Help to build a loop modulating / de-modulating system

I’m trying to build this kinda of system for my degree thesis. It is a
loop system in the sense its structure could be described in this way

file source (byte) —> Digital modulator (QAM , PSK , MSK etc) ---->
Digital de-modulator -----> File sink (byte)

file source is a text file or a jpeg photo just for example. I read the
de-modulator loses the first 5 bits due to the clock recovery, so i
wrote a few lines in python, my steps were :

1) I made a function to read a text file and put its content after
converting the single chars in int with the type converter ord( ).
Then i put the intS i got in an array with also adding a byte of empty
stuffing as the first one ( a single zero). And putting the content in a
byte file source.

*2)*I connected this byte file source to the modulator (GMSK for
example) to get a complex file sink. Then i try to put this last one
like complex *file source *for my de-modulator.

*3)*The output of the de-modulator is a byte file sink. but i don’t
get the data i transmitted ! ! ! ! (i.e. the text file doesn’t open)

*4)*I tried a different approach by scanning the complex sink output of
2), converting the contents to int and then putting it in a complex
to feed the de-modulator. the resulting byte *file sink *is a
text file i can open but i only see the bytes in the text file ! ! !
(the little squares with 1,0 etc)

5)I tried another approach by converting the complex content of the
modulator output to
and feeding the intS into a* byte* file sink.
The file is then scanned and its contents are put as the array
arguments of a complex vector. The de-modulator is fed with this
complex vector and its output its a byte file sink ( the demodulated

in all these cases i don’t succeed in get any good de-modulated data
(i.e. the original text file or a jpeg photo). where am i wrong ? can i
get some hints from anyone of you ?

thx in advance

@ Richard C.

Regarding GNUradio installation on Ubuntu 9.10 i used a little cheat :D.
I added the 9.04 repositories to the 9.10 ones and then i was able to
install smoothly the DEBs from the gnuradio repository,both the stable
and the un-stable ones. So you also get full dependencies if you want to
compile from the git code.

Bye Arturo