Query for any FM technical nerds

Everything technical about radio can be discussed here, whether it's transmitting or receiving. Guides, charts, diagrams, etc. are all welcome.
Post Reply
User avatar
g33ky
tower block dreamin
tower block dreamin
Posts: 281
Joined: Tue Dec 03, 2019 10:39 am
Location: Wirral

Query for any FM technical nerds

Post by g33ky » Sun Apr 26, 2020 3:50 pm

I 99% understand how FM works but theres one thing I've never understood. See img 1:
img1.PNG
No audio is on it so it's not deviating at all, but my question is why does the 19khz pilot not deviate the signal? Even if I inject a 1hz (yes, 1hz) signal into the transmitter, the carrier starts to deviate (a bit). See img 2:
img2.PNG
So my question is what makes a 1hz signal deviate the signal but not a 19khz signal?
You do not have the required permissions to view the files attached to this post.
FM for lyfe!

mikroman
big in da game.. trust
big in da game.. trust
Posts: 67
Joined: Sun Apr 12, 2020 8:25 pm

Re: Query for any FM technical nerds

Post by mikroman » Sun Apr 26, 2020 4:35 pm

Here is graph of 19KHz dev. (at 10 and 100 percent). Everything is there ;)
You do not have the required permissions to view the files attached to this post.

User avatar
Electronically
tower block dreamin
tower block dreamin
Posts: 431
Joined: Wed May 13, 2015 11:43 am

Re: RE: Query for any FM technical nerds

Post by Electronically » Sun Apr 26, 2020 5:22 pm

g33ky wrote:I 99% understand how FM works but theres one thing I've never understood. See img 1:
img1.PNG
No audio is on it so it's not deviating at all, but my question is why does the 19khz pilot not deviate the signal? Even if I inject a 1hz (yes, 1hz) signal into the transmitter, the carrier starts to deviate (a bit). See img 2:
img2.PNG
So my question is what makes a 1hz signal deviate the signal but not a 19khz signal?
I don't think 1hz is enough. but as micro said it would be around 9.5 to 10hz.

Sent from my AMN-LX9 using Tapatalk


Post Reply