Latency of tcpip transmission


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Hello xd,

You’re expecting us to guess what you know:
What are we seeing in that diagram? What are the axes and how are they
scaled? Also: some information of message length, the amount of data
you need to pass through network, why latency is a problem etc would
always help.

Generally, GNU Radio can’t do magic. If your data processing/forwarding
introduces latencies, there’s nothing you can do.
“TCP/IP transmission” doesn’t necessarily give you any indication on how
fast something happens – generally, ack’ing protocols like TCP might be
a bad choice in limiting latency.

Best regards,
Marcus

Hi Marcus:
Thank you for your reply.Sorry for my unclear
introduction to my question.I apology for this.
I just want to know whether someone encounter the
similar question of mine.My question is this:I have two usrps.One is
transmitter while the other is receiver.
1.I use the transmitter to send signals to the receiver.
2.And then receiver calculate the message (very
shot).And through the tcpip,the receiver transmit the message to the
transmitter.

            3.The transmitter resend again.
            Because the receiver keep receiving during this 

processing.So in the interval of the transmitter sending,the receiver
receive some noise.I don’t want receive the noise.
Have some ideas about this?Experts.Thank you.
Best regards,
zs

At 2014-11-28 19:21:15, “Marcus M.” [email protected] wrote:
Hello xd,

You’re expecting us to guess what you know:
What are we seeing in that diagram? What are the axes and how are they
scaled? Also: some information of message length, the amount of data you
need to pass through network, why latency is a problem etc would always
help.

Generally, GNU Radio can’t do magic. If your data processing/forwarding
introduces latencies, there’s nothing you can do.
“TCP/IP transmission” doesn’t necessarily give you any indication on how
fast something happens – generally, ack’ing protocols like TCP might be
a bad choice in limiting latency.

Best regards,
Marcus

On 11/28/2014 11:27 AM, zs wrote:

Hi all:
Thank you in advance.
Environment: gnuradio 3.7.5
The picture below shows the received signal.I will try my best
to explain my problem.I use one usrp N210 to send signal and the other
usrp receive the signal and then transmit the message by the tcpip to
the transmitter.Then the transmitter re-send signal again.I think the
way of tcpip transmission is so fast.But it has the latency as the below
picture shows.Have some ideas to solve it?And have some tools in grc to
solve it?Thanks so much.(the signal inside the blue circle while the
latency is interval of signal).
Best regards,

xd


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Hi zs/xd,

On 11/28/2014 12:58 PM, zs wrote:

Hi Marcus:
Thank you for your reply.Sorry for my unclear introduction to
my question.I apology for this.
I just want to know whether someone encounter the similar
question of mine.My question is this:I have two usrps.One is transmitter while the
other is receiver.
1.I use the transmitter to send signals to the receiver.
2.And then receiver calculate the message (very shot).And
through the tcpip,the receiver transmit the message to the transmitter.
What is “very short”? Numbers, please. Also, sample rate, modulation,
carrier frequency etc might be of interest.
3.The transmitter resend again.
Because the receiver keep receiving during this processing.So in
the interval of the transmitter sending,the receiver receive some noise.I don’t
want receive the noise.
Have some ideas about this?Experts.Thank you.
well, you’ll always receive noise. What’s the problem with that? it’s
the same noise you will see whilst actually receiving data, and to know
when to receive, you’ll need some way of synchronization, anyway.

Best regards,
Marcus

Hi zs,

On 11/28/2014 01:25 PM, zs

What is “very short”? Numbers, please. Also, sample rate, carrier frequency etc
might be of

1.Just 128 complex numbers.The receivers send the 128 complex numbers to the
transmitter through the tcpip.
sample rate=250e3,carrier frequency=3e9
128 samples is not really long, and might in fact be so short that
you’ll see things like the analog amplifiers ramp up, depending on what
you do in between these bursts.

            >well, you'll always receive noise. What's the problem with 

that? it’s

            >the same noise you will see whilst actually receiving data, and 

to know

            >when to receive, you'll need some way of synchronization, 

anyway.

           2.I know,I will always receive noise.But during the interval of 

the transmitter sending,the receive keep receiving.In the interval,no signal
shows,only noise.As shows in the picture,“latency”.I want to detect this,and just
receive the signal to the next block(writing in the gnuradio).
I still don’t understand. Since this latency is all but deterministic,
you already have some signal detection, right?

Greetings,
Marcus