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Title: Matrix Comms (Part 2)
Post by: Neil White on January 31, 2013, 04:26:30 pm
Hi All,

This is a continuation to the Matrix Comms topic from last year. Pete Erskine suggested I post here with some more programming questions regarding the Riedel Artist system. Hopefully this can be a topic where we can discuss the programming and implementation of matrix comms systems from all manufactuers on all sizes of event.

I'd like to start the discussion with a question on the techniques available for monitoring the audio from important panels such as the Show Caller or Stage Manager. I recall Pete mentioned in the summer that there are a couple of different methods for listening to other panels within Riedel Artist, and would be interested to see the programming, as well as the benefits and drawbacks of each method.

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on January 31, 2013, 04:49:21 pm
I'd like to start the discussion with a question on the techniques available for monitoring the audio from important panels such as the Show Caller or Stage Manager. I recall Pete mentioned in the summer that there are a couple of different methods for listening to other panels within Riedel Artist, and would be interested to see the programming, as well as the benefits and drawbacks of each method.

I use several methods.  In the old version of Clear-Com's Matrix Plus II you could totally mimic the audio to and from from another panel without alerting the other user.  Riedel Artist almost has that capability but to listen to the speaker on another panel turns on the "MIC ON" LED on their panel.  Some users protest at this.

Here are my methods.  http://www.bestaudio.com/_private/downloads/monitoring_a_panel.pdf (http://www.bestaudio.com/_private/downloads/monitoring_a_panel.pdf)
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on January 31, 2013, 05:35:57 pm
Here are my methods.  http://www.bestaudio.com/_private/downloads/monitoring_a_panel.pdf (http://www.bestaudio.com/_private/downloads/monitoring_a_panel.pdf)

So if a panel's 2nd channel audio was just set to route to the monitoring key, the MIC ON light would stay lit, but by using the Logic function on each key, the panel behaves as the user expects, ie if all talk keys are off, the MIC ON led is not lit. Then when a user does press a talk key, the audio is routed to both the destination and also to the monitoring key on the comms engineers panel.

Do you typically spend much time monitoring panel listens during a show or do you mainly monitor the conferences and point to point conversations? Since it requires the panel to be in dual channel mode, do you normally only set up these functions for a few key users?

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on January 31, 2013, 08:22:20 pm
Do you typically spend much time monitoring panel listens during a show or do you mainly monitor the conferences and point to point conversations? Since it requires the panel to be in dual channel mode, do you normally only set up these functions for a few key users?

I always monitor the key conferences like Production and Cameras.  In addition on a SM heavy show like the Opening Ceremonies I listen mostly to the entire set of conversations that the Show caller has.

I start allocating panel ports so that every one is a 2 channel and only switch to single channel when I run out.  That keeps most of my options open.  I may do nothing with the second channel but if I need to there is no system reset needed.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 01, 2013, 04:02:16 am
I start allocating panel ports so that every one is a 2 channel and only switch to single channel when I run out.  That keeps most of my options open.  I may do nothing with the second channel but if I need to there is no system reset needed.

So you would assign panels to only odd numbered ports on the matrix, and then if additional panels are required they would fit in between the existing ports.

I would be interested to hear more about the cabling infrastructure required to deploy matrix comms.
Obviously each panel and node needs mains power, backed up by a UPS, and it would be the responsibility of the comms contractor to distribute power as needed. I think there would be three main ways of getting power to each panel:

a) home run a mains cable along with the signal cable from each panel to the node, and have all power distribution take place at the node location
b) run a single mains cable from the node to the panel location and distribute to multiple individual panels there. This probably makes the most sense in locations with large quantities of panels such as control rooms
c) locally power the panel from a source different to that of the node. This is probably a good solution for individual panels located a significant distance from the node, but would require more UPS units.

Is it common to use signal cable multicores (eg 5 way BNC) to distribute multiple panel signals over longer distances without having to pull lots of individual coax cables?

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 01, 2013, 05:36:12 am
Hi Neil,

Typically, my approach to cabling panels is as follows. This holds true for any system, regardless of whether they are on coax/cat5 or whether they are AES (riedel) or 4wire analog (Clearcom/RTS) or IP (Clearcom/RTS)

I agree that each panel should have an uninterruptible power source, and that power should be discrete, and not shared with other technical services.

I run power with the signal, back to a central point. Normally on Powercon connectors. Partly because they dont pop out like IECs (I mainly work in the Music sector, where gear gets treated rougeher...) and also because they don't get pinched by other people.

The mains cable can be very small gauge as the power draw on a comms panel is so minimal. Therefore the combination cable runs are not overly bulky.

I would also say, though, that I ideally like to avoid running things only off of a UPS, since that is an additional point of failure in the power system. In fact, because the events I'm doing typically have excellent managed mains power supplies (either from generators or well designed building mains systems), I've actually seen UPSes fail more often than the mains itself. Switchover PDUs solve this problem, as they allow 2 power inputs, and will do a 1 cycle switchover in the event one should fail. So I can use the UPS as the primary source, and the mains as secondary. Should the UPS fail, no worries...

I'm increasingly fond of running remote clusters of panels over IP. It massively simplifies the cabling, and provided you know networking and use good quality switching, is incredibly reliable. With the current Clearcom systems, the panels have IP built right in! So you add the IP card to the matrix, and you can go ahead and choose whether to connect the panel via 4wire or IP.

In this situation, I can have a little rack sleeve with a UPS, switchover PDU and switch that the panels connect back to locally. This can be powered off a local mains supply, and redundant IP connections sent back to the matrix location.
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 01, 2013, 11:05:55 am
I would also say, though, that I ideally like to avoid running things only off of a UPS,

I totally agree.  My experience is that the failure of UPS's happens and care should be taken in using them.  For the NODE power, since they have dual power supplies and only need 1 to run, I always put one on the mains and the other on the UPS.  This also has the advantage of less load on the UPS.

Quote
I'm increasingly fond of running remote clusters of panels over IP. It massively simplifies the cabling, and provided you know networking and use good quality switching, is incredibly reliable. With the current Clearcom systems, the panels have IP built right in! So you add the IP card to the matrix, and you can go ahead and choose whether to connect the panel via 4wire or IP.

This is a good suggestion.  Riedel has just recently started including IP capability in their panels and nodes.  With the abundance of high speed networks on shows now it makes good sense to use them.  I have not yet had an opportunity to use IP but am happy that the option is there.

Quote
In this situation, I can have a little rack sleeve with a UPS, switchover PDU and switch that the panels connect back to locally. This can be powered off a local mains supply, and redundant IP connections sent back to the matrix location.

What switchover PDU do you use and is it IP addressable?  I would like to find a remote control power system.  Sometimes it is necessary to reboot a remote system.

Pete Erskine
917-750-1134
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 01, 2013, 11:11:11 am
Is it common to use signal cable multicores (eg 5 way BNC) to distribute multiple panel signals over longer distances without having to pull lots of individual coax cables?

Multi core is useful in local situations.  For longer distances I use the 4 or 8 port fiber multiplexer.  This works great for Panels however if it is used to connect to a C44 power supply for beltpacks and the node is rebooted, the C44 does not come back on line and must be manually rebooted.
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 01, 2013, 03:25:35 pm
I neglected to mention the other half of the Artist monitoring functions, The Clone Output Port.  I have added it to the web page mentioned above.

http://www.bestaudio.com/_private/downloads/monitoring_a_panel.pdf (http://www.bestaudio.com/_private/downloads/monitoring_a_panel.pdf)
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 01, 2013, 03:59:34 pm
I neglected to mention the other half of the Artist monitoring functions, The Clone Output Port,

Would you typically just assign the Clone Output Port function to a key on your panel as and when needed during a production, for example when working with a user on their panel settings or for troubleshooting?

For longer distances I use the 4 or 8 port fiber multiplexer.  This works great for Panels however if it is used to connect to a C44 power supply for beltpacks and the node is rebooted, the C44 does not come back on line and must be manually rebooted.

I presume you have to put a CIA cat5 / coax adaptor between each port of the PMX and the C44. I wonder why there is not a CAT5 version of the 4 and 8 way fibre multiplexers.

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 01, 2013, 05:14:37 pm
I'm increasingly fond of running remote clusters of panels over IP. It massively simplifies the cabling, and provided you know networking and use good quality switching, is incredibly reliable. With the current Clearcom systems, the panels have IP built right in! So you add the IP card to the matrix, and you can go ahead and choose whether to connect the panel via 4wire or IP.

I like the idea of using IP for matrix panel connectivity. I am sure as IP equipped panels become more popular and the comms department is installing an IP network at every user position for comms that the number of other services that could be shared on the same network will increase. Audio, Video, Timecode and the Internet are a few that come to mind.

I guess you are using good quality Layer 2 Gigabit Managed Switches from a respectable manufacturer?

I think it is interesting to see the direction that Riedel have taken with their Mediornet product. The idea of consolidating a number of traditionally discrete systems and combining them across all departments on one fiber backbone certainly provides new opportunities for signal distribution and a reduction in cabling infrastructure. They seem to have had success with it on very large events such as the Eurovision Song Contest. I wonder how well the concept would work on smaller shows where there are individual providers for sound, video, broadcast etc with perhaps less planning and co-ordination between departments than is typical on the larger shows.

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 01, 2013, 08:40:27 pm
Would you typically just assign the Clone Output Port function to a key on your panel as and when needed during a production, for example when working with a user on their panel settings or for troubleshooting?

Yes the key would initiate the clone of the other panel which would let you hear the same crosspoints.
Monitor function would still be needed to hear the mic.

Quote
I presume you have to put a CIA cat5 / coax adapter between each port of the PMX and the C44. I wonder why there is not a CAT5 version of the 4 and 8 way fiber multiplexers.

The PMX was designed for panels and works correctly.  Adapting a C44 for it is a kluge and sort of off design.
Title: Re: Matrix Comms (Part 2)-Mediornet
Post by: Pete Erskine on February 01, 2013, 08:46:48 pm
I wonder how well the concept (Mediornet) would work on smaller shows where there are individual providers for sound, video, broadcast etc with perhaps less planning and co-ordination between departments than is typical on the larger shows.

It is a hard sell since each dept--audio, video, comms--usually brings their own interconnect.  The power is in integration, particularly on large video events.  With the built in scaling, format conversion and frame syncs, you can't beat it with any other product as well as having integrated RockNet and Artist.  On events which need massive distribution it is a no brainer and an easy sell since someone must do the additional distribution anyway.
Title: Re: Matrix Comms (Part 2)-Mediornet
Post by: Neil White on February 02, 2013, 08:07:33 am
It is a hard sell since each dept--audio, video, comms--usually brings their own interconnect.  The power is in integration, particularly on large video events.  With the built in scaling, format conversion and frame syncs, you can't beat it with any other product as well as having integrated RockNet and Artist.  On events which need massive distribution it is a no brainer and an easy sell since someone must do the additional distribution anyway.

It seems that this workflow has been well accepted in the broadcast industry, with companies such as Bexel and CP Communications supplying fiber infrastructure for outside broadcasts that is then shared between all of the broadcasters attending an event, for all types of signal transmission.

I would think that a comms company would be ideally placed to become responsible for the overall signal distribution at a live event. They already have to communicate with all of the other production departments during the planning phase to assess comms requirements, and then during the show are deploying comms technology across all departments and areas of the production. As tours and events become larger and the time frames for installation become shorter, a unified infrastructure may become more attractive.

n.
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 03, 2013, 06:06:03 am
I totally agree.  My experience is that the failure of UPS's happens and care should be taken in using them.  For the NODE power, since they have dual power supplies and only need 1 to run, I always put one on the mains and the other on the UPS.  This also has the advantage of less load on the UPS.

This is a good suggestion.  Riedel has just recently started including IP capability in their panels and nodes.  With the abundance of high speed networks on shows now it makes good sense to use them.  I have not yet had an opportunity to use IP but am happy that the option is there.

What switchover PDU do you use and is it IP addressable?  I would like to find a remote control power system.  Sometimes it is necessary to reboot a remote system.

Pete Erskine
917-750-1134

Hi Pete,

Check out the Audionics range of PDUs. They have many versions which are IP addressable, including switchover variants.

I'd like to build a system which incorporated these, and a Moxa serial server for getting status info from the remote UPSes. That way you can have a completely remotely monitor-able system over IP.
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 03, 2013, 06:16:01 am
I like the idea of using IP for matrix panel connectivity. I am sure as IP equipped panels become more popular and the comms department is installing an IP network at every user position for comms that the number of other services that could be shared on the same network will increase. Audio, Video, Timecode and the Internet are a few that come to mind.

I guess you are using good quality Layer 2 Gigabit Managed Switches from a respectable manufacturer?

I think it is interesting to see the direction that Riedel have taken with their Mediornet product. The idea of consolidating a number of traditionally discrete systems and combining them across all departments on one fiber backbone certainly provides new opportunities for signal distribution and a reduction in cabling infrastructure. They seem to have had success with it on very large events such as the Eurovision Song Contest. I wonder how well the concept would work on smaller shows where there are individual providers for sound, video, broadcast etc with perhaps less planning and co-ordination between departments than is typical on the larger shows.

Neil

Hi Neil.

Yes to the good quality switches. Its a must. There are plenty of cost effective managed switch options these days from the likes of HP, Netgear and Cisco.

IP is a useful tool, and works for comms because the required bandwidth is low, and small amounts of latency between remote locations is not only unnoticeable, but doesn't effect the performance of the system at all.

However, I wouldn't touch it with a barge-pole for audio and video distribution. IP is designed to be fault tolerant at the expense of latency. And that latency is variable. This is terrible for time-critical serial data streams such as audio and video. There are plenty of technologies like ethersound and dante which do a good job of adapting IP for this purpose, but its still an adaptation.
The analogy I always use is Powerline Ethernet. There are several companies making excellent, reliable units for sending ethernet over power lines. I've used several in show situations with great success. However, its no subsitute for some cat5 if thats an option. Just because I can make power cables carry all my ethernet, doesn't mean I'm going to forever send all my ethernet over power cables. IP Audio and Video are cool. But only when traditional serial distribution (via fibre or such like) is not available.

I have used Mediornet Compact, and also Optocore and they are interesting technologies. Certainly the future. However, the issue is, as Pete mentioned, that often the infrastructure needs to be seperate for contractual/logistical reasons, but also that Mediornet is an incredibly expensive replacement for just running individual cabling unless you need its networking and routing capabilities. This means its a tough sell for smaller events.

That said, I'd love to have a Mediornet Compact system. I think they are brilliant!
Title: Re: Matrix Comms - Touring Events
Post by: Neil White on February 04, 2013, 07:56:54 am
I would be interested in discussing the deployment of matrix comms systems on touring shows and one off events. There are obviously a different set of challenges with limited load in time and differing venues compared to large scale events such as the Olympics.

I know we touched on the topic of equipment packaging in the other Matrix Comms thread but it is always interesting to hear how different people approach the task. Pete mentioned packaging the matrix panels in stackable racks with all of the I/O on the back panel. Is it common to have an individual case for each key panel? It seems like a lot of small boxes to keep track of at load out. I like the way PRG have packaged the beltpacks, headsets and desktop panels for their Riedel system.
http://www.prg.com/wp-content/uploads/2009/08/ds_pp_riedel_Artist-32-Workbox.pdf

It looks like it would be easy to keep things labelled and see which headsets / beltpacks have been set out. It would also help to keep track of things when it comes time to load out.

What does a typical day look like for a touring comms engineer? I'd imagine after a few shows the programming should settle down and the focus is on the load in and the load out with not too much to do in between?

N.
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 04, 2013, 10:48:16 am
Hi Neil,

Good questions. Most of my comms work is in the touring/one off environment, as opposed to things like the Olympics (although I did work on that) where you have more setup time and the gear is in situ for longer.

There are a few things which are essential for me. In fact, I am currently considering purchasing some of my own components, and if I do, I would rigorously implement the following:

1 - Panel packaging:

For me, desktop panels are often more useful than rack mount panels. This is because typically the people who use matrix panels on a music tour tend to be people not sitting in front of racks (Like LX operators, sound engineers, stage managers, etc...). However, the problem with desktop panels is they often have silly connectors on the back. I like to see:
- Locking power connectors
- only Ethercons for cat5 connections
- Audio I/O & GPI broken out to XLRs
So, making a bolt-on accessory is a good idea here.
Alternatively, rack panels, mounted in sleeves with patchpanels on the back also works nicely.

2 - Equipment storage:

For me, nothing beats a drawers rack. What I'd like to do is have a drawers rack built with replaceable CNC foam inserts so I can configure it for a number of options including
- Headsets
- Panels
- beltpacks
- etc...
Compartments can be labelled for a tour, as well as the packs/panels/headsets so its easy to keep track of them without a sign-in/out sheet.

I would package groups of equipment together. Quick load in and out is essential, and local crew should be fully utilised. So, if you have 5 panels at FOH, 5 at monitors, and a bunch of radio comms for backstage use, then I would send a small case to each location containing everything needed in that area. That way setup and packdown doesn't involved carrying things accross an arena, and once the case is packed and checked, it can be shut and left for the locals to put on the appropriate truck.

3 - Main Casing and Operator position

I like to have my stuff, the matrix, and any extras (radio bases, etc...) in one case. Even if it means it has to be massive. This way, interconnects are already made, and everything is infront of me when I'm at my position. Once power is connected, the matrix boots up and I can go around and connect panels and they liven up.
Load out is quick because I can pull power and multicores to other locations and lid up the case and off it goes. The key is to not have to go back to an area twice. Pack it, and leave it for the truck.

4 - Quick Testing:

I like to be able to test panels as I connect them, so I don't have to re-visit a position. So, I like to have a test tone generator permanently connected to the matrix and active. The return of this port is connected to a radio base or IEM transmitter so I can be at a panel and check the send and return quickly.
I also use a CTP dB-Box with a cat5 adapter so I can plug it into a matrix port and test a line without a panel being connected.
I also like to be able to VNC into the matrix software so I can make changes remotely via an iPad or similar

Thats just a few thoughts. Interested to hear others'

Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 05, 2013, 09:04:45 am
Thanks, Chris,

I echo all your methods.

Last week I worked on an event which used the PRG Riedel Artist system.  I must congratulate Mark Boettcher for assembling what, I believe, is the best Artist rental system I ave ever used.  Not only are all components in drawer work cases with fitted spaces but the assembly of auxiliary parts is very complete right down to adapters for every type headset and audio out/in.

Desktop panels are the nicest to use just because they are desktop, however making an adapter box for the audio I/O and GPIO cant be really done cleanly.  Rack mount panels, like the method used by Clair Broadcast (Wireless First) are more usable.  The tiltable 2RU boxes can be stacked and the back panel on the rear affords a full implementation of all the I/O GPIO and secondary headset ports.

UPS power for all panels is very important.  Doesn't make any sense not to when the node is backed up as well.  PRG packs a few throw down UPS in the work case and Claire also includes them with each rental.  However the cleanest way would be to build the UPS into the panel case.  Here is a very interesting mini ups with universal power supply made by a company in China.  Unfortunately they only sell direct (yes from China) and refuse to establish dealers in the USA.  Their loss.
Leeer-4M (http://www.leeer.com/4M/4M.htm)

Here are some pix from the job last week:
This is the front of the rack.  At the top are Aphex 120A audio Distribution amps.  The 4 Studio Technologies hybrids are just above the patchbay which interfaces the 4-wire ports, the DA, the Wohler panel and the I/O to the hybrids as well as xlr adapters on the back and the front of the rack.
(http://www.bestaudio.com/images/rack%20front.jpg)

On the back of the rack are connections for XLR adapters on the patch bay, audio in for the Wohler panel and 2 wire connections to the Studio Technologies 47 dual power hybrid.  The system also has an ethernet DHCP switch and Apple Access point for wireless control and programming of the system.
(http://www.bestaudio.com/images/back%20connectors.jpg)

Five 12 channel multi connectors, also on the patch bay, provide an easy way to distribute the audio and C3 beltpacks.  The 2 C44 power supplies are at the top of the rack rear.
(http://www.bestaudio.com/images/mults.jpg)


Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 05, 2013, 10:12:03 am
Hi Pete,

That system looks excellent! If (or when) I get my own system, I will build it pretty much like that!

The panel layout looks nice.

I agree with you about desktop panels. Its very straightforward to build little box for rackmount panels with sensible connectors on the back. However, I often find that for operator positions where they are using a console, rackmount panels are just too wide, and thats where desktop panels are better. If you had enough units though, it would be easy to have some custom metalwork made that featured the necessary adaptors.

Out of interest, how do you find the StudioTech hybrids? Do they sound good? Do they auto-null effectively? I have found that some hybrids are great, and some, are not. I like the look of the studiotech ones, and the metering looks very functional.

I'd love to build my own Riedel based system, but Riedel make sure its not really viable for other companies to rent their systems, so its probably a non-starter. In which case, I'd be more inclined to head toward clearcom, as they have a pretty complete line
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 05, 2013, 10:14:41 am
Hi Pete,

That does look like a well packaged system with lots of flexibility. Has the rack got C31 splitters built in to allow a single output from a C44 to be split and sent to different locations through the multis?

I guess PRG have invested in AES grade multi and XLR cables to put it all together. Are they using colour codes or similar to stop the AES cables getting mixed in with standard XLR?

How is the Artist frame configured? 24 Coax Panel Ports, 2 CAT5 cards for the C44s and 24 analogue 4w?

Rack mount panels, like the method used by Clair Broadcast (Wireless First) are more usable.  The tiltable 2RU boxes can be stacked and the back panel on the rear affords a full implementation of all the I/O GPIO and secondary headset ports.

What connector is the GPIO typically broken out to from the db9 connector on the panel?

Cheers,
Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 05, 2013, 10:31:05 am
Hi Pete,

That does look like a well packaged system with lots of flexibility. Has the rack got C31 splitters built in to allow a single output from a C44 to be split and sent to different locations through the multis?

I guess PRG have invested in AES grade multi and XLR cables to put it all together. Are they using colour codes or similar to stop the AES cables getting mixed in with standard XLR?

How is the Artist frame configured? 24 Coax Panel Ports, 2 CAT5 cards for the C44s and 24 analogue 4w?

What connector is the GPIO typically broken out to from the db9 connector on the panel?

Cheers,
Neil

The C31 splitters were in the parts case and not built in.  Building in 4 would have been good.  The C31 does not lend itself to rack mounting since the input is on one side and the 3 outputs on the other.

The Rack Panel GPIO was in the patchbay but no other connectors were associated with it.  Clair's panels bring the GPIO out on barrier strips which I think is the wrong way to go - XLR would be better.

They supplied AES multi and xlr all in purple as well as regular multi and xlr.  Here is the configuration I used on the rack.


Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 05, 2013, 10:40:46 am
I often find that for operator positions where they are using a console, rackmount panels are just too wide, and thats where desktop panels are better.
Clair bros racks have mounting plates on the bottom for Maffer magic arm attachment and are great for mounting on the side of a mixing desk or at the rear reaching over the desk.

Quote
Out of interest, how do you find the StudioTech hybrids? Do they sound good? Do they auto-null effectively? I have found that some hybrids are great, and some, are not. I like the look of the studiotech ones, and the metering looks very functional.
They are very nice and the computer managed null is really good.  These units have power on both pins 2 and 3 when in the internal beltpack power mode which makes the hybrid perfect for feeding a Source Assign Panel.

Quote
I'd love to build my own Riedel based system, but Riedel make sure its not really viable for other companies to rent their systems, so its probably a non-starter. In which case, I'd be more inclined to head toward clearcom, as they have a pretty complete line

It is always an issue when renting in Riedel's market.  As a manufacturer they have an interest in promoting their product and have the ability to rent at a low cost as a loss leader.  There are a lot of rental companies, however, in the USA which have Artist.  The ease of use, flexibility, AES audio, and fiber interconnect are the best of any system, RTS and ClearCom included.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 05, 2013, 11:06:46 am
Here is the configuration I used on the rack.

Hi Pete,

From the AIO port labelling, it looks like each of the Whirlwind 12pr is set up to be 6 inputs and 6 outputs from the matrix? Are the 4W ports that are labelled as RPTR for two way radio interfaces? I guess the BTRs were located in another rack and connected via 12 pair multi also?

Clair's panels bring the GPIO out on barrier strips which I think is the wrong way to go - XLR would be better.

Would you want to see all the GPI on one connector and all the GPO on another, or an indivdual XLRs for each I/O pair?

Has anyone built a Clearcom style flasher that could be integrated with a matrix panel via GPIO yet? It could be powered from a small DC adaptor, as there is already needs to be power available for the matrix panel. It would be easy enough to program a logic function to trigger the output on a panel that you want to call to.
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 05, 2013, 12:41:45 pm
From the AIO port labelling, it looks like each of the Whirlwind 12pr is set up to be 6 inputs and 6 outputs from the matrix? Are the 4W ports that are labelled as RPTR for two way radio interfaces? I guess the BTRs were located in another rack and connected via 12 pair multi also?

Would you want to see all the GPI on one connector and all the GPO on another, or an indivdual XLRs for each I/O pair?

That was a slight annoyance for me - 6 port on a multi and 8 on the frame.  I actually had to think to figure out what multi was in use...also, the way they wired it the first 6 were input and the second 6 were output.  Usually 4-wire ports are used together and it would have been nicer if the box was arranged male/female.

PRG also made a special RJ connector multi box with a series of switches to change the pin out for different uses...BTR, CCI, etc.  It would have been simpler, less expensive and more reliable just to have several RJ connectors for each 4-wire wired in the various pin outs in parallel.

We interfaced three repeaters and 8 RTS systems in this show.  I detailed how we did it in the posting Interfacing RTS 2-wire to a 4-wire system without using a Hybrid (http://forums.prosoundweb.com/index.php/topic,142040.0.html)

Best GPI interface would be male and female 3 pin xlr with the GPIO connected to pins 2-3.

Quote
Has anyone built a ClearCom style flasher that could be integrated with a matrix panel via GPIO yet? It could be powered from a small DC adapter, as there is already needs to be power available for the matrix panel. It would be easy enough to program a logic function to trigger the output on a panel that you want to call to.

Riedel already makes one built into the AES C31 box.  It is triggered by GPO signals through the Performer AES cable.  It is not stand alone for plugging into a panel.  That you can make with any flasher and a power supply.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 05, 2013, 12:45:02 pm
That was a slight annoyance for me - 6 port on a multi and 8 on the frame.  I actually had to think to figure out what multi was in use...also, the way they wired it the first 6 were input and the second 6 were output.  Usually 4-wire ports are used together and it would have been nicer if the box was arranged male/female.

Were the patchbays normalled to always route certain 4 wire ports to multis / local outs or did you have to use patch cables? From the picture it looks like you only needed patch cables to make changes from a default configuration?

N.

Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 05, 2013, 12:50:49 pm
Were the patchbays normalled to always route certain 4 wire ports to multis / local outs or did you have to use patch cables? From the picture it looks like you only needed patch cables to make changes from a default configuration?

It was normaled for the mults A-D and model 47.  Here is the layout.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 05, 2013, 01:03:07 pm
It was normaled for the mults A-D and model 47.  Here is the layout.

I can see how the difference between 6 ch on the multi and 8 on the AIO cards could be difficult to keep track of. Would it have been easier if there was only 4 AIO ports normalled to each multi, and more of the ports freely patchable to local i/o or the remaining multi channels? I guess the other alternative is a higher channel count multipin, perhaps a 20 Channel Whirlwind W2 that could carry 8 x 4W plus 4 patchable lines.

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 05, 2013, 02:03:03 pm
I can see how the difference between 6 ch on the multi and 8 on the AIO cards could be difficult to keep track of. Would it have been easier if there was only 4 AIO ports normalled to each multi, and more of the ports freely patchable to local i/o or the remaining multi channels? I guess the other alternative is a higher channel count multipin, perhaps a 20 Channel Whirlwind W2 that could carry 8 x 4W plus 4 patchable lines.

12 pair is their standard.  You are right - a better way would be to only use 4 pair normaled and the remaining 2 pair un-normaled for other patching.  Then use all 5 mults for 4 wire interface.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 05, 2013, 02:33:43 pm
12 pair is their standard.  You are right - a better way would be to only use 4 pair normaled and the remaining 2 pair un-normaled for other patching.  Then use all 5 mults for 4 wire interface.

I guess it is a balancing act between system flexibility and ease of use. Making every I/O from the matrix, multipins and local panel freely patchable would allow the user to decide how every multpin was allocated. This could be useful, perhaps to dedicate a multipin to 4w interfaces for a rack of BTRs or another to C44 outputs. The comprimise would be the number of patchcords to make the system function.

What is the function of the LCL in and out sockets on the top row of the patchbay?

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 05, 2013, 02:42:25 pm
What is the function of the LCL in and out sockets on the top row of the patchbay?

Local xlr adapters on front and back of the rack.
Title: Re: Matrix Comms and Wireless
Post by: Neil White on February 05, 2013, 03:32:48 pm
We interfaced three repeaters and 8 RTS systems in this show.

I'd be interested in discussing wireless comms and their usage in more detail. I understand the technical differences between full duplex comms, like the telex BTR systems, and semi duplex & simplex systems that are typically based around two way radio equipment.

I know in a large system like the Olympics, there were a lot of radio channels, both semi duplex and simplex. I understand the choice of full duplex comms for users that need to be able to talk and listen at the same time, or for those people who's communication is critical for safety reasons (automation etc) What are some of the factors that are used to decide whether a radio channel should be semi duplex or simplex? In a large system is it typical for a department to have more than one radio channel? Are some channels such as ShowCall set to constantly transmit for the duration of the show?

How are the antenna systems typically deployed for both large shows with dozens of repeater interfaces and shows with just a couple of radio channels interfaced to the comm system?

Neil
Title: Re: Matrix Comms and Wireless
Post by: Pete Erskine on February 05, 2013, 04:09:11 pm
I know in a large system like the Olympics, there were a lot of radio channels, both semi duplex and simplex. I understand the choice of full duplex comms for users that need to be able to talk and listen at the same time, or for those people who's communication is critical for safety reasons (automation etc) What are some of the factors that are used to decide whether a radio channel should be semi duplex or simplex? In a large system is it typical for a department to have more than one radio channel? Are some channels such as ShowCall set to constantly transmit for the duration of the show?

How are the antenna systems typically deployed for both large shows with dozens of repeater interfaces and shows with just a couple of radio channels interfaced to the comm system?

Semi duplex repeaters can be connected to the comm system and when in constant TX all the users can hear the PL channel even when someone else is talking on the radio.  The only person who can't is the transmitting radio.

The radio system on the Olympics use special high power tuned combiners to create a single TX path for the antenna.  Usually there are separate TX and RX antenna systems and both antennas are often duplicated in several places such as on the top of the building, in the tunnels under the stands and in any other place which needs coverage.

Simplex radios are just another radio which the comm system can key the PTT and talk to the channel.  Since this function can be done by a single radio and the Main system antennas are broken up into RX and TX a method needs to be used to split this function of the simplex radio.  Either the RF output goes through a relay switching it into the TX antenna system upon PTT or you use separate radios for TX and RX and just mute the RX radio when transmitting.

In the Beijing Opening Ceremony we had over 50 radio channels interfaced to the system which filled 8 equipment racks.  In London it was less but still a lot.

Here are the system names for Beijing.
Title: Re: Matrix Comms and Wireless
Post by: Neil White on February 05, 2013, 04:47:15 pm
Semi duplex repeaters can be connected to the comm system and when in constant TX all the users can hear the PL channel even when someone else is talking on the radio.

Simplex radios are just another radio which the comm system can key the PTT and talk to the channel.

So genereally, a semi duplex radio channel is going to be necessary when you need to monitor or contribute to a PL that may have multiple paticipants on the wired side of the system. A simplex channel only allows one person on either side of the wireless or wired system to communicate at a time.

I would think this makes simplex a good choice for simple communications during the set up phase and for non show critical channels, but a semi duplex channel is a better choice for departments that require significant co-ordination during a show such as Stage Management.

Is it typical to use separate tx and rx antenna for each repater in a system with just a couple of radio channels or is it more common to use combiner and splitters to the RF to each repeater.

At the Olympics did you use standard Riedel RIFace interfaces with Motorola radios for channels that are in constant transmit or does it need to be a specific repeater capable of maintaining the 100% transmit duty cycle? Were the transmitters switched into constant tx mode by a GPIO interface? If so I guess the programming would be the same as discussed in the other thread but with a latching key on a panel to trigger the PTT.

N.
Title: Re: Matrix Comms and Wireless
Post by: Pete Erskine on February 05, 2013, 07:12:50 pm
So genereally, a semi duplex radio channel is going to be necessary when you need to monitor or contribute to a PL that may have multiple paticipants on the wired side of the system. A simplex channel only allows one person on either side of the wireless or wired system to communicate at a time.

I would think this makes simplex a good choice for simple communications during the set up phase and for non show critical channels, but a semi duplex channel is a better choice for departments that require significant co-ordination during a show such as Stage Management.
The main reason for semi duplex over Simplex is the better coverage area afforded by using a repeater.  Constant TX and comm interface only are features which enhance this repeater function.

Quote
Is it typical to use separate tx and rx antenna for each repater in a system with just a couple of radio channels or is it more common to use combiner and splitters to the RF to each repeater.
Combiners for TX and RX in a large radio system are quite different.  TX needs high power and isolation of the TX inputs.  RX just needs low power rf distribution. 

On a very small show each repeater might have a tuned duplexer to make a single antenna for X and RX on a simplex radio.  This has the disadvantage that the radio frequency can't easily be changes since the duplexer must be re-tuned as well.  For a repeater with separate RX and TX systems you can also use a duplexer with the same limitations.  On the event I did in January, I asked for 5 repeater pairs to be programmed into the system knowing that I only was going to use 3.  Good move since when we got to the site channel 1 of the repeater had some other constant TX system on the channel and we couldn't use it.  Not using duplexers and instead separate RX TX antennas made it ok to change channels.

Quote
At the Olympics did you use standard Riedel Riface interfaces with Motorola radios for channels that are in constant transmit or does it need to be a specific repeater capable of maintaining the 100% transmit duty cycle? Were the transmitters switched into constant tx mode by a GPIO interface? If so I guess the programming would be the same as discussed in the other thread but with a latching key on a panel to trigger the PTT.

In Beijing it was Riedel Riface radios but in London the spec called for an Australian radio to be used.  Both were able to const TX with no problem.  On the Artist a gpo command was part of the vox 4-wire input command so anytime the port was receiving audio the PTT was activated. 
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 06, 2013, 07:07:33 am
Desktop panels are the nicest to use just because they are desktop, however making an adapter box for the audio I/O and GPIO cant be really done cleanly.  Rack mount panels, like the method used by Clair Broadcast (Wireless First) are more usable.  The tiltable 2RU boxes can be stacked and the back panel on the rear affords a full implementation of all the I/O GPIO and secondary headset ports.

I have used Whirlwind's free DesignPro software to put a panel design together for a Riedel RCP. Is there anything else that should be included?

Neil
Title: Re: Matrix Comms and Wireless
Post by: Neil White on February 06, 2013, 07:17:44 am
In Beijing it was Riedel Riface radios but in London the spec called for an Australian radio to be used.  Both were able to const TX with no problem. 

Were these the RF Technology base stations as used extensively by the PA People?

(http://www.papeople.com.au/images/stories/Event_Comms/Technology/radio_comms/img_0214.png)

It sounds like there was no alternative option in the spec, otherwise I would imagine Riedel would have used their Riface radios. Were there any technical advantages to the RFT radios?

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 06, 2013, 08:22:14 am
Bear in mind that a RiFace is just a housing for a pair of Motorola GM radios. Lots of companies i know make their own such housings, with the necessary PSUs, audio interfacing, etc...

Any radio base that will accept line level in and out will work fine. I mainly use the Tait TB7100s. They are nice because they have internal duplexers, and are 1u. They will do constant duty at 40w TX.

The manfrotto magic arm implementation is a great idea. One for the future for sure.

Sometimes I find that having a comms system which isn't based around AES is more flexible for the specific events that I'm doing. Partly because it allows distribution of panels down existing audio infrastructure. I carry breakouts for CC or RTS matrixes that split a port into 3 XLRs (Send, Return, Data). Additionally, traditional analog interfacing allows me huuuuge cable runs on cat5 very easily.

I did the Torch Arrival segment of the opening ceremony, which required comms panels to be distributed along the canal/river that runs through the olympic park. The matrix was under the main footbridge (that ran between Aquatics and Water Polo). I was happily running panels over 600m off cheap, installation grade cat5 that we treated as a consumable and disposed off at the end of the event.

So, AES is cool, but In my world, where I'm working with live music mainly, audio is still all analogue, so sometimes having a matrix that works that way makes for easier interfacing.

One of the reasons I'm interested in something like a Clearcom Eclipse Median is the sheer number of options for interfacing. You can connect a V series panel via traditional 4w+D, IP or via their 'DIG2' system which basically uses a single twisted pair for a panel. Meaning you can run a matrix panel over a single mic cable.
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 06, 2013, 08:57:34 am
I have used Whirlwind's free DesignPro software to put a panel design together for a Riedel RCP. Is there anything else that should be included?

Neil

I would include the Ext mic in, A duplicate of HS A on the rear and a 5 pin headset wired as a stereo HS using the mic and ear from A and the other ear from B.  Also a female Power connector in parallel with the input for aux equipment.  The audio out and in connectors should be transformer isolated.
Title: Re: Matrix Comms and Wireless
Post by: Pete Erskine on February 06, 2013, 08:58:29 am
Were these the RF Technology base stations as used extensively by the PA People?

Could have been them.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 06, 2013, 09:20:13 am

a 5 pin headset wired as a stereo HS using the mic and ear from A and the other ear from B

That's a great idea. Put the panel into dual channel mode, set up the audio patch on the panel to route matrix 1 to Headset A and matrix 2 to Headset B. The Mic from headset A would need to feed both Matrix 1 and 2 sends, and then selecting "Use 2nd Audio channel on this port" when setting up keys would define what gets routed to each ear of the stereo headset.

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 06, 2013, 02:36:17 pm
Sometimes I find that having a comms system which isn't based around AES is more flexible for the specific events that I'm doing. Partly because it allows distribution of panels down existing audio infrastructure. I carry breakouts for CC or RTS matrixes that split a port into 3 XLRs (Send, Return, Data). Additionally, traditional analog interfacing allows me huuuuge cable runs on cat5 very easily.
Yes, this is an advantage.  I often work on TV events and can easily remote an Adam panel from the truck frame using that method over a DT12 mult.  The only advantages for Artist AES is noise immunity and 2 channels over 1 connection.  Sometimes the distance is an issue and that is why they make fiber extensions for the panels (PMX).

Quote
One of the reasons I'm interested in something like a Clearcom Eclipse Median is the sheer number of options for interfacing. You can connect a V series panel via traditional 4w+D, IP or via their 'DIG2' system which basically uses a single twisted pair for a panel. Meaning you can run a matrix panel over a single mic cable.

That was my favorite feature of the ClearCom Matrix Plus systems, the ability to connect a panel over a single mic line.  I was the third buyer of the original system and used it at the Barcelona Olympics Opening and ran panels all over the stadium that way.  Bandwidth was slightly limited but being digital and totally clean made up for it.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 06, 2013, 05:00:17 pm
Hi Pete,

The PRG artist system had the control panel for the comms tech mounted in the rack with the matrix. Do you think the system would be more flexible if this panel was separate from the rack? It would allow the user to position the rack wherever made most sense for installing cables and then set up a control area with master panel, laptop etc. It would also make sense if there were multiple identical racks that could be combined for larger systems, when a master panel with expansion keys in each rack would be unnecessary.

N
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 06, 2013, 05:28:51 pm
The PRG artist system had the control panel for the comms tech mounted in the rack with the matrix. Do you think the system would be more flexible if this panel was separate from the rack? It would allow the user to position the rack wherever made most sense for installing cables and then set up a control area with master panel, laptop etc. It would also make sense if there were multiple identical racks that could be combined for larger systems, when a master panel with expansion keys in each rack would be unnecessary.

Usually I like it separate.  On the Olympics I go for the max expansion panels.  A panel is always needed in the main rack and this one was just the right height for sitting.  Placed a table there and I was set and could change the patchbay easily.  I suppose it could be cleverly designed in a separate slide in rack case which could work in and out of the case.
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 07, 2013, 03:08:34 am
So, On the subject of wireless comms:

Talk to me about Tempest. I've used it once, and had an extensive demo when it came out. But I have a few queries.

Typically, I'm using BTR700 or Pro850 units for wireless comms. But as you add more and more users, frequency coordination can become a headache, particularly if the production is also frequency heavy.

I did a job last week with 26 BTR700 & 800 users, spread accross 5 bases (I set some up for shared return) in London's west end, so much radio congestion from the myriad of theatres all around.

A product like tempest would have been perfect. But I have heard very mixed reviews. Technically, from what i've seen, it seems sound, and the new seamless roaming functionality looks excellent. But what is the real-world audio quality like? One of the reasons a lot of my clients love BTR700 is the large audio bandwidth. It really is a huge step up in quality from a duplex PMR setup. How is Tempest in this regard?

On the tempest front, how about HME DX210. Are you a fan?
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 07, 2013, 08:18:30 am
But what is the real-world audio quality like? One of the reasons a lot of my clients love BTR700 is the large audio bandwidth. It really is a huge step up in quality from a duplex PMR setup. How is Tempest in this regard?

Both Tempest and the DX series suffer from low quality low bandwidth audio.  That is most users complaint.  Audio over digital also gets quickly distorted as you reach the fringe of the coverage area where analog systems get noisey but are still clear communication.

Given a limited area like a theatre or just the stage area both are acceptable despite the audio quality.  Tempest seamless roaming is a big step up in extending the coverage area.  a beltpack can be put into diagnostic mode where it displays the QOS for the to and from signals.  when it reaches 95% digital breaks up and sounds worse.  This way the coverage contours can be established and placement of the next base antennas can be optimized.

on a big show, not crowding the UHF bands is the main selling point for these technologies.  Years ago, my partner Larry Estrin substituted three DX200 systems for BTR800 and hme850 on the Madonna world tour.  Using Dave Clarke headsets made the difference as well. Look at the write up on the Madonna Tour comms HERE. (http://www.bestaudio.com/Intercom_Madonna.htm)

I used five tempest 2400 system on the Presidential debates with much success.  Two bases covered the theatre and a base each was allocated to the TV truck/moderator dressing area, and the 2 candidate dressing rooms.  Our one failure was in a theatre with two firewalls between the theatre and the dressing rooms.  We really needed another base for the space in between where stage manager waited for the candidates.  As it was they lost contact with the show at critical points.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 07, 2013, 08:21:24 am
Both Tempest and the DX series suffer from low quality low bandwidth audio.

How does the Riedel Acrobat compare in environments where the 1.9gHz band is available for use?

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Pete Erskine on February 07, 2013, 08:28:48 am
How does the Riedel Acrobat compare in environments where the 1.9gHz band is available for use?

Acrobat works well.  Slightly better audio quality than Tempest/DX but way worse RF since it uses mostly off the shelf transceivers meant for phone systems.  Setup and adjustment of the transceivers takes a while and not really intended for one off rental use.  In the Beijing Olympics we had coverage in the 4 main VOMS and about 100' out into the stadium.  Barely enough to cross the short end zone but not enough for the length of the field.  At that time we only used 6 antenna locations and the system hadn't been used with more so we were reluctant to expand it during the Olympics.  Since then improvements have been made and I am eager to try it again. 
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 07, 2013, 08:37:25 am
Acrobat works well.  Slightly better audio quality than Tempest/DX but way worse RF since it uses mostly off the shelf transceivers meant for phone systems.

The ability to individually address each beltpack when using a base station interfaced to an Artist system via MADI looks quite powerful. Using Power Over Ethernet to connect the antennas to the base stations should also make it easier to remote antennas wherever needed for coverage compared to having to run RF cables.
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 07, 2013, 09:16:25 am
Hmmm...

Confirms my suspicions.

In an ideal world, I'd want to only own DX200 and Tempest, because the systems are scalable, technically excellent, and dont rely on the UHF spectrum (which also saves licensing costs here in the UK). But audio quality is an issue. Good headsets are an improvement, and I normally have a soundweb in between things like Radio bases and the matrix to provide some software metering and EQ/compression/gating to improve audio quality. This may be a workable solution.

I'm happy to use BTR, but I'd never want to own it. Its just too clunky and inflexible.

I wouldn't touch DECT (1.9Ghz) with a barge pole. Although having remote key panels is cool, being only 2 keys means you could probably achieve the same results with 4 ch tempest systems
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 08, 2013, 05:47:08 am
How do the newer digital two way radio technologies such as Motorola MotoTrbo or Kenwood Nexedge compare to traditional analog two way radio systems for production communications? Are there any significant factors that need to be considered when designing systems that use these type of products?

N.
Title: Re: Matrix Comms (Part 2) - radios
Post by: Pete Erskine on February 08, 2013, 02:18:02 pm
How do the newer digital two way radio technologies such as Motorola MotoTrbo or Kenwood Nexedge compare to traditional analog two way radio systems for production communications? Are there any significant factors that need to be considered when designing systems that use these type of products?

Don't know.  Maybe Henry Cohen will chime in.
Title: Re: Matrix Comms (Part 2)
Post by: Henry Cohen on February 08, 2013, 04:43:03 pm
Quote from: Neil White on Today at 05:47:08 am

    How do the newer digital two way radio technologies such as Motorola MotoTrbo or Kenwood Nexedge compare to traditional analog two way radio systems for production communications? Are there any significant factors that need to be considered when designing systems that use these type of products?


Don't know.  Maybe Henry Cohen will chime in.

I've been summoned . . .

There's two aspects I've found when looking at using DMR (digital [land] mobile radio) in production environments; first as a stand alone communications platform and second, if being interfaced to a hardwired PL system.

As a stand alone platform the biggest considerations are:
- Audio quality; slightly less pleasant than analog but generally fine. In high SPL environments however, TDMA codecs tend to get overwhelmed and intelligibility can suffer greatly.

- TDMA (Motorola Trbo and Vertex) vs. FDMA (kenwood & Icom); we all know what happens when a TDMA GSM phone is transmitting on the control channel when too close to RFI susceptible audio devices. FDMA also has the advantage of being true 6.25kHz voice channels in simplex mode without the need for the repeater, versus analog's and TDMA simplex's 12.5k.

- DMR bases and repeaters have some built-in or easily added option card capabilities for IP back bone connectivity to multiple sites, remote control & monitoring and voting. But this comes at higher base price for the DMR repeaters over analog.

- Analog maintains a price advantage for a similarly durable portable radio.

- DMR in digital mode can offer better battery life per charge.

- Higher tier analog radios can be found in compact models whereas all the current DMR offerings remain at the traditional size and weight.

- At the service fringe, analog will be noisier but can remain intelligible. Digital may remain completely clear a bit further, but will suddenly cut out completely or be unintelligible; it's not a graceful degradation.

- DMR offers immunity from casual evesdropping and many of the radio models offer some level of encryption.


   When interfacing DMR repeaters or bases to a PL system, things can get interesting.

- Some DMR repeaters, when in digital mode, have no A/D - D/A for getting analog 4-wire audio in and out; you must purchase a separate dispatch console interface.

- There's inherent latencies in the A/D and D/A which could cause echoing or other anomalies with the interfacing.

- DMR radios in constant transmit seem to need greater cooling capacity and/or can't be set to the same power levels as analog. Not a major issue unless building multi-channel systems with transmitter combiner(s). 


    I've come to the conclusion that unless there is a feature or features specifically offered by digital radios that one would regularly use, it's not worth changing over one's inventory. That said, the fact that FDMA radios can be true 6.25kHz/voice channel in simplex, the spectral efficiency aspect is not insignificant these days.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 09, 2013, 10:48:04 am
Hi Henry,

Thank you for the comprehensive response.

- Higher tier analog radios can be found in compact models whereas all the current DMR offerings remain at the traditional size and weight.

It looks like Motorola have started to address this with some of the newer MotoTrbo products such as the DP2000 and SL4000 ranges.

I've come to the conclusion that unless there is a feature or features specifically offered by digital radios that one would regularly use, it's not worth changing over one's inventory.

I wonder if the digital radios would make sense as a new investment in radios, since many of then can be used with the older analog systems and then transfered to digital mode if the need arises in the future, perhaps in response to changing spectrum legislation.

Are trunked radio systems something that is best avoided in a production comms environment? I would think it would definitely be a disadvantage for channels that are in constant transmit or heavily used during a show.

Neil
Title: Re: Matrix Comms (Part 2) - radios
Post by: Pete Erskine on February 09, 2013, 11:06:34 am
Are trunked radio systems something that is best avoided in a production comms environment? I would think it would definitely be a disadvantage for channels that are in constant transmit or heavily used during a show.

Trunked radios cannot be in constant TX.  More over they are totally unsuited for the production purpose except maybe as a transportation or runner communication.  Because of the uncertainty of getting a channel in the time sensitive live show environment Trunked radios will not work.

We would probably not like any digital radios for production because of the slight latency and busy channel beeps.  This is not really a problem but production people would complain.  They are use to analog and even the times when two people step on each other is recognized as the users mistake and not the equipment which would be the case in the other TX methods.

For these reasons Analog is the preferred communication in a production like the ones we do for the Olympics and similar events.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 09, 2013, 11:54:09 am
Reading this article http://sportsvideo.org/main/blog/2013/02/08/during-power-loss-super-bowls-wireless-sound-stays-on/ regarding the wireless and comms at Superbowl 2013, it seems like it wasn't standard operating practise to have all the comms equipment on UPS'

Quote
It was more complex for BSI’s larger areas of responsibility. “The power outage was a challenge for everyone,” says Underwood. “The impact to BSI was not immediately apparent as our RF cameras and microphones continued to operate as the transmitting devices are all battery-powered and the receive sites employ a battery backup system. Because all of the TV compound, including BSI’s mobile unit, was on generators, there was no sign except for the darkened images from a less fully illuminated field of play.

“However,” he continues, “our inside-the-stadium communication systems were on house power, and [they] failed on the loss of power. This meant that, although the cameras and microphones were still working, the communications to the operators and our crew was disabled.

“Thankfully, the outside-the-stadium equipment seemed to be on an unaffected power source and were just strong enough to reach the operators and crew with the director PL. The harder part was getting in touch with personnel to switch their radios to the outside channel. Through the use of cellphones and word of mouth, we were able to get everyone switched over. We were able to communicate with production that the MIC1500 talent microphones were still operational but they would not have any IFB facilities until the power was re-established.
Title: Re: Matrix Comms (Part 2)
Post by: Chris Johnson [UK] on February 09, 2013, 12:43:50 pm
That indeed seems to be the case Neil, and seemingly a bit of an oversight?

Although adding UPSes is an additional cost, it would seem to be small compared to the investment already there, and compared to the issues that arise from losing system components.

Title: Re: Matrix Comms (Part 2)
Post by: Henry Cohen on February 09, 2013, 06:03:57 pm
It looks like Motorola have started to address this with some of the newer MotoTrbo products such as the DP2000 and SL4000 ranges.

Yes, I forgot Motorola recently introduced compact models.

Quote
I wonder if the digital radios would make sense as a new investment in radios, since many of then can be used with the older analog systems and then transfered to digital mode if the need arises in the future, perhaps in response to changing spectrum legislation.

Like any other equipment purchase, the answer depends on your specific economic factors.

Quote
Are trunked radio systems something that is best avoided in a production comms environment? I would think it would definitely be a disadvantage for channels that are in constant transmit or heavily used during a show.

See Pete's response.
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 09, 2013, 06:26:28 pm
Hi Henry,

Can you reccomend any good resources for learning more about the components and techniques used in putting together multi channel two way radio systems and antenna systems?

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Henry Cohen on February 09, 2013, 08:04:57 pm
Can you reccomend any good resources for learning more about the components and techniques used in putting together multi channel two way radio systems and antenna systems?

Start with these:

http://www.txrx.com/Resources/~/media/Bird/Files/PDF/Resources/white-papers/HowtoProperlyDesignanInBuildingDistributedAntennaSystemPt1.ashx

http://www.txrx.com/Resources/~/media/Bird/Files/PDF/Resources/white-papers/HowtoProperlyDesignanInBuildingDistributedAntennaSystemPt2.ashx

http://www.txrx.com/Resources/~/media/Bird/Files/PDF/Resources/app-notes/Applications-for-Directional-Hybrid-Couplers.ashx

http://www.txrx.com/Resources/~/media/Bird/Files/PDF/Resources/app-notes/Combiner-and-Receiver-Multicoupler-Design.ashx

http://www.txrx.com/Resources/~/media/Bird/Files/PDF/Resources/app-notes/Directional-and-Non-Directional-Couplers.ashx

http://www.txrx.com/Resources/~/media/Bird/Files/PDF/Resources/app-notes/Insertion-Loss-in-Bandpass-Cavities.ashx

http://www.txrx.com/Resources/~/media/Bird/Files/PDF/Resources/app-notes/Passive-Intermodulation.ashx

http://www.emrcorp.com/documents/Technical%20Information/ferrite_combiners(27-35).pdf

http://www.emrcorp.com/documents/Technical%20Information/reciever_preselector(45-53).pdf

http://www.emrcorp.com/documents/Technical%20Information/Multicoupler_Manual.pdf

http://www.emrcorp.com/documents/Technical%20Information/hybrid-filter_combiners(36-44).pdf

http://www.emrcorp.com/documents/Technical%20Information/rf_isolators(1-14).pdf

http://www.emrcorp.com/documents/Technical%20Information/cavity_resonators(54-67).pdf

To properly configure and align both TX combine and receive multi-coupler systems requires either two real spectrum analyzers that have external input and output triggering or at least a two port VNA in order to look at both VSWR and bandpass/reject simultaneously.

Oh, and check each and every jumper on the SA as you install it  :-[
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 10, 2013, 02:59:29 pm
Start with these:

Hi Henry,

Thanks for the detailed links. I will have a read through and I'm sure I will have some further questions.

Neil
Title: Re: Matrix Comms (Part 2)
Post by: Neil White on February 14, 2013, 04:48:52 am
I have put together a block diagram for a combiner system for 4 channels of semi duplex radio. Am I heading in the right direction?

N.
Title: Re: Matrix Comms (Part 2)
Post by: Henry Cohen on February 15, 2013, 03:21:18 pm
I have put together a block diagram for a combiner system for 4 channels of semi duplex radio. Am I heading in the right direction?

Sort of. The RX side is good. On the TX side, the hybrid coupler is wrong. Hybrid couplers are 2 x 2 (4 port) device; two inputs, two outputs. (There are actually other mult-iport designs, but not relevant here.)

You need a total of three hybrid couplers: The first HC's input ports are connected to TX1 & TX2. The second HC's input ports are connected to TX3 & TX4. One output from each HC is terminated with a load => the total RF power of two transmitters. Each of the other output ports of each HC connects to one of the two inputs of the third hybrid. On the third hybrid's output ports, one port connects to the antenna feed line. The other port has a load capable of => the total RF power of the combined transmitters. (see page 40 of http://www.emrcorp.com/documents/Technical%20Information/hybrid-filter_combiners%2836-44%29.pdf)

The other considerations are:

- RF gain structure on the TX side to make sure the passive losses and any antenna gain ultimately provides sufficient ERP.

- Determining the correct amount of TX to TX isolation, and using the correct isolator(s).

- If the RX frequencies or other adjacent channel users are too close,  or the RF noise floor is rather high, you may want to put a very narrowband, high Q bandpass cavity filters between the splitter outputs and the receiver inputs.
Title: Re: Wireless Comms
Post by: Neil White on February 15, 2013, 04:58:45 pm
You need a total of three hybrid couplers

I have updated the drawing below and included the average losses for each element as noted in the EMR technical note, for a total of approximately 7dB loss per channel for a 4 channel combiner. So for example a Motorola GM360 mobile radio used as a repeater base station TX at 25W would have a power output of around 5W after the combiner system?

\
The other considerations are:
- RF gain structure on the TX side to make sure the passive losses and any antenna gain ultimately provides sufficient ERP

I would assume it is better to use a higher gain antenna than to introduce any amplifiers to the TX side. If amplification is needed should it be located between each transmitter and the combiner system to avoid amplifying any intermodulation products that have occured in the combiner system, and so as not to create intermodulation within the amplifier itself?

Neil

Title: Re: Wireless Comms
Post by: Henry Cohen on February 16, 2013, 02:23:52 am
I have updated the drawing below and included the average losses for each element as noted in the EMR technical note, for a total of approximately 7dB loss per channel for a 4 channel combiner. So for example a Motorola GM360 mobile radio used as a repeater base station TX at 25W would have a power output of around 5W after the combiner system?

Figure closer to 8dB real world loss per channel: Add insertion loss for connectors and coax jumpers. Final ERP will be closer to 4W.


Quote
I would assume it is better to use a higher gain antenna than to introduce any amplifiers to the TX side. If amplification is needed should it be located between each transmitter and the combiner system to avoid amplifying any intermodulation products that have occured in the combiner system, and so as not to create intermodulation within the amplifier itself?

Passive gain is always preferred, provided the gain antenna provides the desired elevation and azimuth beamwidths. An amplifier would go between the transmitter and the isolator. Loads on the isolators will have to be increased accordingly.