Digital Baseband

Pieter, PE1ODJ, known for being a critical purist in the field of audio and video, has evaluated the Digital Baseband board, and has given it his ‘sign of approval’.

We will post a technical description of the inner workings of the Digital Baseband on this page.

The Digital Baseband is realized in a Field Programmable Gate Array, or FPGA. An overview of the hierarchy and components comprising the FPGA will be included. This Digital Baseband incorporates a NICAM encoder which is based on the NICAM encoder Werner developed back in 1999. That encoder used a Digital Signal Processor (DSP) in conjunction with an FPGA, and required external filtering to shape the NICAM modulate.
Since the FPGA used in the Digital Baseband is roughly 200 times more powerfull than the FPGA used in the original NICAM encoder, the DSP and external filters are no longer needed as the FPGA can easily perform these tasks.

One of the production steps is that the BGA’s are inspected using X-Ray technology. Here is a capture of such an inspection.

The digital baseband offers pre-emphasis and steep 5MHz filtering (without any C/L delay issues), NICAM, 4 FM channels, text overlay (for call and so on), morse code generator (for call and so on) and some test cards and a bessel null function to align your FM transmitter. All is controlled by an ESP32 with a 320×240 display. See the manual section for more details.

Currently, these boards are sold out. We’ll make a new batch when enough people want one….