diff options
Diffstat (limited to 'docs/sdr.html')
| -rw-r--r-- | docs/sdr.html | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/docs/sdr.html b/docs/sdr.html index 733a20e..4cc3c2f 100644 --- a/docs/sdr.html +++ b/docs/sdr.html @@ -110,18 +110,36 @@ But still you can add any SDR option afterwards to set or modify them. </pre> <p> +<font color="red">Importaint: Select your RX antenna input!</font> +</p> + +<p> Be sure to select the right RX antenna input. The frequencies we use require the low frequency filter network, so I suggest to connect your antenna to RX_1_L and select "--sdr-rx-antenna LNAL". Different versions of LimeSuite have different default antenna inputs, so be sure to set your RX antenna. </p> <p> +<font color="red">Importaint: Always use two or more channels, to avoid one channel being at the center of the spectrum!</font> +</p> + +<p> My LimeSDR setup causes a bad RX signal, when the RX frequency of the channel (uplink) equals the center frequency of the RX spectrum. This center frequency is used as RX frequency, when only one channel is created for the base station. By creating two channels ('-k 15 -k 17') or an even number would eliminate the problem. The center frequency is between the channels now. </p> +<center><img src="display-spectrum.png"/></center> + +<p> +Press 's' to get an ASCII art graph of received frequency spectrum. +The spectrum's bandwidth is defined by the sample rate (-s) and not by the SDR sample rate! +If you don't get nice peaks, but maybe several peaks, you might over-driven the input. +Note that the peak will spread by the frequency deviation, so the peak might look noisy on the top. +If the peak is quite low, check the input gain. +</p> + <center><img src="display-iq.png"/></center> <p> @@ -135,16 +153,6 @@ If the dots are yellow, or red, the received signal may overdrive the ADC. Especially when the linear view shows a deformed circle (or even rectangle), reduce RX level. </p> -<center><img src="display-spectrum.png"/></center> - -<p> -Press 's' to get an ASCII art graph of received frequency spectrum. -The spectrum's bandwidth is defined by the sample rate (-s) and not by the SDR sample rate! -If you don't get nice peaks, but maybe several peaks, you might over-driven the input. -Note that the peak will spread by the frequency deviation, so the peak might look noisy on the top. -If the peak is quite low, check the input gain. -</p> - <p class="toppic"> <a name="uhd"></a> UHD |