Re: [Discuss-gnuradio] False Packets for benchmark TX/RX
I am using RFX900 (FLEX 900) and the VERT 900 Antennas Best Regards, -- Yahya Ezzeldin <http://www.ieee.org> On Wed, Dec 5, 2012 at 3:36 AM, Marcus D. Leech wrote: > ** > On 12/04/2012 08:15 PM, Yahya Ezzeldin wrote: > > I tried offsetting the carrier frequency (playing at the RX side) but > still ALL the packets are Ok=False. > > Can this be related to the distance between the nodes, I mean is there > some kind of typical distance for the nodes placement for the benchmark? > > Best Regards, > -- > Yahya Ezzeldin > >> >> > You don't note what daughtercard you're using. > > > -- > Marcus Leech > Principal Investigator > Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org > > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] False Packets for benchmark TX/RX
Thank you Tom, I have been experimenting with the working setting that I have now. Why do other modulations like bpsk, qpsk fail while gmsk works perfectly ? Best Regards, -- Yahya Ezzeldin On Thu, Dec 6, 2012 at 5:18 PM, Tom Rondeau wrote: > On Wed, Dec 5, 2012 at 2:23 AM, Yahya Ezzeldin wrote: > >> Thank you Tom and Marcus, >> >> I finally managed to make it work with 100% delivery rate using this >> configuration. >> >> Transmitter: >> * >> Tx-Amplitude = 0.4 >> Rate = 1M >> Samples per Symbol = 4 >> >> Receiver: >> ** >> Rate =1M >> Receiver Gain = 10 >> Samples per Symbol = 4 >> >> I do have some question that I don't understand : >> - >> 1) The main issue turned out to be the rate. When I increased the rate >> from 250k to 0.5M some packets started to pass as true. Increasing it to 1M >> made most of them be accepted as True (pass the CRC32 check if I understand >> correctly). What is the explanation for this ? >> > > Often, the reason higher rates work better is that the relative frequency > offset is lower. You said that you couldn't find a frequency offset that > helped with your 250 kbps signal, so I'm not sure if this is really the > right answer for you. But that's generally the case. > > >> 2) Increasing the samples per symbol further improved the reception, why >> is that ? >> > > Off the top of my head here... GMSK actually introduces ISI, but how that > happens is based on the shaping filter used, which we determine by the > number of sps. Increasing this is probably making a better shaped signal. > > >> 3) The two FFT screenshots at 250k and 1M are as follows. How does the >> difference between them solve the nonlinearity problem, Tom ? >> > > Both of these looked good. I'm not sure it was really nonlinearities, that > was just a guess. The original signal you showed us had a strange bulge in > left half of the signal. These signals here look symmetric and properly > shaped. > > Tom > > > >> -- >> Yahya Ezzeldin >> > > > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Receiving My Own Transmitted Packets after disconnecting from Transmit Path and connecting to Receive Path
Hi,
I wrote a gnuRadio code that allows me to switch between a Tx_Path and
Rx_Path every 10 seconds.
The code is based on the tb.lock() , tb.unlock() functions and the
benchmarks provided with gnuradio.
I am able to do the switching fine, however after switching from
transmission to reception, the node receives some of the packets that were
sent during its own transmission period.
How can I overcome this echo like effect between the TX and RX periods ?
*
*
*In the main() function I have :
*
tb.start()
while True:
time.sleep(10)
tb.lock()
tb.conf_transmit()
tb.unlock()
tb.transmit_packets()
tb.lock()
tb.conf_sense()
tb.unlock()
tb.wait()
*In the top_block class I have:*
def conf_transmit(self):
self.disconnect(self.source, self.rxpath)
self.connect(self.txpath, self.sink)
def conf_sense(self):
self.disconnect(self.txpath, self.sink)
self.connect(self.source, self.rxpath)
def transmit_packets(self):
begin_time = time.time()
pkt_size=1500
pktno = 0
while time.time() - begin_time < 10: # Send for 10 minutes
data = (pkt_size - 2) * chr(pktno & 0xff)
payload = struct.pack('!H', pktno & 0x) + data
self.send_pkt(payload)
pktno += 1
def send_pkt(self, payload='', eof=False):
### Main Function to Send Packets.
return self.txpath.send_pkt(payload, eof)
Best Regards,
--
Yahya Ezzeldin
<http://www.ieee.org>
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[Discuss-gnuradio] Channel Estimation in benchmark OFDM Code
Dear All, Does the benchmark OFDM Code perform Channel synchronization ? I am moving through the code however I can't seem to get the part where this is done ? Can anyone give any pointers regarding this ? The number of pilots ? Estimation technique used ? Best Regards, -- Yahya Ezzeldin <http://www.ieee.org> ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
