Help Regarding Transmitting Gain of USRP N-200

2023-06-25 Thread Arhum Ahmad
Respected sir,
I am using N-200 USRP for transmitting a signal. While transmitting, I have
changed the Gain value in the SDRu transmitting block, but my signal
strength at the receiver remains the same. I also stop and restart the code
but the change in gain does not affect the received signal. I have tried
the changing gain via both available options i.e., input port and dialog,
but it seems to have no effect on the receiver. The signal strength at the
receiver remains the same. I have tried 30 dB(Maximum gain) to 0 dB
(minimum gain) in both cases received SNR is the same (i.e.,15 dB). I am
using a wireless connection in line-of-sight, with minimum Tx gain at least
a few drops in SNR should be observed. I have also tried -50dB (just
checking) but no effect in the SNR is observed. The same thing I have tried
using B210 as Tx, Rx signal strength does change in this case. However,
while using N-200, no effect of changing the gain value is observed. Somehow
 gain value is fixed in N-200 while using the MATLAB SDRu block. Can you
PLEASE HELP ME!!! IT IS VERY, VERY IMPORTANT.

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*Thanks and Regards*
*Arhum Ahmad*
Ph.D. Scholar, Electrical Engineering Department, IIT Ropar

+91- <+91-7015802356>7974897279 | arhum.19eez0...@iitrpr.ac.in
<2016eez0...@iitrpr.ac.in>
Lab No. 323, Communication Research Lab, J.C.Bose Building

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Re: Help Regarding Transmitting Gain of USRP N-200

2023-06-25 Thread Marcus D. Leech

On 25/06/2023 16:49, Arhum Ahmad wrote:

Respected sir,
I am using N-200 USRP for transmitting a signal. While transmitting, I 
havechangedthe Gain value in the SDRutransmitting block, but my signal 
strength at the receiver remains the same. I also stop and restart the 
code but the change in gain does not affect the received signal. I 
have tried the changing gain via both available options i.e., input 
port and dialog, but it seems to have no effecton the receiver. The 
signal strength at the receiver remains the same. I have tried 30 
dB(Maximum gain) to 0 dB (minimum gain) in both cases received SNR is 
the same(i.e.,15 dB). I am using a wireless connection in 
line-of-sight, with minimum Tx gain at least a fewdropsin SNR should 
be observed. I have also tried -50dB (just checking) but noeffect in 
the SNR is observed. The same thing I havetried using B210 as Tx, Rx 
signal strength does change in this case. However, while using N-200, 
noeffect of changing the gain value is observed. Somehow gainvalue is 
fixed in N-200 while using the MATLABSDRu block. Can you PLEASE HELP 
ME!!! IT IS VERY, VERY IMPORTANT.



Well, neither usrp-users nor discuss-gnuradio are support lists for MATLAB.

You haven't mentioned which daughter-card you are using in the N200, 
which would certainly help to fill in information about

  what *might* be going on.


Does your receiver setup use AGC?  Do you know what its set-points are?

If you simply look at the spectrum on the RX end as you vary gain on the 
TX end, do you see a change?   At the higher end,
  SNR may not change very much, depending on how it is being measured, 
etc.