Group3.pptx

VOICE OVER RADIO AND THE

FIRST

TELEVISION TRANSMISSIONS

*1914 — FIRST VOICE OVER RADIO TRANSMISSION Reginald Aubrey Fessenden - who was recognized as the "father" of radio and as the first to actually transmit the sound of the human voice without wires.

1920S — MOBILE RECEIVERS INSTALLED IN POLICE CARS IN DETROIT In the 1920s gangster era, bank robbers and bootleggers made clean getaways time after time, to the great consternation of police. For this was before reliable mobile-radio communications existed, communications that could have quickly dispatched patrol cars to the scene of the crime.

1925- US PATENT NO. 1,544,156 GRANTED TO CHARLES FRANCIS JENKINS FOR "TRANSMITTING PICTURES OVER WIRELESS" (TV). He was granted the U.S. Patent no. 1,544,156 (transmitting pictures over wireless) on June 30, 1925 (filed March 13, 1922).

1927- FIRST LONG-DISTANCE TV TRANSMISSION IN THE UNITED STATES, CONDUCTED BY AT&T BELL LABS. AT&T presents the first demonstration of television in the united states. Secretary of commerce Herbert Hoover's live moving image was transmitted over cable to New York, where it was seen by AT&T president Walter Gifford, and a large audience.

1928- FIRST TRANSATLANTIC TV TRANSMISSION, FROM LONDON TO NEW YORK.

The vision sound was sent across the ocean by short wave radio station 2KZ, of only two kilowatts power. Partial extract from leader in new york times, february 11th 1928.

1928- FIRST TV STATION, W2XB (LATER WRGB), BROADCAST FROM GENERAL ELECTRIC FACILITY IN SCHENECTADY, NY

It later became one of a handful of television stations licensed for commercial broadcasting operation before the end of world war II.

1930- MOBILE TRANSMITTERS DEVELOPED; RADIO EQUIPMENT OCCUPIED MOST OF POLICE CAR TRUNK

1935- FREQUENCY MODULATION (FM) DEMONSTRATED BY ARMSTRONG

Edwin Armstrong tested frequency modulation in 1933 and demonstrated it in 1935 to the institute of radio engineers. Frequency modulation can be used at any radio frequency, but it is not practical at low radio frequencies. It was first demonstrated to the FCC in 1937. The first construction permit for an FM station was issued by the FCC in 1937 and regular broadcasts started in 1939.,

1940s- MAJORITY OF POLICE SYSTEMS CONVERTED TO FM

COMMERCIAL TELEVISION AND THE BIRTH OF MOBILE TELEPHONY

1946- FIRST INTERCONNECTION OF MOBILE USERS TO PUBLIC SWITCHED TELEPHONE NETWORK (PSTN) Mobile telephony is the provision of telephone services to phones which may move around freely rather than stay fixed in one location. Mobile phones connect to a terrestrial cellular network of base stations (cell sites), whereas satellite phones connect to orbiting satellites. Both networks are interconnected to the public switched telephone network (PSTN) to allow any phone in the world to be dialed.

1949- FCC RECOGNIZES MOBILE RADIO AS NEW CLASS OF SERVICE

In the united states, amateur radio licensing is governed by the federal communications commission (FCC) under strict federal regulations.

1940s— NUMBER OF MOBILE USERS > 50K 1950s — NUMBER OF MOBILE USERS > 500K

AT&T launches its new improved mobile telephone service (IMTS) there were many reports of customers waiting 30 minutes or more to place a call. It got to a point where state governments were forced to restrict service to just 50,000-500,000 customers across the entire system. Still, in larger cities like new york city, 20,000 subscribers were forced to share 22 radio channels – which is what led to the long wait times.

1960S — NUMBER OF MOBILE USERS > 1.4M

Bell labs engineers were already looking for ways to implement cell service in vehicles. These researchers theorized that hexagonal cells would work best for vehicles. However, it wasn’t until the 1960s that researchers created the technology systems – like frequency reuse and handoff – that would lead to modern cellular networks.

1960S — NUMBER OF MOBILE USERS > 1.4M 1960S — IMPROVED MOBILE TELEPHONE SERVICE (IMTS) INTRODUCED; SUPPORTS FULL-DUPLEX, AUTO DIAL, AUTO TRUNKING

The First Cellular Network. Bell labs engineers were already looking for ways to implement cell service in vehicles. These researchers theorized that hexagonal cells would work best for vehicles. However, it wasn’t until the 1960s that researchers created the technology systems – like frequency reuse and handoff – that would lead to modern cellular networks.

1976 — BELL MOBILE PHONE HAS 543 PAY CUSTOMERS USING 12 CHANNELS IN THE NEW YORK CITY AREA; WAITING LIST IS 3700 PEOPLE; SERVICE IS POOR DUE TO BLOCKING

Thank You and

God Bless!