ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2] 3 4 ... 6   Go Down

Author Topic: Inside look at a massive comm system for a Mega Show....  (Read 14595 times)

Jason Glass

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 816
    • CleanWirelessAudio.com
Re: Inside look at a massive comm system for a Mega Show....
« Reply #10 on: August 17, 2016, 11:58:17 am »

This is an amazing transmitter combiner.  Typically this method is used on high power commercial broadcast systems but rarely more than 5-6 TX.  Steve has expanded the idea for almost 50 TX frequencies.  The amazing thing is that any one TX only looses 6 dB by the time it gets to the antenna.  NO additional amplification is needed during or after the combining.  All of the loss is due to the little bit of RF that does get through to another TX or the term in a circulator.

HERE is the design PDF for Steve's antenna system

Read about this technology HERE
Hi Pete,

Wow!

It looks like the cost of the hardware would be commensurate with its performance level.

Do you know where he acquired all of those dual junction wideband isolators?

Sent from my mobile phone. Please excuse the inevitable spelling and grammatical errors.

Pete Erskine

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1399
    • Best Audio
Re: Inside look at a massive comm system for a Mega Show....
« Reply #11 on: August 17, 2016, 12:21:52 pm »

It looks like the cost of the hardware would be commensurate with its performance level.

Do you know where he acquired all of those dual junction wideband isolators?

Sent from my mobile phone. Please excuse the inevitable spelling and grammatical errors.

http://procom.dk/products/242-pro-is-380-s1-pro-is-380-d1
Logged
Pete Erskine
917-750-1134
www.bestaudio.com
peter@bestaudio.com

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6143
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: Inside look at a massive comm system for a Mega Show....
« Reply #12 on: August 17, 2016, 12:37:16 pm »

It took Torbeg and Steve 2 days to fine tune the cable lengths and adjust frequencies.  It is not an easy system to setup.  The cable lengths theoretically could b done in advance but in reality small adjustments needed to be done once all channels were online based on how much of the freqs got into other TX.

Using a normal hybrid combiner would put a lot of rf back into each TX and the circulators.  The circulator terminations would get too hot to touch.  Using manifold combining in this system they are cold meaning very little RF is fed back into the previous TX.

A tuning box could be made that electrically adjusts the length of the cable.  Nothing like that exists as a product so manual cable length was the easiest way to do this.

I am told that cellular techs travel with a lot of pre cut cables, sort of like a kit of all the different values of resistors, that they just use to adjust combining, rather than build cables on site.

That is true with the cellular techs.  Running my hand across the loads on the circulations is job one when troubleshooting or inspector a combining system. 

What I don't understand is why the production industry doesn't have the equivalent of a z-match. I just did a search and could not even find a picture, it was a 1/1 inch cube with a variable inductor and capacitor.  It created a tank circuit and allowed poorly designed amplifiers to load better.  Any good RF tech kept a few in their toolbox.  I can't recall if it was a Phelps or a DB product.  At first I thought it was TXRX systems but they are still in business and have no reference of it.

The cable tuning method requires quite a bit of intuition.  Do you use any Smith Charts when you do these calculations?  Have you ever had to employ a tuning stub?

I honestly am just surprised that the methods used by amateur radio operators of my youth is the chosen method for the latest high tech production gear.



Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Pete Erskine

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1399
    • Best Audio
Re: Inside look at a massive comm system for a Mega Show....
« Reply #13 on: August 17, 2016, 12:43:23 pm »

The cable tuning method requires quite a bit of intuition.  Do you use any Smith Charts when you do these calculations?  Have you ever had to employ a tuning stub?

They used a R&SZVH Cable and Antenna Analyzer to visually see the null at a freq.  Put a T on it then a termination on one side and the cable on the other and left the end of the cable open.  Basically a distance to fault measurement, I think.
Logged
Pete Erskine
917-750-1134
www.bestaudio.com
peter@bestaudio.com

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6143
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: Inside look at a massive comm system for a Mega Show....
« Reply #14 on: August 17, 2016, 01:30:02 pm »

They used a R&SZVH Cable and Antenna Analyzer to visually see the null at a freq.  Put a T on it then a termination on one side and the cable on the other and left the end of the cable open.  Basically a distance to fault measurement, I think.

Wow that is nice.  I cut my teeth on the HP 8510.  With the S-Parameter test set it weighed over 200lbs in the flight case

A brief story since you mentioned circulators.

A carrier and a group of tech's that will remain nameless was having trouble commissioning an analog cell site.  This would have been about 88 if I had to guess.  They had replaced LDF on the tower, had the climbers and riggers up numerous times and yet the combiner fault was displaying on computer and shutting down the PA module.  They claimed it would not transmit long enough to get a reading of reflected energy on the analog watt-meter integrated into the combiner circuit.

The boss didn't want be to give these brain surgeons instructions on how to key the radio in maintenance mode so off I went to the town with the test set in Piper Cheyenne with a cargo door so the above referenced test gear would fit in the aircraft. 

I pull up onsite and they expect me to start unpacking my gear.  In fact the local manager was combative from the get go since before I pulled all that crap out of the van (the 8510 and case) I wanted to have a look.  I quickly keyed the radio then ran my hand across the circulators, expecting to find a mistuned cavity and know where to start my work.  Low and behold the output load was hotter than a firecracker after only 3 seconds of about 120w.  I pulled the jumper and peered into the N female attached to the 1 5/8 airline.  The connector was assembled wrong and the centerpin was recessed.  I pointed it out and told them to remake the connector and all should be OK. 

Test set never unpacked, lunch at the waffle house and home in time for happy hour.  I don't think the boys at the cell site had as pleasant a day.



Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Pete Erskine

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1399
    • Best Audio
Re: Inside look at a massive comm system for a Mega Show....
« Reply #15 on: August 17, 2016, 02:37:34 pm »

The connector was assembled wrong and the centerpin was recessed.  I pointed it out and told them to remake the connector and all should be OK. 

Test set never unpacked, lunch at the waffle house and home in time for happy hour.  I don't think the boys at the cell site had as pleasant a day.

That's like checking that their eq is plugged in.  Nice.  I guess you knew where to hit it with a hammer.
« Last Edit: August 17, 2016, 02:40:13 pm by Pete Erskine »
Logged
Pete Erskine
917-750-1134
www.bestaudio.com
peter@bestaudio.com

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6143
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: Inside look at a massive comm system for a Mega Show....
« Reply #16 on: August 17, 2016, 02:51:28 pm »

That's like checking that their eq is plugged in.  Nice.  I guess you knew where to hit it with a hammer.

My mentor had too great phrases check where the last technician was working first and it's always the simple shit.  30 years later I don't think he has ever been wrong. 

One of the mistakes I see engineers make when confronted with massive systems is to get overwhelmed with the scale of it all.  You have to think of it as many small systems put together.  If you don't teach good core troubleshooting skills in the beginning you can't succeed on large systems.

I had this discussion with Henry Cohen when I met him in Cleveland.  He has a land mobile background also.  We have to take the time to be the mentor to the young techs around us. 

If we don't then who is going to take care of all this gear when we are drooling on ourselves and parked in front of a TV watching endless Law and Order reruns?

Take care

Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

archive_2_NeilW

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 277
Re: Inside look at a massive comm system for a Mega Show....
« Reply #17 on: August 17, 2016, 03:11:34 pm »

Each time Riedel Communications provides the pinnacle of comms systems.   The massive communications system allowed very comfortable communications during rehearsals and the actual show.

In terms of overall number of interfaced radios, I think I saw that the system for the last winter games had quite a few more channels. Do you think that was a one-off rather than a trend in mega event comms system design? Would you like to have more radio channels on this show but limited by other factors such as budget or spectrum? Are there additional back to back channels that don't have a need to be interfaced to the wired system?
« Last Edit: August 17, 2016, 03:16:12 pm by Pete Erskine »
Logged

Pete Erskine

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1399
    • Best Audio
Re: Inside look at a massive comm system for a Mega Show....
« Reply #18 on: August 17, 2016, 03:17:15 pm »

In terms of overall number of interfaced radios, I think I saw that the system for the last winter games had quite a few more channels. Do you think that was a one-off rather than a trend in mega event comms system design? Would you like to have more radio channels on this show but limited by other factors such as budget or spectrum? Are there additional back to back channels that don't have a need to be interfaced to the wired system?
Budget is always a factor.  Soche probably was a very low rf usage area so freqs were probably easier to get.   the usage will always expand to the size of the system.
Logged
Pete Erskine
917-750-1134
www.bestaudio.com
peter@bestaudio.com

Scott Helmke

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1653
Re: Inside look at a massive comm system for a Mega Show....
« Reply #19 on: August 17, 2016, 03:57:29 pm »

My mentor had too great phrases check where the last technician was working first and it's always the simple shit.  30 years later I don't think he has ever been wrong.

Great story.   8)

One of my troubleshooting tips is "just look at the damn thing for a couple minutes". Finding a burnt component usually makes the rest of the search a lot shorter.
Logged

ProSoundWeb Community

Re: Inside look at a massive comm system for a Mega Show....
« Reply #19 on: August 17, 2016, 03:57:29 pm »


Pages: 1 [2] 3 4 ... 6   Go Up
 



Page created in 0.079 seconds with 23 queries.