As comparison, a modern phone contains around 50-70 individual ranging receivers similar to the Apollo ranging receiver, all capable of operating simultaneously (each with its own spread spectrum sequence, Doppler shift etc).

The GNSS chip typically has 30-60. The 3G modem (if enabled) has ~10 independent receivers (called "fingers" in CDMA parlance). WiFi has 1 (legacy 802.11b).

It's starting to transition into software defined these days. The antennas themselves are similar size, depending on frequency but the backend systems are now down to a standard server (at least up to 250-ish megasymbols and increasing).

Things like viterbi are designed to be done efficiently in hardware. Doing it in software is limited to CPU core speed. Multi threaded solutions are hard to engineer as the signal is a continuous stream and cannot trivially be split up for parallel processing.

I do grounds stations for a living. Currently building edge clouds to do this at scale where the dishes are placed around the globe.

A modern phone contains around 50-70 individual ranging receivers, all capable of operating simultaneously (each with its own spread spectrum sequence, Doppler shift etc).

The GNSS chip typically has 30-60. The 3G modem (if enabled) has ~10 independent receivers (called "fingers" in CDMA parlance). WiFi has 1 (legacy 802.11b).