Transmission voltage in dB microvolts

Discussion in 'Wireless & RF Design' started by krogerson2, Jan 8, 2009.

  1. krogerson2

    Thread Starter Member

    Jan 8, 2009
    24
    0
    if i have a signal that is .4 μV and it is on a 50Ω system how do i express this in dBμV i tried the .4μ/.2236 and then took 20 log of that and it didn't work
     
  2. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,040
    287
    I don't know where you got the .2236 from.

    Db(uv) = 20 log (v1/v2)=20 log(.4/1)=20 log (.25)=-7.95 db(uv)
     
  3. krogerson2

    Thread Starter Member

    Jan 8, 2009
    24
    0
    thank you i was getting the .2236 from the square root of .001*50 formula
     
  4. krogerson2

    Thread Starter Member

    Jan 8, 2009
    24
    0
    if a microwave transmitter normally requires a +8dBm audio level to driave the input fully. if +10dBm is measured what is the actual voltage level measured assuming a 600ohm system
     
  5. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,040
    287

    As long as you're keeping all your calculations in voltage, you don't have to convert to power...the impedance cancels out. (This assumes the same impedance for input and output signals). If you're calculatiing db for POWER, you'd use 10 log (p1/p2).

    Eric
     
Loading...