Re: [Discuss-gnuradio] 2 RX and 1 TX channel

[kaleem ahmad]

Hello all,

After lot of efforts I am able to receive some data one one of the RX
channels, but it is too bad. To understand how weak it is, for example, I
was actually transmitting a already known data string and then on reception
I was comparing it bit-by-bit with the actual packet and in this way I was
calculating bit error rate and in case of lost packet I was calculating
packet loss rate. It was an already written code for songle RX channel and
my BER was around 1.5% and PLR was also around 1.5%. But with two RX
channels both these parameters are abouve 10%.

I am unable to understand what should I do to receive better data (of same
order as in the case of single RX channel) when I have two RX channels????

Please let me know if I am doing something wrong. I am tried every
possibility!!!!!!!!!!

Best Regards

kaleem ahmad wrote:
> 
> Hallo everyone,
> 
> I dont get any reply so far, may be I can rephrase my question. 
> 
> Actually I was expecting that any code which is working fine for a single
> antenna, will only need little changes (Mentioned above in 1st post on
> this thread) to convert it to multiple antenna. I mean I was expectring
> that I would only need to direct streams of two different antennas to
> folwgraphs of my already working code. BUT its not working in this way.
> 
> I have read all related posts on this forum and examples related to
> multi_usrp in gnuradio_examples but I am unable to understand where I am
> doing wrong, I could not find an answer even from "USRP_Documentation", so
> please let me know after having a look on code (For code please go above
> to first post on this page) where I am doing wrong.
> 
> Do I need to take care of decimation rate when I have two RX channels, I
> am using 160 for both (I think only restriction for decim rate is that it
> should be equal for both. Is there any thing else?). OR are there some
> parameters which need to be handeled differently for 2 RX channels?
> 
> My understanding about deinterleaver is that, it will get the input from
> USRP as a single stream as follows:
> self.connect(self.u,self.deinter)
> and will automatically and correctly divide it into two separate streams,
> and we dont need to do anything else, as follows:
> self.connect ((self.deinter,0), self.rx_filter, self.fmdemod, self.corr,
> self.vec_sink)
> self.connect ((self.deinter,1), self.fft_input)
> 
> Is this understanding about deinterleaver correct or do I need to do some
> special processing to get these separate streams.
> 
> 
> Thanks 
> 
> Kaleem AHmad
> 
> 
> kaleem ahmad wrote:
>> 
>> In addition to my above mentioned question, please also comment on what
>> should be the value of mux (I am setting 0x3210) and what should be the
>> value of fpga_filename,
>> 
>> Please again note that I want to use 2 RFX2400 cards with one USRP1, and
>> 2 rx streams will be there each through RX2 antenna of 2 RFX2400 cards
>> and there will be one tx stream through any one of these cards.
>> 
>> Best Regards
>> 
>> Kaleem Ahmad
>> 
>> 
>> 
>> kaleem ahmad wrote:
>>> 
>>> Hello every one,
>>> 
>>> I am using USRP1 + RFX2400.
>>> 
>>> I want to use 2 RFX2400 cards. Overall I will have 2 RX streams and 1 TX
>>> stream from this system. Following are main parts of my RX_Path
>>> (complete code for RX-Path is also attached, if you want please have a
>>> look on that, TX-path is not here). I am unable to receive anything from
>>> any of the channels although the same RX-path was working when I was
>>> using a sinle antenna. Only following lines were mainly changed. Please
>>> have a look and let me know if my configuration for 2 RX (on separate
>>> RFX cards, but one USRP1 main board) and one TX channel.
>>> 
>>> 
>>> u = usrp.source_c(0, decim_rate=self.usrp_decim, nchan=2
>>> self.subdev = (self.u.db[0][0] , self.u.db[1][0])
>>> self.u.set_mux(gru.hexint(0x3210))  
>>> 
>>> #Set the gain to the midway point
>>> self.subdev[0].set_gain(60)
>>> self.subdev[1].set_gain(60)
>>> 
>>> #Set the recieve frequency
>>> self.r0 = usrp.tune(self.u, 0, self.subdev[0], 2.41e9)
>>> self.r1 = usrp.tune(self.u, 1, self.subdev[1], 2.41e9)
>>> 
>>> self.subdev[0].select_rx_antenna( 'RX2')        
>>> self.subdev[1].select_rx_antenna( 'RX2')
>>> 
>>> self.deinter = gr.deinterleave(gr.sizeof_gr_complex)        
>>> 
>>> #enable Auto Transmit/Receive switching
>>> self.set_auto_tr(True)
>>> 
>>> self.connect(self.u,self.deinter)
>>> self.connect ((self.deinter,0), self.rx_filter, self.fmdemod, self.corr,
>>> self.vec_sink) # One RX antenna for regular data reception
>>> self.connect ((self.deinter,1), self.fft_input) #Other RX antenna for
>>> fft window, this fft will be further processed
>>> 
>>>       
>>>  http://www.nabble.com/file/p24305532/receive_path.py receive_path.py 
>>> 
>>> Best Regards
>>> 
>> 
>> 
> 
> 

-- 
View this message in context: 
http://www.nabble.com/2-RX-and-1-TX-channel-tp24305532p24352988.html
Sent from the GnuRadio mailing list archive at Nabble.com.