Assisted listening and heating...

[Simon Lewis]

yes - it is sound related...!

 

Has anyone successfully used an infra red assisted listening system in a venue fitted with infra red heaters? Logic suggests this might be a non starter, but there are three different infra red wavelength ranges used with these heaters (apparently) and it may just be that they can co-exist? I am seeking information from the venue as to exactly which heater type they have...

 

I understand that the iDSP Listen Technologies systems sold via Ampetronic can handle sunlight without a problem... will other brands behave nicely?

[sunray]

I've had problems with HF fluo lighting and senny receivers but never IR heating.

[Simon Lewis]

I've had problems with HF fluo lighting and senny receivers but never IR heating.

Could I ask which type of IR heater that was?

 

 

 

[agermich]

No experience of the IR heater problem, but if you do need an alternative to IR, the Sennheiser Tourguide system is what we use for audio describing and assisted listening.

 

https://en-uk.sennheiser.com/integrated-systems-visitor-guidance-systems-tourguide-2020-d

[sunray]

I've had problems with HF fluo lighting and senny receivers but never IR heating.

Could I ask which type of IR heater that was?

Done a few jobs in marquee's with hired in IR space heaters and also a couple of venues with the IR ceiling panels.

When we got caught short on a job we purchased a load of 446 radios and in ear headphones from ASDA which worked surprisingly well at only £3.23 per person

[Simon Lewis]

...the Sennheiser Tourguide system is what we use for audio describing and assisted listening.

 

Thanks - the 2020D is a great system - two of the larger local venues have them, and they test quite impressively wrt to range, quality, orientation etc.

 

[adam2]

I would be very surprised indeed if infra red heaters interfered with infra red comms of any modern type.

 

There are numerous sources of infra red radiation in everyday life including sunlight, camp fires, barbecues, incandescent lamps, gas or oil lamps, and many heating appliances not specifically marketed as infra red. The infra red used for sending data or signals is modulated at a high and known frequency, the receiver "looks" for this frequency and is unlikely to be "fooled" by steady sources or those modulated at low frequencies like line frequency or by a flickering flame.

 

Only slightly O/T some special fire alarms detect infra red with a low frequency modulation, they are intended to quickly detect flickering flames in large open areas. Such alarms are vulnerable to false alarms from other sources including sunlight reflected from ripples on water, and flocks of birds passing between sun and detector. Such low frequencies are not used for communications.

 

 

 

[Simon Lewis]

There are various IR based ALS out there, and they do typically use modulated carrier to minimise interference, but even the newer types state they "can be affected by strong sunlight, if it falls directly on the detector".

Obviously, there's a difference between sunlight and IR sources, but the building in question has multiple linear quartz IR heating tubes, and I believe they operate around the 780 nm to 1400 nm region.

My cheat sheet (which I think was from the older Sennheiser IR system) states:

 

 

Direct sunlight on the receiving diode will swamp the transmitted signal. (A bright cloudy sky reduces effective IR radiator power by 60%).

Artificial light contains some IR - e.g low pressure mercury vapour lamps (Hg line 1014nm).

 

Stage lighting (tungsten) produces considerable IR and IR transmitters must be placed close to and directly facing receivers.

High frequency fluorescent tubes have operating frequencies of 30 - 45kHz. If dimmed, this rises to ~ 70kHz. These frequencies may interfere. With the receiver. Furthermore, the mercury emission line can cause problems, especially the wideband channels 95kHz and 250kHz. However, the higher frequencies of 2.3 and 2.8MHz are immune.

Camera flashguns produce interference in the audio signal.

 

 

 

[dbuckley]

We have IR ceiling heaters, so not bright red, but just radiated heat, and IR assisted listening, a Williams system. No conflict at all.

 

The emitter is on the back wall of the balcony, and you can still receive happily under the balcony, as long as there is white stuff for the IR to bounce off.

[Bryson]

We just swapped our infrared system out for the https://www.listentech.com RF based system. (72MHz or 216 MHz) We were finding that certain cameraphone flashes were enough to cause loud white noise on the old Sennheiser IR system. (Plus we were down a transmitter, so had to do something...)

 

We're pleased with it so far, although to be honest, the frequency with which we hand it out has gone way down in recent years as hearing aid technology gets better and better.