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Coordinating Zaxcom wireless with Lectrosonics. Do you need to?


Trey LaCroix
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I'm fairly new to Zax wireless and a long time user of Lectros. I have a coordinated list for 14 Lectro channels (praying to god we won't need to use that many) and was to add 2 Zaxcom channels in for booms. I have regularly heard that there is "no intermodulation" with Zaxcom Digital Wireless. Does this mean that the transmitters won't emit any harmonics/overtones that could cause intermodulation? Or are they immune to intermod from other transmitters (meaning that I would still have to coordinate them to not screw with the lectros)?

 

I hope I'm asking this question in a way that makes sense.

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If you were using an entirely digital system, then intermodulation would not be a problem - although there are still minimum spacing requirements between each frequency.

 

If you go by the book, then with a mixed system of analogue and digital mics, you should prepare a full co-ordination, as if they were all analogue.

 

If your Zaxcoms can tune to the Lectro co-ordination, then use the frequencies you have prepared. If they don't, then don't stress, just tune the analogue and digital units as far apart from each other as you can, and you should be fine.

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I would recommend getting the FreqFinder App from NewEndian. It’ll coordinate for you as you enter frequencies and tells you if you are getting intermod or not. You can also add the character name and this really helps to keep track of all frequencies around the set. I tend to include walkie-talkie frequencies, too. 

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On 8/4/2020 at 7:16 PM, Trey LaCroix said:

I'm fairly new to Zax wireless and a long time user of Lectros. I have a coordinated list for 14 Lectro channels (praying to god we won't need to use that many) and was to add 2 Zaxcom channels in for booms. I have regularly heard that there is "no intermodulation" with Zaxcom Digital Wireless. Does this mean that the transmitters won't emit any harmonics/overtones that could cause intermodulation? Or are they immune to intermod from other transmitters (meaning that I would still have to coordinate them to not screw with the lectros)?

 

I hope I'm asking this question in a way that makes sense.

 

I'm using a computer, RF Explorer and Wireless Work Bench (And Touchstone pro for export the scans)

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6 hours ago, Trey LaCroix said:

Thanks for clearing that up guys. I will use Freq finder for this.

Freq Finder is definitely the way to go.

 

One thing to keep in mind though, is that F.F builds a co-ordination on each successive frequency as you enter them. It doesn't take everything in and then spit out a comprehensive solution (like workbench or WSM).

 

I would suggest that if the Zaxcoms tune lower than the Lectros, that you start there first and then add the lectros next.

 

I have had times, especially with mixed systems, when I had very few options for the later frequencies, which I sometimes couldn't use because of environmental conditions.

 

Re-starting the co-ord with different units first can make a difference if you don't like the results you get.

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21 hours ago, ramallo said:

 

I'm using a computer, RF Explorer and Wireless Work Bench (And Touchstone pro for export the scans)

Hi ramallo,

how can Wireless Work Bench see the spectrum of RF Explorer?

Wireless Microfone Analyzer is able to see RF Explorer on USBtoUART.

christian

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On 8/10/2020 at 5:59 PM, soundchris said:

Hi ramallo,

how can Wireless Work Bench see the spectrum of RF Explorer?

Wireless Microfone Analyzer is able to see RF Explorer on USBtoUART.

christian

You need the TouchstonePro for do a connection with the RF Explorer, and this program can export a CSV file for the WWB

 

This is a scan imported in the WWB

Captura de pantalla 2020-08-11 a las 23.21.56.png

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I think it helps to think about intermod like we do audio overload/clipping. When your audio signal is too hot, it sounds weird. The distorted sound is the extra frequency content that is generated.

Intermod products are extra frequencies generated by overload. The overload occurs in any active circuitry: transmitters, receivers, active antennas, etc. A transmitter's circuitry can be overloaded by another nearby transmitter, and those transmitters can then transmit the intermod generated by that overload.

Things that help intermod are the same things that help audio overload: less powerful signal and high dynamic range circuitry. In wireless, that means low power transmission and distance between devices. It also means passively filtering out frequency content that isn't the desired signal.

Can you simply attenuate the signal? Yes, but in audioland, if you have two actors, one very close to the microphone and one far away, turning down the gain will make it hard to hear the one that's far away.

So why can we coordinate channels for intermod? The extra frequency content is predictable. When your audio recorder gets overloaded, it sounds weird, but you can still understand the speech. That's because the original content is still there. The extra power just gets dumped into other frequencies. We avoid tuning to those frequencies. But the more extra power, the more extra frequencies are generated.

What does it mean when a manufacturer says "No Intermodulation"? It usually means within their system, their transmitters run at a low enough power and their receivers have quality filtering and/or dynamic range that none of the devices can overload each other in normal operating circumstances.

But every device that has an Op-Amp has a dynamic range. I personally have had a lot of trouble with walkies (1-5 watts) and the Sony 470 mhz digital system and would generally recommend systems that do not include that frequency range in their tunable range.

Generally speaking, wideband devices have been detrimental to wireless performance. Fitting a large bandwidth into the same physical case means wider front end filters. Filtering out non-signal frequency content is one of the biggest weapons we have. The old Audio Ltd systems had 16 channels, each with a dedicated filter. Lectro 411s had an array of very narrow filters (tracking receivers).

 

To answer your question:

Zaxcom transmitters have a relatively low output power (25/50/75 mW). They shouldn't cause much trouble for the Lectrosonics transmitters or receivers.

Zaxcom recently released their 214/414 receivers with increased RF dynamic range. I haven't used them, but RF dynamic range is one of the keys to performance. They are wideband though, which means wide filtering. And you might be running the Lectrosonics system at 100 mW. Usually the physical distance between devices is enough to make that power output fine. But that is when you want to coordinate channels.

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On 8/11/2020 at 7:30 PM, NewEndian said:

I think it helps to think about intermod like we do audio overload/clipping. When your audio signal is too hot, it sounds weird. The distorted sound is the extra frequency content that is generated.

Intermod products are extra frequencies generated by overload. The overload occurs in any active circuitry: transmitters, receivers, active antennas, etc. A transmitter's circuitry can be overloaded by another nearby transmitter, and those transmitters can then transmit the intermod generated by that overload.

Things that help intermod are the same things that help audio overload: less powerful signal and high dynamic range circuitry. In wireless, that means low power transmission and distance between devices. It also means passively filtering out frequency content that isn't the desired signal.

Can you simply attenuate the signal? Yes, but in audioland, if you have two actors, one very close to the microphone and one far away, turning down the gain will make it hard to hear the one that's far away.

So why can we coordinate channels for intermod? The extra frequency content is predictable. When your audio recorder gets overloaded, it sounds weird, but you can still understand the speech. That's because the original content is still there. The extra power just gets dumped into other frequencies. We avoid tuning to those frequencies. But the more extra power, the more extra frequencies are generated.

What does it mean when a manufacturer says "No Intermodulation"? It usually means within their system, their transmitters run at a low enough power and their receivers have quality filtering and/or dynamic range that none of the devices can overload each other in normal operating circumstances.

But every device that has an Op-Amp has a dynamic range. I personally have had a lot of trouble with walkies (1-5 watts) and the Sony 470 mhz digital system and would generally recommend systems that do not include that frequency range in their tunable range.

Generally speaking, wideband devices have been detrimental to wireless performance. Fitting a large bandwidth into the same physical case means wider front end filters. Filtering out non-signal frequency content is one of the biggest weapons we have. The old Audio Ltd systems had 16 channels, each with a dedicated filter. Lectro 411s had an array of very narrow filters (tracking receivers).

 

To answer your question:

Zaxcom transmitters have a relatively low output power (25/50/75 mW). They shouldn't cause much trouble for the Lectrosonics transmitters or receivers.

Zaxcom recently released their 214/414 receivers with increased RF dynamic range. I haven't used them, but RF dynamic range is one of the keys to performance. They are wideband though, which means wide filtering. And you might be running the Lectrosonics system at 100 mW. Usually the physical distance between devices is enough to make that power output fine. But that is when you want to coordinate channels.

Thank you so much for the informative and extremely detailed response! My questions are answered. Great apps by the way!

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