US 5,774,193 AGranted

Digital television (HDTV) and analog television (NTSC) broadcast systems combined for simultaneous broadcast

OwnerThomas J. Vaughaninventor

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Abstract

An HDTV broadcast transmission system and an analog NTSC broadcast transmission system are carried on the same tower and broadcast to the same area by adaptation of both systems: the NTSC system including: (a) a source of analog NTSC video signals, (b) an NTSC analog video signal exciter producing NTSC IF modulated analog video signals, (c) an NTSC frequency up converter and power amplifier producing NTSC RF modulated analog video signals (NTSC RF signals), (d) an NTSC broadcast antenna and (e) an all band VHF and UHF signal transmission line having an input end and an output end; the HDTV system including: (1) a source of digital video signals, (2) a digital video signal encoder producing IF modulated digital video signals and (3) a frequency up converter and power amplifier producing RF modulated digital video signals (HDTV RF signals) and an HDTV broadcast antenna; by combining the HDTV RF signals and NTSC RF signals at the input end of the transmission line and separating them at the output end and feeding them to the NTSC antenna and the HDTV antenna, respectively. In a preferred embodiment, the HDTV antenna is supported on the tower below the NTSC antenna and the antennas radiation patterns cover substantially overlapping broadcast reception areas around the tower.

Claims22

Dependent claims

Combined NTSC and HDTV broadcast systems, the NTSC system producing an NTSC Channel band herein called RF.sub.NTSC and said HDTV system producing an HDTV Channel band herein called RF.sub.HDTV, the NTSC system including an NTSC transmitter system and NTSC broadcast antenna, the HDTV system including an HDTV transmitter system and HDTV broadcast antenna, and both of said antennas carried at the top of a common support tower, comprising,

(a) a transmission line having a transmitter end at the bottom of said support tower and an antenna end at the top of said support tower,
(b) means at the bottom of said support tower for combining said RF.sub.NTSC and said RF.sub.HDTV from said first and second transmitter systems, respectively, and feeding said combined RF.sub.NTSC and RF.sub.HDTV to said transmitter end of said transmission line, whereby said transmission line conducts said RF.sub.NTSC and said RF.sub.HDTV to said antenna end thereof and
(c) means at the top of said support tower for separating said RF.sub.NTSC and said RF.sub.HDTV conducted in said antenna end of said transmission line and feeding said RF.sub.NTSC to said NTSC antenna and feeding said RF.sub.HDTV to said HDTV antenna,
(d) said means for separating is a two band coupled line device including an RF.sub.NTSC lowpass filter and an RF.sub.HDTV highpass filter, both connected to said antenna end of said transmission line,
(e) said lowpass filter feeds said first antenna,
(f) said highpass filter feeds said second antenna and
(g) said highpass filter is a waveguide for which the waveguide cut-off frequency is above said RF.sub.NTSC and below said RF.sub.HDTV,
(h) whereby said NTSC antenna broadcasts said RF.sub.NTSC and said HDTV antenna broadcasts said RF.sub.HDTV.

5 more elements

First and second broadcast transmission systems producing RF signals in different frequency bands, referred to herein as RF.sub.LOW and RF.sub.HIGH, the first system including a first transmitter system and first broadcast antenna, the second system including a second transmitter system and second broadcast antenna, and both of said antennas carried on a common support tower, comprising,

(a) a transmission line having a transmitter end at the bottom of said support tower and an antenna end at the top of said support tower,
(b) means at the bottom of said support tower for combining said RF.sub.LOW and said RF.sub.HIGH from said first and second transmitter systems, respectively, and feeding said combined RF.sub.LOW and RF.sub.HIGH to said transmitter end of said transmission line, whereby said transmission line conducts said RF.sub.LOW and said RF.sub.HIGH to said antenna end thereof and
(c) means at the top of said support tower for separating said RF.sub.LOW and said RF.sub.HIGH conducted in said antenna end of said transmission line and feeding said RF.sub.LOW to said first antenna and feeding said RF.sub.HIGH to said second antenna
(d) said means for separating is a two band coupled line device including an RF.sub.LOW lowpass filter and an RF.sub.HIGH highpass filter, both connected to said antenna end of said transmission line,
(e) said lowpass filter feeds said first antenna,
(f) said highpass filter feeds said second antenna, and
(g) said highpass filter is a waveguide for which the waveguide cut-off frequency is above said RF.sub.LOW and below said RF.sub.HIGH,
(h) whereby said first antenna broadcasts said RF.sub.LOW and said second antenna broadcasts said RF.sub.HIGH.

5 more elements

Dependencies are inferred from the claim text.