| Author |
Message |
    
Tech181 (Tech181)
| | Posted on Wednesday, August 29, 2001 - 12:00 am: | 
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In my travels I read many times that the Sound Tracker radios perform poorly with clipped modulation limiters or just too much mod period.
While ragchewing with one of the locals tonight I talked to a fella that sounded absolutely crappy. I asked him what kind of radio he was running and he told me it was a Cobra with the Sound Tracker circuitry.
I asked him to turn off the Sound Tracker and he complied. What a difference! From overmodulated and distorted to clean and loud. A marked improvement!
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ChillyDog
| | Posted on Wednesday, August 29, 2001 - 10:40 am: |
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Steve,
Do you know what modifications he had in his Sound Tracker Cobra? Clipped limiter, NPC, NPC-RC, or ???
Thanks,
Bob |
Skullman
| | Posted on Wednesday, August 29, 2001 - 5:55 pm: |
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Just my past experience here, but the sound tracker works great, only when the recieving radio is also a soundtracker. Both guys have to have identical radios to appriciate the soundtracker function. Turn it off, and it's just as good as any Cobra CB. I've had several of them, and the same results each time. Maybe that's why Cobra re-released the old 29 ltd classic. Don't get me wrong they're great radios, it's just that if the guy you're talking to doesn't have the soundtracker function he'll call it "soundcrapper".
CEO of DEADMAN INC. |
ChillyDog
| | Posted on Wednesday, August 29, 2001 - 3:35 pm: |
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Thanks, Steve!
I've been tempted to experiment with mods for a Sound Tracker, but don't really know where to start. They do seem very sensitive to adjustments and accessories, and don't like power mikes at all.
The Sound Tracker compander works OK with other Sound Trackers, but too many users don't seem to understand that _both_ radios need to have the compander to work. This guy you mentioned must be one of them.
Thanks again!
Bob |
bruce
| | Posted on Wednesday, August 29, 2001 - 9:11 pm: |
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how does the sound tracker work is it pre/de emphis like the old FM systems ? since i dont own one im just interested in the compaction sceam |
ChillyDog
| | Posted on Thursday, August 30, 2001 - 2:13 pm: |
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The Sound Tracker is a compander. That means it compresses the audio dynamic range (loudness) on transmission and then expands it on reception. Com=compress, pander=expand. When transmitting it makes the quieter sounds louder and the louder sounds quieter. When receiving it restores the sound levels.
What companding does is effectively moves the desired audio signal above the noise during transmitting and "squishes" the noise during receiving. It does work, but both transmitter and receiver must be working together.
Bob |
bruce
| | Posted on Thursday, August 30, 2001 - 8:25 pm: |
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so it is a compresser on recive audio that looks for the same form of compression from the other transmitter on fm radios we used to expand the high range on trans and decrease the high range on recive to decrease noise kinda like the old doby systems for tape of years ago. |
ChillyDog
| | Posted on Friday, August 31, 2001 - 8:59 am: |
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Bruce,
You've got it! FM pre-/de-emphesis is very similar to companding. The only difference is that pre-/de-emphesis works in the frequency domain (different frequencies are modified in different ways) and companding works in the amplitude domain (different signal levels are modified in different ways).
Bob |
bruce
| | Posted on Friday, August 31, 2001 - 10:17 pm: |
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Am i showing my age all this work and i can remember the good old days when we used simple ways duel diodes straped to self bias and clip above that point. Then came the noise blanker simple device just shut things down during a noise spike. Still back many years ago i remember the smell of 25 tubes cooking in the dark makes me wonder what ever happend to my 6h6 self ajusting ANL? |
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