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[Non-DoD Source] Re: Auto plug conversion

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mark.bitterlich(at)navy.m
Guest

Posted: Tue Mar 08, 2016 8:15 am Post subject: [Non-DoD Source] Re: Auto plug conversion

Never thought I would disagree with Jan ...... but   



Jan, I agree with your math of course,  but it's not commonly applied as a reason of choice between modulation modes in my opinion.  The final answer to your comment regarding the number of sidebands is of course the bandwidth of the signal, which you mentioned.  Way back in the day when FM radios were using deviation that was 30 or more KHz wide, I would have agreed with your rationale, but that has changed tremendously over the years with better discriminator design.   While AM still has (in theory anyway) about a 6 KHz bandwidth, the receivers are running about 10 KHz on their band pass requirements due in part to past specifications that required wiggle room due to L.O. instability.  Since then, communication FM signals have lowered deviation to about 12 KHz, and recently have cut that down over half using deviation of 2.5 KHz giving a total bandwidth of 5 KHz.  Thus current FM communication radios (in this country) have bandwidth that is LESS than Amplitude Modulation !!



I believe the truth is, A.M. was the original design and F.M. was a "Johnny come lately"  and your reasons were indeed accurate back in the day.   Today the cost to re-equip every aircraft on Planet Earth would be cost and labor prohibitive, but just for the reason you mention (noise detection) today FM radios would be a much MUCH better choice as evidenced by the fact that commercial communication has moved to it TOTALLY and they have even more restrictive bandwidth requirements than we do.



Mark

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Viperdoc

Joined: 19 Apr 2014
Posts: 484
Location: 08A

Posted: Tue Mar 08, 2016 9:30 am Post subject: [Non-DoD Source] Re: Auto plug conversion

Ah screw it. Turn the damned radio off and go fly. It's a big sky out there. Besides ADSB is going to be our see and avoid savior. 😳

Eye balls out!

Check 6😜

Doc

Said tongue in cheek.



Sent from my iPad



[quote] On Mar 8, 2016, at 10:14 AM, Bitterlich, Mark G CIV NAVAIR, WD <mark.bitterlich(at)navy.mil> wrote:

 

 

 

 Never thought I would disagree with Jan ...... but   

 

 Jan, I agree with your math of course,  but it's not commonly applied as a reason of choice between modulation modes in my opinion.  The final answer to your comment regarding the number of sidebands is of course the bandwidth of the signal, which you mentioned.  Way back in the day when FM radios were using deviation that was 30 or more KHz wide, I would have agreed with your rationale, but that has changed tremendously over the years with better discriminator design.   While AM still has (in theory anyway) about a 6 KHz bandwidth, the receivers are running about 10 KHz on their band pass requirements due in part to past specifications that required wiggle room due to L.O. instability.  Since then, communication FM signals have lowered deviation to about 12 KHz, and recently have cut that down over half using deviation of 2.5 KHz giving a total bandwidth of 5 KHz.  Thus current FM communication radios (in this country) have bandwidth that is LESS than Amplitude Modulation !!

 

 I believe the truth is, A.M. was the original design and F.M. was a "Johnny come lately"  and your reasons were indeed accurate back in the day.   Today the cost to re-equip every aircraft on Planet Earth would be cost and labor prohibitive, but just for the reason you mention (noise detection) today FM radios would be a much MUCH better choice as evidenced by the fact that commercial communication has moved to it TOTALLY and they have even more restrictive bandwidth requirements than we do.

 

 Mark

 

 

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_________________
Viperdoc

jan.mevis(at)informavia.b
Guest

Posted: Tue Mar 08, 2016 9:38 am Post subject: [Non-DoD Source] Re: Auto plug conversion

Thanks for the corrections Mark!



I reasoned from the mathematical physicists point of view (which I am).



Time to study some real radio techniques!

Jan



On 08/03/16 17:14, "Bitterlich, Mark G CIV NAVAIR, WD"

<owner-yak-list-server(at)matronics.com on behalf of

mark.bitterlich(at)navy.mil> wrote:



[quote]

<mark.bitterlich(at)navy.mil>



Never thought I would disagree with Jan ...... but   



Jan, I agree with your math of course,  but it's not commonly applied as

a reason of choice between modulation modes in my opinion.  The final

answer to your comment regarding the number of sidebands is of course the

bandwidth of the signal, which you mentioned.  Way back in the day when

FM radios were using deviation that was 30 or more KHz wide, I would have

agreed with your rationale, but that has changed tremendously over the

years with better discriminator design.   While AM still has (in theory

anyway) about a 6 KHz bandwidth, the receivers are running about 10 KHz

on their band pass requirements due in part to past specifications that

required wiggle room due to L.O. instability.  Since then, communication

FM signals have lowered deviation to about 12 KHz, and recently have cut

that down over half using deviation of 2.5 KHz giving a total bandwidth

of 5 KHz.  Thus current FM communication radios (in this country) have

bandwidth that is LESS than Amplitude Modulation !!



I believe the truth is, A.M. was the original design and F.M. was a

"Johnny come lately"  and your reasons were indeed accurate back in the

day.   Today the cost to re-equip every aircraft on Planet Earth would be

cost and labor prohibitive, but just for the reason you mention (noise

detection) today FM radios would be a much MUCH better choice as

evidenced by the fact that commercial communication has moved to it

TOTALLY and they have even more restrictive bandwidth requirements than

we do.



Mark

--

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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