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Author Topic: Freespeak ii - Audio Stutter  (Read 4817 times)

Marc Soame (UK)

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Re: Freespeak ii - Audio Stutter
« Reply #10 on: June 27, 2016, 06:04:28 am »

Are there internal cell systems inside the venue?  What is cell strength on phones?

Reflections and directionality have nothing to do with this.  High noise floor is the problem.

Try your antenna run outside the building.  Success in fixing this has been done by putting antennas far from the high noise floor.

Walk the venue looking at the noise floor.  Is the band below -100 dBm?  Noise floor above -80 will totally stop the system.

Hi Pete/ Henry/ Jason,

Back in the UK now so more time to try and learn more about the problems experienced and how to preferably avoid or solve in the future.

I have little experience in scanning DECT and was hoping to gain more insight into what you look for yourself when using FSii?
- Noise floor of -100dBm is ideal
- Noise floor of -80dBm is a critical limit to system use.
- Consistent or burst transmission by FSii is considered 'normal'
- Spectrum use of the bands nearby and potential intermod or bleed increasing noise floor.

I believe FSii uses GFSK frequency modulation and I'm trying to research the details of how it works but I'm ultimately trying to build a picture of comparison to when I normally scan for Radio Microphones/ IEM's etc. I unfortunately wasn't trained as an Electronics/ RF Engineer.


Pete, you mentioned Henry and yourself experienced this Audio Stutter problem recently. Could you explain any similarities or differences you had and how you worked towards a solution if you got one?


Kind Regards,

Marc
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Pete Erskine

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Re: Freespeak ii - Audio Stutter
« Reply #11 on: June 27, 2016, 10:13:48 am »

Hi Pete/ Henry/ Jason,

Back in the UK now so more time to try and learn more about the problems experienced and how to preferably avoid or solve in the future.

I have little experience in scanning DECT and was hoping to gain more insight into what you look for yourself when using FSii?
- Noise floor of -100dBm is ideal
- Noise floor of -80dBm is a critical limit to system use.
- Consistent or burst transmission by FSii is considered 'normal'
- Spectrum use of the bands nearby and potential intermod or bleed increasing noise floor.

I believe FSii uses GFSK frequency modulation and I'm trying to research the details of how it works but I'm ultimately trying to build a picture of comparison to when I normally scan for Radio Microphones/ IEM's etc. I unfortunately wasn't trained as an Electronics/ RF Engineer.


Pete, you mentioned Henry and yourself experienced this Audio Stutter problem recently. Could you explain any similarities or differences you had and how you worked towards a solution if you got one?


Kind Regards,

Marc

Scans of dect band with SA on peak hold only tell you of the noise floor and dect is being used.  To actually see the DECT band you need a DECT monitor.  It's a software defined radio and will display all the time slots in use at the time.  25 in the us and 40 in Europe, I think.

Hardware: Revolabs 01-DECTMTR-01  http://www.revolabs.com/products/accessories/cables-accessories

Software: http://www.revolabs.com/getattachment/efe99a00-76f0-4052-9603-7f221ae13342/DECT-Monitor-Software-Download

Also FYI I have attached the polar plots fore the FSII antennas.



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Jens Palm Bacher

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Re: Freespeak ii - Audio Stutter
« Reply #12 on: June 27, 2016, 02:18:22 pm »

Sounds familiar to a gig i did in this hall:
https://ing.dk/sites/ing/files/dsc_4033.jpg

Basically metal roof, metal sides, a big audience riser in metal and floors of concrete with metal...
We had some pretty scary multipath problems, IEM beltpacks with clear view to a CP5000 and 250mW carrier having dropouts, Motorola walkies not working etc.
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Pete Erskine

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Re: Freespeak ii - Audio Stutter
« Reply #13 on: June 27, 2016, 04:56:21 pm »

Sounds familiar to a gig i did in this hall:
https://ing.dk/sites/ing/files/dsc_4033.jpg

Basically metal roof, metal sides, a big audience riser in metal and floors of concrete with metal...
We had some pretty scary multipath problems, IEM beltpacks with clear view to a CP5000 and 250mW carrier having dropouts, Motorola walkies not working etc.

Did you try the IEM at 50mW?  250 is too much for use indoors.
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Jens Palm Bacher

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Re: Freespeak ii - Audio Stutter
« Reply #14 on: June 27, 2016, 05:37:12 pm »

Did you try the IEM at 50mW?  250 is too much for use indoors.
I didn't set it up, the application engineers from the big german WL manufacturer did, and they all agreed it was severe multipath problems. The digital mic system we used also had some initial dropout problems even though the signal strenght was perfect.
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Re: Freespeak ii - Audio Stutter
« Reply #14 on: June 27, 2016, 05:37:12 pm »


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