RX-only C-band receive station registration, form 312

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grich
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Re: RX-only C-band receive station registration, form 312

Post by grich » Sat Mar 24, 2018 9:53 pm

ncradioeng wrote:
Sat Mar 24, 2018 8:03 am
3.7 - 4.2 GHz. I think most of the AT&T land-based microwave channel and modulation specs carried over to the satellite transponder specs. It was all about making phones calls back then.
And a TV network or two.

http://long-lines.net/

If you're a phone geek, this link will be a colossal time-suck. :D

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kkiddkkidd
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Re: RX-only C-band receive station registration, form 312

Post by kkiddkkidd » Sun Mar 25, 2018 6:05 am

grich wrote:
Sat Mar 24, 2018 9:53 pm

If you're a phone geek, this link will be a colossal time-suck. :D
Isn't that the truth. I spend a couple of hours digging thru the site and learned the name of several local sites that I have seen all my life and a few whereI have worked on 2-way and FM equipment. But never found a single mention of what frequencies they used.

Later,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

TPT
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Re: RX-only C-band receive station registration, form 312

Post by TPT » Sun Mar 25, 2018 6:55 am

The point-to-point terrestrial microwave and C-band downlink transponder frequencies were set up so that they were interleaved with each other. Since this provided some isolation, as long as your dish was not directly aimed at the TI, the use of some kind of shielding would allow the dish to work. If you had a terrestrial link in the same neighborhood as your dish, you might be able to install a filter that would beat down the TI enough so you could get the satellite to work.

At our studio site, there is an MCI microwave tower about 1500 feet to the east of us. When it was active it communicated with a tower towards the NE, and another tower towards the SW. From our site this second tower was at 254 degrees, as I recall, AMC-8 was around 225 degrees. We were able to screen out the "back-scatter" from the periscope antennas on the nearby tower by using a hardware cloth screen behind our 12' dish. Then we decided to pick up a program from Premiere Networks. Their transponder downlink frequency was on an adjacent channel to one of the active feeds from that MCI dish. With an L-band filter from Microwave Filter we actually got this to work. Sort of. Then we located a good contact for MCI's engineering & they shut down that link. Their engineer wanted to kill the system, and this was a good excuse.

At the time geosynchronous satellites were being planned, I suspect there was some coordination and consultation with A.T.& T. My belief is that A.T.& T. was already planning to abandon many of these terrestrial microwave links in favor of fiber. So this band was not really contemplated as a shared band--eventually most of the terrestrial services (especially in urban areas) would be abandoned, leaving it to satellite receive-only.

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Re: RX-only C-band receive station registration, form 312

Post by TPT » Sun Mar 25, 2018 7:09 am

Numbers of receive dishes:

Market #249, Parkersburg-Marietta. One TV studio with three on-air channels (NBC/CBS/Fox). One cluster with 6 stations, one with 4, EMF outlet, NPR state public radio, and two other 3 station clusters (one is mine). All have satellite dishes.

Just off the top of my head--without driving around and looking--4 at the TV station (look at 199 Television Plaza, Parkersburg on Google street view); two at my station and at the other small cluster. I-Heart has 4 (not sure what they are all for), and Burbach 2. WVPubRadio feeds their satellite transmitter with a dish, as does EMF.

That's 16 receive dishes in one small market.

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kkiddkkidd
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Re: RX-only C-band receive station registration, form 312

Post by kkiddkkidd » Sun Mar 25, 2018 9:24 pm

TPT wrote:
Sun Mar 25, 2018 7:09 am
Numbers of receive dishes:


That's 16 receive dishes in one small market.
I am estimating that there are 15,000+ C-band links in use as opposed to the registered 1500... Estimating (conservatively) that half of all licensed full power AM&FM stations have A dish, several hundreds of LPFM and satilators, all 4000+ full or LP TV stations have 2 or more dishs, hundreds of cable TV headends have several dishes, a few thousand TVRO/FTA users, probably several hundred C-band distance learning systems at schools and universities.
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Kevin C. Kidd CSRE/AMD
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AM Ground Systems Company
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TPT
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Re: RX-only C-band receive station registration, form 312

Post by TPT » Mon Mar 26, 2018 7:00 am

The primary purpose of registration was protection against changes in terrestrial microwave links. Since these were fixed path links--usually using massive self-supporting towers (or even those concrete towers), the only dish owners who would need this protection were those:

A: With a dish right next door to the tower, where a new link might blank a transponder, or a new path might shoot by the dish;

B: A dish at a distance, but aimed more or less towards this tower.

When these terrestrial links began to be abandoned about twenty years ago, there was little point in generating new registrations.

grich
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Re: RX-only C-band receive station registration, form 312

Post by grich » Mon Mar 26, 2018 1:08 pm

kkiddkkidd wrote:
Sun Mar 25, 2018 6:05 am
grich wrote:
Sat Mar 24, 2018 9:53 pm

If you're a phone geek, this link will be a colossal time-suck. :D
Isn't that the truth. I spend a couple of hours digging thru the site and learned the name of several local sites that I have seen all my life and a few whereI have worked on 2-way and FM equipment. But never found a single mention of what frequencies they used.

Later,
Here's a chart listing frequencies and polarities on a certain path. One hop is Ku band, the rest is 3700-4200.

http://long-lines.net/places-routes/Han ... 31120.html

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kkiddkkidd
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Re: RX-only C-band receive station registration, form 312

Post by kkiddkkidd » Mon Mar 26, 2018 5:38 pm

grich wrote:
Mon Mar 26, 2018 1:08 pm
Here's a chart listing frequencies and polarities on a certain path. One hop is Ku band, the rest is 3700-4200.

http://long-lines.net/places-routes/Han ... 31120.html
Thanks,

That helps a lot. Would I be incorrect to assume that most of their links used basically the same C-band frequencies?
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

TPT
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Re: RX-only C-band receive station registration, form 312

Post by TPT » Mon Mar 26, 2018 7:16 pm

When I researched this several years ago, it appeared that was the case.

rftranstv
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Re: RX-only C-band receive station registration, form 312

Post by rftranstv » Mon Apr 02, 2018 8:53 am

I have heard rumors of a repack of C-band spectrum? Anyone have any thoughts?

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Re: RX-only C-band receive station registration, form 312

Post by TPT » Mon Apr 02, 2018 11:43 am

That's what we are talking about--proposal for terrestrial shared use with C-band down links floated by FCC Commissioner O'Rielly.

Nothing concrete beyond that except may include "mobile" uses.

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kkiddkkidd
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Re: RX-only C-band receive station registration, form 312

Post by kkiddkkidd » Mon Apr 02, 2018 12:31 pm

rftranstv wrote:
Mon Apr 02, 2018 8:53 am
I have heard rumors of a repack of C-band spectrum? Anyone have any thoughts?
I have heard the same rumors and have included that exact question in my list of questions for an article. I have submitted my list of questions to Commissioner O'Rielly's press attache but have not received a response yet.

Later,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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kkiddkkidd
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Re: RX-only C-band receive station registration, form 312

Post by kkiddkkidd » Mon Apr 02, 2018 12:37 pm

TPT wrote:
Mon Apr 02, 2018 11:43 am
That's what we are talking about--proposal for terrestrial shared use with C-band down links floated by FCC Commissioner O'Rielly.

Nothing concrete beyond that except may include "mobile" uses.
I have also heard rumors of a reduction and repack of transponder channels.
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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KC9AIC
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Re: RX-only C-band receive station registration, form 312

Post by KC9AIC » Mon Apr 30, 2018 3:42 pm

I'd like to register my dish, but I don't have any information as to its make and model. Can anyone ID it for me? It's about 10 or 11 feet in diameter, and there is a blue H logo on the feed horn that has faded with age.
20180430_170838crop.jpg
Dish Photo 1
20180430_170909.jpg
Dish Photo 2

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kkiddkkidd
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Re: RX-only C-band receive station registration, form 312

Post by kkiddkkidd » Mon Apr 30, 2018 3:58 pm

OLD, OLD, OLD Harris Corp (not necessarily Harris Broadcast but basically the same). Possibly not even 2 degree compliant. I may have a spec sheet on it somewhere and still have at least 1 in standby operation.

Is the LNB mounted on the back of the dish instead of out in front as normal?

Regards,
--
Kevin C. Kidd CSRE/AMD
WD4RAT
AM Ground Systems Company
http://www.amgroundsystems.com
KK Broadcast Engineering
http://www.kkbc.com

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