Another exchange with corrections to what Stuart was originally told about the attached photos during his tour of the LABC back in 2016;
On Friday, September 16, 2016 12:24 PM> wrote:
Hope your email account will allow file attachments.
In the included attached images taken during a tour of the LABC back in 2012. First regarding photo of the 1 meter dishes the tour guide explained to the dbstalk.comcorrespondent ...
<< While you're walking around, it's easy to miss these 1-meter dishes (still twice the size of the ones on your home.) They're almost visible at the center left of the aerial shot. They pick up the satellite signals that the big dishes transmit, so that engineers inside the building can analyze and monitor it for quality control, 24 hours a day, 7 days a week. >>
Is this because the small dishes are so close to the big uplink ones they actually receive stray RF from them which the engineers can then use to monitor the uplink signals?
And in second photo, it was explained to our correspondent ...
<< There was one last surprise in my tour of the sports center. You would think DIRECTV engineers would have their hands full with US Sports. This part of the facility also handles sports for a lot of the other countries where DIRECTV operates as well. Take a look at the closeup of the rack and you'll see the rare LHR22 Sky+ HD DVR. It may not look all that different from our HR22, but it's only for Latin America. >>
Now while I'm sure there's a way to have the actual signals fed back to the US. Still just curious to your knowledge as to how these subscriber equipment receivers are actually receiving the foreign downlink signals for SKY Mex., DLA, and Puerto Rico while in Los Angeles?
[Anonymous] response on 9/16/2016 at 4:19 PM PST:
Aah, now we're talking something I can really comment on, [Final part of sentence here edited out at source's request].
The group of six dishes to the right of the picture ... [edit here at request of source] ... that was built and installed by a local company for US downlink monitoring. They were the 1.2m Alaska/Hawaii dishes of the time ... [edit at request of source] ... chose them for the extra 5dB or so margin they have over the Slimline. They are set up as redundant pairs.
One dish (on the right of each group) has an LNB for 99, 101 and 103 then the center one is 110 and the left is 119. There are two complete sets of Alaska/Hawaii dishes that run to two separate power supplies and sets of amplifiers with failure detection and auto switch to backup. RF levels out of the first amps are around -5dBm per transponder, which is a very hot level then its split to a bunch of fiber transmitters and other junk.
I had one of the big L-band amplifier companies take their green is good, red is bad amplifier status light for RF level and run it out at TTL level for backup switching. The amplifiers are AGC type so the distribution system always has about the same level at all locations at all times and during rain only the SNR changes. Only the primary side alarm signal feeds the switch so if there is actually a satellite failure the system won't sit there and toggle back and forth.This system feeds most of the confidence monitoring at LABC and there is an identical system at CBC. I have pictures of the system somewhere plus all engineering drawings.
For actual uplink monitoring before the satellite each transmit antenna has 50 to 60dB couplers in each polarity just before the feed horn in the dish and on some dishes its brought back into the building for monitoring and other antennas its got uplink to L-band converters in the antenna and the monitoring signals are brought into the building at L-band. There are no direct pick up antennas for the transmit dishes.
On the DTVLA sports thing, very little was done at LABC and for most of the CBC history it was all done at the CBC. I designed three sets of dual talent voice over booths that were used extensively during the last several FIFA soccer seasons plus lots of baseball games. Interpreters or talent or in many cases, so called talent, would have live ESPN or other sports channels fed into the booth plus live internet for stats. They would then translate the games into either Spanish or Portuguese.
Usually we had separate audio feeds for the ESPN English announcers and separate crowd sounds (nat sound). The nat sound would be mixed with the translators commentaries and you would never know they were not at the live show. In some cases where they couldn't separate the crowd sounds (mostly baseball) they would use canned crowd sounds at different levels and that would get mixed with the translators. The person running the audio board had to know the teams and players and their popularity so he or she could ride the appropriate amount and type of crowd noise.
Many years ago much of the DTVLA sports production transferred to one of the Latin American countries and much less is done at CBC or LABC except for maybe FIFA and Olympics.
Much of the original DTVLA system is easily received along the southern border of the US except for the very southern beams. There is also a hot spot from G3C into the DC and NYC area for monitoring at DTVLA corporate headquarters in NYC. I also designed most of the downlink distribution for that.
When Puerto Rico was still on G3C the only US site that could receive the single spot beam was CBC and they tapped the uplink and converted to L-band. Otherwise the other transponders were simply CONUS transponders that could be received anywhere in the US by doing some tricks. You had to use a separate linear pol dish to receive them, then filter out everything but those specific transponders, then combine that with a downlink from a DTVLA dish that has the same frequency range for the linear transponders filtered out. The end result is a combination of two different dishes but worked fine and the receiver didn't know any different.
For Sky reception, IS-9 then IS-21 has a fine signal into much of the southern US and it works fine. I still have a DTVLA and Sky consumer dish on my house. Not sure about the newer 70 deg Sky stuff. My office had a stack of receivers running all the time although I had little time to watch TV. I had separate receivers for US HD, DTVLA, Sky and Puerto Rico as they were switching to the US system. We had direct but weak reception of the US Puerto Rico feeds in California, not sure if that was by design or ?? All that was fed to a couple of large monitors and very good stereo with Tannoy pro monitors and sub woofer. ... [a final sentence edited out here at source's request]
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Edited by HoTat2, 17 September 2016 - 09:58 AM.