AMM 34-36-00 if you don't have access, only the first General paragraph.
G__e_n_e_r_a_l
The primary function of the Multi-Mode Receiver (MMR) is to receive and
process Instrument Landing System (ILS) and Global Positioning System (GPS)
signals. The MMR is a navigation sensor with two internal receivers.
A. ILS Receiver
The function of the ILS is to provide the crew and airborne system users
with lateral (LOC) and vertical (G/S) deviation signals, with respect to
the approach ILS radio beam transmitted by a ground station.
The localizer operates in a frequency band which ranges from 108.1 MHz to
111.95 MHz and the glide uses the band from 329.15 MHz to 335 MHz as
defined by ARINC specification 710.
B. GPS Receiver
The GPS is a radio aid to worldwide navigation which provides:
- the crew with a readout of accurate navigation information, e.g.
position, track and speed
- the Flight Management, Guidance and Envelope Computer (FMGEC) with
position information, after hybridization in the Air Data/Inertial
Reference Unit (ADIRU) with inertial parameters, for accurate position
fixing.