On 7/6/2015 1:29 PM, Jon Paris wrote:
Good points Buck - thanks.
Maybe you can share some of your procedural Python because everything I’ve ever seen was completely OO.
I'm part of a ham radio project which uses a PIC to record analogue
voltages from an HP141T spectrum analyser and transmits the values via a
simple terminal emulator to a text file. The general idea is to be able
to capture a CRT image and put it in your documentation or post it on a
web page, etc. Quite a trick for a machine which was made in the 1970s.
This program plots the values from that text file - in essence
reconstructing the analogue CRT display in a way that can be saved as a
.png or .pdf file.
The original code was written by a French radio amateur, which explains
the comments and naming convention. It's very procedural, and yet it
uses several Python libraries like NumPy.
# drawsan201.py: Spectrum drawing from SAN2PC rev 2.xx recorded files
# Roland Cordesses,F2DC, Feb.28, 2009
#
============================================================================
# Version 200 (Feb. 2009 and following days) process the new file format
generated
# by SAN2PC re v2.xx. This format stores only amplitudes as 8 bits words
# and no longer the associated frequencies information, thus greatly
improving the time to
# transfer data from SAN2PC to the PC. Moreover, this new format stores
more than
# 3 kpoints instead of 1 kpoints.
# This mitigates the amplitude errors related to the K ratio
(K=TotalScanWidth/Bandwidth
# analyzer settings) being larger than 1000 in the old SAN2PC program.
You can now use a K
# value up to 3000 without any significant error.
# 200A Computes P(dbm) from the 8 bits values of the recorded file
# 200C Computes the frequencies from fdeb,ffin, scan and nbdata read in
the header
# 200C Reads the reflev info from the file header
# 200C Includes automatic switching of freq axis in accordance with stepfreq
# 200D Should work with any Fcentr and Scan combination !!!
# 200D Fix a small issue in the frequency interpolation
# 200E Doesn't display frequency labels values on X axis but only the
Center Frequency below
# the Frequency axis
# 200F Displays Fdeb and Ffin below the frequency axis
# 200G Handles the wrong file names and file types in a more friendly
way than before !
# 200H Some minor improvements
# 200I Now the power scale is similar to the one displayed on the S.A screen
# 200J Convert filename and answer1 to lower case.
# Rev 2.00 is the first distributed beta version
# Rev 2.00.1 fixes a problem when the scanwidth unit is 'KHz'
#
# Rev 2.01 Modified to accept parameters in batch
# First argument is file name, including extension.
# If the first arg is specified, the program will not prompt to
save; it will
# automatically save as .png
## I use it with a batch file that processes all the capture files
within a directory:
# KC2HIZ
#================================================================================
# import pdb # : for debug ONLY !!!
import sys
from pylab import *
import numpy as np
from os import getcwd
cur_rep=getcwd()
from os import chdir
chdir(cur_rep)
# pdb.set_trace() # for debug ONLY !!!
# assign extensions
# for input, if prompted, assume .dat
# for output, assume .png unless prompted
# beware of some lossy formats (eg .png)!
ext= ".dat"
# if the first arg is specified, use that instead of asking for the file
name
if len(sys.argv)>1:
nomfic1=sys.argv[1]
ext1=".png"
nomfic=nomfic1
nomfic1=nomfic1+ext1
else:
nomfic1=raw_input("File name without ext : ")
ext1=".pdf" # .ps, .pdf, .png, .emf, .eps, .svg, .raw, .rgba
available
nomfic=nomfic1.lower()+ext
nomfic1=nomfic1+ext1
err=0
while (err==0):
try:
in_file=open(nomfic,'r')
except:
print("File '"+nomfic+ "' not found!!!")
answer2=raw_input("Hit Enter to quit")
break
err=1
in_file.seek(0,0)
textdeb=in_file.read(30)
chset=textdeb
chset1=chset.split()
chtst=chset1[0]# read the first character of the SAN2PC generated
file type (2 means new type)
if chtst!="2": # it's the first rev 1.1x SAN2PC file type
print("SAN2PC rev 1.1x file type : please use Drawsan114 ")
answer2=raw_input("Hit Enter to quit")
break
else: # that's OK : it's the rev 2.xx (new) file type
chfrc=chset1[1]
chscan=chset1[2]
chbw=chset1[3]
chvideo=chset1[4]
chreflev=chset1[5]
lengthchfrc=len(chfrc)
unit=chfrc[lengthchfrc-1]
chsetfin="Fc:" +chfrc + "Hz"+ " ScanW:" + chscan+"Hz/div"
chsetfin=chsetfin+" BW:"+chbw+"Hz"+" Vid.Fltr:"+chvideo+"Hz"
for index in range(len(textdeb)):
if textdeb[index]=='*':
inddeb=index+3
long=len(chfrc)
chfrc1=chfrc[0:long-1]
chunitfcr=chfrc[long-1]
# computes the center frequency multiplier value from the Fcenter unit
(M, G)
if (chunitfcr=='M'):
fmult=1
else:
if (chunitfcr=='G'):
fmult=1000
fcentr=float(chfrc1)
# computes the scan multiplier value from the chscan unit
long2=len(chscan)
chcoeff=chscan[long2-1]
if (chcoeff=='k' or chcoeff=='K'):
mult=0.001
else:
if (chcoeff=='M'):
mult=1
else:
if (chcoeff=='G'):
mult=1000
chscan1=chscan[0:len(chscan)-1]
scan1=float(chscan1)
scan=10*scan1
freqratio=fmult/mult
scan=scan/freqratio
scan3=scan/10
reflev=float(chreflev)
fdeb=(fcentr-(scan/2))
ffin=(fcentr+(scan/2))
locs=range(10)
for i in range (10):
locs[i]= fdeb+i*scan3
in_file.seek(inddeb,0)
newtext=in_file.read()
indexfin=newtext.index("*")
finaltext=newtext[:indexfin]
fichtempo=open('tempo','w')
fichtempo.write(finaltext)
fichtempo.close()
in_file.seek(0,0)
in_file.close()
nbmajmarker=scan/10
# Automatic computing of frequency string format "majform"
if (nbmajmarker<0.001):
majform='%3.4f'
else:
if (nbmajmarker<0.006):
majform='%3.3f'
else :
majform='%3.2f'
if len(sys.argv)>1:
answer1="y"
else:
answer1=raw_input("Save picture as "+ext1+" (y/n) : ")
answer1=answer1.lower()
fichtempo=open('tempo','r')
X=load(fichtempo)
s=X
nbdata=len(s)
stepfreq=scan/nbdata
t=np.arange(nbdata,dtype=np.float)
maxpower=-170
minPower=100
orig=800
# computes frequencies from fdeb to ffin
for i in range(nbdata):
t[i]=fdeb+(float(i)/float(nbdata-1))*scan # WB8DNO adds this line
to compute interpolated values.
# Feb 2009 fix : (nbdata-1) instead of (nbdata) for a proper
frequency estimation
# computes power in dBm
s[i]=reflev-(orig-s[i]*4)/10
if (s[i]>=maxpower):
maxpower=s[i]
nbmaj_y=10 # number of freq grid lines
displminpower=reflev-80
from matplotlib.ticker import MultipleLocator, FormatStrFormatter
majLocator_y=MultipleLocator(nbmaj_y)
minLocator_y=MultipleLocator(1)
majorFormatter = FormatStrFormatter(majform)
grid(True)
ax=subplot(111)
plot(t,s,linewidth=1)
xlabel(chfrc+'Hz',fontsize=16)
ylabel('dBm',fontsize=16, rotation=0)
xlim(fdeb, ffin) # set x axis limits
ylim(displminpower,reflev)
xticks(locs)
chfdeb=str(fdeb)
chffin=str(ffin)
# Display Fdeb and Ffin
text(fdeb-(nbmajmarker/10),displminpower-4,chfdeb+chunitfcr+'Hz')
text(ffin-(nbmajmarker/1.5),displminpower-4,chffin+chunitfcr+'Hz')
# Axis properties
ax.xaxis.set_major_formatter(majorFormatter)
ax.yaxis.set_minor_locator(minLocator_y)
ax.yaxis.set_major_locator(majLocator_y)
# No X axis labels
setp(gca(), xticklabels=[])
# Display S.A settings
title(chsetfin)
if (answer1=='y'):
savefig(nomfic1)
if len(sys.argv)==1:
show()
fichtempo.close()
err=1# the end
midrange.com
