Yesterday I purchased a Motorola S9 stereo bluetooth headset for my cell phone. My phone plays music and the radio, so the purchase is not quite as vain as it might first appear, and I tend to listen to sermons during my ride to and from work. Since I ride my bike, having a wireless headset really helps, as wires tend to get caught up in my helmet, and frankly, when I am riding it is quite a hassle to dig my phone out - much easier to tap a button and answer the call on the fly.
So I charged it up (it has a six hour play time) and gave it a listen. The mid tones were excellent, and the high tones perhaps a hair too shrill, and the base perhaps a bit lacking - but that is to be expected from the speaker style. It was certainly nothing to complain about. The range was good, and the sound quality better than merely "acceptable". It was light, and dare-I-say-it stylish. The perfect headset for listening to wireless audio in stereo. I could hardly wait to test it out on the road!
So this a.m. I got put it on and found (thankfully) it did not interfere with my bike helmet, and was not uncomfortable at all - I could barely tell it was there. I put on some tunes, and away I went! Only within 20 yards I was already quite disappointed.
What had been crystal clear indoors, was suddenly, and inexplicably choppy. The signal was cutting in and out consistently, perhaps two or three times in any given ten second interval. It was maddening. I couldn't understand why the reception was so poor. Indoors it seemed fine, but out here on the road the reception was horrible.
As something of a tech professional, I am not without some resource with regards to the matter. That is, I didn't immediately say, "I can't believe this thing is a piece of junk" and get myself into a huffy-snit. Instead I got into trouble shooting mode.
First question: What's going on?
Answer: I am losing the signal very often, and quite periodically.
Off-the-cuff Considerations:
[1] The temperature is only slightly above freezing.
[2] I am moving on average at about 20 mph.
[3] I am passing underneath a lot of power-lines.
[4] I am moving in a rhythmic manner (pedaling).
[5] My cell phone case has a magnetic latch.
[6] The cell phone is about waist level.
My first thought? Perhaps the phone and headset are too far separated. It doesn't really make sense because yesterday I walked clearly ten feet from the cellphone and the reception was rock solid. But nevertheless, the choppy reception was so annoying I grabbed my cell and lifted it up to the headset.
Nada. Still choppy.
Okay, maybe the magnetic case? I took the phone out of its case, and let the phone hang "commando" style, to see if the reception was better.
Nada. Still choppy.
Perhaps the phone was being jostled around too much? It didn't seem likely (it -is- solid state after all, no moving parts - no wire to plug in and break a connection so to speak). So I slowed down a bit and tried to keep steady.
Hmmm. I tiny bit better maybe?
That was almost infuriating knowledge? Why oh why would it get better if I slowed down?
Then I thought about when I stopped to get the phone out of the case. Hmmm. The choppiness stopped when I stopped. I was seeing a direct link between moving and reception.
That made me think that maybe it was some overhead power lines, or maybe some sort of jostling. I considered the possibility of a Doppler effect, but c'mon - radio waves travel at the speed of light, and I doubt my little 20 mph could produce that kind of interference even if it were possible.
But as I came to the "riverbed" part of my ride, I thought I should be out from under any power lines, and frankly, if there is some stray background noise interfering with the signal, it will likely be less as I go down by the river.
Still the same.
Okay, so I stop and take it out of my one pocket and put it up near my neck...
A little better, but not much. It is still cutting out at least once every five seconds, and the faster I go, the worse it is. Clearly it is [1] very sensitive to movement or [2] it cannot pick up the signal when the phone is at my waist, as well as it can pick it up when the phone is at my chest. Whatever the case, moving the phone higher up on my torso seemed to make the problem slightly better, but by no means acceptable.
I was already sitting down when I suddenly thought - hey, what about my wireless bike computer? Could it be causing interference with the bluetooth?
Bluetooth devices (in North America and Europe) typically operate in the 2.4 GHz range. I was pretty sure my bike computer was in the 900 MHz range, so there shouldn't be any problem right? Okay, so I look up the manual for my bike computer on the internet - no information whatsoever on the radio frequency. I had to get down on my hands and knees and check the device itself. On the device it tells me what transmitter it is using: CE0681 - which is a 2.4 GHz transmitter...
Suddenly it all makes sense.
So, if you are a cyclist and using a wireless bike computer and a bluetooth headset and can't figure out why the headset is acting up, here is why - every time the magnet on your speedometer passes the wireless transmitter, it is sending a pulse to your LED receiver, and that pulse is disrupting your bluetooth headset.
Anyway, that is my troubleshooting story for the day. Wireless Bike Computers and Stereo Bluetooth Headsets do not play nice together.
Update: While I haven't yet removed the offending wireless transmitter from my bike, I did move the magnet on the spokes away from the transmitter, which in theory should stop the transmitter from transmitting, and doing so -did- help the reception, even remarkably so, but it was still not optimal. Before I remove it entirely to see if that will help more, I plan to take my wife's bike out of the shed and give it a spin. I also tried (separately) putting the phone in my pannier (saddle bag) instead of in my front pouch - that made quite a difference as well. Between doing the two the interference is far less frequent, even bearable.
Update #2: Okay, I moved the magnet once again, as far away from the wireless transmitter and viola! Perfect reception all the way home. Not even a single skip. Very nice. Conclusion: it isn't the S9's fault if your reception is bad on a bike when using a wireless bike computer.
Update #3: One more thing - as the weather demands it, I ride with a spandex/fleece hoodie. When I put the headset under the hoodie, and clamp it down under my helmet straps - I find that the reception skips. I am not sure if it is because the buttons are sensitive, or I am putting undue torque on the headset, or if the reception is made worse by doing so - but I noticed it, so I am recording it.
Labels: Motorola S9; cycling |
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