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MD-1 Install and Review
- Thread starter secret squirrel
- Start date
Shadetree Mechanic
Delaware Base Station 808
He should turn the dead key down before he connected the thing. I wonder what it would look like? If this thing keeps the negative peaks from flat lining, then it is doing its job.
If you watch the scope closely with the different carrier/NPC schemes, you can see where the action is. The MD-1 will vary the carrier at an audio rate similar to the regular NPC “galaxy” mod. When you couple the scope signal in, leave the coupling in DC. You’ll see the DC portion of the carrier varying up and down at an audio rate. In theory it should not exceed 100% negative. Improperly set , anything can look like crap
DSB/SC 
Aug 12, 2009
"the only legitimate purpose served by any form of clipping or compression is to improve the S/N ratio in the receiver front-end at the other end of the circuit." only from the receiver end of a communications link can the benefits of processing formats such as compression and clipping be truly evaluated.
https://www.worldwidedx.com/threads/what-npc-rc-mod-looks-like-on-a-scope.16094/page-5#post-151491
https://www.worldwidedx.com/threads/what-npc-rc-mod-looks-like-on-a-scope.16094/page-5#post-151510
https://www.worldwidedx.com/threads...ssion-boards-for-cobra-29.261647/#post-760960
here are how the 4 most prevalent forms of audio processing stack up against each other in their ability to produce an increase in signal intelligibility at the receiver.
audio compression level
25 dB = 1dB. improvement
rf compression level
25 dB. = 1 dB. improvement
audio clipping level
25 dB. = >5 dB. improvement
rf clipping level
25 dB. = >9 dB. improvement
Aug 12, 2009
"the only legitimate purpose served by any form of clipping or compression is to improve the S/N ratio in the receiver front-end at the other end of the circuit." only from the receiver end of a communications link can the benefits of processing formats such as compression and clipping be truly evaluated.
https://www.worldwidedx.com/threads/what-npc-rc-mod-looks-like-on-a-scope.16094/page-5#post-151491
https://www.worldwidedx.com/threads/what-npc-rc-mod-looks-like-on-a-scope.16094/page-5#post-151510
https://www.worldwidedx.com/threads...ssion-boards-for-cobra-29.261647/#post-760960
here are how the 4 most prevalent forms of audio processing stack up against each other in their ability to produce an increase in signal intelligibility at the receiver.
audio compression level
25 dB = 1dB. improvement
rf compression level
25 dB. = 1 dB. improvement
audio clipping level
25 dB. = >5 dB. improvement
rf clipping level
25 dB. = >9 dB. improvement
Last edited:
Shadetree Mechanic
Delaware Base Station 808
The biggest benefit for modulation over 100% is to run an amplifier that is not linear. With the radio running a clean 150%, the amplifier output can be around 90%. So out of the radio, it might look like dual sideband. Out of the amp, it is regular old AM. The modification without an amp is not really helpful for trying to talk any kind of distance in my opinion.
Especially to talk on bigger distance. AM detector need certain lvl of input voltage to start it's work. Low carrier on the other side, no detecting.
Mike
Mike