Timeline for How is "signal strength" characterized on a coaxial cable?
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
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| Jan 29, 2018 at 23:01 | comment | added | feetwet | @davidmneedham – ah ha: that makes sense! | |
| Jan 29, 2018 at 22:40 | comment | added | davidmneedham | @feetwet , I imagine the signal levels for cable TV systems are the range that they are due to the need to be similar to the levels for over-the-air antennas. | |
| Jan 29, 2018 at 22:36 | comment | added | feetwet | Right, there's no point in increasing signal power unless you can do so without increasing noise power. It sounds like you're saying that in practice most of the noise on a data cable comes from the transceivers, rather than the cable and its environment. But I'm astonished to learn that state-of-the-art data devices are sending signals measured in milliVolts across an 18AWG conductor (which means the current couldn't be more than a few Amps). Is there a clear reason the powers are kept to such low levels? | |
| Jan 29, 2018 at 21:43 | comment | added | davidmneedham | I would say that 75-ohm coax is more likely to be encountered in everyday life (cable television, cable internet) for the average person. | |
| Jan 29, 2018 at 21:40 | comment | added | Bimpelrekkie | Why would the power level be a practical consideration? You cannot only talk about power, it is Signal power over Noise power (S/N) that is important. Indeed if you'd use more power without increasing the noise, S/N would increase so the datarate can increase. The power limit is not in the cable but the device sending the data and the device receiving the data. There are practical limits on S/N we can use and these aren't in the cable but in the transceiver electronics. | |
| Jan 29, 2018 at 21:26 | comment | added | feetwet | Why is the power level on a 50-ohm coax data cable not a practical consideration? What voltage or current levels will we observe in practice, and if we're not pushing the power limits of the cable then why are they not higher so that we can get more data across? | |
| Jan 29, 2018 at 20:58 | history | answered | Bimpelrekkie | CC BY-SA 3.0 |