Using MPX over IP allows for centralised signal processing; simultaneously encoding the output from the audio processor, stereo encoder and RDS encoder. This MPX signal is then distributed by an MPX codec to one or multiple locations over the IP network for direct injection to the Transmitter.
Significant savings can be gained in CAPEX and from OPEX savings on-site with reduced energy consumption, cooling, wiring and less rack space required.
MPXoIP is supported on the APT Multi-Channel Codec in both AES and Analogue domains and on the APT IP codec in the AES domain.
Benefits of an APT MPX over IP codec solution
Over Modulation Cancellation
A unique feature of APT MPX Codecs is their ability to cancel out undesired peaks and troughs of the MPX signal to reliably prevent overmodulation, caused by dropped IP packets, which can lead to regulatory fines or penalties and are therefore to be avoided. APT MPX codecs deploy a ‘watchdog’ service to ensure that, should there be any distortion or corruption of the signal, it will not lead to overmodulation.
Bandwidth reduced MPXoIP option to 2.3MBits
In most applications only RDS data is transmitted in addition to the audio programme. With the RDS carrier is at 57kHz; however, the MPX signal can be up to 100kHz. APT codecs offer a Bandwidth Reduction option to cut the spectrum at 64kHz, leading to a significant saving of the bit rate in the IP network.
Low Latency MPXoIP Solution
APT codecs have long had a reputation for low latency transmission and MPXoIP transmission is no exception to this. In customer and in-house testing, APT codecs offer the lowest latency by a significant margin. The graph below shows the actual performance of the APT MPX Codec vs a leading competitor.
MPXoIP protection using SureStream
Just as SureStream Technology is very effective at protecting audio data from packet loss when transporting over IP, it also affords the same level of protection to the MPX Signal. With seamless delivery, SureStream enables transmission over lower-cost IP networks without any of the side-effects which occur with traditional FEC methods.
MPXoIP Unicast, Multiple Unicast & Multicast
APT MPX codecs offers IP casting modes such as unicast, multiple unicast and multicast. This opens up the all the possibilities of point-to-multipoint distribution of the MPX signal.
Hybrid topology available using Digital In / Analogue Out
Supporting both formats enables the signal domain in the studio to be completely independent of the signal domain at the transmitter site. APT codecs can receive a digital MPX signal and play it as an analogue signal at the transmitter (hybrid topology).