# Problem with receiver section in BPSK

**URL:** <https://www.ruby-forum.com/t/problem-with-receiver-section-in-bpsk/242139>\
**Category:** GNU Radio\
**Created:** [May 30, 2015, 3:13pm UTC](https://www.ruby-forum.com/t/problem-with-receiver-section-in-bpsk/242139 "2015-05-30T15:13:25Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\
**Post date:** [May 30, 2015, 3:13pm UTC](https://www.ruby-forum.com/t/problem-with-receiver-section-in-bpsk/242139/1 "2015-05-30T15:13:25Z")

</div>

Hello everyone,

I tried to implement bpsk system.I am successful with the transmission  
part  
but I am able to see the ISI when I am observing the constellation at  
the  
transmitter side. I tried to design the receiver side same as the  
transmitter but just the opposite way i.e, using block Psk demod and  
packet  
decoder, but I am not able to get anything on the receiver side. Can  
some  
one pls help me wid this.

Regards,  
Anil Gaddam

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<div class="post-metadata">

**Author:** ![anilg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/73ab20/32.png) [@anilg](https://www.ruby-forum.com/u/anilg)\
**Post date:** [May 30, 2015, 5:47pm UTC](https://www.ruby-forum.com/t/problem-with-receiver-section-in-bpsk/242139/2 "2015-05-30T17:47:37Z")

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Hi,

On any multipath channel there will be some isi. What do you do to  
suppress that? What kind of filtering/pulse shaping do you do? Does  
matched filtering solve your issue?

Best regards,  
Marcus

Am 30. Mai 2015 15:12:26 MESZ, schrieb Anil Gaddam  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

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<div class="post-metadata">

**Author:** ![anilg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/73ab20/32.png) [@anilg](https://www.ruby-forum.com/u/anilg)\
**Post date:** [May 31, 2015, 1:03pm UTC](https://www.ruby-forum.com/t/problem-with-receiver-section-in-bpsk/242139/3 "2015-05-31T13:03:39Z")

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I don’t understand – are you seeing nothing at all or are you seeing  
ISI?

Again: what’s your pulse shape? Does it fit in your channel bandwidth?  
Do you fulfill the Nyquist ISI criteria?

As you know, there’s solid theory in why ISI occurs, why you need to  
limit your signal’s bandwidth and how you can counter it. What parts of  
these considerations did you address with your transceiver system? You  
only say you do bpsk, but doing symbol mapping is only part of the job  
that a transceiver needs to do.

Best regards,  
Marcus

Am 30. Mai 2015 17:53:25 MESZ, schrieb Anil Gaddam  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

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<div class="post-metadata">

**Author:** ![anilg](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/73ab20/32.png) [@anilg](https://www.ruby-forum.com/u/anilg)\
**Post date:** [May 31, 2015, 1:07pm UTC](https://www.ruby-forum.com/t/problem-with-receiver-section-in-bpsk/242139/4 "2015-05-31T13:07:09Z")

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I’ll reiterate: what do you do tree account for real world channels? You  
haven’t told us _anything_ about your transceiver aside from it using  
BPSK.

Best regards,  
Marcus

Am 30. Mai 2015 20:00:51 MESZ, schrieb Anil Gaddam  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):