| Author |
Message |
    
Assaulter
| | Posted on Sunday, December 21, 2003 - 10:08 pm: | 
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What exactly is low level modulation? What is the purpose of it and what does it sound like?
Thx |
Bruce
| | Posted on Monday, December 22, 2003 - 4:47 am: |
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low level modulation takes place in the blanced modulator. the term is because that is a low level stage opposed to a high level modulation system where the modulation is applyed to the output stage and sometime also the flnal driver. How does it sound? well if done right both sound about the same however low level must travel and be ampufied all the way adding some distorion and limiting it to under 100% modulation. |
Tech8541
| | Posted on Monday, December 22, 2003 - 10:28 am: |
|
low level modulation does not always take place in the b.modulator and does not limit modulation to less than 100%. take the 2510/lincoln, which uses low level modulation, for example. modulation takes place in the tx mixer. a basic tune up can yield 150% modulation. removing 1 capacitor can raise the modulation to more than 200%.
bascially the difference between low level modulation and high level modulation is the low level mod happens near the beggining of the tx chain, and high level modulation happens at the end of the chain. the galaxy/rci radios are high level modulated radios because the modulating audio is delivered to the driver and final/s. the reason low level modulation is used is because it keeps cost down in the multi-mode radios. if you add the audio at the beginning of the tx chain, you don't need a very strong audio signal. this means you don't need the big, and more expensive, audio amps to push the driver and finals. if you notice the biggest device in the rci/rangers is the a.m. modulator transistor. |
Bullet
| | Posted on Tuesday, December 23, 2003 - 12:34 am: |
|
richard,
nice explanation!
merry christmas
bullet |
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