The transport of audio signals
at the last Century
In the early days of radio, the use of audio over long distances was conducted by telephone lines. If radio stations were very important, they can afford to rent expensive hotlines, point to point. This lines had a reasonable response at low frequencies but poor at high. And in addition to cost a fortune ... were noisy. Small radio stations used standard public phone lines, although their poor audio quality
The second method used then and still today, is radio wave link. These VHF/UHF links have coverage of about 60 km with a good frequency response. But their high distortion and noise means that radio links today are the worst part of the audio chain in a standard FM broadcasting. We could say that today the sound of an FM station is limited by the quality of the STL audio link.
Finally, there are digital microwave links with prices of around U$ 15,000 dollars. They have very good quality, but require special authorization to operate (not easy to get) and a high monthly cost fee for using a wide frequency band that this units need. Its coverage does not exceed 50 Km
At the end of last century the extensive use of digital audio and Internet-based developments such as the transmission of data and audio over TCP/IP has changed the landscape completely.
The intensive use of global optical fiber has replaced satellites for communications, making them faster and cheaper.
The transport of high-tech audio
at the XXI Century
The old submarine cables that were tended at 1880 were replaced by satellites after 1960 and now again, a century later, the man returned to the submarine cables ... today's fiber optics that handle high speed data. Internet is running worldwide using this technology.
Gradually the transport of high-quality audio has turned to
Internet. Even in the absence of broadband Internet providers in some locations, the digital link can be achieved using standard links
at 5.8 GHz using WI FI or WI-Max with a range of 50 Km.
This units are low cost because standard mass production.
And the 5,8 GHz microwave band is free of use
The weakness of all these technologies is the PC computer . Its reliability is low, often entering virus or something is not working because the system "crashes" After a power outage is not able to
join to the network again. Its internal electrical environment is very noisy, deteriorating the quality of audio, which requires special audio cards that worth's more than the PC ... and finally, its internal construction is far from having the reliability and construction
quality of professional broadcast equipment.
At this point Solidyne introduces their hardware based professional solution:
The coder/decoder ADA102 ...
ADA 102, a landmark in high quality Audio & Data link
The ADA102 is a digital audio streaming generator,
working stand alone.
Encoder receives a stereo audio signal (analog or digital) turning it into a MP3 or PCM audio streaming,
different protocols (see specifications).
The output coded TCP/IP is at a RJ45 connector, compatible
with Ethernet networks, with direct connection to modem
Through a front panel pushbutton, the ADA102 becomes
Coder or Decoder.
Some models need connection to PC to
ADA102 at the same time manages
Data signals using a RS-232 serial port.
This allows to remote control from studios,
the transmitter or the Digital audio processor.
Or you can send the RDS info to the RDS coder near the transmitter
Four lines allows remote controlling On-Off devices, 2 lines are with relay. Then is easy to switch On-Off transmitters, change antennas, etc
If the Internet signal fails, ADA102 immediately starts to reproduce a special emergency audio program. This program is recorded at the radio station using a typical Pen Drive memory. This program is able to last several hours. When Internet signal starts again, ADA102 stops the program
ADA 102 Decoder, at the other end of the link, manages data stream coming through the Internet or by a microwave link 802.11.x, and convert it to audio signal. Audio is delivered analog balanced or digital stereo AES3, compatible with S/PDif.
The ADA102mpx model includes a third type of output for direct connection to FM stereo transmitter; MPX stereo multiplex.
ADA102 is the world only digital link that converts AES 3 digital audio into a clean MPX signal, with a full digital audio quality
High-precision MP3 encoding
ADA102 handle the new encryption algorithm MPEG 1/2 layer 3 to arrive at standards of excellence. No encoder, operating on a PC, allows you to obtain the 7th degree level of quality (indistinguishable from the original for all ears and all programs.) These algorithms run into an internal high-speed DSP. Encoding at 192 Kbps (kilobits per second) with VBR technology (Variable Bit Rate), allows for a faithful and accurate reproduction of a recording session done at 24 bits @ 192 KHz. This is crucial to face the new FM digital HD radio . But it is also true that still using modern analog FM transmitters, the ADA102 links allows for the excellent sound quality that is always appreciated by the audience.
Please, listen to audio demos
We recommend you to use good quality PC speakers, with separate woofer,
or use headphones.
Also, you can download the MP3 file to listen elsewhere.
To do this, click the right mouse button over the link under the text,
and choose the option "Save..."
Listen to a streaming audio created with the ADA102 at the speed of 192 Kbps with grade 7 audio quality and VBR mode. This is the recommended speed for all the links.
The excellent quality you are hearing now is the same you will get in all the transmission rooms of your radio network, connected to Internet. Note that a speed of 192 Kbps is very well handled by the existing networks of broadband Internet. The program material, English and Spanish, includes MP3 encoded music to check that double encryption does not affect the final quality.
Now listen to the same program above, but encoded at only 128 Kbps VBR
This reduced speed may be used in some critical links with networks of highly saturated Internet. Note that at this same encoding speed, a PC encoder sounds pretty poor. But in contrast, with the ADA102, the radio station gets a very good performance, difficult to distinguish from the previous one.