[BC] Re: Split level combine and the loss of the analog-onlytransmitter

[Chuck Lakaytis]

We have several HD installations in Southeast Alaska that have separate 
analog and digital antennas.  The low power HD is the Haris mini hd.  Matt 
Holmes wrote a script for the Burk remoted control to adjust the analog to 
keep it at the proper level with respect to the digital.  He did this 
because there is no obvious to remotely trim the HD power.  Bird BPME 
wattmeters are used for power measurement.

Chuck Lakaytis
Director of Engineering
Alaska Public Broadcasting, Inc.
135 Cordova Street
Anchorage, AK 99501
907 277 6300
907 277 6359 FAX
907 301 4339 Cell
----- Original Message ----- 
From: "Mark Humphrey" <mark3xy at gmail.com>
To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
Sent: Monday, April 09, 2007 5:43 AM
Subject: Re: [BC] Re: Split level combine and the loss of the 
analog-onlytransmitter


> On 4/9/07, Xmitters at aol.com <Xmitters at aol.com> wrote:
>> If I lose my analog-only transmitter and the Analog + HD transmitter
>> survives, Is the FCC going to let me run the allowed HD power as dictated 
>> by my
>> full-power RF mask, or are they going to want me to reduce the HD power 
>> to the
>> appropriate level consistent with the amount of analog power I'm putting 
>> out at
>>  the time?
>
> Good question.   I checked the FCC website, it appears that you must
> conform with the iBiquity hybrid specifications, as directed in this
> document:
>
> http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-03-831A1.pdf
>
> iBiquity's hybrid mask is referenced to the analog carrier, so my
> interpretation is that you must reduce the digital carriers if you
> lose the analog-only transmitter.
>
> However, it's interesting to consider that some stations using
> separate analog and digital antennas might be several dB out of
> tolerance with the mask if signals are measured in the field.
>
> One of the Philadelphia HD stations has been using a master antenna
> (wrap-around panel design with a near-omni pattern) for analog and a
> slightly-lower side-mounted antenna for digital.  These antennas are
> mounted on a 12-foot face tower and I'm on the back side.  When I
> measure their mask, the digital sidebands about 10 dB lower than
> normal.  I haven't taken field measurements on the opposite side of
> the tower yet, but would expect the opposite effect: several dB of
> digital "enhancement".
>
> Mark
> _______________________________________________
>
> The BROADCAST [BC] list is sponsored by SystemsStore On-Line Sales
> Cable-Connectors-Blocks-Racks-Wire Management-Test Gear-Tools and More! 
> www.SystemsStore.com       Tel: 407-656-3719    Sales at SystemsStore.com
>
>
>