Milwaukee WTMJ & WISN AM radio questions

[radio50]

Does anyone know for sure whether the Milwaukee, Wisconsin AM radio stations, WTMJ (620 kHz) and WISN (1130 kHz) are still transmitting IBOC (HD Radio) signals? If they stopped, when was that?

How do these stations control their carrier frequency? Is it GPS, Rubidium, OCXO, TCXO, simple quartz crystal or ?? It is different if they are running IBOC or not?

 

[Boombox]

I would think that if those stations are broadcasting IBOC you would be able to tell, because you'd definitely hear it on a local station. If you're not hearing it, they probably turned it off.

 

[radio50]

You are probably right. My HD Radio receiver has never been a great performer, and is not locking to IBOC on these stations. I don't hear anything special on adjacent channels. I thought someone might know for sure.

And I'm curious from a technical standpoint about how these stations control their carrier.

 

[radio50]

FWIW, I started hearing WTMJ-AM's IBOC (HD Radio) transmissions again, a couple days ago. Was IBOC off around the end of May / start of June? Or was my receiver just being flaky?

I'm curious how they control the carrier frequency of their transmitter. Is it GPS, Rubidium, OCXO, TCXO, etc? Does it depend on whether they are transmitting IBOC as opposed to plain AM? Just wondering about this technical stuff.

(I originally posted this in the HF/MW/LW forum but didn't get much response. The moderator moved it here on my request since it's a "Wisconsin Radio" topic, although not scanner-related).

 

[Gasman315]

JUst got out of my truck TMJ was HD