Portsdown 2020 Receive Enhancements

Software version 2020043000 introduced significant enhancements to the Receive and video-handling functionality of the Portsdown.

LNB Voltage Switching

For those users who have made G4KLB's LNB Voltage Switching board Serit_LNB_DC_supply, the Portsdown will now switch the supply between "off", 13V and 18V. It will not turn the tone on (as would be required to receive the top end of the commercial Ku Band).

This function can be selected from the "RX", "Config" menu, where the button cycles through 3 states: "LNB Volts Off", "LNB Volts 18 Horiz" (as required for DATV on Es'hail-2) and "LNB Volts 13 Vert". The chosen setting is stored in the configuration file and applied every time receive is selected.

VLC Video Player

The 3 video players available for the receiver are the simple "H264 No Audio" player, "OMX Player", which should display MPEG-2 and H264 signals with audio and the recently introduced "VLC Player".

The advantage of VLC player is that it will display some H265 signals. It will fail to display some signals, and will tear or "fold-over" the picture on others. The disadvantage is that it sometimes crashes and leaves the RPi with a white background screen, or occasionally locked up; it is hoped to make it better behaved as a better understanding of its functionality is gained.

VLC player is not compatible with simultaneous display of the signal parameters, so these are obscured as soon as a valid image is displayed.

One other advantage is that VLC player will decode the audio from the Wideband Beacon, although not the video.

Screen capture (Snap) is available in all the video players by touching the far lower left of the display. There is, as yet, no indication of a valid snap (see below).

Screen Capture "Snap"

It is possible to store a screen capture ("Snap") of the display when receiving using the Portsdown Receiver, or when using the Comp Video, Pi Cam, C920 or IPTS Monitors. In all cases the Snap is triggered by touching the lower left corner of the touch screen (to be precise, the lower 1/6 and the left 1/8). There is no confirmation of the snap at the time.

Snaps can be viewed from the "Snap Check" button on Menu 2. If there are no snaps stored, then the button will do nothing (a brief flash of the Portsdown Logo). If there are multiple snaps stored, the most recent is displayed first. You can cycle through all of the stored snaps backwards by touching the lower left of the screen, and forwards by touching the lower right. Touching elsewhere exits the snap viewer.

The snaps are also