Holy FCC Part 15 violation, Batman!

[giza]

So... I'm up at my parents' place in Allentown for the Labor Day Weekend. While chatting with my father a few minutes ago, I was idly scanning the 70cm (420-450 Mhz) band on my ham radio. Suddenly, the scanning stopped and I heard music playing. Now, sending music over the ham radio bands is illegal, so that shouldn't be happening. I listened for a few seconds, and it suddenly dawned on my that my father's radio was softly playing the SAME song! I asked him to turn off the radio and when he did, the music stopped.

So we did some more experimenting, and discovered that different stations caused music to be played on different ham frequencies. Here are my observations:

95.1 Mhz -> 425.600 Mhz
98.1 Mhz -> 435.475 Mhz
100.7 Mhz -> 442.550 Mhz

What's really strange is that these frequencies aren't even harmonics. The multiplication factors of each frequency in the 70cm band are 4.47, 4.43, and 4.39, respectively. I've never heard of anything like this happening before.

Anyone ever heard of anything like this happening before? Anything I can do to fix the problem?

Comments

[nius.livejournal.com]

Well, your T7H's first IF is 45.15 MHz. 425.600/45.15 = 9.42635659.

Now, according to Wikipedia, the IF of most FM VHF receivers is 10.7MHz, so 95.1/10.7 = 8.88785047. My guess is the IF of your father's receiver is slightly higher, thus creating a mixed signal that is a harmonic of the 70cm ham band.

Also, if his receiver is of extremely high quality, it may be a double-conversion superhet, like your HT, and have two IFs. Probably using 455kHz, the same as your HT's second IF, so I think it's pretty obvious how you could pick up signals from his mixer if you're sharing IFs :)

Ever wonder how Radar-detector-detectors work here in Virginia (where Radar detectors are illegal)? They catch your IF.

[nius.livejournal.com]

s/higher/lower - the IF of your father's receiver would be approx 10.09 to create a harmonic of 425.6. I was thinking my fractions backwards when I typed that.

[kellic.livejournal.com]

Are your subspace transducers K model or M? If K you need to upgrade them. This problem was fixed in M type model. Something about the quantum states being shifted due to a bad Konfabulator filament.

*Runs away before Giza can thwack him* :x)

[garrwolfdog.livejournal.com]

Man, this raises all sorts of physio-philosphical questions,.... Pythagorus would have LOVED it!,. if he hadn't been brutally linched by an angry mod a few thousand year back,... and wouldn't have considerd the mathematics, required to make radio work, as an abomination and proberbly would have had you secretly executed at sea for indulging it,....
Hmmmmmmm,... i'm fairly sure I had a point,... cant' recall what it is though,....

[taral.livejournal.com]

Hm... well, it's unlikely your scanner's picking up things in its IF range, so the radio's probably producing harmonics from its IF mixer. Not sure why the slopes are funny though... (435.475-425.6)/(98.1-95.1) != (442.55-435.475)/(100.7-98.1)

[giza.livejournal.com]

*reads up on superhets* Heh. Neat stuff.

Eh, his "receiver" is a GE Boombox that's about 15 years old.

What my real question/concern is, is this a Part 15 violation? Do I need to tell him to stop using the radio?

I'm also unclear how I've got harmonics coming out on different frequencies if the IF is support to be constant. Am I missing something?

[andrew7782.livejournal.com]

When I was in Virginia Beach I was picking up a TV station in the 2 meter bands. Contacted the FCC, but I don't know if anything came of it because I was home by the time they replied.

[nickhalfasleep.livejournal.com]

"Dad, under Part 15 of the FCC code I demand you turn off your radio"

[giza.livejournal.com]

I tried that. Well, I didn't demand, but I suggested it to him.

Then again, he voted for Bush because "John Kerry is a LIBERAL". So draw your own conclusions.