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Author Topic: Directional antennas for *finding* interfering sources?  (Read 5244 times)

Lyle Williams

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Re: Directional antennas for *finding* interfering sources?
« Reply #10 on: November 05, 2016, 06:53:18 am »

The other thing about searching for interfering signals - if you aren't allowed to turn them off there is no point in physically finding them.  See them on the spectrum analyser, avoid them.
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brian maddox

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Re: Directional antennas for *finding* interfering sources?
« Reply #11 on: November 05, 2016, 10:42:21 am »

The other thing about searching for interfering signals - if you aren't allowed to turn them off there is no point in physically finding them.  See them on the spectrum analyser, avoid them.

Of course it is helpful to know where they are so you can deploy your antennas in the most strategic way to avoid them as well.
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Pete Erskine

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Re: Directional antennas for *finding* interfering sources?
« Reply #12 on: November 05, 2016, 02:20:05 pm »

This may be a stupid question, but, at your level, do you ever use Doppler-shift-based antenna arrays for finding RF sources?

Thanks!

-Russ

I have looked a some but this is too complicated for casual use.  The directional antenna, not requiring power, one flat paddle, can do the same job just as easy.
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Scott Helmke

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Re: Directional antennas for *finding* interfering sources?
« Reply #13 on: November 05, 2016, 10:02:39 pm »

The other thing about searching for interfering signals - if you aren't allowed to turn them off there is no point in physically finding them.  See them on the spectrum analyser, avoid them.

Granted, but my situation is a football stadium - I don't think I have my actual "lettre de marque" from the head of the athletics department in my laptop case any more, but I'm reasonably sure I could shut somebody down if I needed to.
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Ike Zimbel

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Re: Directional antennas for *finding* interfering sources?
« Reply #14 on: November 07, 2016, 04:22:07 pm »

Any recommendations for very directional UHF antennas for tracking down interference & uncoordinated sources?

I do the frequency coordination for a local Big Ten football stadium, and we have a couple TTi spectrum analyzers and a nice R&S FSH spectrum analyzer. Handy gear for checking on things, beyond the Axient spectrum manager that keeps scanning the bigger picture. 

I rarely have problems with non cooperating media, but it would be nice once in a while to have something really directional to try to track down unknowns. What's available (or could be built reasonably) in the UHF TV spectrum?  I really can't justify something huge to carry around, though.
I use this baby with my TTI. I find that the futuristic Star Trek-ish styling makes folks think that I can pick up far more with it than I actually can...
On a serious note, be aware that signals can bounce around and appear to come from somewhere other than where they're originating from. Case in point, I spent an hour, with the aid of the GDC and two other guys with SA's tracking down this rogue signal at an empty MetLife stadium this past summer. At one point, the signal really seemed to be strongest coming from an area in the upper stands, to the left of one end zone...and there just happened to be someone from the press sitting up there with a laptop. The GDC was working that area and he went over and checked it out...no dice. It was around this time that I started to look in the opposite direction, and shortly thereafter realized that the signal was coming from our own tech world which was set up in the concrete bunker formed by the end zone seats (ie under the seats). The offending device was a single PSM-1000 Tx that I had walked by 67 times by that point, sitting on a road case by the monitor console. The ME had pulled it out of the rack (which was under a tarp a few hundred feet away) to use as a local cue mix, and he had TOLD me as much. What he didn't tell me was that it was an additional channel to the ones I had allocated. In any event, my point is that the signal was basically being channeled out of that bunker and up into the stands.
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Diogo Nunes Pereira

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Re: Directional antennas for *finding* interfering sources?
« Reply #15 on: November 09, 2016, 03:59:07 pm »

Additionally you will need an adjustable pad to control the level so that it is not overloading your meter or SA.

Hi. Any suggestions on such a device? I already own a selection of in-line Mini-Circuits attenuators with SMA connectors, but it seems like something adjustable would be more practical.

Is this something you can buy or have you built your own?

Thanks.

D
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Jason Glass

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Re: Directional antennas for *finding* interfering sources?
« Reply #16 on: November 09, 2016, 04:08:07 pm »

I use this baby with my TTI. I find that the futuristic Star Trek-ish styling makes folks think that I can pick up far more with it than I actually can...
On a serious note, be aware that signals can bounce around and appear to come from somewhere other than where they're originating from. Case in point, I spent an hour, with the aid of the GDC and two other guys with SA's tracking down this rogue signal at an empty MetLife stadium this past summer. At one point, the signal really seemed to be strongest coming from an area in the upper stands, to the left of one end zone...and there just happened to be someone from the press sitting up there with a laptop. The GDC was working that area and he went over and checked it out...no dice. It was around this time that I started to look in the opposite direction, and shortly thereafter realized that the signal was coming from our own tech world which was set up in the concrete bunker formed by the end zone seats (ie under the seats). The offending device was a single PSM-1000 Tx that I had walked by 67 times by that point, sitting on a road case by the monitor console. The ME had pulled it out of the rack (which was under a tarp a few hundred feet away) to use as a local cue mix, and he had TOLD me as much. What he didn't tell me was that it was an additional channel to the ones I had allocated. In any event, my point is that the signal was basically being channeled out of that bunker and up into the stands.
Stepped attenuators like these are excellent for many applications including "sniffing" for interference sources:

http://m.ebay.com/itm/JFW-10dB-2-2G-Ad-justable-Variable-Attenuator-50DR-193-/301310803858

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

Jason Glass

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Re: Directional antennas for *finding* interfering sources?
« Reply #17 on: November 09, 2016, 04:10:02 pm »

Hi. Any suggestions on such a device? I already own a selection of in-line Mini-Circuits attenuators with SMA connectors, but it seems like something adjustable would be more practical.

Is this something you can buy or have you built your own?

Thanks.

D
Stepped attenuators like these are excellent for many applications including "sniffing" for interference sources:

http://m.ebay.com/itm/JFW-10dB-2-2G-Ad-justable-Variable-Attenuator-50DR-193-/301310803858

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

Diogo Nunes Pereira

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Re: Directional antennas for *finding* interfering sources?
« Reply #18 on: November 11, 2016, 05:24:36 pm »



Stepped attenuators like these are excellent for many applications

Thank you Jason.

Ordered one from that link you provided.

Expected delivery date, January 4th...

Such is life in Europe.

Cheers,

D

Sent from my Xylophone using Tapatalk...

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Diogo Nunes Pereira
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Jason Glass

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Re: Directional antennas for *finding* interfering sources?
« Reply #19 on: November 11, 2016, 05:28:11 pm »


Thank you Jason.

Ordered one from that link you provided.

Expected delivery date, January 4th...

Such is life in Europe.

Cheers,

D

Sent from my Xylophone using Tapatalk...
Hi Diogo,

Make sure you also have some SMA-m to BNC-f adapters!

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

ProSoundWeb Community

Re: Directional antennas for *finding* interfering sources?
« Reply #19 on: November 11, 2016, 05:28:11 pm »


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