Thursday, August 16, 2018

The Greatest Inventor

Can you imagine visiting your nerdy friend in his laboratory, a peculiar scientist with human oddities. For example, for dinner each evening he would enter his hotel restaurant and escorted to his table. He would then proceed to wipe each utensil and dish with a clean napkin starting with the knife; then with a new napkin would wipe down the spoon, and again with a new napkin wipe down the fork – this was a daily routine. 


Nevertheless, you’re in his laboratory, with all types of odd-looking electrical equipment around you. Then, your friend, a tall thin man walks up to you; he suddenly snaps his fingers, instantaneously a red fireball flame looking substance is created on his fingertips. He rolls the fireball ball into his hands and not for one second he is nervous about electricity flowing in and out of his body.  He now has your full and focused attention and you’re astonished that the fireball doesn’t burn him.

He rolls it around, on his body, on his head, and then onto your lap. Yikes! He picks up the fireball and places it into a wooden box, then closes the cover.  He opens the cover to show you the inside of the box, there is nothing there – no trace of the electrical red fireball ever existed!

Your friend is Nikola Tesla –  

Tesla conducted this experiment several times during his career; yet, no one has been able to duplicate mysterious experiment

Before I put a sketch on paper, the whole idea is worked out mentally. In my mind I change the construction, make improvements, and even operate the device. Without ever having drawn a sketch I can give the measurements of all parts to workmen, and when completed all these parts will fit, just as certainly as though I had made the actual drawings. It is immaterial to me whether I run my machine in my mind or test it in my shop. The inventions I have conceived in this way have always worked. In thirty years there has not been a single exception. My first electric motor, the vacuum wireless light, my turbine engine and many other devices have all been developed in exactly this way” - Tesla.  


That's how 3-phase [polyphase] AC power was invented - in Tesla’s head. Tesla is responsible for the 120 AC volt electrical systems that we use today. Prior to AC, Edison’s DC power was predominant; although effective, it was inefficient and difficult to transmit voltages over distances.

We all know that Thomas Edison invented the electric light bulb and the equipment to light it, and that George Westinghouse built the world's first hydroelectric power plant at Niagara Falls; both men knew Tesla. Tesla, a Serbian immigrant, was the greatest electrical genius ever!  In his early days, he
worked for Edison “fixing” electrical systems that Edison and his engineers could not.
Edison - Tesla - Westinghouse


Westinghouse was a railroad man, some of his inventions include air brakes and railway signals.  Later in life, Westinghouse became interested in electrical systems and was convinced that alternating current [AC] was better than DC for transmission, thus his association with Tesla.

It started out with GE’s bid to electrify the Chicago Worlds Fair in 1893 using Edison’s DC system. GE lost to Westinghouse, who proposed Tesla’s AC system, and whose bid was 30% less costly. Furthermore, that same year, the Niagara Falls Power Company decided to award Westinghouse [using Tesla’s polyphase AC] to generate power from Niagara Falls to electrify Buffalo. Many doubted that the falls could power all of Buffalo. By 1896 Buffalo was fully lit, and it wasn't too long after that GE decided to dump DC systems and switch to AC as well.

Back, earlier in 1892, Tesla created a basic design for radio and in 1898 obtained a patent using the design for a radio controlled boat.  In 1898 at Madison Square Garden, Tesla exhibited his radio-controlled boat to the public for the first time.

The boat had an antenna, which received the radio waves coming from a transmitter controlled by Tesla. The receiver device used was a coherer. The coherer received the radio waves and mechanically converted them to steer the boat’s propellers, thus allowing Tesla to control the boat from his transmitter.  This made front-page news in the newspapers, as Tesla may have been the first to demonstrate the use of radio waves as a medium for remote control.  
Tesla's Radio Controlled Boat

Now, we all know that Guglielmo Marconi as the inventor of radio, but how many really know of Tesla’s work in radio? Marconi claimed all the first patents for radio. Tesla tried to prove that he was the creator of radio but it wasn't until 1943, where the US Supreme Court deemed Marconi’s patents invalid; however, not many know about Tesla's radio work.

Tesla’s coils, that when tuned to its resonant frequency, was able to magnify electrical signals. With these coils used in the transmitter, he found that he could transmit and receive powerful radio signals in 1895. However, that same year disaster struck and all of his work was destroyed by fire.  By 1897, he filed his radio patent and the US Patent Office granted it in 1900. Tesla was able to transmit and receive radio signals 30 miles away at West Point.

The timing could not have been worse as the Italian experimenter, Guglielmo Marconi, built a wireless device for telegraphy. Marconi had taken out the first wireless telegraphy patent in England in 1896.

Marconi submitted applications for a US patent in 1900, and received a grant in 1903. Both Tesla and Marconi filed litigation, and in 1904, the U.S. Patent Office reversed its previous decisions regarding Tesla and gave Marconi a patent for the invention of radio. Reasons for this action were never fully explained, but many feel that Marconi’s strong political and financial backing was at play here.

Marconi won the Nobel Prize in 1911. This infuriated Tesla who felt that Marconi was using several of his inventions. In 1915, he sued Marconi for patent infringement. However, Tesla did not have the financial backing to litigate a large case against a major corporation such as the Marconi Company.  Litigation dragged on for several decades and shortly after Tesla’s death in 1943, the U.S. Supreme Court finally upheld Tesla's radio patent.


The Supreme Court had a selfish reason for doing this. The Marconi Company, which was an English company, was suing the US for use of its patents in World War I.  The Court, to uphold US interest, avoided action by restoring the priority of Tesla's patent over Marconi.  Hence, Tesla holds the US patent for radio communications.

Friday, June 8, 2018

The Origins of Radio Paging

Radio paging systems existed for about 50 years and was a leading wireless technology until the cellular industry exploded. 

Volunteer fire departments, doctors, service companies, construction workers, salesman, businesses and private citizens once used this technology extensively.  Today, principally volunteer fire departments and the medical profession continues to use radio paging.

Pagers, or more commonly known as  “beepers” , are not extinct but have seen a massive decline in users resulting in declined revenues. At the height of the industry [1996], revenues exceeded $4.4-billion.  By 2011, the industry was down 90% [$489-million].

The evolution of paging receiver variations included tone only, tone & voice, numeric and alphanumeric digital signaling, as well as talk-back paging.  You wanted to page someone, you would dial a phone number, leave a voice message, a call back number, or enter a digital message.

However, before all this automation and the ubiquitous "beep – beep - beep" heard from activated pagers, technology was quite deferent and evolved quite rapidly as an essential service.

Prior to the paging industry, those requiring 24-hour answering services generally subscribed to a telephone answering service company.  If you could not answer your calls or were away from your telephone [or didn't have a secretary to answer calls], you would let the telephone answering service know of your unavailability [by phone]. The answering service would then answer calls and take messages.  At a later convenient time, you would call the answering service to obtain your messages from the missed calls. Later, answering services used paging to notify the subscriber of messages.
Florac Paging Receiver


In the early 1950s, Telanserphone, Inc., an early telephone answering service located in New York City, whose owner, Sherman Amsden, was looking for a way to contact customers that they had a message.  Richard Florac, another New Yorker, was approached by Amsden to develop a receiver to alert customers of messages.  Florac designed the pocket receiver and obtained a patent in 1952.  Amsden under Telanserpone and also Aircall were the first companies to utilize this new technology – radio paging.

The first paging receiver was comprised of an aluminum case that included a battery, two miniature vacuum tubes, an activating switch, a tuner, a speaker, two dry cell batteries, and a drooping wire antenna.  The radio electronics used was an amplitude modulated [AM] superegenrative receiver/detector operating on 43 MHz.

Both vacuum tubes were pentodes.  A CK522AX tube, connected as a triode, was used for the RF section and a CK533AX was used an audio amplifier.  One battery provided voltages for tube filaments and the other battery was used to supply plate operating voltages.

The paging broadcast system was comprised of a high power AM transmitter [typically 250 Watts] operating on 43 MHz.  The transmitter was interfaced with a magnetic tape recorder that was set up in an endless loop.  Subscribers to paging services were typically assigned a three-digit number.  A telephone answering service operator would receive a message, then record the subscriber’s three-digit code on the recording tape.

The tape would be updated every fifteen minutes or so and would list the three digit code of subscribers who had messages.  The transmitter would continuously broadcast the revolving tape with user codes and removed after the subscriber called in for their message.

Subscribers would obtain their messages by holding their receiver’s speaker to their ear; they would depress the switch to activate the speaker, if the message was not clear they could “tune” in reception by moving the tunable knob on the receiver.  They would then listen to the tape and listen for their number.  If their number came up on the tape, they would find the nearest telephone and call the answering service for their message.

Later systems evolved to selective calling a pager, alerting individual pagers. The telephone operator would enter the three digit [or other] code on a manual encoder that would generate and send unique signaling tones [dual tone, two-tone sequential] to the transmitter for broadcast. The paging receiver set up on this tone sequence would then beep when activated.

Systems continued to evolve and were interconnected to telephone systems where paging terminals would perform call answering,  generation and delivery of signaling codes, and then messages to subscriber units.
Of course they were not called pagers in the beginning but pocket receivers.  Motorola coined the term Pager in the mid 1950s when they introduced the Handie-Talkie Radio Pocket Pager -  it was the first individual [selective calling] pager. It was also the first receiver utilizing transistors and   Thus the first true “beeper” frequency modulation [FM].

Motorola was a giant force in this industry as they had 80% of the hardware market.  With the decline if paging services, Motorola officially left the paging market in 2001.

Florac AM pagers were still used until the early 1970s until the FCC required that paging systems convert to FM modulation. 


In the late 1960s and early 1970s, Airsignal International, Inc.[AI], which became the largest Radio Common Carrier of that era, were the first to introduce NEC pagers labeled as their brand for their nationwide paging services. AI was one of the first nationwide telephone answering and paging service companies in the US, having operations in many US major cities as well as internationally.




Friday, January 19, 2018

The First Police Radio Communication System

Policing has been around for a long time but it wasn't until radio was introduced that it became the most important tool for the cop on the beat.  There are some studies that show that many officers prefer their radio to their service revolver.

Radio communications began shortly after Marconi’s first successful radio experiments in 1896.  Early on, radio communications, or wireless as it was known back then, was used to telegraph messages from ship to shore using spark transmitters.

Detroit Base Station Equipment
The first commercial broadcast [KDKA Philadelphia] was in late 1919, 1920 saw an explosive rise in broadcast transmitters being installed across the country as radio caught the wildfire. Of course it wouldn’t be long before someone in law enforcement would see wireless applicable to his or her line of work - a weapon of sorts to combat crime!

Thus one individual in the Detroit Police Department was the first visionary that took action – William Rutledge. Rutledge, as Police Commissioner, was a pioneer in helping to develop police communications.  In 1921, just four years after Detroit purchased their first police automobiles, Rutledge began an unsuccessful trial and error attempt to use radio for police work.  Rutledge purchased a 500-watt Western Electric Model 1A broadcast transmitter.  The transmitter was installed by patrolman Bernard Fitzgerald and Walter Vogler, who worked on the experimental effort. The base station was installed on the second floor of the 9th precinct station in the central part of Detroit.

They tried to build receivers to work in moving police cars and couldn’t do it; they tried both voice and telegraph to no avail; receiver sensitivity was almost non-existent; and, vehicle noise interference was predominant – all led to disappointment and the eventual shutting down of the system in 1926 because of unsatisfactory operations.

The problem was installing delicate radio receivers inside vehicles. Vacuum tubes were fragile and the vehicle proved too much of a bad environment for a radio installation.  Police cars tend to have fast starts and quick stops, too much vibration and shaking for a receiver and especially vacuum tubes of that era; if the components survived then receivers could not stay tuned.  Other problems included antenna mounting, the effects of weather; and, automobile ignition noise interfering with signal reception.

And of course, regulators in Washington impeded the development of police radio in Detroit.  In 1921, the Commerce Department [no FCC at the time] authorized W8BNE for the Detroit police department on 1500 kHz, which was an Amateur radio license.  Three months later it was reclassified as an experimental station, and so on and so forth until the regulators got their act together.

Year
Call Sign
Type
Frequency [kHz]
1921
W8BNE
Amateur
1500
1921
W8XAB
Experimental
800
1923
KOP
Limited Commercial
833
1924
KOP
Broadcast
1080
1926
WCK

1710
Both failure and success came from within the Detroit Police Department.  Radio mechanics [as they were called at the time] in Detroit were eventually able to construct a radio set that could stand the jolting it got from the vehicle as well as mitigating automobile noise interference.

Robert Batts, an engineering student at Purdue, in 1927 had a summer job working in a downtown Detroit radio parts store.  He assisted their customers in building broadcast radio sets.  Even though RCA and others were selling radios, people were still constructing radios from kits. Batts also had a pick-up truck that had a receiver and a loop antenna that he used to track down interference; thus using radio in a vehicle.  He was definitely interested in radio and was pursuing a career in this field.
Batts and Cox


One of Batt’s customers was Kenneth Cox, a Detroit motorcycle patrolman. They struck up a friendship based on discussions on how to make receivers work in police cars. When Batts went back to Purdue that fall, he and Cox continued to communicate their radio designs by mail. Cox knew he could make radios work in police cars and built a model wrapped up in foam rubber based on their collaborative work. Cox then went to Rutledge to convince him that the department should make another run at it, and demonstrated by dropping his prototype receiver on the floor, turning it on, showing that it still worked.

Rutledge, understanding radio’s potential role in law enforcement gave his approval. Cox enticed Batts to return to Detroit to work on the system. Batts reluctantly left Purdue, and was eventually hired as a patrolman, allowing him to be compensated for his radio work effort. He immediately began working on the new receivers.

The first 1921 base station transmitter installation downtown was deemed by Batts to be in a bad location as buildings and power lines impeded optimum operations.  He had the equipment moved to the second floor of the police station that was located on Belle Island in Detroit.  Vogler and Fitzgerald then rebuilt the station per Batts recommendations.  They converted the transmitter to utilize crystal control rather that the self-excited oscillator that was originally used. 

A guyed mast was installed on the building for the transmitting antenna. The amplitude modulated [AM] transmitter was rated at 400 watts of power.  The transmitter required 1,800 volts of plate voltage, and was powered from two motor generators. 

Batts designed a new vehicle radio receiver that was key to the technical success. 

There was several type of mobile radios built as experimentation improved performance.  The receivers had 5 or 6 tubes depending on the receiver design type; some using AC, some using DC tube types.  In time they found that the 5-tube set using DC tubes was achieving the best results.   The receiver was a three stage tuned RF unit. Copper compartments were constructed for shielding the RF section, and tuning capacitors were locked for mechanical stability and to prevent the radio operator from changing to another frequency or station. Batts understood that shielding was important to mitigate noise interference.  He also designed spark plug noise suppressors.

The receiver was initially mounted inside the back of the car’s front seat with foam rubber to minimize the inertia of the receiver’s weight to prevent shocks getting to the tubes. 

The mobile antenna initially used was a “tophat” antenna installed on the top of the car [see picture].   Batts changed this design by having the antenna woven into the fabric of the car’s roof. They experimented with both grid and wire copper antennas.
Detroit Radio Car
This required carefully installed insulators to ensure that nothing became grounded.

The vehicle receiver [mobile radio] utilized a loudspeaker as it was determined that earphone equipment was not conducive to police mobile radio application.  Batts custom built speakers as considerable loudness was needed to be clear of noise and interference.

Persistent work by Kenneth Cox and Robert Batts, and the visionary Commissioner Rutledge, led to the development of an improved radio system, especially mobile radio receivers.   

Thus, in April of 1928, the Detroit Police Department made history as the first to dispatch patrol cars regularly by radio after about nearly a decade of struggle and disappointment. Bernard Fitzgerald was its first official radio dispatcher. Detroit was successful in making receivers work inside police cars. This achievement got overnight worldwide attention.

Within eighteen months in December of 1929, the City of Cleveland was the next to go on the air.  Robert Batts, who at this point left Detroit for Indianapolis, led the City to get law enforcement to go wireless.  Kenneth Cox took a leave of absence from Detroit Police Dept. and moved to Chicago in 1929 to help them install their first police radio system. Walter Vogler succeeded Cox as Detroit’s radio mechanic.
Fitzgerald

By 1931, over 62 police departments across the country were utilizing radio in their police cars.

1928 was the year that police radio communications began. Although in primitive form, with communications being one way [dispatcher to mobile] it changed the way police conducted their business forever.   It is interesting to note that under the KOP broadcast call sign; the police department was obligated to provide programming material during the daytime. Police calls were aired to police vehicles when needed.  Providing program material must have been difficult, as live performers, musicians and singers had to be hired to fill in the days programming – the police musical band got plenty of airtime!  This shows the amount of significance that Commissioner Rutledge must have had in radio as a police tool.  Police programming content also included a listing of stolen cars as the public was involved in crime fighting.