Hello PSN,

Question: Does any/all of this seem right or wrong to you ?

The layout of the circuits are as follows:
1. Geophone Preamplifier and Damping circuits X500 no filtering
2. Equalization Filter and amplifier  X21 filter at (1/18.8) Hz
3. Antialize filter X1 N=8 at 10Hz
4. DC blocker X1 N=1 at (1/100)Hz
5. Voltage Follower X1
6. Distribution Manifold circuit
    A. A/D converter X1
    B. Analog Meter circuit X20 

Hs10-1 Vertcal Geophone
435 ohms at operational temperature
G = 2.99 V/(in/sec)
hm = 0.35
Fc = 1Hz
Mass = 33 ounces avd.

Given:
Generator Constant:
2.99V/(in/sec)
Geophone resistance:
435 ohms
Damping resistor = 205 Ohms
Preamplifier with gain of 500 and no filtering
Preamplifier Low Pass Filter N=1 of the following
Rf = 1 Meg
Cf = 3uf
gain is X21
When I Plug in my numbers,
The OVERALL amplifier gain was computed
only for 1 Hz.

1. minus Voltage loss related to damping resistor

K1 = 20 log(Rd/(Rg + Rd))
     =  -9.888 dbv

2. plus DC voltage gain of preamplifier (no filtering)

K2 = 20log((R1 + R2) / R1)
     = 53.979

3. plus DC voltage gain of filter stage

K3 = 20log((R1 + R2) / R1)
       =26.510

4. minus voltage gain due to filtering at at 1Hz
K4 = 20log(Xc/Z)
     =-25.518
Xc = 1/2PiFC
Z = SQR(r^2 + Xc^2)

5. Overall:
K = K1 + K2 + K3 + K4
   = -9.888 + 53.979 + 26.510 + -25.518
   =  45.083dbv or X179.535 AT Only ONE HERTZ

I do not worry about dampend generator constant
( Ge ) since it is covered under Item number one as a loss.

This should mean that only at one hertz
my Ge going into the 16 bit A/D is
2.99 X 179.535 or 536.80965 (Volts/(inch/second))
This should translate to Volts/(cm/s) like this
Ge = 536.80965 / 2.54 = 211.3423819 (Volts/(cm/sec))
Going into the A/D converter which is Volts Per Count = (5Volts / 32767counts)
This means One count is the following:
211.3423819 V/(cm/s) X (32767 Counts/ 5 Volts) = 13850.11166 Counts/(cm/sec) or
1/13850.11166 (cm/sec)/COUNT or 7.220158E-6 (cm/sec)/count or
*******************
One Count equals 72.20158 nano meters per count At 1Hz and only 1Hz

*******************

This gain will have to be recalculated for any other frequency.
I also have N=8 LPF at 10Hz and a N=1 100sec HPF Dc blocker.
Does any of this sound right to you ?

Is this the right way to calculate overall AMPLIFIER gain etc. for WinSDR ?

What is the best way to handle the magnitude correction ?
Like if no correction at all.
It is my guess, by adjusting the generator constant
because it might not meet factory specifications.
All the other numbers seem to be known.

Please do not challenge my damping resistor at this moment.
I have chosen a value of 205 Ohms for my own selfish reasons.

Regards,
geoff



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