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DTV Channel 2 DX

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    DTV Channel 2 DX

    I had some low VHF DTV DX this morning including a lot of WGGS in South Carolina and some WHDF (Florence, AL) and WTHC in Atlanta. Most noteworthy was my reception of KBRO's ATSC 3.0 signal from Denver. That's 441 miles away me. A picture of my HDHomeRun HDFX-4K-DEV tuner's display of the sub-channels is shown below:
    Click image for larger version  Name:	KBRO20240614.png Views:	0 Size:	13.0 KB ID:	1685
    Some pictures of my antennas and other equipment are at:
    2023 TV Antennas & Equipment - WTFDA Forums
    My antenna used for DTV channels 2 & 3 reception is a personally designed 9-element 86' high Yagi​ with a 24' boom.
    Last edited by WHJ; 06-14-2024, 09:50 PM.

    Due to my reception of a rare channel 2 ATSC 3.0 signal I thought that I would provide simplified comments on ATSC 3.0 signals. I used my Anritsu MT8222A analyzer to provide spectrum diagrams of the signals. Note the Resolution and Visual Bandwidths that I had had the analyzer set at. The analyzer has GPS linked frequency accuracy. I made the measurements on the initial ATSC 3.0 signals in this area: KMCI and KSMO in Kansas City.

    As shown below, data carriers are spaced about 1,700 Hz apart and are FM modulated with a 97 Hz tone.
    Click image for larger version  Name:	KMCI Data Carriers.png Views:	0 Size:	50.9 KB ID:	1689
    The channel edge pilots are precisely 84 kHz from each edge of the channel. They appear to be the best place to measure any channel frequency deviation. The two KC ATSC 3.0 transmitters appear to have GPS locked frequencies while the Rohde & Schwarz GPS transmitter at KXVO in Omaha is not. The KXVO transmitter has those channel edge markers a few Hertz away from that 84 kHz figure. Other brand ATSC 3.0 transmitters might have different bandwidths. Their center frequency will obviously be the center point between the two channel edge pilots (unless it’s one of the 11 channel-6 stations transmitting a FM signal on 87.75 MHz).

    There are other marker carriers which are unevenly spaced across the channel. Below, the lowest 500 kHz of the channels is shown. Due to the bandwidth and RBW chosen, the above data carriers cannot be seen below. With those settings, they collectively look like the flat top of a square wave.
    Click image for larger version  Name:	KMCI & KSMO Markers Low.png Views:	0 Size:	79.6 KB ID:	1690
    The markers have about a 10 dB greater amplitude than the data level. Due to their narrow bandwidth, they add little to the collective power of the transmitted signal. With an even greater level, the pilots of ATSC 1.0 signals on the same channel can be seen. The 1.0 data level is over 15 dB below the 3.0 data level. With that difference, the stronger 1.0 pilot has not been hurting reception of the ATSC 3.0 signals.
    Last edited by WHJ; 06-15-2024, 05:32 PM.