Jump to content

RF Killer


echo

Recommended Posts

Working on a show... Using an SSM transmitter and lectro recivers, it works fine on every actor except one. Even using a different transmitter or changing the fq doesn't stop the hits. Area is showing up fine on RF explorer.... It seems that the actor is an RF killer.

 

Anyone have any ideas?

Link to comment
Share on other sites

What Vin said -- definitely check the actor for a cell phone or other device.  I had one actor drop an ear prompter playback recorder into a pocket next to a transmitter (most digital devices emit some spurious RF). 

I've also found that sweating talent seem to absorb RF.  In the small of a back can be the worst placement as some people are indented a bit there so the antenna is surrounded more by the body, plus often their back is to the receiving antenna, increasing the water-filled mass that the signal needs to travel through.

Where are you placing the transmitter?  What type of antennas are you using?  What distance?

 

Link to comment
Share on other sites

REPLICANT ALERT!!!

Check to see if his wardrobe has any metailc cloth near your antenna..

and just to see if his entire body is a problem... try finding an area on the outside of his wardrobe where the pack does work... and then try to hide it under clothing there..

Seriously...

Check to see if he has a blackberry device.... or any personal electronics at all.

I have met and worked with a few people that do interfere with electrical devices from time to time (including my spouse).. boom him if he's like that..

Edited by Christopher Mills
Link to comment
Share on other sites

also remember,actors will say their cell phone is off so "don't worry" the ringer is off but the phone is still xmitting.

 

                                                                                                            J.D.

Edited by jrd456
Link to comment
Share on other sites

hello Echo 

Maybe a bit off topic,but I do curious about the real world SSM user experience as I'm thinking of getting them soon.

On the hits you described,how far was that ? 

Are you using shark fin with SSM ?

Which receiver ?

For 50mW what's your maximum straight line range with it ?

Battery life ?  

best 

Cloud 

Link to comment
Share on other sites

I have run into maybe 1 out of 25 people where inexplicably the wireless RF output from transmitters on their bodies is down by 1/3 compared to everybody else, even people standing right next to them. As Larry Fisher often reminded us here, "human beings are basically just big bags of water, and that's a hostile environment for RF."

Edited by Marc Wielage
Link to comment
Share on other sites

I have run into maybe 1 out of 25 people where inexplicably the wireless RF output from transmitters on their bodies is down by 1/3 compared to everybody else, even people standing right next to them. As Larry Fisher often reminded us here, "human beings are basically just big bags of water, and that's a hostile environment for RF."

Maybe some peoples electromagnetic field is very inconveniently not intermodulation free :)

Link to comment
Share on other sites

Working on a show... Using an SSM transmitter and lectro recivers, it works fine on every actor except one. Even using a different transmitter or changing the fq doesn't stop the hits. Area is showing up fine on RF explorer.... It seems that the actor is an RF killer.

 

Anyone have any ideas?

Maybe you should consider using a Lectrosonics SMQV transmitter that can be set to 100mW or even 250mW RF output?

Is it possible to position the antennas closer to the actors? Or setting up a pair of really close antennas for that particular actor (depending on how much movement the actor does)?

I have a theory that the person's BMI might be a part of the problem, however it's not always the case. I sometimes work with a lady that's a RF Vampire and it just amaze me how she's able to absorb radio frequencies - she's like a vortex! :-)

Normally I get very good coverage with my Shure systems - I also set the frequencies using RF Explorer - but with this particular lady I get line-on-sight 15 meters range, then dropouts. She walks into a building, no signal, together with another person wearing a transmitter and I have good coverage from the second system - even with a couple of walls in between me and them.

I've tried pretty much everything with little success. Sometimes I move her transmitter around depending on the angle we're filming and I've experimented with disabling the squelch on the receiver which is okay working with documentaries, but totally not okay working with a show.

 

Cheers

Fred

Link to comment
Share on other sites

 

The smaller the transmitter pack the worse the radiation from it will be. The pack itself is part of the antenna. It has to act as a proper counterpoise for the antenna in order for it to work well. This might be a factor in this situation. 50mW does not help here either.

Glenn

 

Link to comment
Share on other sites

 

The smaller the transmitter pack the worse the radiation from it will be. The pack itself is part of the antenna. It has to act as a proper counterpoise for the antenna in order for it to work well. This might be a factor in this situation. 50mW does not help here either.

Glenn

 

Are you saying Glenn, that all these smaller and smaller transmitters that are available are in fact compromising range for a given output power?

Interesting never seen that stated before.

Link to comment
Share on other sites

The output of the SSM is accurately stated.  While the body pack may be smaller, it by no means inhibits the measured radiated output of the transmitter.  There is still plenty of aluminum there to form an effective ground plane for the antenna.     As pointed out in the original post, the problem is appearing only on one of several actors.  Were the transmitter design an issue - it would have the problem common to all.

One other thing to check is to see if the antenna on that particular actor is being placed differently - bent back on itself perhaps to accommodate clothing or costuming requirements.  I had a wardrobe mistress one time place a transmitter in a pocket with the antenna bent back up so it was literally pushed back against the case of the transmitter - effectively an RF short from antenna to ground.

Power on the SSM is not compromised due to size, it is lower than the SM due to battery capacity - we can't have high power and tiny battery, it just doesn't give you good battery life.  If you need higher power, the SM is only about 30% larger by volume, much less dimensionally.    

Edited by Gordonmoore1
added last paragraph
Link to comment
Share on other sites

REPLICANT ALERT!!!

Check to see if his wardrobe has any metailc cloth near your antenna..

and just to see if his entire body is a problem... try finding an area on the outside of his wardrobe where the pack does work... and then try to hide it under clothing there..

Seriously...

This can seriously be a problem: When clothes have aluminium inside for thermal purposes. I once had that problem with a woman wearing winter clothes - she was a real RF killer! I got crazy because you couldn't see the metal from the outside and it took a long time to find out ...

Link to comment
Share on other sites

This can seriously be a problem: When clothes have aluminium inside for thermal purposes. I once had that problem with a woman wearing winter clothes - she was a real RF killer! I got crazy because you couldn't see the metal from the outside and it took a long time to find out ...

Good point, It's currently winter moving to spring here in NZ and still thermals weather. Will have to remember to look for lined clothing.

I've had a few RF killers over the last month or so, often helped by moving the TX to whatever side of the body is closer to the RX and walking along with them just out of shot.  But then, some times it's just voodoo..

Grant.

 

Link to comment
Share on other sites

 

Power on the SSM is not compromised due to size, it is lower than the SM due to battery capacity - we can't have high power and tiny battery, it just doesn't give you good battery life.  If you need higher power, the SM is only about 30% larger by volume, much less dimensionally.    

hello Mr Moore 

awhile ago Larry posted here that he found this new battery can runs the SSM six hours,and according some of your dealer's website I saw capacity of that battery is 1000mAh. Recently I did a research found out that a NP50 here by FUJI is rated Li-ion 3.7V,1600mAh,5.8Wh.The seller told me it's the same size as those 1000mAh batts. Have you seen this battery before and this might give your product a longer run time.(?) and if so,is it possible to give a higher RF output for the SSM ? Like SM we know 250mW would give us almost an half run time but when we need that extra range it always comes in handy.

best

Cloud 

Link to comment
Share on other sites

Cloud Wang - Good afternoon!

There are a LOT of NP50 batteries out there due to so many Fuji Fine-Pix cameras using them.  We tested quite a few and found most did NOT deliver the rated amperage they claimed. In many cases they were obviously fakes (one clue is rather fuzzy printing on the label - poor copies) and even recycled batteries just re-labeled.  However, if you try one successfully, post the model and source (who you bought it from here) so others will know.  If the battery you describe really has the capacity, then you will get really good battery life beyond our tests with the currently supplied battery we provide from Fuji (which is actually made by on an OEM basis by another manufacturer with whom we are now working).  So I advise caution but if you have a few bucks to gamble, give it a try!

As far as upgrading the output power of the SSM goes, that design is now pretty much locked in.  Raising power will pull more current, which will add to the internal heat load. The SSM runs nice and cool now.  Jacking up the power without increasing the surface area means a hotter unit. (like trying to run an MG with a V8 but on the original radiator).   The governing factors for the SSM design were 1) full feature set and 2) small as possible.   

Link to comment
Share on other sites

To add to Gordon's comment: We tested a LOT of batteries for the SSM and most of the time the stated capacities were flat out lies. And gross lies at that. The highest capacity battery that we found is the one we are shipping. It was also 3 times more expensive than the junk batteries.

Best,

Larry F

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...