[Milsurplus] AI response to Jack Antonio’s request on FM v AM in aircraft.

[Brenda Gentry]

The capture effect is quite pronounced in older FM receivers with 
discriminators and ratio detectors. Newer auto FM receivers will detect 
two stations at once, one of my favorite stations that is thirty miles 
away is interfered with  when atmospherics change propagation patterns. 
The interfering station is heard clearly with the desired one. My FM 
tuner that uses a discriminator will play the stronger. FM tuners and 
receivers were once tested and rated for capture ratio. When reliability 
and knowing if there are two stations transmitting at once are 
paramount, the older technology may still be the best.

   B. Gentry, KA2IVY








On 7/31/25 11:02 AM, Jim Whartenby via Milsurplus wrote:
> I have a feeling that the capture effect is more pronounced with the 
> old Foster-Seeley type of discriminator then with the modern phase 
> locked loop discriminator that is used in today's FM radios.   One ICs 
> now replaces most of the old FM circuitry.
>
> Regards,
> Jim
>
> Logic: Method used to arrive at the wrong conclusion, with confidence. 
> Murphy
>
>
> On Thursday, July 31, 2025 at 02:57:44 AM CDT, Hubert Miller 
> <kargo_cult at msn.com> wrote:
>
>
>
> I often "FM band dial twiddle" whilst long distance driving. I not 
> infrequently note some unidentified distant FM bc station totally 
> overriding for a variable period of  time some also weak FM station i 
> am listening to.  AM bc stations are so well freq controlled now that 
> if there's any audible beat, your best guess is that one station is 
> Mexico or overseas. You can hear both audios at once. Yes, it is hard 
> to sort out, maybe impossible, but both - or more - are in there.
>
> Re AI - it seems that Ebay has done a good job selling it to the 
> rubes. These glowing AI listing descriptions all sound so alike, very 
> high BS factor.
> -Hue Miller
>
> Sent from my Galaxy
>
>
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