# number of samples and Amplitude accuracy,what's the solution to this problem

I'm colleceting data samples from a device (temporal signal) in order to analyze it with FFT function in MATLAB R2015b,first i get N=4063 data points with (delta_t=0.000015s) so my frequency resolution is (delta_f=1/N*delta_t)=16.4Hz,this give me pretty good results with amplitude,but when i did another measurment with N=8192 data points (delta_t=0.000061) to obtain better resolution,the amplitude is not correct,i don't know really how to deal with this issue.so please if any body can help me with this i will be grateful,thank you

ps:i'm new in signal processing

below my code in MATLAB

sig_2=asp_ach_de1;
Fs2 = 1/0.000061;      % Sampling frequency
T2 = 1/Fs2;            % Sampling period
L2 = 8192;             % Length of signal
t2 = (0:L2-1)*T2;      % Time vector
% FFT FUNCTION
Y2 = fft(sig_2(:,2))
Q2 = abs(Y2/L2);
Q1 = Q2(1:L2/2+1);
Q1(2:end-1) = 2*Q1(2:end-1);
f2 = Fs2*(0:(L2/2))/L2; %FREQUENCY
figure(3)
plot(f2,Q1)


• Hiii! can you please also provide that asp_ach_de1 signal? or do you want us to predict it ? – Fat32 Jan 21 at 16:55
• thank you Fat32,but how i'm suppose to share it with you here,it's 8192 line txt file or how to attach it. – bishop solaco Jan 22 at 5:43
• here's the 2 signals asp_ach_de1 "4k and 8k", gist.github.com/bishopreb85/19b056cfbea0d8c10e7ff1d0fa389d00 – bishop solaco Jan 23 at 8:48