Portsdown 2020 Buster Software

Introduction

The Portsdown Buster Software is a major change from previous Portsdown Software. The complete system needs retesting (and much of it needs re-writing) so only specific features will initially be declared as fit for use, with more features being added to the list as testing progresses.

The changes being introduced with this software include:

• A new LimeDVB mode that uses custom Firmware for a LimeSDR Mini to produce DVB-S and DVB-S2 signals.
• The ability to select whether LimeSDR calibration takes place before transmission
• A specific capability to transmit 1MS DVB-S2 with high reliability for use in repeater transmitters.

The notes below apply to the latest release 202002140, built on Portsdown Buster 2020-02-05.

Tested Modes of Operation using LimeDVB Firmware

To load the LimeDVB custom firmware, first check the current Firmware standard (Menu 3, Lime Config, Lime FW Info). It should be 1.30. If not, update it to 1.30 (Menu 3, Lime Config, Update to FW 1.30). Once at this standard, update with the DVB Firmware (Menu 3, Lime Config, Update to DVB FW).

If you do not have a touchscreen (for example setting up a repeater transmitter), you can achieve the same actions by using the Lime Config Menu on the Console (see Console mode Instructions) after connecting to the Raspberry Pi by ssh.

EasyCap input, H264 DVB-S2 output using LimeDVB

This mode transmits reasonable pictures at symbol rates from 125 kS to 3 MS.

Pi Camera input, H264 DVB-S2 output using LimeDVB

This mode transmits reasonable pictures at symbol rates from 125 kS to 3 MS, both with and without a USB Microphone dongle.

Animated Test Card (TCAnim) input, H264 DVB-S2 output using LimeDVB

This mode transmits reasonable pictures at symbol rates from 125 kS to 2 MS, both with and without a USB Microphone dongle.

Static Test Card input, H264 DVB-S2 output using LimeDVB

This mode transmits reasonable pictures from Test Card C (with callsign caption if selected), or the contest numbers card at symbol rates from 125 kS to 2 MS. Audio is disabled when using the static test card or contest numbers.

C920 Webcam input, H264 DVB-S2 output using LimeDVB

This mode transmits good pictures and audio at symbol rates from 125 kS to 2 MS. Note that maximum definition from the C920 in this mode is currently 800x448. This is because of problems with the Linux driver for the camera.

EasyCap input, H264 DVB-S output using LimeDVB

This mode transmits reasonable pictures at symbol rates from 125 kS to 6 MS.

EasyCap input, MPEG-2 DVB-S output using LimeDVB

This mode transmits stuttering pictures at symbol rates from 125 kS to 6 MS. Not sure how to make it better!

Pi Camera input, H264 DVB-S output using LimeDVB

This mode transmits very good pictures at symbol rates from 250 kS to 9 MS, both with and without a USB Microphone dongle.

Pi Camera input, MPEG-2 DVB-S output using LimeDVB

This mode transmits very good pictures at symbol rates from 250 kS to 9 MS, both with and without a USB Microphone dongle.

C920 Webcam input, H264 DVB-S output using LimeDVB

This mode transmits good pictures and audio at symbol rates from 125 kS to 6 MS. Note that maximum definition from the C920 in this mode is currently 800x448. This is because of problems with the Linux driver for the camera.

C920 Webcam input, MPEG-2 DVB-S output using LimeDVB

This mode transmits good pictures and audio at symbol rates from 500 kS to 6 MS.

Animated Test Card (TCAnim) input, H264 DVB-S output using LimeDVB

This mode transmits reasonable pictures at symbol rates from 125 kS to 6 MS.

Static Test Card input, H264 DVB-S output using LimeDVB

This mode transmits reasonable pictures from Test Card C (with callsign caption if selected), or the contest numbers card at symbol rates from 125 kS to 6 MS. Audio is disabled when using the static test card or contest numbers.

Static Test Card input, MPEG-2 DVB-S output using LimeDVB

This mode transmits reasonable pictures from Test Card C (with callsign caption if selected), or the contest numbers card at symbol rates from 333 kS to 6 MS. Audio is disabled when using the static test card or contest numbers.

Tested Modes of Operation using the Portsdown Filter-Modulator Board (DVB-S only)

EasyCap input, H264 output

This mode transmits reasonable pictures at symbol rates from 250 kS to 2 MS.

Pi Camera input, H264 output

This mode transmits reasonable pictures at symbol rates from 125 kS to 2 MS, both with and without a USB Microphone dongle.

Animated Test Card (TCAnim) input, H264 output

This mode transmits reasonable pictures at symbol rates from 125 kS to 2 MS, both with and without a USB Microphone dongle.

Static Test Card input, H264 output

This mode transmits reasonable pictures from Test Card C (with callsign caption if selected), or the contest numbers card at symbol rates from 125 kS to 1 MS. Audio is disabled when using the static test card or contest numbers.

C920 Webcam input, H264 output

This mode transmits good pictures and audio at symbol rates from 125 kS to 2 MS. Note that maximum definition from the C920 in this mode is currently 800x448. This is because of problems with the Linux driver for the camera.

EasyCap input, MPEG-2 output

This mode transmits reasonable pictures at symbol rates from 1 MS to 5 MS.

Pi Camera input, MPEG-2 output

This mode transmits reasonable pictures at symbol rates from 250 kS to 5 MS, both with and without a USB Microphone dongle.

Static Test Card input, MPEG-2 output

This mode transmits reasonable pictures from Test Card C (with callsign caption if selected), or the contest numbers card at symbol rates from 250 kS to 5 MS.

C920 Webcam input, MPEG-2 output

This mode transmits good pictures and audio at symbol rates from 250 kS to 5 MS.

LongMynd DATV Receiver

The LongMynd DATV Receiver software (which works with a MiniTiouner) is included in this Portsdown build and has the same functionality as previous Portsdown versions.

Composite Video Output

The Composite video output works well both as a transmission mode (for driving analog transmitters) or as a second display. The output can be enabled when a 7 inch screen is in use from a button on the System Config menu reached from Menu 3.

Output to BATC Streamer

This version of Portsdown can send video and audio to the BATC streamer. The supported input devices are a Pi Camera (with USB mic dongle), or an EasyCap for Composite Video input. The test card can also be sent. Remember to set up your stream name and key in Menu 3, Set Stream Outputs, Amend Preset (then press the preset to be amended).

Limitations

LimeSDR Models

Only the LimeSDR Mini (hardware versions 1.1, 1.2 and 1.3) is supported by this build. It is hoped to add LimeNET Micro support, but the LimeSDR USB will not be supported.

USB Webcams

The only USB Webcam that is planned to be supported in Portsdown Buster is the Logitech C920. If you have other webcams working with Portsdown Jessie or Portsdown Stretch, then please keep using the older software.

Reduced Power Output

The Power output from the LimeSDR Mini using the LimeDVB software is less than that available using Portsdown 2019. This has yet to be exactly characterised but initial indications are that at Lime Gain 100 it is 4 dB less than the line on this chart LimeSDR_Mini_Output_Power_Levels which was drawn up using the older software at Lime Gain 88.

Increased Delay at Low Symbol Rates

At low symbol rates, there is an increased delay in the video/audio stream - maybe 15 seconds increase at 333 kS. It is hoped that this can be reduced in a future update.

Limited DVB-S2 Modes

The custom LimeDVB firmware only supports QPSK and 8PSK (untested as yet). It does not support 16APSK or 32APSK.

Carrier Mode using LimeDVB

When carrier mode is selected with LimeDVB as the selected output, and LimeDVB gateware loaded, the carrier is only transmitted at a very low level (-40 db?).

LimeRFE Control

Although there is a button to enable/disable a USB-connected LimeRFE, this does not yet do anything.

FreqShow

It has not been possible to make the FreqShow spectrum view work with this build.