I have used the PCS500 and K8016 together for circuit analysis for quite some time. This function is very usefull and similar instruments would cost a lot. I had problems with the K8016 that its output did not always follow the setup (some comms problem (I did disable the LPT plug and play)). I have now bought the PCGS1000 and is very glad to say that there is no such problem. I was however evaluating my new combination when I picked up the following problems.
In the 1st place a bode plot is normally defined as Gain = 20Log(Output amplitude/Input amplitude). This is especially true in terms of circuit analysis where the transfer function is independant of the input signal used. The PC lab2000SE software however gives a different answer for different input signal level. This is wrong since if you connect a short between the 2 scope signals it will sometimes tell you it has a gain of more, or less than 1.
The 2nd problem due to the measurement method is that when using automatic setup (and choosing AC as recommended) the scope AC transfer is actually measured (below 10Hz (I’m interrested in measurement between 1 and 100 Hz)). This is wrong since the measurement instrument should not introduce anything to the circuit under analysis.
The sollution is simply to calculated the gain from both input signals on the oscilloscope as is done for the phase measurement. I’m not sure if this is a new problem or not but I havent seen this before and I’ve just installed Version 3.08
I include the measurement results of a piece of coax (short) which should have Gain of 1 (0dB) and phase of 0 over the full frequency range :?
Hz Vrms dBV deg
1.00 0.472 -6.516 3.5
2.00 0.859 -1.323 2.7
3.00 1.131 1.070 2.8
4.00 1.307 2.328 2.7
5.00 1.434 3.131 2.4
6.00 1.512 3.590 2.3
7.00 1.568 3.909 2.1
8.00 1.610 4.138 1.6
9.00 1.635 4.271 1.7
10.0 1.659 4.394 1.2
20.0 1.729 4.757 0.6
30.0 1.745 4.835 -0.4
40.0 1.752 4.873 -0.6
50.0 1.758 4.898 0.0
60.0 1.760 4.911 -0.3
70.0 1.756 4.890 -0.4
80.0 1.758 4.899 -0.7
90.0 1.759 4.905 -1.0
100 1.760 4.912 0.0
200 1.767 4.945 -0.1
300 1.767 4.945 -0.2
400 1.764 4.928 -0.5
500 1.752 4.871 0.0
600 1.756 4.890 -0.3
700 1.758 4.900 -0.2
800 1.760 4.908 -0.5
900 1.754 4.879 -0.4
1000 1.760 4.910 -0.1