Bluetooth bandwidth and battery tests (Q35)

[The_Professor]

Question to Q35 testers, settle an engineering discussion.

LDAC 999 = 1Mbit
666 = 0.6Mbit
333 = 0.3Mbit

Bluetooth is 2.4Ghz, same frequency as microwave ovens which use the H-O bonds in water / fat resonant frequency to excite and heat. The human body is 2/3rds water and fat so human body absorbs 2.4Ghz hence degrades bluetooth signal.

With over-ear headphones the antenna is outside the body off-skin, so we’d not expect the receiver to have an issue. Similarly a source away from the body like on a desk, is off the body should also be fine.

So the question is if bluetooth 5.0 can transmit 1Mbit through the body.

Can a Q35 owner who can fix to LDAC 999 (not auto) can place their paired connected phone inside their pocket, same and opposite side of body, and see if that causes an issue?

Related question, has anyone measured the battery impact on LDAC 333 666 999?

LDAC (codec)

Nguyen-EJ-edit.pdf

A related question for the above external over-ear headphones, for other potential future LDAC 999 products, is antenna length

Source https://gaidi.ca/weblog/designing-a-bluetooth-antenna-how-to-go-about-it

So you see how antenna length impacts performance, so a much shorter antenna than the optimal 25mm (an inch) degrades performance. Performance can be offset to a degree by battery usage, so the interesting discussion is an in-ear design with necessarily more absorption by the human body and a shorter antenna and a small battery.

The terrific Q30 teardown video

shows battery

and antenna (dipole) so about an inch long for optimum signal

The also terrific L2P teardown

You see the battery

and antenna from the FCC listing

which looks also dipole and shorter than the Q35 antenna so you’d logically expect a weaker signal so consume more power, and you’d expect to be shorter distance for a given bandwidth / codec.

[VertigoXX]

Nice post. Technical issues are mostly not discussed well enough

[The_Professor]

Thanks, I’m more interested in the engineering than the sound they make.

In the above video you see the microphone right inside the ear on the Apple product, vs the coaxial armature of the L2P. There truly is a tougher set of choices for in-ear of sound quality vs ANC, and battery life vs quality vs distance.

[Duane_Lester]

Here is what I will say. As stated, I took the headphones to get the mail and it started to have some distortions at about 150 ft away. About 120 it was still good. I was also doing some clicking of the touch to change the ANC and turning my head and such but I do not remember any difference when touched or not.

I will say that any distortion from the body is probably limited. I mean I was at work and as I stated, I had about a couple of walls more than at home and the headset was in my bag, and in the case and it was probably a good 180 or more and they still had a connection. (I found that by accident as I was checking out something on my phone and noticed there was no noise).

I do not have them with me at work, so any further test can not be done for that until I get home.

My son has the q30 now and I wanted to compare whether the LDAC actually gave the distance as the q30 as I would think the q35 would gave a better connection as far as distance.

[The_Professor]

Was LDAC auto or fixed to 999?

You’d expect logically that 999 would cut out at less distance than 666, and 333 to cut out furthest.

I’d also expect headphones to be better than in-ear like-for-like bitrate. Anyone capable of that test?

[jercox]

I don’t know about forcing it to LDAC mode - the box is checked and the status on my phone says LDAC High Quality Audio in use.

I tried it with my phone at my desk and walking to the far end of my bedroom - which is where bluetooth always starts to cut out on most devices (something like 5 or 6 walls plus miscellaneous dresser / shelves in between, probably 30 feet). It broke up as I walked around the last corner, just like it does without LDAC, and the same as most / all bluetooth devices I have tried. Walking out to the mailbox from my desk (50-60 feet, straight line of sight through one wall) has no issues.

I can’t find any through body position that causes issues with the connection, with or without LDAC. I have had issues at times with in ear headphones, when the connection is cross body and I turn my head at certain angles, but not here.

Battery life I haven’t tested extensively, but not an obvious and dramatic change between on and off.

For both issues, performance is better than my use cases require. On body no issues, within a normal range of use as well. 40-50 feet or through several rooms, exceeds what I use it for.

Normal usage variability is great enough that I probably wouldn’t notice a change in battery life across a device that lasts all week - probably less than the change based on how long I spend on conference calls.

[The_Professor]

Thanks for putting in the effort.

Before break-up, did you detect drop in audio quality? It’s the auto aspect of LDAC “Best Effort” means quality should in theory degrade as the underlying bluetooth bandwidth drops below 1Mbit.

https://www.sony.net/Products/LDAC/

It would require the ears of a better person than me, as all Soundcore products sound just fine to me.

[ktkundy]

hmmm i havent had the biggest issues with LDAC as of yet but dont kow if mine is at 999 or lower LDAC I do notice that if i have a bunch of other stuff with bluetooth on an im not right next to my phone it breaks up a little

[roger186]

Is the 999 / 1Mbit the bit rate achieved or the bandwidth used?

I suspect it’s the bit rate and by using data compression techniques, the bandwidth used is significantly less.

[The_Professor]

It’s the compressed actual radio transmission rate - bandwidth. Bluetooth 5.0 itself can to 2Mbits, but at what cost in battery (radio, compute).

Bluetooth 5.2 has LE Audio but that’s a different topic.

Thanks to the above posts, the Q35 seem very robust on LDAC, so the curiousness shifts to how good you can do it in-ear with smaller battery or shorter antenna?

[jercox]

I’m not the best one to judge on quality, but there was no perceptible change before it just started to break up / stutter in and out.

There isn’t much obvious in the phone interface about quality. I had my daughter wear the earbuds while at a distance so I could see the phone, and there was no indication of a change.

[The_Professor]

Hey silly me.

I don’t own any Soundcore with LDAC (never selected, never won) but I do own Sony with LDAC.

Seems in developer mode I am already LDAC and auto bitrate. These my options

So what I can do is fix mine to specific speeds and see what distance they drop.