Struggling with Deity BP-TRX

[gabeelder]

I recently purchased two pairs of BP-TRX microphones. I'm having a number of issues and I'm trying to determine whether there are issues with the units, or my semi-amateur operation. (I am primarily a camera person)

Some background: I'm using four BP-TRX units as two pairs, connected directly to a Sony FS7. I am using Countryman B3 mics. I am using the self-recording feature on both transmitters.

 

-Electronic noises on transmitter: I was hearing short bursts of electronic beeping, which i traced back to one of the two transmitters.  These noises exist when monitoring the transmitter through the headphone port, and in the recordings on the MicroSD cards. These noises are also transmitted to the receiver. These noises only occurred on one transmitter, but in multiple locations on different days. I tried switching the transmitter and receiver in the pair, but this did not fix the problem.

- Unexpectedly frequent dropouts: when using the two sets of tx/rx at close range, outdoors (4-5ft) I get sometimes get continuous dropouts. They seemed to be related to the proximity of the transmitter to the subjects body. were ~slightly~ improved by placing the transmitter on the ground.

- Strange phenomenon related to using two mics: after prepping mics the night before, with no issues, I was on location and could only get audio outputting through one of the two sets. Both receivers showed strong RF signal. While troubleshooting, I turned off the mic that WAS outputting audio, and the other mic suddenly started outputting. I turned the original mic back on, and the output on the second mic cut out again. throughout these issues, both receivers showed the correct ID for their transmitters. I re-paired both sets individually which solved the problem.

 

These units were a recent purchase, and I am motivated to get them working properly because the self-recording feature would be hugely helpful for my work. That said, after using them on four shoots, I'm yet to have a day go smoothly. I'd be enormously grateful for any guidance/wisdom.  Here are some other relevant operating details:

 

RF power: Auto

Low Cut: 50hz

Freq boost: 5db

input gain: 18db

Micro SD card: Transcend 32gb (per deity recommendation)

Timecode: off

[PMC]

If i interpret your issue correctly, it sounds like both tx were tuned to the same freq until you repaired.

From the start, turn on one tx and pair it to the reciever. Leave it turned on. Then turn on the second tx and pair that. It will automatically tune past the tx1 freq. Choosing a clean/unoccupied freq.

 

The reason the receiver showed strong signal from both tx before you retuned is both channels of rx were probably seeing the same one freq.

[IronFilm]

What other 2.4GHz equipment do you have your on camera?? As quite frequently there is a lot. (follow focus, wireless video monitors, etc) All of that can severely mess with your receiver that is also on the 2.4GHz band.

 

Also sounds like you might have pairing issues too, make sure you're setting up each pair independently in their own group for themselves. Would be worthwhile re-reading the manual again on this point, to double check you're following the process right. 

[gabeelder]

Thanks @PMC and @IronFilm, I appreciate you taking the time! I think you're correct about the pairing issue.  It would be helpful if the BP-TRX was able to display the channel being used.  I wish I could chalk up the interference to other 2.4ghz devices, but I'm not using any other wireless tech.  The noises were persistent even with everyone's phones set to airplane mode. the fact that the interference was present in the transmitter's recording file makes me suspect that there is some sort of electrical fault in one of the units... 

[Freeman]

I'm having exactly the same issue. 

 

I recently got 2x BP-TRX units (timecode kit), 1x HD-TX and 1x DUO-RX for various uses (mainly corporate video stuff where I need to chuck a mic on someone quickly or get TC/waveform sync with very little time to set up). Love the idea, but I'm getting horrific RFI noise on both the BP-TRX units to the point of them being unusable for my purposes. 

 

I've tried pretty much everything. Unpairing/re-pairing, isolating each unit by powering off, firmware update on everything, changing every setting including RF power/latency, turning TC off, trying every possible tx/rx configuration between units, system reset. No luck.

 

I'm not in a place with unreasonable 2.4ghz interference, just a normal house with a standard wifi router and a couple of mobile phones nearby. I even tried unplugging my router and turning off every other device nearby running on 2.4ghz. 

 

Feeling pretty stuck and considering returning them.

 

Observations:

• noise type is an intermittent mid/high frequency stuttering very typical of digital RF interference you'd hear on a cheap mobile phone or similar. It's incessant but often disappears momentarily depending on how the units are positioned, but it's there most of the time. 
• loud enough that audio is functionally unusable (-20db to -10db under typical dialogue, registers on the VU meter clearly)
• clearly audible through the transmitters headphone output as well as the receiving unit
• carries across to the transmitters onboard microsd recordings, identical to the headphone output and receiver
• noise stops when transmitter is unpaired from the receiving unit or the receiver is powered off
• same issue on both BP-TRX units when transmitting, regardless of whether it was being received by DUO-RX or another BP-TRX
• RFI noise volume increases with input/preamp gain
• noise volume reduces when included mic (W.Lav) is unplugged, but still audible
• noise volume reduces when another mic (sennheiser ME2ii) is used instead of the included W.Lav
• noise is not present when using the REC ONLY mode
• the same issue is not present when transmitting from the HD-TX with the W.Lav to any units (DUO-RX or BP-TRX), indicating it's a problem with the transmitter mode on both BP-TRX units

 

I've messaged Deity support but haven't heard back yet.

 

Is this a known issue that someone like @Andrew From Deity could shed some light on? If so, is there a way of resolving this or have we just got faulty units that need to be RMA'd?

 

I'm really determined to make these work if possible.

[Freeman]

Here's a look at the spectral display if anyone's interested or could provide insight. This was a recording taken from the transmitting BP-TRX's SD card. Seems to be grouped in harmonics upwards from 400hz. Overlaps most of the useful dialogue frequency range so it's not great...

[Paul F]

You could try one of the free wifi analyzer apps to see what's running in the 2.4G band, what the signal strength is, and how it all overlaps with the Deity unit. Out of curiosity, I'd be interested to know how much of the 2.4G band the BP-TRX uses.

[kevcarlson]

@FreemanAny updates on this?  I just got the Connect kit, with the BP-TRXs and DUO receiver.  Right away I got interference using the Tx and DUO with a Tram mic.  

It might be less with the stock mic--need to try more things.  

Anyone know what is happening here?  I can't imagine a more ideal location than where I am right now... Is the lav cable being used as an antenna, causing a difference with different mics?

[Paul F]

Welcome to the wild world of 2.4G, the unregulated band that has everything on it but the kitchen sink.  There is no way to know what is on that band unless you have a spectrum analyzer and even then, it won't tell you much. Here is just a smattering of what your device is competing with:

 

[kevcarlson]

56 minutes ago, Paul F said:

Welcome to the wild world of 2.4G, the unregulated band that has everything on it but the kitchen sink.  There is no way to know what is on that band unless you have a spectrum analyzer and even then, it won't tell you much. Here is just a smattering of what your device is competing with:

 

Thanks @Paul F, but any explanation on why the stock mic that came will it seems to not have as much interference?

[Paul F]

I don't see anything in the documentation that says the BP-TRX has diversity receiver capability, which would mean there would be no reason to use the microphone as an antenna. Besides, you are using the BP-TRX as a transmitter, in which case, it would use only one antenna. 

 

RF stuff is so freaky, who knows what the microphone might have to do with it*. Maybe the RF off the antenna is coupling into the mic input better with the Tram. Try coiling it up into a tight coil and see if that effects it. That might indicate if the mic cable is a problem or just a coincidence that it performs better without the Tram.

 

*Larry probably knows, but he can't say anything on this topic.

[kevcarlson]

Thanks again @Paul F!

[borjam]

On 11/12/2022 at 5:52 AM, Paul F said:

I don't see anything in the documentation that says the BP-TRX has diversity receiver capability, which would mean there would be no reason to use the microphone as an antenna. Besides, you are using the BP-TRX as a transmitter, in which case, it would use only one antenna. 

In a system like the BP-TRX, the receiver is actually a transceiver because it's sending feedback information to the transmitter. 

On 11/12/2022 at 5:52 AM, Paul F said:

 

RF stuff is so freaky, who knows what the microphone might have to do with it*. Maybe the RF off the antenna is coupling into the mic input better with the Tram. Try coiling it up into a tight coil and see if that effects it. That might indicate if the mic cable is a problem or just a coincidence that it performs better without the Tram.

 

 

It must be a problem in the analog domain. These units transmit digital audio, which means that RF interference would cause drops. Maybe RF interference to the microphone, as you say, is causing this. I would try to coil the microphone cable around a small ferrite bead, a couple of turns or so. If that works it would mean you found where the problem is.

 

It doesn't need to be 2.4 GHz. The interfering signal affecting the microphone could be in a different band. 

 

Speaking of the 2.4 GHz band, and this is a long shot, look for alarm movement sensors. Some older ones transmit a strong signal on the 2.4 band, although more modern units work at 10 GHz.