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Author Topic: Freespeak ii - Audio Stutter  (Read 4822 times)

Marc Soame (UK)

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Freespeak ii - Audio Stutter
« on: June 23, 2016, 02:11:49 am »

Hi All, long time lurking. A shame to kick off my first post with a help request.

I was hoping to pick your brain on Freespeak ii. I have 1 Base station and 20 belt packs, [with two antenna matrix splitter units]

Problem
All packs suffer from audio stutter with occasional dropout at certain points - never needs to reconnect to base however.
Most packs sit with an error rate of 1. Enough to hear audio stutter.
RSSI is very high - over 45 always, normally over 50.
LQ on site survey is 2 sometimes 3. Never more.
Distance from Antenna is only 40m before level drops drastically.
Stuttering seems to be worse when moving around, though standing still only seems to reduce this not eliminate the issue

Environment
Large open area with a show in-the-round
Ceiling is approx 25m high with a large proportion of it being metal.
No walls on the sides within approx 70m
I have scanned the 1.88-1.9Ghz spectrum and it looks very clear although it may be burst interference.

Setup
I have 4 Transceivers within a 20m radius providing coverage for a zone at the south position for the bulk of the users.
Dead centre under the stage 40m away is another Transceiver to provide a coverage zone there for the key 4 users that go to area.
FOH at north position is another Transceiver for any stray users wondering there. 80m away from the south position [40m from stage].
All Antennas are locally powered.


Solutions Attempted
I have tried making sure all the cable to every antenna is within 10m incase of time alignment issues from antenna to base - no difference
Varying height of antennas incase of path length cancellation - no difference
4x antennas in very local zone - around 5m apart from each other with all packs on to stop roaming - no difference
Reset base station back to default incase of bug within show file. - no difference
1x Antenna directly into base station with one beltpack for simple setup testing - no difference


Speculation of Problems
The problem could to be a combination of a few things in my opinion.
- slow handoff between antennas (about 3sec to slow)
- potential reflections from the ceiling (although the stage antenna is flat on the floor which would eliminate reflections and audio stutter is still present when connected to it)
- Some form of packet loss causing audio to drop regularly.

I have an audio record of the audio stutter available as well as plans showing dimensions etc.

Any pointers or other areas to look at is greatly appreciated.

Kind Regards,
Marc
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Henry Cohen

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Re: Freespeak ii - Audio Stutter
« Reply #1 on: June 23, 2016, 02:12:13 pm »

Where is this deployment (city, state, country)?

Is the latest firmware loaded into the packs, base and transceivers?

How is your SA configured to determine that ". . . it looks very clear" (reference level, RBW, dB/Div)?
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Pete Erskine

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Re: Freespeak ii - Audio Stutter
« Reply #2 on: June 23, 2016, 02:51:09 pm »

Hi All, long time lurking. A shame to kick off my first post with a help request.

I was hoping to pick your brain on Freespeak ii. I have 1 Base station and 20 belt packs, [with two antenna matrix splitter units]



And to add to Henry's note (he just went through this issue on our last show).

Where are you located?  That not the US DECT Band.

Is the noise floor in DECT 1920-1930 (USA DECT Band) high?  Look at it with spectrum analyzer.  should be less than -100dBm for the best spectrum.  In the USA, Sprint typically bleeds into the DECT Band. and since they don't have good filtering makes the noise floor high.  Technically the DECT band is a guard band between cellular carriers and they shouldn't be bleeding into it but...

Does Venue have indoor Cellular antennas?  You can sometime see them as a white dome in the Hallways.  Be sure to be at least 20 feet from any of these antennas with your FSII antennas.  Installers often set TX power in the venue at max incorrectly - (More is better?).  Speak to the venue and have them contact the supplier and turn down the TX power.  It usually will be done.

Space your FSII antennas around the venue 1 USR, 1 USL, 1 DSR, 1 DSL, 2 at FOH, etc.  Keep them as high as possible so users won't be blocked by crowds around them.

Cable length is not affecting this issue.  Adjusting the cable length is to synchronize the antennas so they efficiently hand off.  Start with the all at lowest - if a specific antenna is sticky (it wont let go of the pack even when you are far away and closer to another antenna)  adjust it's cable length.

Walk test using one pack to listen and 1 to talk to hear the stutter.

When you have a few HOURS upgrade the Firmware just released. 

Below is a link to the latest version of the FreeSpeakII firmware package that came out last week.
 
This release includes the ability to swap between AB to CD volume controls by tapping the MENU key on the beltpacks when configured even though the release notes do not say it.
 
FIRMWARE AND CONFIGURATOR SOFTWARE;
http://clearcom.ftpstream.com/50396/f6c99869d7652438d50e7dc77370b89e/product%2breleases/FSII%2bBase/V2.1.0A/FSII%2bBASE%2bV2.1.0A%2bfiles/Firmware/FSII-BASE%2b2-1%2bFirmware.zip
 
RELEASE NOTES;
http://clearcom.ftpstream.com/50396/ca362d56a81a34853d2baaa1a4f3bae6/product%2breleases/FSII%2bBase/V2.1.0A/399G135E%2b-%2bFSII%2bBase%2bstation%2bV2.1.0A%2bRelease%2bNote.pdf
 
You do need to upgrade the firmware of the base (APP) (manual page 165 section 11.2) and the beltpacks (manual page 100).  Only upgrade 4 packs at a time despite what the manual says - it's done over the air so be sure they are fully charged.

Mismatched belt packs can operate together on a system.
The base firmware and the software configurator should always be matched
 
As always with firmware upgrades, make sure to allow yourself plenty of time!
 
Tech support can be reached at 510 337 6600 > Option 2 and via support@clearcom.com

« Last Edit: June 23, 2016, 03:07:53 pm by Pete Erskine »
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Marc Soame (UK)

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Re: Freespeak ii - Audio Stutter
« Reply #3 on: June 23, 2016, 06:10:25 pm »

Where is this deployment (city, state, country)?

Is the latest firmware loaded into the packs, base and transceivers?

How is your SA configured to determine that ". . . it looks very clear" (reference level, RBW, dB/Div)?

Hi Henry,

Thanks for taking the time to reply,

Porte du Versailles, Paris, France - I'm from London out for this show particularly.

The spectrum analyser (TTI) was borrowed. Noise floor was consitent at -100dBm. Occasional burst of transmission reaching -50dBm. Unit was live at the time so presumed to be from the FSii base itself.

Latest firmware as far as i'm aware. Haven't got the units to hand now. The rental company is very good for this normally- i have faith they are up-to-date.

Marc

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Marc Soame (UK)

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Re: Freespeak ii - Audio Stutter
« Reply #4 on: June 23, 2016, 06:28:29 pm »

And to add to Henry's note (he just went through this issue on our last show).

Where are you located?  That not the US DECT Band.

Is the noise floor in DECT 1920-1930 (USA DECT Band) high?  Look at it with spectrum analyzer.  should be less than -100dBm for the best spectrum.  In the USA, Sprint typically bleeds into the DECT Band. and since they don't have good filtering makes the noise floor high.  Technically the DECT band is a guard band between cellular carriers and they shouldn't be bleeding into it but...

Does Venue have indoor Cellular antennas?  You can sometime see them as a white dome in the Hallways.  Be sure to be at least 20 feet from any of these antennas with your FSII antennas.  Installers often set TX power in the venue at max incorrectly - (More is better?).  Speak to the venue and have them contact the supplier and turn down the TX power.  It usually will be done.

Space your FSII antennas around the venue 1 USR, 1 USL, 1 DSR, 1 DSL, 2 at FOH, etc.  Keep them as high as possible so users won't be blocked by crowds around them.

Cable length is not affecting this issue.  Adjusting the cable length is to synchronize the antennas so they efficiently hand off.  Start with the all at lowest - if a specific antenna is sticky (it wont let go of the pack even when you are far away and closer to another antenna)  adjust it's cable length.

Walk test using one pack to listen and 1 to talk to hear the stutter.

When you have a few HOURS upgrade the Firmware just released. 

Below is a link to the latest version of the FreeSpeakII firmware package that came out last week.
 
This release includes the ability to swap between AB to CD volume controls by tapping the MENU key on the beltpacks when configured even though the release notes do not say it.
 
FIRMWARE AND CONFIGURATOR SOFTWARE;
http://clearcom.ftpstream.com/50396/f6c99869d7652438d50e7dc77370b89e/product%2breleases/FSII%2bBase/V2.1.0A/FSII%2bBASE%2bV2.1.0A%2bfiles/Firmware/FSII-BASE%2b2-1%2bFirmware.zip
 
RELEASE NOTES;
http://clearcom.ftpstream.com/50396/ca362d56a81a34853d2baaa1a4f3bae6/product%2breleases/FSII%2bBase/V2.1.0A/399G135E%2b-%2bFSII%2bBase%2bstation%2bV2.1.0A%2bRelease%2bNote.pdf
 
You do need to upgrade the firmware of the base (APP) (manual page 165 section 11.2) and the beltpacks (manual page 100).  Only upgrade 4 packs at a time despite what the manual says - it's done over the air so be sure they are fully charged.

Mismatched belt packs can operate together on a system.
The base firmware and the software configurator should always be matched
 
As always with firmware upgrades, make sure to allow yourself plenty of time!
 
Tech support can be reached at 510 337 6600 > Option 2 and via support@clearcom.com


Hi Pete,

Thanks for replying. I have followed your guidance many times - lurking in the shadows! Good to speak!

As mentioned above, Paris France. FSii base in European model. Should have mentioned this in the original post. My apologies.

No Celluar antennas within visual distance.

I normally mount antennas onto speaker stands at maximum height. Ie 3m high roughly. I have been varying the height on this event to stop Multipath cancellations. More below.

I am more than happy to post a plan showing antenna positions etc with cable routes to explain more easily.
Antenna cable length varies from 5m (antenna into maxtrix 3m into base station 2m) to 200m (basestation to matrix 100m, to antenna 100m)
My initial problem solving solution was thinking the cable length difference may effect 'time alignment' at the basestation. Thus adding 2x 100m drums of Cat5 to the local 5m Antenna. Made no difference.
I am aware of the 'cable compensation' tab in the config editor. I tried this first but it made to difference. I was told by a Clearcom tech it didnt work anyways so tried a physical compensation also.

Tried stripping back configuration to Basestation, 1x antenna, 1x beltpack. New show file incase of bugs. No difference.

All firware is up-to-date as far as i am aware. No packs to hand in this reply.


Spoke to clearcom earlier. They think it is environmental with combination of multipath reflections. No solution from them on this so far.

I have tried Blackwrap to create a 'lid' to the antennas from the metal ceiling 25m above. It has improved audio stuttering but no way near a normal operating system.

Marc


 
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Pete Erskine

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Re: Freespeak ii - Audio Stutter
« Reply #5 on: June 23, 2016, 06:45:14 pm »


As mentioned above, Paris France. FSii base in European model. Should have mentioned this in the original post. My apologies.

No Cellular antennas within visual distance.


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.
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Henry Cohen

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Re: Freespeak ii - Audio Stutter
« Reply #6 on: June 23, 2016, 07:21:31 pm »

Porte du Versailles, Paris, France - I'm from London out for this show particularly.

The spectrum analyser (TTI) was borrowed. Noise floor was consitent at -100dBm. Occasional burst of transmission reaching -50dBm. Unit was live at the time so presumed to be from the FSii base itself.

Are you certain you have a European FSII (1880-1900 MHz) and not a North American model (1920-1930 MHz)? Looking at your TTI with the FSII system on will be blatantly obvious.
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Jason Glass

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Re: Freespeak ii - Audio Stutter
« Reply #7 on: June 23, 2016, 11:54:05 pm »

Also try setting your TTI to "max hold" mode and let it run for a while to catch transient peaks. Most affordable SA's scan too slowly to catch FHSS signals in other modes

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

Marc Soame (UK)

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Re: Freespeak ii - Audio Stutter
« Reply #8 on: June 24, 2016, 06:47:03 am »

Also try setting your TTI to "max hold" mode and let it run for a while to catch transient peaks. Most affordable SA's scan too slowly to catch FHSS signals in other modes

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

Thanks again chaps for the suggestions. Appreciate the time taken. 

I should say now the gig has finished. The system was usable to a degree and i ended up running a lot more Helixnet beltpacks out as backups.

It was an empty shell type hall. No internal phone system that we noticed or could measure. Admittedly no one performed a site visit to scan the spectrum for FSii before the load in. Definitely a mistake that will be rectified.

Absolutely certain it is a European model. It was previously a demo unit for the main Clear Com Distributer in the UK.

Reflections:
I also have a dialogue with clear-com tech support going on. I sent them config files, plans, photos of the venue. Log files from the diagnostics tool and an audio record with commentary of location position etc.
They think it is reflection based problems. They have advised putting the antennas as high as possible to stop the multipath cancellation. Hard to achieve when the roof height is 25m but the trusses height for the LX, PA, Video etc is 10m.

I think its time to sell my Win Radio G33-WSM which only scans to 1000mhz and by a TTI 5000 Series.

Marc
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Pete Erskine

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Re: Freespeak ii - Audio Stutter
« Reply #9 on: June 24, 2016, 08:30:23 am »


I think its time to sell my Win Radio G33-WSM which only scans to 1000mhz and by a TTI 5000 Series.

Marc

Interesting experience.

We have done many events in basketball arenas with no issues so I don't think reflection is the issue.

The tti-5000 is good and easier to carry in your backpack and use.
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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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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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