: a 600-meter "longwave" (500 kHz) and a 325-meter "shortwave" (930 kHz). The modulation signal frequency was 840 Hz. During the day, it guaranteed communication within 250 miles (402 km), and at night, it could reach over 2000 miles (3218 km).
Main receiverFor the Marconi MultiTuner+ Marconi magnetic detector / Fleming valve detector + standard telephone equipment.
Auxiliary transmitterFor use with a 1.5W standard spark transmitter featuring a 10-inch coil. When using a charger and battery, it can cover up to 40 miles (64 kilometers) during the day.
Auxiliary receiverFor non-tunable powder detectors/offsetters + ink jet printer.
2. Amplitude-modulated wave（DW）
The early spark gap transmitter emits a damped wave, also known as an attenuated or damped wave (not a continuous CW signal). In AM mode, it sounds like crackling or buzzing. The sound of the sparks during transmission is the modulated audio signal.
The damped wave, also known as a simple spark, was used in the 1920s.
Continuous wave CW operation of modern transmitters.
The 840 Hz synchronized "modulated" rotary spark emission waveform of the Titanic. This might be called a "modulated continuous wave".
The image shows the patterns of the three E-type sparks. From left to right, they are at 60 Hz, 120 Hz, and 750 Hz.
It can be seen that increasing the frequency of sparks leads to significant improvements in both pitch and efficiency.
The diagram illustrates the principle of asynchronous rotary spark gap emission. Higher spark frequencies result in better performance.
IfThe peak voltage of the synchronous generator should be synchronized with the rotational spark gap.This can lead to better performance.
Translator's Note:A typical spark gap has only one set of electrodes, and the spark frequency is determined by the electrode spacing. When the switch is pressed, the capacitor charges, and the voltage gradually increases. When the voltage exceeds the breakdown voltage of the air, a discharge channel forms, creating a column of sparks. The spark discharge channel, capacitor, and inductor form an LC damped oscillation until the voltage no longer supports the formation of the discharge circuit, at which point the discharge terminates. Subsequently, the capacitor recharges to the discharge voltage for another discharge. For a 700 Hz spark generator, this type of discharge occurs 700 times per second.
For asynchronous rotating spark generators, the electrode spacing is significantly smaller than that of conventional spark gaps. In this case, the discharge frequency is determined by the rotational speed of the spark gap. During a single discharge, the electrodes rotate to complete the discharge, while the next set of electrodes quickly rotates to initiate another discharge. This increases the spark frequency to improve emission efficiency.
For synchronous rotary spark generators, the electric generator and discharge plate rotate synchronously. This allows each discharge to occur at the absolute peak value of the AC generator's voltage, maximizing the efficiency of the discharge. This requires the number of electrodes on the discharge plate to be twice the number of poles on the generator. For example, for a 700Hz side tone, a 350Hz AC signal (with two absolute maximum values per cycle) is required. Assuming the generator has 4 poles and 8 poles, there should be 16 electrodes on the discharge plate. The motor speed needs to be 700 ÷ 8 × 60 = 5250 rpm.
3. Marconi 5kW Synchronous Rotating Spark Generator
As shown, the system uses 100V-110V DC power to operate, requiring a maximum of 60A current during transmission. The electrical energy is initially used to drive the system.Electric generator set(Motor Generator Set or M-G set) outputs AC power of up to 5kW at 300V and 420Hz. The minimum DC motor power is 10 horsepower. The generator parameters are: 6300 rpm, gear ratio of 8, and a current of 17A during operation. The rotating discharge plate has 16 discharge terminals.The generator rotor rotates synchronously with the rotary spark gap.This results in an emitted frequency of 840 Hz.
When the power switch is activated, the electrical energy passes through a step-up transformer and is converted to 10-14 kV, which is then transmitted to the rotary spark generator and the LC main oscillator.
On the left side of the diagram, the motor field rheostat (Motor Field Rheo) is used to set the motor's power and speed, as well as the signal tone.
On the right side of the diagram, the alternator field rheostat (Alternator Field Rheo) is used to adjust the high voltage and also to control the quality of the spark.
The current through the switch is approximately 17A at 300VAC. Due to the high voltage and current, a relay is actually used for control purposes.
The diagram shows the principle of operation for a 5kW rotary spark generator used on both the Olympic and Titanic (basic, but correct).
This is a very sophisticated and precise piece of engineering, which was essentially a super radio for amateur wireless enthusiasts in 1912.
The diagram shows a complete schematic of the wireless communication equipment on the Titanic, created by EA8EX.
4. Components of some radio transmission devices
Tuning lampIt functions as both a radio current meter and a tuning instrument. It can be used to verify the transmitted current or tuning state by observing the brightness of the bulb.
WithGrounding protectionofSpark gap switch for on/off operation(With a 0.01-inch mica insulation gap), it enables fast switching between sending and receiving.（QSK）
Marconi magnetic reed relay（1910）Translator's Note:Low-power spark generators allow for direct control of circuit switching using a switch. For high-power equipment, the current and voltage are very high, requiring relays to be used to indirectly control the circuit.
Physical objects on board the Olympia ship.
The picture showsElectric switch for an executioner's platform(Guillotine Key), a Marconi key used for the 5kW rotating spark transmitter on the Titanic.
The lever on the side is used for a short-circuit receiver to protect it during transmission.
Marconi 5 kW Electric generator set(M-G set), includingMechanical synchronous rotating spark gap("Disc-type electrostatic device"), and placed inside a protective enclosure. As shown in the figure, the motor, generator, and discharge disc are all mounted on the same shaft and rotate at the same speed.
The transmitting equipment in the "silent room".
The silent room on the Titanic, reconstructed in the 2003 American documentary "Deepwater Phantom," featuring a rotating spark generator.
Actual photographs taken underwater using a submersible in 2002.
5. Titanic's receiving equipment
Marconi invented the radio tuner, and received a patent (number 7777) in 1900. The picture shows...Marconi road tuner(Marconi Multiple Tuner): Tuning range is 2600-100 meters (120 kHz - 3 MHz). Patented by Marconi in 1907, widely used from 1907 to 1918. Typically used with the "Maggie" magnetic detector.
This device can adapt to various types of antennas and match signals from different antennas to a receiver within a wide frequency range. However, the device can only choose between high selectivity and high sensitivity.
When an operator chooses to communicate with a distant, weak signal using radio, they sacrifice selectivity and become susceptible to interference from nearby, high-power radio stations operating on adjacent frequencies.
The Marconi Multiple Tuner, designed by C.S. Franklin in 1907, offered improved sensitivity and lower losses compared to previous devices. It could operate in the 100-2600m band (3MHz-120kHz).
The image shows Marconi's "Maggie" magnetic detector. Operators at the time particularly liked its sensitivity, which was superior to the spare Marconi electronic tube detector.
The diagram shows the principle of the "Maggie" detector, invented by Ernest Rutherford in 1895, and improved upon by Marconi in 1902. It is much more sensitive than the powder detectors. It was the standard detector used by Marconi Company from 1902 to 1918.
This device operates based on a nonlinear magnetic hysteresis effect (only half of the AC input wave magnetizes the iron wire), thus generating an output signal, functioning similarly to a diode.
Another main sonar device on the Titanic wasFleming vacuum tube detector. The image on the right illustrates the principle of a common vacuum tube detector. However, in reality, the detectors used on the Titanic did not have couplers; instead, they were directly inserted into the Marconi three-way tuner and the large "T" antenna. Theoretically, it was more sensitive than the magnetic detector "Maggie." In practice, however, its reliability was very poor. The Marconi version used two vacuum tubes in a full-wave circuit.
6. Overview of radio room photos
The only known photograph of the Titanic's radio room. This is a photo taken by H. Bride, showing passengers disembarking in Queenstown, Ireland.
The radio room on the Olympic.
A movie still from the film "Titanic".
7. Actual performance of Titanic's wireless equipment
Marconi Company guarantees that the Titanic's wireless system will provide reliable communication over a distance of 250 miles (402 kilometers) during daylight hours.
During the sea trials in Ireland (April 2-3):
Night communication was excellent, and stable links were established with Tinerfe (1900 miles / 3057 km) and Portos de Ace (2600 miles / 4184 km).
The communication system provides stable daytime operation, maintaining continuous contact with vessels and coastal radio stations over distances exceeding 400 miles (644 kilometers).
During navigation:
During the period from April 7th to 14th, MGY successfully transmitted hundreds of messages to coastal radio stations and the Cape Race station in Newfoundland, all destined for the United Kingdom.
On April 13, a malfunction occurred in the radio system, causing the 5kW transmitter to fail. The operator worked through the night trying to fix the problem. The cause of the failure was a short circuit due to a 14kV rubber-insulated cable grounding. Both operators were extremely fatigued during the repair process and continued working until late on April 14.
After colliding with an iceberg (April 14):
After colliding with the iceberg, the Titanic's radio system remained functional, maintaining good communication with at least 12 other ships and receiving information from at least 24 ships. It also successfully established contact with the Cape Race radio station. The radio equipment continued to operate for several minutes before the ship sank on April 15th.
Before the Titanic sank, a total of 24 ships received distress signals. The shore-based radio stations were located at:
Cape Race, Newfoundland Island (Call sign: MCE)
Sable Island, Nova Scotia (call sign MSD)
Siasconset, Massachusetts (call sign MSC)
Sea Gate, New York (Call sign: MSE)
The final distress signal ("CQD") was received at 02:17 local time (UTC 05:27), followed by flooding in the engine room and failure of the generators. Phillips stopped working, went to the engine room to turn off the main switch, and then fled. However, the upper deck had been flooded, and Phillips was unable to escape; the Titanic sank within 3 to 4 minutes.
MKC's reply to MGY via telegram
Four. The Sinking of the Titanic
Timeline of the disaster
(Measured at the local time of the Titanic, which was 5 hours and 50 minutes ahead of New York time)
April 10th - 14th
A total of 250 Marconi telegrams were sent.
April 14
9:50 PM – OP C. Evans of the Californian:We have come to a complete stop, completely surrounded by ice."We have stopped the ship; there's ice all around."
11:50 PM – The Titanic's lookout spots an iceberg.
11:50:37 PM – The Titanic strikes an iceberg (at a distance of 500 yards, at a speed of 22.5 knots).
April 14-15
11:58 PM 128:14 AM — Captain Smith visits the radio room.
April 15
12:15 AM ——— The Titanic repeatedly sent out 6 emergency radio messages:CQD CQD CQD from MGY 41.46N 50.14W
12:15 – 12:45 AM — Multiple vessels and land-based radio stations responded, leading to a surge in communication volume.
12:25 AM – The Carpathia (callsign MPA) called the Titanic:Cape Cod has messages for you.
12:27 AM – Titanic (call sign MGY) responds:Come immediately. We have sighted Berg. It's a CQD vessel.
12:45 AM —MKC MKC SOS SOS de MGY MGY MGY(MKC is the call sign for the Olympic)
02:17 AM – Received the last signal from the Titanic:CQD from MGY The signal transmission was interrupted for half of its duration.
02:20 AM – The Titanic breaks apart and sinks.
If possible
There were many coincidences that could have prevented the Titanic disaster.
April 10-14 – Telegraph operators Brady and Philip of the Titanic sent out 250 miscellaneous passenger telegrams, which affected communication regarding the iceberg warning and other ships. The two operators were very tired.
April 13th – The transmitter malfunctioned, so Philip spent 6 hours troubleshooting. Therefore, he was unavailable on the evenings of April 14th and 15th.I'm very tired.。
4:50 PM on April 14 – SS Mesaba to Titanic（MGY）Send message
Halted. The sea was covered in ice.
"Stop! The sea surface is completely covered in ice."
The telegram starts with "Ice report" instead of "MSG".Therefore, the telegrams were piled up on Philip's desk before the accident occurred.Not passed on to Captain Smith.。
April 14th, at 9:05 PM – C. Evans, the Californian's radio operator, sent the following message:SOM, we have come to a halt and are surrounded by ice.
However, Philip sent:D D D D I am working on Cape Race.
At that speed, faster ships had priority in communication; this was famously known as the "shut up!" rule.
At 11:55 PM on April 14th – Evans had been on duty since 7 AM, so he left for the night at 11:35 PM. At 11:50 PM, the Titanic lookout spotted the iceberg.At this point, the Californian was only 11 miles away from the Titanic!
At 12:05 AM on April 15th, Philip began sending CQD. Many distant ships could hear it.
At 12:20 AM on April 15th – Charles Groves, aboard the Californian, was attempting to receive signals, but did not know how to activate the magnetic telegraph's winding mechanism. At this time, the Titanic was continuously sending out CQD distress calls.
From 12:30 AM to 2:10 AM on April 15th. The captain of the Californian, Lord, and a lookout spotted the lights and rockets from the Titanic approximately 11 miles away. Due to the cold water mirage, the Titanic appeared very distorted."I don't need to call Evans to confirm on the radio, or go there to check. I think this ship couldn't possibly be the Titanic."
Six days later.
The Type B inflatable life raft saved Bradley's life, but Philip sacrificed himself, and his body remained on the raft. Other crew members from Mackay-Bennett of Halifax were also aboard the raft.
On April 15, 1912, the collapsible lifeboats of the Titanic were approaching the Carpathia.
Survivors of the Titanic on the deck of the Carpathia – "Women and children first"
Harold Breed was boarding the Kapasia. Due to his severe injuries, Breed worked on the Kapasia's radio for several hours, giving Cottam, the Kapasia's telegraph operator, a chance to rest.
On the left is Jack Phillips, 25 years old, a senior telegraph operator on the Titanic. (SK)
On the right is Harold Bride, 22 years old, a junior telegraph operator on the Titanic.
From left to right: C. Groves (on the California), C. Evans (on the California), and Cottam (on the Capasia).
The impact of the Titanic sinking on radio.
On the one hand, 710 people were rescued thanks to radio communication during this incident, demonstrating its crucial role in emergencies. The Titanic's radio system continued to function effectively until just minutes before the ship sank, when the generators flooded. All radio operators performed admirably or heroically: Cyril Evans, Harold Cottam, Jack Philips, and Harold Bride.
However, on the other hand, the lack of adequate regulations and operational procedures for radio communication at the time created significant vulnerabilities, which ultimately led to the accident and the loss of another 1514 lives.
The International Telecommunication Union, founded in 1865（ITU）Responsible for controlling, managing, and establishing all international communication standards. From June 4 to July 5, 1912 – six weeks after the sinking of the Titanic – a conference was held in London.International Wireless Telegraphy Congress1912 International Radiotelegraph ConventionThe focus was on the Titanic disaster.
Unlike before, there was no longer any opposition to the idea of mandatory mutual communication. Marconi Company announced that it would only allow its radio stations to communicate with other Marconi radio stations in emergency situations.
Ultimately, as a result of the Titanic disaster, the conference added the following new regulations:
Follow the national allocation of call signs in alphabetical order.Translator's Note: At that time, there were only three call signs, distinguished by their first letter; radio stations belonging to the Marconi Company started with the letter "M".
According to the requirements, priority should be given to sending weather and time reports to ships. Ships in the area are required to avoid transmitting these reports while doing so.
All radio transmissions in the vicinity of a vessel in distress must be controlled by that vessel. In emergencies, it is necessary to suspend the transmission of long messages.
The radio operator must receive and follow instructions directly from the ship's captain.Translator's Note: At that time, the radio operator on board was employed by Marconi Company.
The ship's radio system must be able to operate for at least 6 hours without generator power. If the main radio on the ship does not meet this requirement, a secondary radio that meets this requirement should be installed.
Maintain continuous 24-hour radio surveillance of all large vessels.
Radio room clock: with a 3-minute silent timer and an automatic alarm timer.
On the other hand, the United States passed its first radio law.The US Radio Act of 1912It was approved in August of that year and complied with the regulations set by the International Telecommunication Union (ITU).
All radio stations and operators must obtain a license.
All ships must maintain a 24-hour radio watch.
The 600 MHz band (500 kHz) is an emergency frequency, and priority should be given to urgent messages.
There are two 3-minute periods of silence each hour to handle emergency calls.
"SOS" is the standard distress signal.
Amateur radio stations are only allowed to operate on frequencies up to 200 meters, i.e., above 1.5 MHz!
V. Conclusion
Ultimately, the regulations regarding radio communication, which were either introduced or improved as a result of the Titanic disaster, likely saved more lives than those lost on the Titanic.
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