Hello everyone,
Tom, thanks for that, that was a good start for me, but I'm still am having
the problems.
This is how I make my modulator for dqpsk, the way I make the modulator for
dbpsk is mostly the same. Tom, at first I thought you meant I might need to
change the samples_per_symbol paramter. I did this, on the transmitter and
receiver, with no results. I'm pretty sure you were talking about something
else,
Here are my modulators. All I'm doing is switching between them.
modulator = gnuradio.blks2impl.dbpsk.dbpsk_mod(
samples_per_symbol=2,
excess_bw=0.35,
gray_code=True,
verbose=False,
log=False)
modulator = gnuradio.blks2impl.dqpsk.dqpsk_mod(
samples_per_symbol=4,
excess_bw=0.35,
gray_code=True,
verbose=False,
log=False)
Here is my transmitter.
class tx_top_block(gr.top_block):
def __init__(self, mod):
gr.top_block.__init__(self)
modulator=mod
self.packet_modulator = blks2.mod_pkts(
modulator,
access_code=None,
msgq_limit=4,
pad_for_usrp=True,
use_whitener_offset=False
)
usrp2_sink = usrp2.sink_32fc(network_interface)
usrp2_sink.set_interp(interpolation)
usrp2_sink.set_center_freq(center_freq)
usrp2_sink.set_gain(usrp2_sink.gain_max())
self.connect(self.packet_modulator, usrp2_sink)
def main_loop(self):
packet_size = 1000
max_num_packets = 100000
repeat_packets = True
try:
data = "Hello, World!\n"
data = data + (packet_size-len(data))*' ' # pad rest of packet
self.start()
print "Started Transmitter"
while True:
for pkt_num in xrange(0,max_num_packets):
self.packet_modulator.send_pkt(data, False)
if not repeat_packets:
break
self.packet_modulator.send_pkt('', True) # Tell the source to
block if it is done transmitting
self.wait() # Wait for radio to
finish.
except KeyboardInterrupt:
pass
print "\n\nExiting."
Thanks For Any Help,
Devin
On Mon, Apr 26, 2010 at 10:35 AM, Tom Rondeau <trondeau1...@gmail.com>wrote:
> On Mon, Apr 26, 2010 at 1:30 AM, devin kelly <dwwke...@gmail.com> wrote:
> > Hello Everyone,
> > I've made a basic DBPSK transmitter and receiver. I can receive ASCII
> > strings fine and the spectrum looks exactly as it should.
> > However, if I swap the DBPSK modulator/demodulator for the DQPSK
> > modulator/demodulator, my system breaks. I can no longer receive the
> same
> > strings and the spectrum looks very strange. It's much wider and
> triangular
> > shaped.
> > Same goes for the D8PSK system and the D16PSK system I recently was
> asking
> > about.
> > I believe marcin_w asked a similar question a few days ago and I haven't
> > seen a reply yet (am I wrong?) My question is, should I be doing
> something
> > different? Do I need to add in some extra block when I switch from DBPSK
> to
> > DQPSK? While searching old posts, I found some people talking about
> DQPSK
> > not working correctly, but that was about a year ago.
> > Any help would be greatly appreciated.
> > Devin
>
>
> Well, you haven't really told us what you are doing (code-wise), so
> it's hard to tell...
>
> Have you compared your code to the dbpsk/dbpsk2 and dqpsk/dqpsk2
> blocks in the source code? That might give you a hint.
>
> My best (blind) guess is that you are feeding the modulator the wrong
> number of bits per sample. You have to send a dbspk a chunk size of 1
> bit / byte while the dqpsk takes 2 bits/byte chunks.
>
> Tom
>
--
http://users.wpi.edu/~dkelly/
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