The National Association of Broadcasters is asking the Federal Communications Commission to reconsider how it defines media competition in its upcoming biennial report. NAB wants the FCC to factor in technological changes, shifts in consumer behavior as well as the current advertising climate when determining how to treat ownership caps and other rules related to competition.
According to the NAB, many of these changes are “splintering the previously ‘mass’ audio market and diverting audiences to myriad other options, at the expense of traditional radio.”
Some of its radio-specific arguments include:
With all these factors in mind, NAB is asking the commission to factor in non-broadcast competition in the upcoming report and then again in its quadrennial review.
The post NAB Presses FCC to Update Its Competition Definitions appeared first on Radio World.
New technical rules are now in place for the nation’s low-power FM service.
On April 23 the Federal Communications Commission issued a Report and Order revising and clarifying technical rules for LPFM stations, though not all of the proposals proffered in the previous Notice of Proposed Rulemaking made it into the final order.
The commission adopted four main proposals, including expanding the permissible use of directional antennas; permitting waivers of protections of television Channel 6 by a specific group of reserved channel stations; expanding the definition of minor change applications for LPFM stations; and allowing LPFM stations to own boosters. According to the commission, these changes are designed to give low-power FM stations the means of improving their service as well as offering greater flexibility and removing some regulatory burdens.
[Read: LPFM Stations Seek Technical Upgrades]
The use of directional antennas is notable. When the commission created the LPFM service in 2000, it opted to allow only omnidirectional antennas because it wanted to implement service quickly and sought to establish simplified application preparation and processing.
The revised rule allows LPFM stations to apply to use directional antennas to comply with treaty obligations to Canada and Mexico without the need to submit a proof-of-performance document. The revised rule also permits LPFMs to apply to use directional antennas to protect other broadcast stations from interference; in this case, though, an LPFM station has to submit a proof of performance.
LPFM proponents expressed support for directionals because they would provide more flexibility for stations looking to relocate and operate near international borders. Several groups representing full-power broadcasters, including the National Association of Broadcasters, the New Jersey Broadcasters Association and others, opposed the idea, questioning why LPFMs would need directional antennas to reach more listeners given the highly localized purpose of the LPFM service.
But the commission said it found “no compelling reason to continue restricting the use of directional antennas in the LPFM service to TIS [travelers information service] stations and second adjacent waivers.” The commission said that it expects LPFM applicants will use the option primarily in border regions and similar circumstances where the benefits justify the additional expense.
In a statement about the issue, Commissioner Michael O’Rielly said he was sympathetic to commenters who expressed concern regarding the potential deployment of more directional antennas by LPFM stations. “[I] have to trust that proofs of performance will provide adequate insurance against misuse,” he said. “Further, I understand that these antennas are expected to be used primarily in locations near our country’s international borders, but this is an important issue that I intend to watch closely as these rules are implemented.”
The commission also moved to redefine the types of LPFM facility changes that qualify as “minor.” The goal here is to provide additional flexibility for LPFM stations to relocate their facilities. Based on the fact that LPFMs typically have 60 dBu service contours with a radius of slightly more than 5.6 kilometers/3.5 miles, and that the contours of two such facilities can be expected to overlap at double that distance at 11.2 kilometers/7 miles, the FCC voted to allow LPFM site changes up to 11.2 kilometers (or to any greater distance that would result in overlapping 60 dBu service contours between the existing and relocated facilities).
The new rules also allow for a LPFM licensee to own and operate FM booster stations. The NPRM tentatively concluded that FM boosters should be available on a nonwaiver basis to any LPFM station that might be able to operate a booster without causing interference to itself. Accordingly, the commission proposed to amend its rules to incorporate guidelines for potential LPFM use of an FM booster in lieu of use of an FM translator. Under the original proposal, such booster stations could receive the signal of the commonly-owned LPFM station by any means authorized in the FCC rulebook.
One area in which the commission elected not to make a change involved eliminating the rules requiring radio stations operating in the FM reserved band to protect TV6. The NPRM proposed to eliminate TV6 distance separation rules for LPFM, NCE, Class D and FM translator stations operating on reserved band FM Channels 201–220 stations after completion of the LPTV digital transition. In a separate finding after release of the NPRM, the Media Bureau asked for comment on the continued use of TV6 for analog audio services. Because that proceeding could have implications to TV6 protection requirements, the commission decided to defer further action on this issue.
The current proceedings sprang from a petition for rulemaking by REC Networks in 2018 that aimed to address various issues that preclude more successful deployment of LPFM stations, especially in suburban and core urban areas. At the time, REC Networks noted two main causes in particular: what it called “unnecessary overprotection” of other broadcast facilities by LPFM stations; and disparity in the relationship between LPFM stations and FM translators, which REC noted should be defined as equal in status.
The resulting Notice of Proposed Rulemaking proposed to modernize technical aspects of the commission’s rules governing LPFM radio stations, sought comments on proposals to improve LPFM reception, and requested comments on increasing flexibility in siting of LPFM stations while maintaining interference protection to other radio stations.
The post FCC Finalizes LPFM Rule Changes in New Order appeared first on Radio World.
Sen. Ted Cruz (R.–Texas) is proposing that the Federal Communications Commission not grant broadcasting licenses to some applicants who intend to change the language of the station they are purchasing, the Washington Free Beacon’s Adam Kredo reported last week.
Cruz says this would effectively eliminate a loophole that has allowed foreign propaganda to be spread in the United States. The legislation was prompted by the 2018 purchase of a radio station owned by Phoenix TV — a media outlet connected to the Chinese government — operating under a temporary license and using a Mexican radio tower to broadcast Chinese-language content in southern California.
According to the Free Beacon, the legislation would also apply to those who want to buy radio towers in Canada that would have signals that could reach the United States, as well as Mexican towers.
The Crux legislation apparently would make an exception for language changes when it can be proved that the new owners are “free from foreign government influence,” the Free Beacon says.
This issue was put in the spotlight earlier this spring when a Phoenix TV reporter was allowed to participate in a White House press conference.
The post Cruz Proposes Law Limiting Station Language Changes to Eliminate Propaganda appeared first on Radio World.
A Foley, Ala., broadcaster has applied for an auxiliary waiver it says will ameliorate the negative effects it is experiencing from the COVID-19 pandemic and subsequent stay-at-home order.
Blackbelt Broadcasting President Damon Collins is seeking an FM auxiliary authorization that would increase WLYB(FM)’s power from 3.4 kW to 8.0 kW. According to the waiver application, Collins seeks the change in reaction to changes in commuting and listening habits due to the pandemic — shifts that Collins and others anticipate will be long-term if not permanent.
“This upgrade will help reach our rural communities who depend on our station. With more listening now done at home, this increase will improve our coverage without creating interference issues to other stations,” Collins wrote in an email to Radio World.
WLYB has also been a proponent of a proposed new FM class called C4. But Collins emphasizes that here the station is seeking an FM auxiliary permit that is secondary and can be cancelled at any time. “This FM Auxiliary permit effort does not replace the FM Class C4 petition. That initiative is still ongoing,” he said.
Specifically, Blackbelt Broadcasting is concerned that “The loss of the commuting listener base disproportionately affects lower-powered broadcasters … who depend significantly upon outdoor reception in vehicles in order to retain audience share.” Additionally, Collins said that, due to financial and technical constraints, lower-powered stations like his are less able to shift to streaming in order to reach indoor listeners.
Additionally, the application says “the present and anticipated lasting sudden and unpredictable listening pattern shift due to the SARS-CoV-2 outbreak precisely satisfies” the FCC’s criteria that “a waiver request must be due to special and unique circumstances.”
Although Blackbelt Broadcasting does not anticipate the change would cause interference, they say WLYB would revert to the original licensed parameters of its main authorization if there are six unresolved listener complaints.
However, WLYB is continuing to serve its community, which has been hard hit by the crisis.
“We have focused our efforts to provide community information to our listeners. We provide reports and interviews from our local and state leaders on the pandemic. Updates on testing, services available, and stories the impact our community. We are helping all businesses by letting our listeners know they are open by providing updates. Everyone is working together during this crisis,“ Collins said.
According to Collins, Sumter County, Ala., where WLYB is located, “is one of the poorest counties in the state. The infection rate is high. The economy was fragile before the pandemic. Education and information on the crisis is important. Stations like WLYB(FM) provide a valuable service to many rural communities.”
WLYB signed on the air in 2013. It runs an adult contemporary music format, but Collins emphasizes that the station’s mission is to be community oriented, focusing on Livingston, where its studios are downtown. It also broadcasts from Meridian, Ala., translator W263CF.
“Radio is a critical resource to many rural communities. We hope that the FCC will consider this waiver to help rural stations reach underserved listeners,” Collins concluded.
The post Alabama FM Seeks Power Increase to Deal With Changes Due to Coronavirus appeared first on Radio World.
To help broadcasters during the COVID-19 health crisis, Digigram has accelerated the release of Iqoya Guest Preview, a “smart and equipment-free” solution for home broadcasting.
According to the company, the light remote web-based broadcasting solution does not require any equipment or software installation, and lets users manage remote interviews of guests from anywhere.
The system turns web browsers into a two-way codec, providing a connection link to journalists working remotely. Thus, the company says, staff can immediately connect via their PC or smartphone to their studio with quality audio.
Digigram points out that Iqoya Guest Preview requires no app installation, no download or specific settings.
The post Digigram Introduces Iqoya Guest Preview appeared first on Radio World.
Admittedly, there’s really not much in the way of transmitter maintenance today, save for routine cleaning and occasionally sending an ill-performing module back to the manufacturer for repair or swapout. Vacuum tube-based units required more attention but could operate for fairly long stretches with little more than replacing failed tubes.
There was a time though when operating a certain breed of transmitter meant changing out large carbon electrodes several times during an operating shift, switching to a standby rig to allow the main to cool long enough to remove a prodigious amount of soot from its interior, replacing an transmitter insulator that had begun to burn while on the air, and the regular topping off a reservoir with alcohol, kerosene or maybe even gasoline.
This was what it took to keep the kilowatts on the air some 100 years ago. I’m referring to the Poulsen arc converter technology for generating a continuous carrier wave.
PUTTING A NUISANCE TO WORK The arc transmitter or “converter” in its simplest form. It’s nothing more than a DC arc with a series-tuned circuit connected across the arc electrodes.Most readers will have witnessed what happens when a path is abruptly broken in an energized circuit (anything from opening a knife switch to using a screwdriver to discharge a large capacitor). There is a bright flash of light and (depending) on the amount of voltage and current involved, a sound anywhere from a small “smack” to that of a lesser thunderbolt. The phenomena involved is an electrical arc — a flow of relatively low-voltage, high-current across an open space.
It was at one time (in pre-incandescent lamp days) used for artificial lighting, and even after the advent of the Edison lamp, served for several decades as a high-intensity light source in motion picture projection and some large spotlights.
Today, the electrical arc comes in handy for welding, “electro-erosive” fabrication of metal parts, and melting metals in high-temperature furnaces. Otherwise it’s a sometimes dangerous and expensive nuisance that occurs when relay contacts open or screws aren’t snugged down tight in power panels.
Early in radio’s history, however, the electrical arc was at the core of some of the most powerful transmitters ever put on the air.
NOT TO BE CONFUSED WITH “SPARK”! A small tabletop “arcphone” radio transmitter. The arc chamber and its associated hydrocarbon liquid reservoir are seen at the center right. The transmitter’s carbon microphone projecting above the top is firmly attached to the unit, as it became very hot in operation and could not be hand-held.Now, I’m not referring to the big “rock crusher” spark transmitters championed by Marconi and others in radio’s caveman days. Those were rather diametrically opposed to arc technology, as their operation involved relatively low currents and very high voltages (tens of thousands), and generated a “damped” wave oscillation that produced a very wideband (spread spectrum) type of signal.
Arc transmitters, or “converters” as they were known (they converted DC into radio-frequency AC), with the exception of the very large devices, typically operated with potentials of a few hundred volts and currents usually measured in the hundreds of amps.
The Marconi “rock crushers” were fine for communication via telegraphic code (well, not really, but they got the radio industry started). However, for Reginald Fessenden and other visionaries who desired to transmit speech and perhaps music, they were useless as the damped oscillation (think ringing a bell) produced was not suited as a carrier wave that could be modulated with an audio component.
Fessenden solved the problem of generating a continuous wave by pressuring the General Electric folks to produce an alternator that spun fast enough and had enough poles to generate an output in the LF portion of the radio spectrum. That took time, and it was not cheap either.
A production model Federal Telegraph arc transmitter. Although the size is not stated in the photo data, it is likely in the 30 kW range.Elsewhere, others explored the production of continuous radio waves — or, as they were called back then, “undampt” waves — and found that a certain property of the electrical arc made it a good candidate.
Arc transmitter technology stemmed from the discovery by English physicist William Duddell in the 1890s that if a series-resonant circuit were connected across an arc, an oscillation developed, with its frequency determined by the external inductance and capacitance. Following in Duddell’s footsteps, Danish inventor Valdemar Poulsen (also the inventor of magnetic recording) made improvements on Duddell’s “singing arc.” He secured a patent for his work in 1903 and began marketing the first arc transmitters.
A 200 kW unit manufactured for the U.S. Navy. The plumbing (pipes and hoses) necessary for cooling the arc’s large electromagnet and its copper anode are clearly visible. The array of cylindrical devices at the bottom left appear to be replacements for the consumable carbon cathode.The technology formally arrived in the United States in 1909, when Cyril Elwell, a recent Stanford University engineering graduate who had done work in the field of electrical arc furnaces, became interested in Poulsen’s technology and secured patent rights to manufacture the transmitter. This Palo Alto, Calif., venture was originally known as the Poulsen Wireless Telephone and Telegraph Co., but later changed its name to the Federal Telegraph Co., and manufactured arc converters in varying sizes until the arrival of the high-power vacuum tube transmitter in the early 1920s.
HOW DOES IT WORK? In this 1957 photo, Federal Telegraph’s Leonard Fuller (middle), and Cyril Elwell (right) admire an early electric light bulb owned by another early Federal employee, Douglas Perham. Perham was also a broadcast pioneer, establishing station WJAM (now WMT) in Cedar Rapids, Iowa in 1922.It’s useful to consider the physics of the arc converter (transmitter). While striking a DC arc is a simple and basic exercise — momentarily pushing energized electrodes together and then separating them to create the arc — putting it to use in making radio waves involves an understanding of the physical phenomena surrounding such an electrical discharge.
The most intriguing (and valuable) aspect of the arc is that it belongs in the category of devices possessing “negative resistance” characteristics. These include tunnel and Gunn diodes, vacuum tubes when operated under certain conditions (the dynatron oscillator), neon-filled tubes and lamps, and even ordinary fluorescent lamps.
This diagram is from a “Boys Build Your Own Arc Radiophone” type of article appearing in a popular 1916 magazine (The Electrical Experimenter). As shown in the drawing, audio modulation is achieved by inductively coupling the output of a carbon mic (telephone transmitter) into the “tank” circuit of the arc. The transmitter could also be audio modulated by connecting the mic at points designated with the circled “x,” as well as by breaking the antenna lead and connecting the mic in series with it. (The upper left connection point is especially interesting — dangerous — as it places the mic across a choke connected to a DC source of as much as 500 volts.)True to Ohm’s law, when the voltage flowing through an ordinary resistor increases, the current increases proportionally (I=E/R). The opposite occurs in negative resistance devices; an increasing voltage results in lowered current flow through the circuit.
A catalog drawing of the largest arc converter produced by Federal, a 1,000 kW model. The technology was scaled up for 2 and 5 megawatt units, but the technology became obsolete before these went into production.And while this sounds like a violation of physics, a negative resistance, in a way, produces power, rather than consuming it, as would a carbon resistor. Without getting too technical, in an arc converter, the negative resistance characteristic of the arc counteracts the positive resistance associated with the series-resonant circuit connected across it, thus maintaining its oscillations, which would otherwise die out in short order. (The same principle as in conventional radio transmitters in which an amplifying device [tube or transistor] supplies energy to sustain tank circuit oscillations.) While not a perfect sine wave, the arc converter’s oscillations are pretty close, and can serve as a carrier wave.
This diagram is fairly representative of the arc converters produced by Federal Telegraph for the U.S. Navy. Note the apparent lack of a capacitor in the output circuit. In practice, the capacity between the antenna and ground formed this circuit element. This was done as a way of sidestepping Marconi transmitter patents.Actually, it’s not quite that simple, as more enhancements (add-ons) are necessary to make a truly practical and workable arc-based transmitter. A powerful magnetic field and a continuous source of hydrogen are also necessary. The magnetic field is needed to “blow out” the arc during an RF cycle and the hydrogen is used to help residual ions from around the arc electrodes during this once-per-cycle downtown.
As seen in the above diagram, the electrodes are connected in series with the windings of the electromagnet so that when the arc is struck, the magnet is energized and blows out the arc, which in turn extinguishes the discharge. Heat and a few residual ions ensure that the arc is immediately re-struck as soon as the magnetic field is dumped. Of course, all of this is happening at an RF rate, so the arc would appear to be continuous to an observer. (Refer to the “Physics” sidebar for additional details.)
Note that even though the arc is being extinguished and re-lit during an RF cycle, the converter could not be “keyed” for radiotelegraphy in the same manner as other sources of radio-frequency energy, as the time interval between the “dits” and “dahs” would be far too great and the arc would have to be manually reignited.
This was solved, in what today would be a rather inelegant way, by connecting the telegraph key across a portion of the RF inductor used to set the transmitter’s frequency. During “key down,” turns would be shorted out, shifting the frequency higher. (With the really big converters and their accompanying very large RF currents, a relay with correspondingly heavy contacts was used. This is shown at the bottom right in the above diagram of a large U.S. Navy converter.
Of course, this frequency-shift keying used twice the amount of spectrum, but in the 1910s and 1920s, who cared?
(My own early mentor, who was born in 1904 and developed an interest in radio during the period when arc converters ruled the airwaves, recalled that the really good radiotelegraphy operators could copy this “back” or “compensating” wave as it was called, with equal dexterity, listening for the “holes,” rather than the carrier.)
A “workaround” of sorts was eventually devised to conserve spectrum, but it was somewhat cumbersome and not employed everywhere. This involved dumping the converter’s RF into a dummy “antenna” (load) during “key up” conditions so that only the transmitting frequency reached the antenna.
TRANSMITTING SPEECH AND MUSIC An operator gets ready to place a Federal 1,000 kW transmitter on the air.Early on, experimenters found that the continuous wave output of the converters could be modulated with speech. Elwell used this feature to advantage, establishing a two-way radiotelephone service between Sacramento and Stockton, Calif., in competition with Ma Bell. It was claimed that the wireless audio quality was better than that of the wired service.
Others, most notably Lee De Forest and Charles “Doc” Herrold, began broadcasting speech and music via arc or “arcphone” transmitters. However, as pointed out, the machine’s output, if close to a sine wave, was not exactly; and the center frequency, if close, did vary a little. Early adopters referred to this as “fuzz” or “hair” on the signal. Today, we would likely refer to it as phase noise.
Charles “Doc” Herrold (center, in the doorway) powered his early-1900s San José, Calif. AM radio station with arc technology of his own design. This photo appears to show two of the converters built into the table at the left. A phonograph turntable is visible as is a microphone. Although Federal’s transmitters were designed to operate in the VLF portion of the spectrum, the size of Herrold’s air-core inductors above the arc chambers would seem to indicate that he operated considerably higher up into the RF spectrum. The station was licensed in 1915 as 6FX. After WWI, it moved to vacuum tube technology and was relicensed as KQW, later becoming San Francisco’s KCBS.(Although not stated in his patent claims, Herrold may have burned his arc under water in an attempt to filter out some of the fuzz and possibly to supply the needed hydrogen through electrolysis.)
Audio modulation was achieved by simply connecting a carbon microphone (telephone “transmitter”) in the antenna or ground leg of the transmitter output. (Fessenden modulated his high-frequency alternator in the same fashion.) The varying resistance of the microphone element with sound produces a corresponding change in antenna current. Of course, with higher power converters, some means for dissipating the I2R losses in the carbon element had to be provided, with solutions ranging from a water-cooled mic, the use of multiple microphones connected together, and even a “lazy Susan” arrangement for rapidly switching a fresh mic into the circuit while the one previously in use cooled down.
GAS ON THE FIREEarly on, the upper frequency of the arc transmitter’s oscillations was limited by the curve describing the negative resistance; however, it was discovered, likely by accident, that introduction of a hydrocarbon-containing vapor or substance (it was actually the hydrogen component) greatly enhanced the performance of the arc and could move its frequency upward.
The patent drawing for Herrold’s arc transmitter. The arc burned under water and the electrodes are broken into several sections.As the arc transmitter technology progressed, a number of hydrogen-containing substances were tried, including alcohol, kerosene, methane, acetylene, hydrogen gas and even steam. Interestingly, the converter’s operating frequency range could be shifted by substitution of these liquids, gases or vapors. (Of course, the operation of an intense source of heat in close proximity to flammable compounds was not without risk, as will be pointed out later.)
Ethyl alcohol seemed to be the favored hydrocarbon, at least for the lower-powered arcs, and one can’t help but wonder if this might not have been an added incentive when looking for employees to pull an overnight shift at the transmitter site. The alcohol used was likely pure 200 proof ethanol, or close to it, as “denatured” alcohol didn’t come into widespread use until after the Volstead Act ushered in prohibition in 1920.
TRUTH IN ADVERTISINGIt should be noted that while the arc converter was a simple way of transforming DC into radio waves, its operating efficiency was not that great, bordering at best around 50%, so with the larger units, a carefully engineered cooling system was essential.
Also, Federal, likely bolstered by their ad agency, seemed to overlook this efficiency factor in their product catalog. For instance, their “one megawatt” converter actually delivered only about 500,000 watts of RF. The rest of the DC power had to be dispersed as heat, and just as in “modern” vacuum tube transmitters, the water-cooling system had to be electrically isolated from the converter’s copper anode. In the very high-power installations, this required two cooling loops with a heat exchanger and an outdoor “spray pond” in the secondary loop.
OSHA, PLEASE LOOK THE OTHER WAY As the microphone used to modulate an arc transmitter in the simplest way carried large RF currents and became quite hot in normal operation, a means for removing heat was necessary. Several schemes were devised, including water cooling. Charles Herrold and E.A.B. Portal were issued a U.S. patent for the water-cooled mic used at his “arcphone” radio station.Obviously, the high-voltage, high-current potentials (typically from 500 to 2,000 volts and upwards of 500 amps, depending on converter output power) employed in larger arc transmitters were dangerous to the point of lethality.
However, arc transmitters posed another very serious hazard to life and limb. This was their propensity to explode violently if operating instructions weren’t followed to the letter, due to the aforementioned requirement for the continuous introduction of hydrocarbon-containing compounds into the arc chamber.
Precautions against the electrocution threat included these words to the wise: “Great care must be taken by operators working about an arc in operation, and any part of the oscillatory circuit, starting from the copper, must be avoided. An operator at one high-power station on the Atlantic Coast once started to refill the alcohol feed cup from a large metal can while the arc was in operation — he never did it again.”
Equally lethal accidents, but not always causing immediate death, included opening the arc chamber while the converter was in operation, or even after it was shut down if a prescribed amount of “cooling down” time was not observed. Violation of this rule could result in the transmitter literally becoming a “flame thrower.”
“Another stunt to be avoided is the opening of the arc chamber door immediately after the arc has been extinguished, for the sudden contact of the internal heated hydrogen with the external atmosphere will cause an outburst of flame which may result in severe burns to anyone within range. With large arcs, a period of ten minutes should elapse before the door is opened.”
The “always read the instructions completely before plugging it in” type of disclaimer also included the following, hopefully circumventing a slightly different type of “flamethrower” event:
“At least one fatality and several serious injuries have come to the attention of the writer owing to the operator having ‘struck’ the arc when the carbon [electrode] had not been properly fastened in its receptacle. In these instances, [with] the hydrocarbon gas having reached a sufficiently great pressure, the loosened carbon was blown out of its holder followed by a stream of flame, proving disastrous to the operator, who invariably stands on that side of the arc when starting it.”
At least one big arc transmitter was reborn as a nuclear particle accelerator. This Federal 1,000 kW unit was transformed into what was then the world’s largest cyclotron. It’s shown with cyclotron inventor Ernest Lawrence, right. At left is Stanley Livingston, a graduate student who had worked with Lawrence in perfecting the cyclotron.(Another precaution was offered for those working around the giant “converters” that would be of little worry in today’s world of quartz-movement clocks and watches. This was the avoidance of bringing one’s prized timepiece near an operating converter, as the intense magnetic field could permanently damage the steel mainspring-driven movement.)
There were a number of early arc converter martyrs, and doubtless the list would have kept growing if the technology had not been pushed out of the way by the perfection of the vacuum tube as an RF oscillator and power amplifier in the 1920s. Actually, as late as 1922 — at least according to a U.S. Bureau of Standards publication that year, the arc was still the “go-to” source for high-power long-distance communications, with an estimated “80 percent of all the energy actually radiated into space for radio purposes during a given time” emanating from arc transmitters. (This excluded amateur stations, which still largely utilized damped wave spark apparatus.)
LIFE AFTER OBSOLESCENCEOnce more modern and efficient ways of producing a continuous wave emerged, not all of the dangerous, and sometimes problematic, arc converters were reconciled to the metal recycler. At least one, and probably more, were tapped for nuclear research.
In the late 1920s, a race of sorts was underway on several shores to “split” the tiny atom in an effort to learn more about its internal workings. One of those heavily involved was the University of California’s Ernest O. Lawrence, future Nobel Laureate. He devised a tabletop model of a machine that could accelerate subatomic particles faster and faster until they had sufficient energy to pass through the electrostatic barrier of the atomic nucleus and send its constituents flying in all directions.
Once Lawrence, aided by a grad student, succeeded in making the tabletop nuclear particle accelerator — or “cyclotron” as Lawrence dubbed the device — work, the challenge was on to build a bigger and better model. (The cyclotron’s operation is based around a large magnetic field, just as in the arc converter.)
It so happened that once the vacuum tube had sunset activities at Federal Telegraph, there were some unsold arc converters literally rusting away at the company’s Palo Alto, Calif., facility. Lawrence learned of this from Leonard Fuller, chairman of the university’s EE department, and it was not difficult to secure one of the last of this breed of transmitter and relocate it to the Berkeley radiation research lab for just the cost of the move. There, it was stripped of the arc chamber, and the magnetic core became the heart of the first big cyclotron, known as the “27-incher,” the diameter of the magnetic poles formed from the big electromagnetic. This machine produced energies of 5,000,000 electron volts, and was later upgraded to give an 8 MeV push to deuterons, and it could also eject alpha particles at energies of up to 16 MeV.
The Physics of Arc Converter OperationAside from producing a continuous wave oscillation, an arc transmitter, or converter, is differentiated from a spark transmitter in a number of other ways. A spark machine can be powered from either an AC or DC source, while an arc device must have direct current. Spark transmitters utilize a fairly wide gap between the discharge electrode; those in an arc device are relatively close together.
Typically, both electrodes in a spark transmitter were made of the same metal (in many cases, tungsten), and while erosion does occur, the electrodes had a fairly long useful life. In an arc converter, the anode was almost always copper with a concave end, and the cathode was always graphite with a pointed end. Due to the very high currents involved, the cathodes had to be changed on a regular basis; typically, every few hours. The copper anode lasted longer, but had to be water-cooled, something not practical with the graphite electrode, which was rotated by a small motor during operation to equalize wear.
Another major difference between the spark and arc machines was the requirement for a strong magnetic field across the arc chamber and also a steady source of hydrogen during operation. As mentioned, this magnetic field was necessary for extinguishing or “blowing out” the arc during the RF oscillation cycle.
Hydrogen, the lightest and most mobile element, was used during these RF cycle “down times” to help clear the space between electrodes of residual ions generated by the intense arc plasma. The phenomena of arc “blowout” may be familiar to those who have done DC arc welding on, or close to, a steel structure. The arc plasma constitutes a conductor, and the magnetic field induced into the ferrous material tends to push the arc aside, sometimes making it tricky to control the weld.
Early in the evolution of the arc converter, the effect of the external magnetic field on arc performance was not well understood (leading to some major problems when it was desired to construct transmitters with increased power outputs). However, experimenters were aware that such a field greatly affected the performance and efficiency of the converter. One experimenter noted that without a magnetic field, the maximum RF current that could be delivered to the transmitting antenna was eight amps or so, but with the addition of the field, and everything else equal, an antenna current of 100 amps was easily obtainable.
Federal Telegraph’s Cyril Elwell, the American arc converter entrepreneur, was able for a while to build increasingly more powerful machines by simply scaling up the mechanical parameters (proportionally including the size of the arc electrodes, chamber, cooling system and electromagnetic field).
But he hit a major stumbling block when trying to go beyond 30 kW. This difficulty was not resolved until a young man with a recently-minted electrical engineering degree and a strong interest in arc technology, Leonard Fuller, was hired by Federal about the time that Elwell made a decision to exit the business. Fuller devoted much time in developing a sound physical understanding of what was really going on within an arc converter. (He eventually took Master’s and Ph.D. degrees based on his arc technology research.)
It was Fuller who realized that the intensity of the magnetic field needed for arc blowout was not directly proportional to the size of the machine or the desired output. He developed the concept of “tuning” the magnetic field strength to maximize output at a given operating frequency. With longer wavelengths there is more time available to clear the residual ions from the arc gap than at shorter wavelengths, thus a stronger magnetic flux is needed for higher frequency operation. (In the larger arc transmitters, magnetic fields upwards of 16 kilogauss [1.6 Tesla] was required. Most modern medical nuclear magnetic resonance imaging machines operate with a field strength in this range.)
Once Fuller understood fully the action of the magnetic flux, it became possible to design and build arc converters without any upper limit in operating power. Federal delivered a number of one megawatt machines, and plans were drawn up for two and five megawatt models, but due to the rapid pace of high-power vacuum tube transmitter technology, and the increasing relocation of long-distance radio communications from long wave to HF spectrum, these very high-power converters never made it into production.
Even though Federal rated its products in terms of DC power consumption, their 1,000,000-watt model produced about a half-megawatt of RF — still a very impressive number with antenna currents measured in hundreds of amps! The downside was the requirement to get rid of the other half megawatt of heat, which was usually solved by outside spray cooling ponds.
An Early Federal Telegraph Employee Describes His Experiences in Working for the CompanyThis article on arc converter technology was inspired by a 1963 oral history in which a former Federal Telegraph employee, Archie M. Stevens, was interviewed by Erwin Rasmussen, who captured some of early radio’s history from those still alive who had been a part of it.
The recorded audio interview (actually a two-part session with another pioneer, Ken Laird, and available online) begins with Stevens’ remembrance of the 1906 San Francisco earthquake while he was a student at nearby Stanford University. After earning an engineering degree from that school in 1909, Stevens was approached by one of his former instructors about a job with a startup company. As he recalled in the interview:
“Just about that time, I ran across Elwell, who had been my instructor in electrical engineering. He said ‘Why don’t you come with me? We’re starting a radio company down here called the Poulsen Wireless Telephone and Telegraph Company and we’ve got some very intelligent Danish engineers and machinists and a whole mix of stuff.’”
Stevens accepted the offer and rather quickly was assigned a position of responsibility in the fledgling enterprise.
“He made me chief draftsman and put me in charge of the machine shop,” said Stevens. “And then made me assistant engineer. That was a pretty big title, as I think we had 15 men all told.”
Stevens recalled that he was responsible for engineering drawings for both equipment manufactured and complete stations constructed with it. This included the massive towers used for the very low frequency antenna systems employed with Federal arc converters.
“I used to design the towers,” said Stevens. “In order to get the job done quickly, I would order the lumber and then take my drafting board out in the field and sit there and draw them [the towers], because we’d have to change the bolts and splices and that stuff [so much]. Elwood got the big contract for the 800-foot wooden towers in Rome. Mind you, people kept saying, ‘You can’t build wooden towers that are 600-feet high.’ [Well] we built them 800-feet high and they stood for 30 years. [We used] select first-quality pine from Oregon with 20 to 21 or 22 rings per inch. We made sure that it was kiln-dried lumber. That was the most important thing. Then we’d give them two or three coats of first-grade white lead paint… we put them together and we put in plenty of white lead.”
(Stevens recalled that at one station an airplane crashed into one of his towers and the tower withstood the impact, trapping the aircraft and saving its pilot from possible death if the plane had fallen all the way to the ground.)
In reflecting on the ever-present danger associated with using hydrogen and hydrogen-bearing compounds, Stevens recalled an episode when he was testing a new station installation, communicating with the operator of another arc station, and almost destroyed it the new facility.
“Sometimes we used pure hydrogen,” he said. “Well, I started out with pure hydrogen, but I didn’t blow enough air and set off a tremendous explosion which broke about a two-quart container of wood alcohol. I was alone at night and I went back and said I’m on fire; hold up a minute until I can get the fire out. I was scared that time.”
He also provided some insight on audio modulating the “fire-breathing” arc machines.
“The difficulty in modulating the arc was that you had this tremendous magnetic field with reluctance so big you couldn’t change it exactly as the voice of the speaker. So, the only way to do it was with what we called a closed oscillatory circuit with the arc and loosely coupled to an antenna — sometimes 10 or 15 feet away — with an inductance … you could modulate the current in the antenna, but you couldn’t modulate the arc itself. That’s how we used to telephone. We used to talk to Stockton and San Jose … but we had to stop the telephone [service] because there was no money in it.”
Interestingly, Stevens sheds some additional light on the large WWI-era communications facility planned for Monroe, N.C. and mentioned in my own April 19, 2017 Radio World Engineering Extra story about insulator manufacturer Arthur Austin.
According to Stevens, the station was to have been located much further north, possibly Maine, but Secretary of the Navy Josephus Daniels, a North Carolinian, insisted that the facility be constructed in his home state. Federal produced, but never delivered, the giant arc converters ordered, as the war ended before station construction could get under way. Stevens noted that one of these “war surplus” transmitters was given to Ernest Lawrence to be used as the foundation for the first large cyclotron.
The complete interview with Stevens and Laird is available online. Even though the audio quality is less than perfect, provides much insight into what it was like to work for Federal Telegraph and the pre-vacuum tube era of radio in general.
FURTHER READINGAdams, Mike and Greb, Gordon B., “Charles Herrold, Inventor of Radio Broadcasting,” McFarland, Jefferson, N.C., 2003.
Aitken, Hugh G. J., “The Continuous Wave: Technology and American Radio, 1900-1932,” 1985, Princeton University Press, Princeton, N.J.
Boucheron, Pierre H., “Arc Undampt Transmission,” Radio Amateur News, Oct. 1919
Byron, William J., “The Arc Method of Producing Continuous Waves,” The AWA Review, Vol. 7, 1992, The Antique Wireless Association, Bloomfield, N.Y.
Davis, Nuel Pharr, “Lawrence & Oppenheimer,” 1968, Simon and Schuster, New York
Fuller, L. F., “The Design of Poulsen Arc Converters for Radio Telegraphy,” Proceedings of the IRE, Vol. 7, No. 1
Secor, H. Winfield, “Construction of a Collin’s Radiophone Arc,” The Electrical Experimenter, Feb. 1916
Stone, Ellery W., Lieutenant USNRF, “The Poulsen Arc,” United States Naval Proceedings, Vol. 46, No. 2, July 1920; U.S. Navy Institute, Annapolis, Md.
The post When Brute Force Transmitters Ruled the Air appeared first on Radio World.
When radio engineers get together and talk about cybersecurity, many shake their heads that there are still stations out there that haven’t taken basic steps to protect their key systems including emergency alerting.
A new reminder email has gone out to EAS participants in broadcasting and beyond, once again emphasizing the point. The email came from Lisa Fowlkes, chief of the FCC’s Public Safety and Homeland Security Bureau.
“We are aware of various reported instances of EAS equipment connected to the internet with weak or otherwise inadequate network security and/or unsecure device setting configurations that potentially leave them vulnerable to IP-based attacks,” she wrote.
“We remind EAS participants that if EAS equipment lacks basic security maintenance, it can be vulnerable to disabling or exploitive attacks.”
The email recommends that stations change default passwords, update their equipment with current security patches and secure EAS equipment is behind properly configured firewalls and other defensive measures.
[Related: Is Your EAS Equipment Secure?]
“The commission’s Communications Security, Reliability, and Interoperability Council IV (CSRIC IV) has developed several security best practices for EAS Participants, and we encourage all EAS participants to review them and implement those that apply to their situation.”
The best practices are discussed in a 2015 EAS report here, and are listed in detail in prior report here.
“If there are any questions regarding the security of EAS equipment, we encourage EAS Participants to contact their EAS equipment manufacturers,” she added. “We appreciate your efforts to make the EAS a vital, beneficial and secure national platform for the distribution of alerts that save lives and property.”
The post FCC Reiterates: Protect Your EAS Gear appeared first on Radio World.
The author is membership program director of the National Federation of Community Broadcasters. NFCB commentaries are featured regularly at www.radioworld.com.
Some of the great legends at my old community radio station were of the late-night in-studio musical performances. Some nights, local and touring artists who were fresh off a gig and a few drinks would shamble over to the studios near downtown, plop down in one of our sundry donated chairs, and weave stories about the road and what inspired all those songs. On more than a few of those nights, or early mornings, those musicians would take out their guitars and play a bit.
It was never polished or rehearsed. To crib the old Kanye West line, they were talking like it was just you and me.
[Read: Community Broadcaster: Now What?]
And then there were times when the whole band and crew would roll up after last call, do a quick and dirty gear set up, and just jam live on the air with anyone who showed up.
Such moments are part of community radio’s spontaneity and history. Whether you are WFMU or KEXP or somewhere in between those coasts, live music on the air has been part of who we are. It is our repudiation of the spit-shined corporate sound of so much of commercial radio, which rarely includes local performers or organic sounds. Where it feels like big radio sold the soul of music, with nary an errant chord or impromptu laugh or weird song, for advertising dollars, community radio has embraced in-studio performances, with all their hiccups and informality. Community radio’s championing in-studio concerts has gone on literally for generations.
Will a post-coronavirus world mute the music?
Already, many U.S. states have postponed live concerts. Live Nation and Ticketmaster are scrambling to avoid a financial cliff amid canceled and delayed shows. And the live-performance outlook isn’t looking great in the future. Epidemiologist George Rutherford voiced a common sentiment among health experts when he said, “I realize tons of people make their living doing this stuff, but I see [concerts] as pretty far down the list [in terms of opening events back up].”
For community radio stations, how we move ahead with business as states reopen and caution is encouraged is still a serious matter. College and community radio have typically had a very open attitude about students, community members and the public having access to their facilities. It is likely few have done an audit of their volunteer and staff to determine who could be at risk for contracting COVID-19. And then there is the issue of the public: who enters the building, when and under what safety protocols?
Then there is the situation with guests, including musicians — some of whom have been in areas hard hit by COVID-19.
In the short term, community and college radio seeking to reopen for the still quarantined may take inspiration from the many livestreamed concerts available to the public. Such shows, shared on platforms like Facebook Live, could give your station some techniques for hosting a socially distanced performance.
A few stations have organized lineups of artists playing live or recorded from their homes as a virtual festival. Hot technology like Zoom can allow you to make a given artist a gathering host. Musical communities are doing something similar with the viral collaborations we’re all hearing about; stations could also bring people together in this fashion.
Reopening for in-studio performances will require a careful review of a station’s cleaning policies, building access and setting clear expectations of volunteers and guests. While getting back to creating memories is a laudable goal, it cannot come at the expense of the health of everyone.
The post Community Broadcaster: Does Music Die? appeared first on Radio World.
Inovonics has released new firmware for its Sofia line of SiteStreamer+ remote monitoring receivers. Models 565, 567 and 568 are the recipients of the free upgrade.
[Check Out More Products at Radio World’s Products Section]
Leading the new items is a restricted login setting for casual users. Inovonics describes this as a “Look but don’t touch” setting allowing users to see readings and operate the units but not make any setting changes.
UDP streaming has been added as well, joining analog, AES3, AoIP (AES67) and Dante streaming options. Instructions for firmware updating are here.
Info: www.inovonicsbroadcast.com
The post Inovonics Updates Sofia Line appeared first on Radio World.
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