All digital AM IBOC testing: Ten pounds of dung in a five pound bag, still

[KB1OKL]

An experienced broadcast engineer's opinion of the potentially looming all digital tests on medium wave. The title says it all and he backs up his opinion:

"Alternate title: Why Medium Wave frequencies do not work for high speed data transmission

Much ink has already been spilled on the merits of HD Radio or lack thereof. The latest NAB sponsored project is the all digital mode test of AM HD Radio. As of this writing, four stations have volunteered to conduct the all digital (no analog) test on their facilities. I predict no great performance improvement in AM HD Radio system will be demonstrated from these tests.

Medium wave is the radio frequencies between 300-3,000 KHz, which is where the Standard Broadcast or AM broadcasting service in the US exists. There are several reasons why trying to make a 20 KHz wide linear digital signal work in those frequencies posses some technical problems:

Electrical noise is very prevalent below 1,000 KHz
Ratio of bandwidth to available frequency is low, therefore low data rates must be used
Narrow bandwidth of existing antenna systems, particularly directional antennas and phasors
Existing uses of the frequencies in question"

Read more at:

http://www.engineeringradio.us/blog...ten-pounds-of-dung-in-a-five-pound-bag-still/

 

[iyiyi]

Izzat so?

Looks like we are about to find out what substance is in what container pretty soon!

See ya on the flip flop!

-

 

[tomservo]

iyiyi, you can't fight physics.

If it were up to me I'd go for the "repacking" of the band by moving smaller stations out to VHF channels 5-6 and opening up the existing band to be less congested, re-focusing it as a place for regional signal coverage.

 

[nd2023]

iyiyi, you can't fight physics.

If it were up to me I'd go for the "repacking" of the band by moving smaller stations out to VHF channels 5-6 and opening up the existing band to be less congested, re-focusing it as a place for regional signal coverage.

I'd rather have HD signals on VHF 2-6, or multiplexed on a DTV-audio system.

 

[tomservo]

iyiyi, you can't fight physics.

If it were up to me I'd go for the "repacking" of the band by moving smaller stations out to VHF channels 5-6 and opening up the existing band to be less congested, re-focusing it as a place for regional signal coverage.

I'd rather have HD signals on VHF 2-6, or multiplexed on a DTV-audio system.

What's the digital TV scheme they use in Europe… 8-VSB? I understand they chose that because it's robust enough to enable mobile reception, unlike our ATSC. Many luxury cars available over there have digital OTA TVs built in. Maybe that could be repurposed to enable an audio only multicast of some sort for digital portable radios here? That would be a good way to pack in many new stations on channels 5 & 6.

 

[ajc_trw]

iyiyi, you can't fight physics.

If it were up to me I'd go for the "repacking" of the band by moving smaller stations out to VHF channels 5-6 and opening up the existing band to be less congested, re-focusing it as a place for regional signal coverage.

I'd rather have HD signals on VHF 2-6, or multiplexed on a DTV-audio system.

What's the digital TV scheme they use in Europe… 8-VSB? I understand they chose that because it's robust enough to enable mobile reception, unlike our ATSC. Many luxury cars available over there have digital OTA TVs built in. Maybe that could be repurposed to enable an audio only multicast of some sort for digital portable radios here? That would be a good way to pack in many new stations on channels 5 & 6.

ATSC is 8-VSB, Europe uses DVB or (C)OFDM (the C stands for coded but is mostly used for OTA TV) IIRC DAB uses OFDM as does DRM.