Definitely digital. There's no way to develop the film out there and they would have run out long before they finished the misson.
Cameras - There are several camera on-board the Voyager spacecraft. Here is a link to the Instruments page on the Voyager website. This site provides diagrams of the optical elements of each of the cameras, but it doesn't seem to provide specific specifications on the detectors. On NASA's Planetary Data System website, there are detailed specifications on each camera. Links to those pages are provided below.
- The Infrared Interferometer Spectrometer (IRIS) - 128x128 pixel format mercury-cadmium telluride detector
- The Ultraviolet Spectrometer (UVS) - Note: this page is really hard to read as it looks like it was scanned from a two column format with the columns interleaved. But it looks like this detector has 128 channels for the spectra.
- the two Imaging Science Subsystem (ISS) vidicon cameras
- The Photopolarimeter System (PPS) - One pixel - an EMR 510-E-06 photomultiplier tube (PMT) with a tri-alkali (S-20) photocathode.
Data was stored on a digital tape drive and then played back during transmission periods. During the planetary encounters, data was accumulated much faster than it could be relayed back to Earth. Images were downloaded as fast as possible, but mostly the data built up on the tape drive and was then played back over the long interplanetary stretches.
As for getting the data back, it was transmitted back to Earth and received by NASA's Deep Space network of radio dishes placed around the world specifically to receive transmissions from the various space probes out in the solar system. The rates are very low by todays standards, but this is late 1960s and early 1970s technology.
Voyager telemetry operates at these transmission rates
- 7200, 1400 bit/s tape recorder playbacks
- 600 bit/s real-time fields, particles, and waves; full UVS; engineering
- 160 bit/s real-time fields, particles, and waves; UVS subset; engineering
- 40 bit/s real-time engineering data, no science data.
So the best transmission rate is 7.2 kilobits per second.
Here is a link to the official Voyager website.