This input sample source plugin gets its samples from a [PlutoSDR device](https://wiki.analog.com/university/tools/pluto). This is also known as the ADALM-Pluto. ADALM stands for Analog Devices Active Learning Module and is targeting students in electrical engineering and digital signal processing. Of course it can be used as a radio device like any other SDR.
☞ PlutoSDR is physically implemented as a 1x1 SISO device although the AD9363 chip does have a second Rx and a second Tx channel. Revision C of the board claims to have pads to allow hackers connecting the second ports externally however for now only the first Rx channel is supported by this plugin.
☞ When running the Pluto on Ethernet interface you have to create a non discoverable device reference in the [user arguments dialog](https://github.com/f4exb/sdrangel/blob/master/sdrgui/deviceuserargs.md) from the main window Preferences > Devices menu. You must use the `PlutoSDR` hardware ID then specify the device address with a `uri` parameter in the user arguments for example: `uri=ip:192.168.1.10`. Note that this will become effective once SDRangel is restarted.
This is the center frequency of reception in kHz. The limits are set as those of the AD9364: from 70 to 6000 MHz. PlutoSDR can be fooled to think it has a AD9364 chip with a very simple software hack described [here](https://wiki.analog.com/university/tools/pluto/users/customizing).
AD9363 extended frequency range is not guaranteed but would work normally particularly in the lower range.
- Magenta (or pink) square icon: an error occurred. In the case the device was accidentally disconnected you may click on the icon to stop, plug back in, check the source on the sampling devices control panel and start again.
This is the sample rate at which the ADC runs in kS/s (k) or MS/s (M) before hardware decimation. Hardware decimation is only partially controlled by the user using the FIR decimation factor (12). The value here is the value returned by the device interface therefore it is always exact.
In device to host sample rate input mode (8A) this is the baseband I/Q sample rate in kS/s. This is the device to host sample rate (8) divided by the software decimation factor (5).
In baseband sample rate input mode (8A) this is the device to host sample rate in kS/s. This is the baseband sample rate (8) multiplied by the software decimation factor (5)
Use this slider to adjust LO correction in ppm. It can be varied from -20.0 to 20.0 in 0.1 steps and is applied in hardware. This applies to the oscillator that controls both the Rx and Tx frequency therefore it is also changed on the Tx plugin if it is active.
This button opens a dialog to set the transverter mode frequency translation options. The details about this dialog can be found [here](../../../sdrgui/gui/transverterdialog.md)
- **SW** section: These buttons control the software DSP auto correction options
- **DC**: auto remove DC component
- **IQ**: auto make I/Q balance. The DC correction must be enabled for this to be effective.
- **HW** section: These buttons control the hardware AD9363 DC and I/Q compensation
- **RFDC**: RF DC correction
- **BBDC**: Baseband DC correction
- **IQ**: I/Q imbalance correction.
☞ There is a reason why you would like to remove any I/Q correction: this is for the reception of signals that are symmetric in I and Q (real signals). More details [here](https://wiki.analog.com/university/tools/pluto/users/non_quad) something not very well known about SDR and DSP.
The I/Q stream from the PlutoSDR is downsampled by a power of two by software inside the plugin before being sent to the passband. Possible values are increasing powers of two: 1 (no decimation), 2, 4, 8, 16, 32, 64.
- if decimation n is 4 or lower: Fc = SR/2^(log2(n)-1). The device center frequency is on the side of the baseband. You need a RF filter bandwidth at least twice the baseband.
- if decimation n is 8 or higher: Fc = SR/n. The device center frequency is half the baseband away from the side of the baseband. You need a RF filter bandwidth at least 3 times the baseband.
The AD9363 has many port options however as only the A balanced input is connected you should leave it as the default. This is a provision for people who want to hack the board. The different values may be found in the AD9363 documentation.
Use this toggle button to switch the sample rate input next (8) between device to host sample rate and baseband sample rate input. The button shows the current mode:
- **SR**: device sample rate input mode. The baseband sample rate (1.5) is the device to host sample rate (8) divided by the software decimation factor (5).
- **BB**: baseband sample rate input mode. The device sample rate (1.5) is the baseband sample rate (8) multiplied by the software decimation factor (5).
This is the device to host sample rate or baseband sample rate in samples per second (S/s). The control (8) is used to switch between the two input modes.
The limits are adjusted automatically. In baseband input mode the limits are driven by the software decimation factor (5). You may need to increase this decimation factor to be able to reach lower values.
Use the wheels to adjust the sample rate. Pressing shift simultaneously moves digit by 5 and pressing control moves it by 2. Left click on a digit sets the cursor position at this digit. Right click on a digit sets all digits on the right to zero. This effectively floors value at the digit position. Wheels are moved with the mousewheel while pointing at the wheel or by selecting the wheel with the left mouse click and using the keyboard arrows.
This is the Rx analog filter bandwidth in kHz in the AD9363 device. It can be varied from 200 kHz to 14 MHz in 1 kHz steps. Use the wheels to adjust the value. Pressing shift simultaneously moves digit by 5 and pressing control moves it by 2.
The AD9363 chip has an optional FIR filter in the Rx decimation chain as the last decimation block. Use this button to activate or deactivate the filter.
The FIR filter settings are the same on Rx and Tx side therefore any change here is automatically forwarded to the Tx GUI.
The filter limits are calculated as 0.05 and 0.9 times the FIR filter input frequency for the lower and higher limit respectively. The FIR filter input frequency is the baseband sample rate (5) multiplied by the FIR interpolation factor (9)
For bandwidths greater than 0.2 times the FIR filter input frequency the filter is calculated as a windowed FIR filter with a Blackman-Harris window. This has a high out of band rejection value at the expense of a slightly smoother roll off compared to other filters. The bandwidth value sets the -6 dB point approximately.
The FIR filter block can provide a decimation by 1 (no decimation), 2 or 4. This controls the minimum possible baseband sample rate as already discussed in (8).
The FIR filter can introduce a gain that can be set to -12, -6, 0 or 6 dB. The FIR has a fixed gain of 6 dB so to maximize dynamic range one would set the gain at -6 dB so that the overall gain is set at 0 dB.
