Tales of disaster – Page 8 – Engineering Radio

Shut up! shut up! I am working Cape Race

So sent wireless operator John “Jack” Phillips on the night of April 14th, 1912, and likely sealed the fate of some 1,514 passengers and crew of the RMS Titanic, radio call sign MGY. That message was sent in response to the radio operator on the SS Californian/MWL, who was attempting to report icebergs nearby.

Of course, it would be a gross error to blame the sinking of the Titanic on the radio operator, he was but one small link in a long chain of events that unwound that fateful night one hundred years ago. Beginning with the ship’s design and ending with the Captain of the Titanic, Edward Smith, many seemingly unconnected decisions lead up to the ultimate disaster that befell the Titanic.

After about four days at sea, during the late morning/early afternoon of April 14th, the Titanic began receiving wireless messages indicating “growlers, bergs, and ice fields” were in the area. The Captain decided to alter the ship’s course to the south, out of the supposed ice fields.

In spite of numerous reports of nearby ice, the Captain did not order the ship to reduce speed. It continued on at 22 knots (41 kp/h) up until the time it struck the berg. Lookouts were posted in the crow’s nest, near the bow, to spot icebergs. This was considered normal operating procedure at the time but is the most significant factor in the collision. A number of nearby ships had spotted ice and had greatly reduced speed or stopped for the night. Further exacerbating the situation, the lookouts on the Titanic did not have binoculars, which was due to a mix-up before they sailed from England.

Some of the ice reports received later in the day and evening did not make it to the bridge. Wireless operator Jack Phillips was either repairing a malfunctioning spark gap transmitter or was sending messages from passengers to Cape Race Radio/MCE, Newfoundland. At the time, the (wireless) radio operators were not a part of ship’s company but rather were employed by the Marconi Company for the purpose of sending messages for profit. Any notion of safety or distress communication was an afterthought.

The SS Californian, the closest ship to the Titanic at the time it sunk, was attempting to broadcast another ice warning to all ships in the area at about 10:30 pm. The message was broken off by Phillips with a terse: “SHUT UP! SHUT UP! I AM WORKING CAPE RACE” At about 11:30 pm, Cyril Evans, the Californian radio operator closed the station and went to bed. Ten minutes later, the Titanic struck the iceberg.

The Titanic used a 5 KW synchronous rotary spark gap transmitter, which was state of the art at the time. The power is measured at the input of the DC motor. Considering the efficiencies of the motor and generator, the ability of the spark gap to generate RF, and the efficiency of the tuning circuits and antenna, the actual power radiated by the transmitting antenna would have been significantly less, on the order of a couple of hundred watts. The above schematic is not exactly the same as the unit installed on the Titanic, as the meters and additional controls for motor speed and generator voltage have been omitted. Additionally, some sources report the transmitter as a 1.5 KW non-synchronous unit. The difference between the two would be very apparent in the sound of the received signal; a synchronous transmitter had a tonal quality to it versus a non-synchronous or simple spark gap, which sounded like hissing. Wireless operators from shore stations and other ships who worked the Titanic reported that they were using a synchronous unit.

The transmitter used two frequencies; 600 meters, or 500 KHz, and 300 meters, or 1,000 KHz. Because of these frequencies, the maximum range during daylight hours was about 200-400 miles (322-644 km). At night, the ranges were considerably more, 1,000-2,000 miles (1600-3200 km), which is typical for medium frequencies, including the AM or standard broadcast band in use today. Thus the effort by the Titanic radio operators to clear the backlog of message traffic during darkness, when Cape Race was about 374 miles (602 km) away.

Another part of the problem was with the transmitting and receiving apparatus itself. The transmitters were crude and generated broad harsh signals. The receivers were also very broad, and nearby transmitting stations could easily wipe out all frequencies on early receivers. That is what likely prompted Phillips’ outburst, something termed today as blanketing interference. Vacuum tubes (aka valves) had yet to be accepted for widespread use as amplifiers and most receivers were simple tuned circuits connected to a detector of some type. As such, receivers were far less sensitive and selective than they are today.

Interestingly, the Titanic had both types of receivers on board. The main receiver was a tuned circuit with a Marconi Magnetic detector (aka “Maggie”) and a valve receiver as a backup. The valve or vacuum tube was likely a simple diode detector connected to a tuned circuit.

After the collision, Jack Phillips stayed at his post sending out distress messages and communicating with other ships en route to assist. Long after the Captain told the radio operators they were dismissed, Phillips persisted until power was lost and the radio room began flooding. He perished shortly after in the 28° F (-2°C) water, however, assistant operator, Harold Bride, survived.

There is also some bit of discussion about the rudder commands given after the iceberg was sighted. Most accounts say, First Officer, William Murdoch, gave the command “Hard over starboard” which would be the equivalent of the right full rudder, effectively pushing the back of the ship to the left.

As rudders work, the amount of water flowing over the rudder determines its effectiveness or loading (resistance to water flow). With the center screw turning at full speed, the rudder would have quickly loaded and pushed the rear of the ship away from the center line by re-vectoring the water coming from the propellers. There is no way to know if this would have changed the outcome as not enough is known about the maneuverability of the Titanic. Her sea trials consisted of about seven hours of sailing time before passengers were embarked.

The next commands issued were “full astern,” on the engine room telegraph. Because of the design of the ship, it took about thirty seconds to engage the rudder and backing engines. The ship continued straight ahead at 22 knots (11 meters per second), traveling 372 yards (340 meters) before beginning to turn. The center screw had no reverse, so it was simply stopped. Once the engines were reversed, the rudder lost much of its effectiveness due to turbulent flow and stalling. The ship could not maneuver around the iceberg, striking it in a glancing blow springing the hull plating in five forward compartments on the starboard side.

As it was the Titanic’s maiden voyage, the first officer did not have much deck time and was likely less familiar with the maneuvering characteristics of the ship versus other ships he had conned. On most other ships of the time, including the SS Californian, which had just completed the identical maneuver, that combination of rudder and engine room telegraph commands would have been appropriate to stop and swing the ship around the berg.

The SS Californian was within sight of the Titanic as it sunk, observing several “rockets” (as many as eight) being fired. When informed of the rockets, the Captain of the Californian asked for their color but did not move to investigate or wake the wireless operator. According to some of the Californian bridge crew, the Titanic looked strange in the water, like something was wrong. The Californian attempted to signal the Titanic with a blinking light, which was not acknowledged. Inexplicably, the Californian never attempted to investigate further until 5:30 am the next morning when wireless operator Evans was back on duty and reported the sinking to the bridge.

Therefore, the entire chain of events that led up to the disaster includes:

Too few lifeboats for passengers and crew
Not enough training in the deployment of lifeboats
Very short sea trial period for the ship’s crew before passengers were embarked
Overconfidence in the water-tight door system in keeping the ship afloat
Binoculars for lookouts were not procured in time for sailing
The ship’s rate of speed is too fast for the conditions, with numerous reports of ice in the area
The ship’s radio operator dismissed ice report from the nearest ship (almost within view at the time) so he could continue to send paid message traffic
The combination of helm and engine room telegraph commands did not produce optimum maneuvering
Failure of the nearest ship to recognize distress flares (or rockets) as such and render assistance

Change any one of those nine things and the outcome might be entirely different. Something to ponder.

The result of this disaster was the formal codification of shipboard safety requirements known as SOLAS or Safety Of Life At Sea. Those standards include the transmission of distress signals, distress communications, numbers of lifeboats, radio watches, fire suppression systems, and training for passengers and crew. Currently, the distress communication system is known as the Global Maritime Distress Safety System or GMDSS.

Troubles at the Tower

Troubles at the AM tower; I don’t know why, it won’t switch power.
Over the phone I can tell, the program director’s day is not going very well.
Press the “day” button but there is no kerchunk, the directional coupler shows the load is junk.
Out into the big field, I go to find the problem quickly and fix it just so.
The wind is cold, the snow is deep, I think of the contract terms I must keep.
Reaching the tuning house, take out the keys, lock, do not be frozen, please.
Once inside, there I find, no big surprise, the mice have been a working this pre-sunrise.
A nest they have build in a most inconvenient place, in the back of the phasor wiring chase.
Oh, the wires they have chewed, the circuit’s destroyed, all for the lack of mousetraps deployed.
As I reach in to clean out the mess, the smell of mouse makes me gag, I confess.
The fuses are blown, the contactor is jammed, perhaps, if I am lucky, I can move it by hand.
A large screwdriver strategically employed, I pry up slowly, further damage to avoid.
The bar thunks up, the contacts engage, the transmitter is ready to apply amperage.
Call on the cell phone, tell them it’s fixed, stand back and watch the base current meter, transfixed.
Then; Up it goes! Wonderful radio frequency current flows!
I clean up, lock the door, lock the gate, carrying bad news the owner will hate.
The damage is grave, the repair bill is steep, if a good relationship with the FCC you desire to keep.
Business is off, the accounts are low, is this really necessary, he wants to know.
The terms of the license are your obligation to keep, getting caught out of tolerance will not be cheap.
Looking forlorn, the owner says in disgust, it is only the AM, but fix it if you must.
Happy as a lark, with a song in my heart, I dig though the manual and order the part.
Time to go home, eat breakfast, brush teeth, take a shower. I have another client to see before the noon hour.

Dedicated to all those who have been there, done that and the breed of RF men and broadcast engineers who are slowly fading away.

Lightning season

Here in the northeast, there are seasonal variations in the types of weather phenomena encountered. Blizzards in the winter, severe thunderstorms, and the occasional tornado in the summer, at least that is the way it normally happens. This year, we have already had two thunderstorms and a stretch of unusually warm weather. My highly advanced personal weather prognostication technique consists of looking at trends, and the trend thus far this year is warmer with more storms.

When the weather RADAR looks like this, it is too late.

To that end, it is time to go around and check all of the grounding and lightning suppression methods at various transmitter sites and studios. I would rather spend a few minutes extra now than get called out in the middle of the night for an off-air emergency related to a lightning strike.

Proper grounding of all equipment, RF cables, and electrical service entrances is the minimum standard for transmitter sites. Proper grounding means a common point grounding system connected to one ground potential.

To that end, all coaxial cables that enter the building need to have their outer shields bonded to the site grounding system at the base of the tower and the entrance of the building. With an FM station where the antenna is mounted at the top of a tall tower, the coaxial cable outer jacket acts as an insulator along the length of the tower. A lightning strike on the tower will induce a very high potential on the outer conductor of an ungrounded transmission line. After entering the building, the lightning surge will find the next path to ground, which will likely be a coax switch or the transmitter cabinet. Neither of those two outcomes is desired.

Thus, it was time to ground the transmission lines at WRKI, the FM transmitter we moved last January.

Fortunately, Andrew, Cablewave, Dielectric, and others make grounding kits for various size coaxial cables. They are very easy to apply and make a solid connection between the outer conductor and the site ground.

The kit contains a copper band bonded to a ground wire, stainless steel clamp, waterproofing, tape, and a pair of bolts.

The concept of transmitter site grounding is pretty simple and inexpensive to implement. Thus, it is surprising to me how many transmitter sites, especially older sites, do not have adequate grounding. That is an accident waiting to happen.

For more on transmitter site grounding, check Nautel’s publication (.pdf) “Recommendations for Transmitter Site Preparation.”

What is the deal with those FEMA/DHS AM backup transmitters?

Back last February, it was reported that FEMA/Department of Homeland Security was mysteriously constructing prepackaged AM transmitter buildings at various PEP (Primary Entry Point) transmitter sites across the country as something call “Primary Entry Point Expansion.” These buildings contain a 5 KW Nautel AM transmitter, EAS gear, satellite equipment (the exact equipment list is undisclosed), and a backup generator all in a shielded (Faraday Cage), prefabricated building placed inside a fenced-in compound at the station’s transmitter site. The buildings are being put in place, but not connected to anything in the outside world. They are planning to have about 80 (the number keeps increasing) of these structures in place by when the project is completed in mid-2013.

FEMA/DHS IPAWS expansion project — FEMA/DHS IPAWS PEP expansion project

Why, inquiring minds want to know, would they do that?

The new buildings and equipment are, of course, not provided to the government for free. I would estimate each unit costs at least $200,000 based on the following:

A new solid-state 5 KW AM transmitter costs $50-55K
A new 35 KW generator costs $23K
A new, shielded communications structure costs $70-85K
Misc racks, equipment, wiring, shipping, installation costs, fuel tanks, fencing, etc $40K

Those prices are roughly what a private company might pay, the government procurement costs would be higher. Multiply by 80, which equals at least $16M, perhaps double that when project administration is considered. In the distant past, through something called the Broadcast Station Protection Program (BSPP), FEMA did provide generators, fuel tanks, transfer switches, and occasionally a bomb shelter to key EBS stations throughout the country. In the recent past, FEMA and the government, in general, have been reluctant to fund even mandated changes in the EAS system, first in 1997 when EAS was first implemented and again in 2011 when the CAP modifications were required. Why are they now spending at least $16M to provide EMP-hardened facilities for AM radio stations?

The rationale for this current wave of government spending, as reported in several industry periodicals, is simply a matter of supplying in-depth backup facilities in accordance with Executive Order 13407. The design of the structure and manner of installation seems to indicate the primary concern of FEMA is some type of Electromagnetic Pulse (EMP). If an EMP were to happen and it took out the station’s main transmitters, these could be connected to the existing antenna system and switched on. They would provide emergency programming and interface directly with FEMA’s IPAWS (Integrated Public Alert and Warning System).

The interesting thing about this is that there is a coincidence with the upswing of solar cycle 24. Back in 2008, likely when this project was likely first dreamed up, the predictions were for a great number of sunspots in this cycle. That has not happened and in fact, this cycle is now predicted to be the weakest solar cycle since 1823. Even weak sunspot cycles can create problems, but does that warrant supplying 80 backup transmitters, generators, fuel tanks, and buildings to various AM broadcasting stations throughout the country? Further, solar flares and Coronal Mass Ejections (CME) are fairly slow-moving events, the sun is well monitored; alerts would be issued and precautions are taken.

One other thing to consider: HEMP (High altitude Electromagnetic Pulse from a nuclear air burst). AM transmitters are more robust when it comes to HEMP than FM transmitters. This is because of their modulation type and frequency of operation. A 5 KW AM transmitter can withstand RF voltages six or eight times its nameplate carrier rating. Tube-type transmitters are even more robust than solid state. The FM broadcast band falls right in the middle of the HEMP fast pulse frequency (72-225 MHz), which will likely resonate in the tuning circuits of the transmitter exposed to it and destroy all of the active devices. Not so with AM transmitters.

A HEMP event would cause catastrophic damage to the electrical grid across wide areas of the continent (see also; Starfish Prime). The voltages instantaneously induced on computer circuit boards and power supplies would be so high, they would likely burst into flames if they were close enough to the detonation. The same for almost all other electronic devices with circuit boards. It would set the country back one hundred or more years, technologically, causing massive disruptions in the food supply chain. Such an act would surely be met with massive nuclear retaliation by the US. The military has not only hardened all of its communications and command facilities, but they have also undergone rigorous EMP testing, finding and fixing design flaws. Thus, the US military’s capacity to wage war would continue undiminished after a HEMP event, a fact that all other members of the nuclear club are surely aware of.