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mark22
03-25-05, 07:51 AM
How to calculate signal loss when using a combiner?
1-Please need help to figure out how to calculate the loss when using a 2-way combiner (diplexer). Assuming that I have two leads that I want to combine; OTA signal 14 dB and satellite signal 24 dB; the loss would be -4 dB. From which number I subtract 4, from 14 or from 24?
2-Also, it is absolutely necessary to have the signals to be combined of the same level (or very close; how close?) or they can be like in my example (14, 24)?
3-If they have to have the same level, how I do that?
Thank you
Mark
1-Please need help to figure out how to calculate the loss when using a 2-way combiner (diplexer). Assuming that I have two leads that I want to combine; OTA signal 14 dB and satellite signal 24 dB; the loss would be -4 dB. From which number I subtract 4, from 14 or from 24?
2-Also, it is absolutely necessary to have the signals to be combined of the same level (or very close; how close?) or they can be like in my example (14, 24)?
3-If they have to have the same level, how I do that?
Thank you
Mark
kuhurdler
03-25-05, 09:12 AM
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mark22
03-25-05, 09:34 AM
So probably to play safe I should substract 3.5 (or 4 dB in my example) from the lowest, resulting signal being 10dB?
Blizzard
03-25-05, 09:55 AM
How to calculate signal loss when using a combiner?
1-Please need help to figure out how to calculate the loss when using a 2-way combiner (diplexer). Assuming that I have two leads that I want to combine; OTA signal 14 dB and satellite signal 24 dB; the loss would be -4 dB. From which number I subtract 4, from 14 or from 24?
2-Also, it is absolutely necessary to have the signals to be combined of the same level (or very close; how close?) or they can be like in my example (14, 24)?
3-If they have to have the same level, how I do that?
Thank you
Mark
You are talking about two different frequency signals, you would subtract 4dB from each and that would tell you the loss on that signal. Don't think of it as the combiner adding the two signals together, but merely placing the two signals on a single cable. You still need to treat each as a individual entity.
Also, to get the true loss you really need to calculate the cable loss at each frequency and each connector will typically add about 0.1dB loss to the path.
1-Please need help to figure out how to calculate the loss when using a 2-way combiner (diplexer). Assuming that I have two leads that I want to combine; OTA signal 14 dB and satellite signal 24 dB; the loss would be -4 dB. From which number I subtract 4, from 14 or from 24?
2-Also, it is absolutely necessary to have the signals to be combined of the same level (or very close; how close?) or they can be like in my example (14, 24)?
3-If they have to have the same level, how I do that?
Thank you
Mark
You are talking about two different frequency signals, you would subtract 4dB from each and that would tell you the loss on that signal. Don't think of it as the combiner adding the two signals together, but merely placing the two signals on a single cable. You still need to treat each as a individual entity.
Also, to get the true loss you really need to calculate the cable loss at each frequency and each connector will typically add about 0.1dB loss to the path.
mark22
03-25-05, 11:22 AM
Ok, it makes sense now to treat them individually. Hmm, to calculate at each frequency becomes too difficult for me. Anyway what do you mean "each connector"? You mean every F connector? Those also creates losses? Anyway I guess they are negligible being so low.