FM can be heard as AM?

Is this a bug or a feature?

I was demonstrating the tuner to PaulG this morning and, from the remote, tried switching from FM to AM. Normally, when I do this, my sole AM preset kicks in.

Today, however, the FM station I happened to have tuned in came in as if it was am AM signal! (The circuitry was actually tuning in the FM frequency as if it was just AM.) What's more, I could toggle back and forth.

I don't see anything about this in the docs/faq, so I wanted to ask here before filing a bug report.

Of course, now I can't seem to replicate what I did before. When I rebooted the player, after that, the functionality worked as expected.

I will say that I was also demonstrating searching, moving through presets via both the player and remote buttons, and changing preset banks (A/B/C/D).

Comments welcome!

Both I and another person witnessed this behavior, so it is real.

That's right. No pretend FM/AM stories HERE, no sirree.

There was a known bug in earlier versions of the software that was similar to what you describe. However, I thought this bug was fixed during the internal alpha stage.

What version of the player software are you running?

More detail: There are certain audio filters that get applied to the AM signal, they are designed to make the normal characteristics of an AM radio signal sound more pleasing to the ear. There was a bug in one of the earlier software releases which caused these audio filters to sometimes be applied even when the selected station was an FM station. When this happened, it would make the FM station sound like an AM station, all tinny with no bass. Is this the bug you're describing?

I'm running 2.0b13 with the latest Hijack.

It definitely sounded like an AM station. Not only that, but the display changed such that it showed me as being in AM mode instead of FM mode, only the frequency was still an FM frequency and it sounded like an AM station.

Okay, this is a new bug, then.

Roger that. Sending off an email (once I attempt to try and reproduce it exactly ... I think if I tinker with the button presses enough, I can recall the pattern).

I am not really an expert in radio or anything, but it sounds like it is more the filter issue than a modulation technique issue. If the signal was understandable, then it was using frequency modulation to 'decode' the FM signal. If you use AM on an FM signal, you will not get anything that makes sense.

Exactly. Like I said, there was an old bug where it applied the AM DSP filters to the FM audio. Looks like it's a newer version of that same old bug.

I've put it on the internal bug list. I haven't reproduced it myself, so if anyone can post exact steps for reproduction here, that would be helpful.

Tony, I'll work to retrace my steps and reproduce it. (I know it didn't take much ... !)

Yup, noticed it here too, shortly after installing beta13.

Didn't believe my ears, so I ignored it.

-ml