I try another UmTRX board, and it's OK. The difference from the channel 0 and 1 is very small.
jiangwy
From: Alexander Chemeris Date: 2013-08-02 17:30 To: wyjiang CC: UmTRX Subject: Re: Re: The Difference of Signal Strength From Two Channels on The Same Board is Big Ok.
Also check that a correct input is selected on both chips (--lms-get-rx-lna option).
Then, could you check whether this is consistent among both UmTRX you have?
On Fri, Aug 2, 2013 at 12:55 PM, jiangwy wyjiang@ljshuoda.com wrote:
I use the following command
./umtrx_lms.py --lms {1,2} --lms-get-rx-vga2-gain
the outputs are all the same ( 15 ).
jiangwy
From: Alexander Chemeris Date: 2013-08-02 16:20 To: wyjiang CC: UmTRX Subject: Re: The Difference of Signal Strength From Two Channels on The Same Board is Big Hi Jiang,
Are you sure you're setting Rx gain properly for both channels? I recommend you to use umtrx_lms.py script from this repository to check Rx LNA and Rx VGA settings for both LMS chips: https://github.com/fairwaves/umtrx_scripts
On Fri, Aug 2, 2013 at 12:09 PM, jiangwy wyjiang@ljshuoda.com wrote:
Hi Alexander Chemeris,
According to rx_multi_samples , I write a program to receive samples from two channels on the same board. The program receive samples from 2 channels and calculate the signal strength respectively. The signal is from a BTS arround. I find the difference of signal strength is very big, about 20dB, and channel 1 is bigger than channel 0. I exchange the antenna and feeder of the them, but the result is same. I think there is some problem, but I cann't find it. Would you please give me some sugguestion?
Best Regards.
Jiang Wenyi
-- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru