RF Interference

[nevo]

Hi audio brains trust.

ive had a intermittent problem with my SRBs

This has happened 3 times now.

Last week I was on a TVC with two talent and a boom on wireless. Sending a mono guide to camera with a LMA .

CLIENT and agency on comtek pr216 .

Used the Freq finder app to coordinate and ran a scan on RF EXPLORER

The day was going fine ,talent about 30 feet from me....Had been recording for several hours no problem,then started getting dropouts

Did a scan on SRBs and they have broadband interference like the front end is being overloaded.

Did a scan on RfExplorer. Looks clean.

I got my bigger rig out (664 and venue field ,same blocks same freq setup and zero problems.

Later when I scanned SRBS again all totally fine and I’ve worked a few jobs since with SRB ,NO problems.

This has happened 3 times....usually in the heat of the battle.

The last time ...I tried to turn the bag TX off and the 633 off and rescanned re powered and the hash was still there..,on two different blocks 26 /20

I was thinking maybe 5G testing ? As they are rolling that out at the moment.but the RF explorer showed clean spectrum.....

I am stumped!

Ant

The previous time it happened,I was on a travel show and had talent on a zip line doing a PTC.

SMQV at 250 mw...I was getting about 200m clean audio line of sight,then all of a sudden dropouts at 10 feet and hash all over the scan

Nothing changed in my setup.....

[Philip Perkins]

Yeah, could be testing, police, military, hackers or another shoot close by using the same block.  Bad day at the office--sorry!  What happened when you tried other RX?  Same thing?  It is possible that your SRB needs a Rio Rancho vacation.

[nevo]

Yep swapped to venue and all was good.

Its the intermittent nature that makes it difficult...I could send back to lectro and I’m sure the units would behave.

live used same setup on a few days since and all totally fine.

Quite frustrating and not having faith in your kit can be a bit unsettling.

[RadoStefanov]

1 hour ago, nevo said:

Hi audio brains trust.

ive had a intermittent problem with my SRBs

This has happened 3 times now.

Last week I was on a TVC with two talent and a boom on wireless. Sending a mono guide to camera with a LMA .

CLIENT and agency on comtek pr216 .

Used the Freq finder app to coordinate and ran a scan on RF EXPLORER

The day was going fine ,talent about 30 feet from me....Had been recording for several hours no problem,then started getting dropouts

Did a scan on SRBs and they have broadband interference like the front end is being overloaded.

Did a scan on RfExplorer. Looks clean.

I got my bigger rig out (664 and venue field ,same blocks same freq setup and zero problems.

Later when I scanned SRBS again all totally fine and I’ve worked a few jobs since with SRB ,NO problems.

This has happened 3 times....usually in the heat of the battle.

The last time ...I tried to turn the bag TX off and the 633 off and rescanned re powered and the hash was still there..,on two different blocks 26 /20

I was thinking maybe 5G testing ? As they are rolling that out at the moment.but the RF explorer showed clean spectrum.....

I am stumped!

Ant

The previous time it happened,I was on a travel show and had talent on a zip line doing a PTC.

SMQV at 250 mw...I was getting about 200m clean audio line of sight,then all of a sudden dropouts at 10 feet and hash all over the scan

Nothing changed in my setup.....

what frequency?

[nevo]

20 and 26 ...

[borjam]

Maybe I am asking a very silly question, my apologies in advance.

 

How do you guys perform a RF Explorer scan? Some digital transmission systems work with very short bursts, so a regular spectrum analyzer has a limited detection probability unless you leave the analyzer running for some minutes and set up so that it holds the peak levels. Otherwise you might miss the offending transmissions.

 

 

[EmRR]

We recently had an LCD monitor start spraying RF causing wireless dropouts, which didn't show up in scans.  Found it the old fashioned way, turning things on and off one at a time.  

[daniel]

4 hours ago, borjam said:

Maybe I am asking a very silly question, my apologies in advance.

 

How do you guys perform a RF Explorer scan? Some digital transmission systems work with very short bursts, so a regular spectrum analyzer has a limited detection probability unless you leave the analyzer running for some minutes and set up so that it holds the peak levels. Otherwise you might miss the offending transmissions.

 

 

Do scan on RFX, do scan on RX, set freqs to what seems best at the time, maybe take a photo of RFX screen, leave it running the duration of filming, if you get a hit, check RFX screen - might show you where in the spectrum it was. RFX has different display modes.

 

[karlw]

Are you in the US? Block 26 is now subject to testing by T-Mobile and possibly other data carriers who have purchased spectrum in the range between 614 and 698 MHz. 

 

There is info about this on our web site: https://www.lectrosonics.com/fcc-spectrum-updates.html

[Michael Capulli]

First thing that came to mind - quarter watt transmitter 10 feet from an SRB receiver - you probably are overloading the receiver. When i've experienced this with the SR receivers it sounds like IMD. Make sure if you are using the SRB that you are properly spacing your frequencies. You have to check the literature - there is a certain way you need to set them up

 

[nevo]

Turned everything off but receivers.....I’ve done some testing and some RF is introduced when I plug in HDSDI monitor.

But that’s not the whole story I suspect......

[Fauzan]

Nowadays I'm pretty much suspecting 4G/5G base station as the culprit of RF-issues. It's been quite frustrating. Remember 10-15 years ago RF was quite worry free (to remember that we used to work on Lectrosonics 195-without diversity and locked to single channel!)