But my point is that if the signal strengths were being added linearly, you should see the S-meter jump to 44 over S9.
However, you are very aptly making my point. The overall gain of the receiver is reduced to accomodate the strongest signal which also reduces the output of the lower signal by that amount. Think of it as turning down your RF/IF gain by a factor of 2500. How many signals could you hear? I have a 10 dB attenuator and I know what kind of signals it would take to get through a 30 dB attenuator. This is exactly what happens with a receiver with poor IM3 performance. The AGC reduces the overall gain because of the nearby strong signal and you lose the one your after. As you point out, there are logarithimic implications in current receiver designs. This is what I meant when I said the signals don't simply add (perhaps I should have said algebraically). You don't get both an audio tone at an S9+10 dB (BPL signal levels) AND an audio tone at the same level an S8 signal by itself would generate AT THE SAME TIME. The audio output of the S8 signal is reduced dramatically (by a factor of 2500 as you point out) in the presence of a stronger signal. To get adequate performance of this kind would require a receiver with dramatically better dynamic range of each and every amplifier, RF/IF/Audio. One that in essence wouldn't require any AGC at all. I ain't going to pay for one! I'm not saying that this isn't perhaps a solution in a small number of cases, however, I don't think it should be promoted as a way to say to the FCC Ok, BPL isn't as bad as the ARRL and other hams have been saying, all hams can work work around it. As Bonnie pointed out in a recent post, this might give a 20 - 30 dB advantage. That means you would need S8 or stronger digital signals if BPL is ariving at 10 to 20 dB over S9. While this may mitigate BPL interference somewhat, it is far from an adequate solution and shouldn't be promoted as such. Nor, is it correct to say that the engineers saying this just won't work are wrong. With today's receivers, it is more correct than incorrect. Jim WA0LYK --- In [email protected], Chris Jewell <[EMAIL PROTECTED]> wrote: > > jgorman01 writes: > > just did this using my RF generator. WWV at 5 Mhz is about 10 over > > S9. The generator is at about S5 with no antenna connected and the > > lead just resting on top of the transceiver. When I switch the > > generator on, the S-meter moves not a bit. You would expect it to > > jump considerably if the RF signals were being added together. > > If the S-meter calibration is the classic 6 dBs per S-number, the > ratio between S5 and S9+10dB is 34 dB, or a factor of more than > 2500:1. 1 uW added to 25 mW, for example, should not be expected to > make a visible difference in a meter reading. > > 73 de KW6H, ex AE6VW > > -- > Chris Jewell [EMAIL PROTECTED] Gualala CA USA 95445 > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
