- This topic has 14 replies, 5 voices, and was last updated 15 years, 5 months ago by
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Hey , i think i ve found a bug !
When you use Airomete wirh Breakaway through the "mix" imput mode you create a 31 degrees phase drift !!!
When you use Airomate with Breakaway through "left" or "right" imput
mode there is no phase drift! ( 0 degrees)1st question : why Leif says that it is very important to chose on I/O settings the "mix" mode in RDS pipeline and not the "left" only or "right" only?
2nd question : why do i have phase drift 30degrees ONLY when i listen to Leif’s suggestion to chose the "mix" mode on I/O settings ?
3rd question : what are the problems that a big phase drift causes?
is this very bad? loss of loudess? loss of lock on recievers?The phase of what is drifting…. RDS? Which way is it drifting (i’m assuming positive since you didn’t put a negative sign in)? And how long does it take for whatever is drifting to drift to 30-31 degrees?
I used the pira fm spectrum analyzer,
when i select from the I/O settings of Breakaway RDS imput with left only or right only it has 0 degrees drift
when i select …."mix" as Leif suggests i ve got 31 degreess drift!the 31 degreess are possitive.
I use vista 64bit , and breakaway virtual cables..
Jessie, why Leif says that it’s very important to chose "mix" on I/O RDS settings of Breakaway ?
and why with "mix" i ve got phase drifts ?
Do you mean phase shift? Because drift is something that is variable over time. Shift can be too, but it also can be the same over time where a drift is not.
And… what is phase shifting? the RDS?
Hi Camclone:
When Airomate generates Pilot + RDS in "RDS Only" mode, with synchronization channel enabled, then RDS and Pilot will come out of Airomate separately — for example RDS in Left, and Pilot in Right.
If you then tell BBP to listen only to Left, BBP will not see the Pilot from Airomate, and it will generate its own (and say Pilot Absent). If so, pilot will be completely unsynchronized with RDS.
If you tell BBP to listen only to Right, BBP will see the Pilot from Airomate, but not the RDS, and thus you won’t get any RDS at all 🙂.
This is why I recommend using "Mix" — BBP will then see both, just as it should.
If they end up out of phase by 31 degrees, than is likely a bug in BBP! Looks like I need to investigate further.
Unfortunately the display on my Pira.cz analyzer cracked in my suitcase 🙁. Hopefully I’ll be able to use it with the serial software. Otherwise, I’ll just have to buy a new one, and be more careful next time.
I don’t believe RDS phase shift is disasterous (it makes no difference for loudness, and should not make any difference in reception) but it’s certainly not correct.
Best,
///LeifOh, just to make sure we’re on the same page:
Phase Drift is when the phase shift between two signals changes over time, correct? 🙂
///Leif
Camclone, you are 100% correct!
Here’s what 19 + 57 kHz in phase looks like:
Here’s what it looks like through Breakaway:
That’s definitely phase shifted. Thanks for the heads up!
I’m not sure how this obvious error slipped by me. I’ll get to the bottom of it.
///Leif
Good investigation!
Leif: Months ago I talk with you with a problem with RDS, when I combine Airomate with BBP, more RDS screens jumps without see in the receiver.
Could this be the problem?
If I only use Airomate, the RDS works perfectly!
Thanks!
Didac, it could be! It depends on the inner workings of your receiver.
Any receiver which uses the pilot to decode RDS would definitely be affected by this error.
However, I don’t know that most receivers do, because you can run RDS on an FM mono station, without having a pilot at all, and the receiver would then not have any pilot at all to lock on to!
Anyway, I have fixed the problem — looks beautiful now! I also implemented a much more accurate way to do 90 degree phase shift in my MPX encoders/decoders, resulting in 70dB stereo separation instead of the previous 50dB! 🙂
Best,
///LeifOh! It’s perfect!
Great news!
Does the separation will improve for all users? Or just for using RDS?
Thanks!
I waiting the version with this error fix to try the RDS and post my results.
Stereo Separation should improve for all users, but it won’t make an audible difference. Vinyl records are only 20-25dB stereo separation, and they already sound fully stereo. 50 or 70dB makes no difference.. 70 is a higher number, though. 😉
Best,
///LeifAnd here’s what 19000+57000hz looks like through BBP after the fix:
Please note that 19000 + RDS will NOT look like this. The RDS signal is a modulated subcarrier, not a 57000hz sinewave. To test phase alignment you’ll have to actually generate 19000 + 57000hz in phase (easily done with Adobe Audition — generate 19k in the left channel, 57000 in the right, and optionally mix the channels together) and feed it into the RDS input of BBP.
New BBP version (and BBP ASIO) should be out in a few days. It has taken much longer than anticipated — I keep having to push it back due to factors outside my control, but I’m starting to see the light at the end of the tunnel. Let’s just hope they’re not the headlights of a train 🙂.
Best,
///LeifI think that after that bug fix , breakaway FM will be just PERFECT!
It’s the only bug , i am sure about that, i ve tested it, i ve taken it to the limits of audio 🙂
So, until Leif releases the latest version which will have 0 degrees phase at 57k subcarrier IT IS VERY IMPORTANT FOR YOUR COMPATIBILITY WITH THE RECIEVERS TO CHOSE ON AIROMATE THE FOLLOWING :
Airomate settings..
57k subcarrier = 330 degrees .
so after that it will go to 0 degrees.I made that untill leif relieases the latest version with 0 degrees
Leif, I feel very happy with my investigation 🙂
I will always check everything to be sure 🙂I ve had problems with a sony reciever’s AUDIO !!!! and the fault was the phase drift! the reciever ( car radio) was making the audio sound very compressed and pumping up at the bass! , after the correction of the phase drift the problem disapeared!
lol ! i l have 1%…more.. car radio audience…from today 🙂
Is this bug fixed in the Breakaway that you download at this time…
Or do I have to wait till a new version comes out…Otto,
I believe will be fixed in the next release!!! 🙂
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