FM Translation Equipment

[dave.swartz]

The church standard for translation equipment appears to be the Williams AV products. The Receivers are the R37 and the transmitters are the PPA T27. The microphone provided is the MIC 044.
The microphone is directly attached to the front of the unit. Audio level can be controlled using a potentiometer on the front of the transmitter. As shipped the gain is at around 75% of max. There is an audio level indicator on the front of the transmitter. Per the manual Never On = Audio source is TOO LOW. Blinks occasionally = Audio source is OPTIMAL. Always on = Audio source is TOO HIGH. Using the provided MIC 044 the indicator never blinks. After adjusting the Audio level to maximum we still don't achieve an audio source that is loud enough.

When our interpreter speaks into the microphone he is barely heard above the noise floor. Increasing the audio output on the receiver amplifies background noise as well as the interpreter audio. This audio signal sounds terrible because of all the background noise. This is common to all our stakes translation equipment. (3 different languages)

Does anyone have any insights or suggestions for how to make this system functional? If you are successful what microphone are you using?

The system is designed to transmit audio at a maximum of 75 kHz of deviation (Williams AV published spec). This is significantly higher deviation than +- 5 kHz which is typically used in narrowband FM. If you apply Carsons rule (FM Bandwidth = 2(Δf + fm), where Δf is the peak frequency deviation and fm is the highest modulating frequency. ) You get 2(75kHz + 3kHz) = 156 kHz of bandwidth. A look at the ALS frequency chart shows that the channels are spaced at a minimum of 200 kHz spacing.

How are we, using the equipment we have, to get a strong enough microphone signal. We are using the Audio Technica System 10 wireless microphone that each meeting house is provided with to feed a stronger signal into the microphone jack. The receiver has a level control allowing us to input the proper audio levels. Our challenge with this solution is that we are tying up a wireless microphone. The interpreter would also like a light weight headset based system. This is also not the church standard.

I am looking for information on how others have overcome these challenges. What am I overlooking? Thank you for your help.

[BrianEdwards]

This has been such a pain for our members, we have the identical problem. We have tried the easier ideas/solutions I've found here in the Forum. We need to see about getting a new wireless mic since ours also isn't working as it should, so we're currently using a member's own mic (non-standard solution). We are a dual-language unit, and a small unit without any A/V savvy members who could figure this out. And in spite of engaging our local Stake tech and local FM Group, what they can provide is this standard solution which delivers a very weak audio signal that is full of noise --and if there's a wall in-between the translator and listeners, game over. If I had to listen to the translation, I'd be challenged to feel the spirit myself.

Anything beyond plug-and-play is likely to exceed our unit's technical understanding, and my expectation is always that the Church should be able to provide a solution that is "adapted to the capacity of the weak and the weakest of all saints"

[dave.swartz]

Here is a update to this situation.

1. Williams AV has found that their is a defect in their current stock of the Mic 044 units.
2. They are awaiting a second shipment to confirm if this defect still exists in their second production run.
3. Williams AV is sending us their Mic 100 microphone for testing. We will test if this is an acceptable substitute. We will test this microphone using professional RF test equipment that can measure transmitter deviation.
4. Results of this testing will be provided to Williams AV and they will identify next steps.
5. The church meetinghouse technology team has been notified of this issue.

Please give this process time to take place before reaching out to your FM group or the vendor. I will post the results of this work in this forum.
This is a great long standing vendor of the church and we appreciate their support. Things happen and we need to be patient and respectful as we work towards resolution.

Please consult my earlier postings regarding an interim work around solution.

All the best,
David Swartz
STS Federal Way Washington Stake

[dave.swartz]

Just a quick update. The Mic 100 microphone from Williams works well. The audio from the Mic is strong, and I needed to turn down the mic gain on the transmitter.
When I get time I will post the test results.

If you are struggling with low deviation and poor performance of the Williams AV translation equipment that you have received in the past year this may be the solution, until they can get repaired Mic 44 units in stock.