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Project Summary

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Tom M0LTE edited this page Jan 8, 2022 · 1 revision

Goals

  • To build an accessibly priced, integrated, portable 25-50W 2m SSB transceiver, with controls on the front and connectors on the back.
  • To release a reproducible reference design that anyone can build to use for themselves
  • Not to try to solve everything up front, but instead build a minimally viable product and add features through iteration
  • To work in the open with collaborators

Block diagram

image

(lucidchart)

Bill of Materials

  • Raspberry Pi 4
  • Official 7" touchscreen
  • LimeSDR Mini
  • 13.8V DC input
  • No keyboard / mouse input, everything through the touchscreen
  • G4DDK band-pass filter on TX
  • Gain block
  • RA35H1516M 40W PA
  • USB for audio input / output

Software

  • Transceiver as GNU Radio flow graph
  • Custom rig controller service
    • C# .NET 6 worker service
    • Detect PTT via GPIO
    • Handle PTT via muting in GNU Radio via message passing
      • provide sequenced outputs for RX/TX changeover relays via GPIO pins
  • Custom UI running on the 7" touchscreen
    • HTML5 + WebSockets -> rig controller service (SignalR)
    • Boot straight into Chromium in kiosk (full screen) mode

Case

Ideally 3D printable

Front dominated by touchscreen

  • a dual USB connector (USB headset, USB tuning knob?)
  • maybe an RJ45 connector for a fist speaker-mic
  • maybe a shutdown button?

Rear

  • Single N/BNC/SMA antenna connector
  • Anderson PowerPole DC input
  • USB
  • PTT (phono)
  • Loop for external PA?

Top

  • Speaker?

Bottom

  • provision for rubber feet

Shape

  • 857D-ish footprint
  • touchscreen tilted back a bit for use on the ground / desk

Internals

  • PCBs are likely to be 100mm x 100mm max, possibly multiple
    • expecting an RF board
    • thinking about including a DC protection board (Gareth Blades' design)
  • PSUs
    • 5V for Pi (VERY fussy about undervoltage)
    • 12V for PA
  • Raspberry Pi 4
  • LimeSDR Mini
  • Cooling
  • Battery?

V.next

This is stuff which would be lovely to have but should be iterated on later since it's not strictly required to meet the original goals.

  • Full duplex cross band VHF/UHF operation for LEO satellites
    • Doppler correction
    • Pass prediction, rotator control
  • Integrated WSJT-X modes
  • Integrated logger / integration
  • GPS
  • Hardware tuning knob
  • Integrated LiFePO4 battery
  • Tolerate 18V DC input - drill batteries
  • Tolerate abrupt power off
  • Waterfall
  • USB host / TS-2000 emulation / expose USB audio
  • Back end for hamlib / rigctld
  • FM
  • FreeDV
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