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Re: [Discuss-gnuradio] Power,Band width and spectrum switch problems
From: |
Johnson_lu |
Subject: |
Re: [Discuss-gnuradio] Power,Band width and spectrum switch problems |
Date: |
Thu, 1 Jul 2010 06:34:37 -0700 (PDT) |
Thanks for the reply.
I tested the parameter tx_amplitude=0.001 and I can get little transmit
power I wanted.
I can observe the bandwidth from the spectrum analyser. I also changed the
bitrate and modulation to get different bandwidth. But I still have some
questions about the difference of the transmit bandwidth and the filter
bandwidth.
Marcus D. Leech wrote:
>
> On 06/30/2010 08:05 PM, Eric Blossom wrote:
>> On Tue, Jun 29, 2010 at 11:23:36PM -0700, Johnson_lu wrote:
>>
>>> Hi guys,
>>> Could anybody can help me for these problems?
>>> 1、I varied Tx_amplitude from 0.1 to 1 and measured the output with a
>>> spectrum analyzer. But the changes are very little. The output is almost
>>> the
>>> same when Tx_amplitude is 0.1 and 1. How can I reduce the transmit
>>> power to
>>> a very little value?
>>>
> All else being equal that should produce a 10dB change in signal power,
> unless *something* in the
> chain is already at saturation due to other factors in the Tx chain.
> Keep in mind that a 10dB change
> on a logarithmic scale isn't very much.
>
>>> 2、How do I know bandwidth of transmission and reception channels in
>>> tunnel.py?
>>>
> There seem to be *two* versions of tunnel.py in the examples--which one
> are you talking about?
> Have you put the output of the transmit side on a spectrum analyser?
> That would tell you
> unambiguously what the bandwidth is, but also careful and
> knowledgeable inspection of the
> code will tell you what the theoretical bandwidth is.
>
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
>
>
>
> _______________________________________________
> Discuss-gnuradio mailing list
> address@hidden
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>
>
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