System for the certification of a passive optical network and for the detection of problems and faults in the last sections (6, 7) of a monofibre plant (2,6,7), which is suitable for use in passive optical networks between the Optical Line Terminal "OLT" device housed in a telephone central office and the user device of an Optical Network Termination "ONT", connected to the corresponding wall socket, and including optical dividers or splitters which, in the downstream direction, are adapted to distribute the optical signal to all of the users within a tree-and-branch architecture, and in the upstream direction, adapted to combine the optical signals from all of the ONTs, using a transmission window and a reception window in the monofibre plant (2,6,7) for the Fibre to the Home "FTTH" deployments, characterized in that the system comprises: • a portable and autonomous OLT emulator device connected to a wall socket of the central office to access the plant infrastructure and • a remote testing unit "RTU" connected to a subscriber wall socket, such that the OLT emulator comprises: • an Application-specific Integrated Circuit "ASIC" or Field-Programmable Gate Array "FPGA" implementing the Gigabit-Capable Passive Optical Network "GPON" protocol on at least one electro-optical module connectable to different PON networks with the capacity to measure optical power, and said ASIC or FPGA connectable to flash memory and RAM peripherals; • a packet processor, connected to the ASIC or FPGA to generate the service traffic to be tested, and a second microprocessor dedicated to the control of provision and testing functions; • at least one external USB external data port and an Ethernet port to connect to an external PC to update firmware, while the RTU comprises: • a GPON chipset or an FPGA with an embedded microprocessor with flash memory and RAM peripherals; • an ONT electro-optical module, joined to the chipset or FPGA, adapted to measure the optical power received; • an optical circuit capable of separating reflected light and sending it to an OLT electro-optical module with the capacity to measure power; • a first optical filter adapted to communicate with the ONT electro-optical module capable of separating the downstream wavelength from the upstream wavelength; • an optical circulator with a first port P1 connected at the 1310 nm output of the first optical filter, as well as with a second portP2 connected to a second optical filter to recover the monofibre signal along with the downstream wavelength coming from the first filter; • a PIN that can be activated to detect the reflections of the connections emitted in the OLT electro-optical module and which PIN is connected to a digital logic block that is adapted to communicate with the activation of the burst transmission of the ONT electro-optical module; • an optical fibre coil connected to an optical connector with an Angled Physical Contact "APC"-type polish; • a USB-type external connector and an Ethernet-type external connector for the connection to an external PC; and • a Lithium-Polymer battery block that ensures the autonomy and portability of a field system that does not require electricity to operate. • a portable and autonomous OLT emulator device connected to a wall socket of the central office to access the plant infrastructure and • a remote testing unit "RTU" connected to a subscriber wall socket, • an Application-specific Integrated Circuit "ASIC" or Field-Programmable Gate Array "FPGA" implementing the Gigabit-Capable Passive Optical Network "GPON" protocol on at least one electro-optical module connectable to different PON networks with the capacity to measure optical power, and said ASIC or FPGA connectable to flash memory and RAM peripherals; • a packet processor, connected to the ASIC or FPGA to generate the service traffic to be tested, and a second microprocessor dedicated to the control of provision and testing functions; • at least one external USB external data port and an Ethernet port to connect to an external PC to update firmware, • a GPON chipset or an FPGA with an embedded microprocessor with flash memory and RAM peripherals; • an ONT electro-optical module, joined to the chipset or FPGA, adapted to measure the optical power received; • an optical circuit capable of separating reflected light and sending it to an OLT electro-optical module with the capacity to measure power; • a first optical filter adapted to communicate with the ONT electro-optical module capable of separating the downstream wavelength from the upstream wavelength; • an optical circulator with a first port P1 connected at the 1310 nm output of the first optical filter, as well as with a second portP2 connected to a second optical filter to recover the monofibre signal along with the downstream wavelength coming from the first filter; • a PIN that can be activated to detect the reflections of the connections emitted in the OLT electro-optical module and which PIN is connected to a digital logic block that is adapted to communicate with the activation of the burst transmission of the ONT electro-optical module; • an optical fibre coil connected to an optical connector with an Angled Physical Contact "APC"-type polish; • a USB-type external connector and an Ethernet-type external connector for the connection to an external PC; and • a Lithium-Polymer battery block that ensures the autonomy and portability of a field system that does not require electricity to operate.