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XTRX: updated documentation with real time scheduling tricks and other minor updates

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f4exb 2019-01-04 05:09:55 +01:00
parent 733f3d4ba4
commit 7173032645
2 changed files with 41 additions and 5 deletions
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21
plugins/samplesink/xtrxoutput/readme.md
View File

@ -20,6 +20,23 @@ If libraries are installed in a custom place like `/opt/install/xtrx-images` add
`-DXTRX_DIR=/opt/install/xtrx-images`
<h2>Real time scheduling</h2>
You may find in the log some info (green) messages from `libxtrx` mentioning that some task cannot be set with real time priority. While this is not an absolute necessity to make XTRX work you may want to allow your user or a specific group your user belongs to to set tasks with real time scheduling.
In most Linux systems this is done by editing the `/etc/security/limits.conf` file (with sudo rights). In this file you may add these lines for your user (ex: `user`):
```
user - rtprio 99
user - memlock unlimited
```
For a group the syntax is the same but the group name is prefixed with `@` like:
```
@realtime - rtprio 99
@realtime - memlock unlimited
<h2>Interface</h2>
![XTRX output plugin GUI](../../../doc/img/XTRXOutput_plugin.png)
@ -34,7 +51,7 @@ Device start / stop button.
<h3>2: DAC sample rate</h3>
This is the sample rate at which the DAC runs in kS/s (k) or MS/s (M) after hardware interpolation (9). Thus this is the host to device sample rate (11) multiplied by the hardware interpolation factor (9). Please note that a hardware decimation of 4 is required for the device to work properly.
This is the sample rate at which the DAC runs in kS/s (k) or MS/s (M) after hardware interpolation (9). Thus this is the host to device sample rate (11) multiplied by the hardware interpolation factor (9). Please note that a hardware decimation of at least 4 (the default) is required for the device to work properly.
<h3>3: Center frequency</h3>
@ -87,7 +104,7 @@ Use the "Cancel" button to dismiss your changes
<h3>9: LMS7002M hardware interpolation factor</h3>
The TSP block in the LMS7002M hardware has an interpolation chain that acts on both Tx channels. It is composed of 5 halfband interpolation stages and therefore can achieve interpolation between 1 (no interpolation) and 32 in increasing powers of 2: 1, 2, 4, 8, 16, 32. Please note that a factor of at least 4 is required. Lower values are experimental.
The TSP block in the LMS7002M hardware has an interpolation chain that acts on both Tx channels. It is composed of 5 halfband interpolation stages and therefore can achieve interpolation between 1 (no interpolation) and 32 in increasing powers of 2: 1, 2, 4, 8, 16, 32. Please note that a factor of at least 4 is required (this is the default). Lower values are experimental.
Thus the actual sample rate of the DAC is the stream sample rate (11) multiplied by this factor. In the screenshot example this yields a 12.288 MS/s rate at the DAC (3.072 * 4).

25
plugins/samplesource/xtrxinput/readme.md
View File

@ -18,6 +18,24 @@ If libraries are installed in a custom place like `/opt/install/xtrx-images` add
`-DXTRX_DIR=/opt/install/xtrx-images`
<h2>Real time scheduling</h2>
You may find in the log some info (green) messages from `libxtrx` mentioning that some task cannot be set with real time priority. While this is not an absolute necessity to make XTRX work you may want to allow your user or a specific group your user belongs to to set tasks with real time scheduling.
In most Linux systems this is done by editing the `/etc/security/limits.conf` file (with sudo rights). In this file you may add these lines for your user (ex: `user`):
```
user - rtprio 99
user - memlock unlimited
```
For a group the syntax is the same but the group name is prefixed with `@` like:
```
@realtime - rtprio 99
@realtime - memlock unlimited
```
<h2>Interface</h2>
![LimeSDR input plugin GUI](../../../doc/img/XTRXInput_plugin.png)
@ -44,7 +62,7 @@ Record baseband I/Q stream toggle button
<h4>1.4: ADC sample rate</h4>
This is the sample rate at which the ADC runs in kS/s (k) or MS/s (M) before hardware decimation (8). Thus this is the device to host sample rate (5) multiplied by the hardware decimation factor (3).
This is the sample rate at which the ADC runs in kS/s (k) or MS/s (M) before hardware decimation (3). Thus this is the device to host sample rate (5) multiplied by the hardware decimation factor (3).
&#9758; Note that changing the hardware decimation factor (3) or the device to host sample rate (5) may change the DAC clock sample rate and therefore the Tx side hardware interpolation factor and/or host to device sample rate.
@ -160,8 +178,9 @@ Use this button to adjust the gain of tha PGA when manual gain mode is set (9.1)
Use this combo box to select the antenna input:
- **Lo**: Selects the low frequency input (700 to 900 MHz nominally)
- **Hi**: Selects the high frequency input (2 to 2.6 GHz)
- **Lo**: Selects the low frequency input. You should use this one and this is the default
- **Wide**: Selects the wide band frequency input. This is not connected and should not be used
- **Hi**: Selects the high frequency input. You may use this one as well with no actual difference with "Lo".
<h3>10: Stream status indicator</h3>