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Re: [Discuss-gnuradio] Bypass work function

From: Jeff Long
Subject: Re: [Discuss-gnuradio] Bypass work function
Date: Thu, 02 Oct 2014 07:09:26 -0400
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.1

If you can tolerate the stream stopping, use Power Squelch. Otherwise, time to dive in and follow Tom's advice from May - disable the CMA taps update loop when there's no signal. This whole idea assumes you have a mostly quiet channel, stationary tx/rx, etc. Interested to hear what you come up with.

- Jeff

On 10/01/2014 11:24 PM, bob wole wrote:
I applied this and this is useful in condition when you do not want to
process noise, because it is being multiplied by zero when there is no
signal. But I want that CMA taps remain unchanged when there is no
signal or just noise. In the above scenario CMA taps change due to
presence of noise, because it tries to equalize noise as well.  Thanks
for your comment.


On Mon, Sep 29, 2014 at 7:19 PM, Jeff Long <address@hidden
<mailto:address@hidden>> wrote:

    Try using a "threshold" off the "mag squared" and feed that into a
    multiplier after block2 (with appropriate type adapters). As long as
    block2 doesn't have a huge delay or do rate changes, this should work.

    - Jeff

    On 09/29/2014 10:23 AM, bob wole wrote:
    > Hi thanks for your comment. block2 is the gnuradio "CMA equalizer
    > block". I want the CMA block to remain quiet when there is no signal of
    > interest.
    > Bob
    >     Bob,
    >     Saw this the other day, but there isn't a lot to go on here. If block2
    >     is your own, you can make it do the bypass. You can also use some of 
    >     logic blocks and a multiplier depending on what you're doing. There
    >     isn't really a concept of on-the-fly switching in GNU Radio.
    >     - Jeff
    >     On 09/26/2014 01:02 PM, bob wole wrote:
    >      >
    >      > People, any ideas on it?
    >      >
    >      > --
    >      > Bob
    >      >
    >      > On Wed, Sep 24, 2014 at 12:04 PM, bob wole <address@hidden 
    >     <mailto:address@hidden <mailto:address@hidden>>
     >      > <mailto:address@hidden <mailto:address@hidden>
    <mailto:address@hidden <mailto:address@hidden>>>> wrote:
     >      >
     >      >       I have following flowgraph:
     >      >
     >      >
     >      >
     >      >
     >      >     What I want to do is that I want to bypass the "work"
    function of
     >      >     block2 when the threshold level of probe_mag_squared
     >     I do
     >      >     not want to stop(), lock(), disconnect the flow graph.
    Is this
     >      >     possible using stream tags, or message passing etc ?
    Any example
     >      >     code would be nice.
     >      >
     >      >     --
     >      >     Bob

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