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Worldcast Systems - Radio & TV Broadcast Solutions



FM is still the technology that reaches the most listeners worldwide. At the same time, efforts are being made optimizing effort and costs of this distribution, and indeed to keep them as low as possible.  

Only a few years ago, the only way to generate an MPX/composite signal was to combine the signal components at each transmitter site. The consequence for the program operator was and still is a large number of decentralized installed devices of the same category. These are at least one audio codec, one stereo encoder, one RDS encoder, and the exciter.

The "sound" of the station is often the trademark of the broadcast. For the same perception, a sound processor should ideally be installed at each transmitter location; and these have to be adjusted precisely identically.  

With the transmission of a centrally generated MPX/Composite signal, the majority of the equipment mentioned above is eliminated, and a single central processor guarantees the sonic signature. The cost of site maintenance is significantly reduced.

Especially the operation of transmitters at smaller gap-filling locations or in metropolitan areas where it is often necessary to save physical space (costs calculated on the device footprint) and to minimize the complexity of the site MPX/composite transmission is a must.  

Also, with our new APTmpX data format, you can confidently transmit your MPX/Composite signal at a data rate of 900kbps without affecting the quality of the transmission. 



Professional IP STLs for MPX-Composite delivery

mpx delivery diagram


APT's Solution for MPX/Composite over AES over IP

Simplicity & Cost Reduction

Simplification of the signal processing chain leads to a considerable cost reduction of the broadcast STL.

Optimal Latency

APT codecs have low latency, and latency control of the MPX/composite signals results in extended audience reach through optimized MFN and SFN networks.


Less Hardware

Eliminates the need for multiple hardware such as RDS encoders, stereo generators and audio processors at multiple transmitter sites as only one is needed at the studio source.


  • Hybrid transmission combining digital composite/MPX at the studio with analog composite at the transmitter site or vice versa is easily achievable.
  • Studio positioning of audio processors means easier for serving and adjustments


Transport Optimization

Options for reducing the bit rates:

  • By adjusting the bandwidth of the MPX/Composite Spectrum to the minimum required, network utilization is reduced.
  • The new compression format APTmpX transmits your high-quality composed signal at even lower bit rates.

Redundant IP transport:

  • IP transport with APT SureStream added to the IP network, and the FM link benefits from packet redundancy without adding any additional link latency.

Overmodulation Cancellation

A unique feature of the APT MPX/Composite codecs is the ability to counteract the interferences caused by IP packet loss during transmission of the MPX/Composite signal, which would result in severe and undesirable carrier overmodulation.




APT technologies ensure the highest quality transmission of your MPXoIP signal


Enjoy A Seamless Transition To Digital With APT's Codecs For MPXoIP.

APT MPXoIP Multichannel Codec

The APT Modular Codec Frame is a compact, space and power-efficient solution with a capacity of transporting up to eight channels of MPX/Composite content over IP links. Equipped with redundant power supplies as standard and populated with the universal Codec modules, it enables fully digital distribution of the Digital MPX/Composite signal using an AES connection over an IP network. This 100% digital path eliminates D/A and A/D conversions which may cause degradation of signal quality and could introduce distortion.  

For maximum compatibility with existing analog MPX/Composite equipment, the AoIP card provides support for both Analog and Digital MPX transmission. Offering analog-analog, analog-digital and digital-digital MPX/Composite distribution all on a single platform provides broadcasters with a solution for the current needs and a clear and affordable migration path for the future.

APT Codec Frame

APT Modular Codec Chassis which can accommodate up to four codec modules and a multichannel AES67/Dante Module. See AES67/Dante Module brochure

AoIP Module

AoIP Module

Together with the standard input/output interface, the universal codec module offers all connections for analog and digital audio, digital MPX/composite and AUX data for up to two program feeds, or, in duplex mode select the analog or digital codec input at the transmitter site for a low bit-rate monitor stream back to the studio. With the license for digital MPX/Composite, the extensive audio algorithm library is further extended by the MPX/Composite modes, including the new revolutionary APTmpX format. The AoIP module provides the perfect migration path from discrete signal transmission to MPX/composite at any time. 

Analog MPX/Composite Interface Card

Analog MPX/Composite Interface Card

The analog MPX/Composite input/output module is the right solution if your transmitter cannot yet process digital MPX/Composite. The high-quality digital MPX/Composite of your sound processor is the source and is connected to the transmitter as an analog signal. With the analog interface, the transmitter and RDS encoder installation remains unaffected. Even RBDS/RDS information could be transmitted as a discrete serial signal. We call it "Cross-Domain" transmission. 


Cross-Domain Transmission

AES over IP diagram

Cross Domain Transmision is the ideal migration path to completely digital signal processing in the studio while the transmitter can remain analog. The quality of the broadcast even over transmitters with analog MPX/composite inputs benefits from the high-quality digital signal source.


APT IP Codec


Feature-packed and cost-competitive, the APT IP CODEC offers the most complete set of IP features ever included in APT's extensive range. This universal IP audio codec also offers a wide range of algorithms as standard on a solid DSP platform with dual IP ports and redundant power supplies. Perfect for STLs for MFN and, thanks to APT's SynchroStream technology, also for SFN networks or mission critical applications, the APT IP CODEC provides all the latency control and monitoring functions required.

As the ideal gateway for your home studio applications, it offers reliable and versatile connectivity. Compatibility with other manufacturers' codecs is achieved through SIP connectivity and its extensive N/ACIP compliance.


Customer Stories


How it's done in New Zealand

With contribution of Markkus Bekker of Southern Broadcast Ltd.


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