In August 1998 Radyne/Comstream
Corp. stopped producing the ABR200 and introduced the new ABR202. The ABR200 has long been the industry standard for Satellite Audio Broadcasters. Download the Radyne/Comstream ABR202 specification sheet [PDF format]. The receiver operating with the MPEG layer II "Musicam®" encoding alogrithm is in use in most of the Worlds [certainly European and American] satellite delivered networks. S+AS Limited has designed, supplied, installed and commissioned several networks in Europe using this equipment and provides this page as a condensed version of the two Radyne/Comstream
technical bulletins which explains the differences between the two receivers and what is required to introduce one or more ABR202 receivers into an existing ABR200 audio broadcast network.
Several links are also provided to the S+AS Limited FAQ section for reference and further explanation of the terms used. After visiting the FAQ, to return to this page click on your browsers "Back" button. If you have any comments on this page please EMail firstname.lastname@example.org with 'ABR.html' in the subject line.
There are a number of significant differences between the two units which I have broken into two sections Physical and Technical.
S+AS Limited has copied most of the information below from a missive written by Radyne/Comstreams ABR202 Program Manager, Dean Wood, dated September 4 1998. Other information has been added by Mike Bartlett who has now supplied and installed a number of ABR202s and has had the oppertunity to fully test them at S+AS limited's facility in Scotland. for more details please EMail email@example.com.
1 Deals with the physical appearance of the unit.
2 With the technical differences.
2a Mentions some "interesting stuff".
3 Adobe Acrobat PDF files.
The physical differences
The ABR200 was supplied in an unique [to Radyne/Comstream
] chassis, IU high, encased in metal, the unit has been a major instrument in the development of satellite broadcast radio services for more than 7 years. The unit was shipped with a 19" rack mount kit and despite being only 1U high required an extra 1U of rack space for cooling. The ABR202, as Dean points out, is shipped with "a new versatile rack or table mount architechture".
The 202 is 2U high, employs a shorter chassis and is supplied with
"integrated rubber feet" and can be installed "directly
between other rack-mounted equipment with no additional air space
required". The top case is now moulded plastic and the front panel
employes fewer LED's. Each new, bi-colour LED, has a multiple function
providing all of the front panel indications used on the ABR200. On
the rear panel the D15 AES/EBU port is now seperated from the user
data which is supplied via a 9 pin D type. The exclusion of the "L
Band" [or Video] output means that if more than 1 is to fed from a
single antenna system then a splitter must be included. S+AS Limited
has developed and tested a range of active and passive IF
splitters ranging from the 2 way passive SAS.2FP, to
the SAS.8SA which can be used to connect up to 8 receivers
to a common source, download
the specification document, for more detail.
The technical differences
The major change, technically, is the adoption of the Standard ISO MPEG layer II audio coding alogrithm in preference to Musicam® coding and the ability of the DeModulator to cope with continuously variable data rates from 64Kbps up to 20Mbs.
Therefore to introduce an ABR202 into an existing network the audio codec, normally installed at the uplink, will need to be reset to operate without Musicam® encoded audio streams. There are two types of Radyne/Comstream
Audio codec the DAC [Digital Audio Codec] 400 and the DAC700, both are able to operate in either Musicam® or standard ISO MPEG mode with the default [up to August 1998] being Musicam®. For instructions on how to change the coding alogrithm click here for the 400 and here for the 700. An ABR200 with V1.14 [or later] software will operate in either the Musicam® or standard ISO MPEG mode without any configuration change. ABR200 receivers with software versions earlier than this will need to be upgraded before you switch off the Musicam® coding if they are to continue to provide audio output.
One of the other changes to the audio receiver is the introduction of Viterbi and Viterbi + Reed Solomon DVB [and non DVB] FEC which will make the receiver compatible with other manufacturers systems and as a future model, available for multimedia or MCPC applications. Previously the ABR200 had only operated with Radyne/Comstreams proprietory sequential error correction.
The new MCPC ABR200 will permit re-allocation of bandwidth between multiple audio and high speed data streams with the added benefit of control over individual sites from a central location. With a little imagination it is clear that this new generation Radyne/Comstream chassis is an adaptable data receiver which can be used for a multiplicity of applications.
There appears to be some problem with the DC protection circuit for the LNB supply. Several receivers have been returned with the 1Ohm [protection] resistor destroyed. Extreme care must be taken when replacing or removing the IFL from the rear of the reciever or the LNB that a short is not made.
A problem exists with the ABR firmware [V1.xx] which will, during aquisition, default to FD_0. If FD_0 has not been defined then AQ will equal 0. Therefore if you are pre-programming receivers prior to field installation you must set Format Definition 0 [Zero] and FD_1 to the required parameters. If FD 0 is not set and the ABR202 is unplugged from the mains or a reset occurs, prior to a carrier acquisition, the ABR2002 will fail to acquire on power on. The only way to get the ABR to restart the acquisition process, is to issue the command AQ_2 to the M&C port using a DTE. Version 2.00 software [released on December 10 1998] cures this problem, as with this new release FD_1 is the default aquisition format and FD_0 no longer exists. Contact
for more information.
Another fault has been reported to SAS, this deals with the AES-EBU digital output port. It appears that some of the identification flags are set incorrectly, noteably the "copy protection", "domestic quality" and "44.1KHz" sample rate are set "on". All of these can create problems and Comstream are working on this [April 99], a software update is expected soon.
Update : (June 2000) - A new board, needed to cure the AES/EBU fault is now available from radyne/Comstream. The redesigned board which cures jitter problems features a new PLL circuitry and re-programmed chip set.
One of the more useful additions to the ABR202 is the Volume Control command. VC allows the unit to output a signal +/-8.5dB from the received level, or, put another way, +/-8.5dB from the input level to the DAC. The manual states that the default VC setting = 9, on the one's that SAS have seen this has been set to 8 which acording to one of our customer reproduces the Codecs input level over the satellite link.
The Audio Test command (AT) has been severely trimmed in the ABR202. The ABR200 had 7 options putting 2 tones on both or alternate Left and Right channels, in the ABR202 there is only one tone available [1KHz], which is either ON both channels or OFF [AT_1 or 0].
If you plan to use Viterbi coding with the new ABR202 you must use the High speed Modulator card, this also applies if you use Reed Solomon or DVB Reed Solomon, which requires the HS modulator and appropriate RS card.
The DAC400 can be set to operate with either the Musicam® or Standard ISO MPEG coding by setting a dip switch which is found on the rear panel. Switch number 4 defines, or selects, the coding type. If it is in the DOWN position the codec is operating with Musicam® moving the switch to the UP position will change the CRC calculation alogrithm to Standard ISO MPEG. This coding type is required by the new ABR202. Changing the position of this switch will cause the network to lose sync and the ABRs [with software V1.14 or later] will re-aquire and operate normally, without loss of audio quality, with the new coding type.
The DAC700 employs a software 'switch' to change between Musicam® and Standard ISO MPEG coding. The command [AS] "Alogorithm Select" should be changed from the default value of "0" to "1". This can only be achieved by communicating with the DAC M&C port using a DTE ie. a pc or dumb terminal employing a VT100 ASCII RS232 protocol. If you do not know how to do this or require assistance please contact S+AS Limited, see our contact page for details. Note: All DAC700s will revert to Musicam® coding if their power source is cycled. A new software version [higher than V1.3] must be installed to correct this situation.
ABR202 .......... Radyne/Comstream specification sheet [89Kb]
ABR202 .......... Installation/Operation Manual [3380Kb]
ABR200 .......... Installation/Operation Manual [1539Kb]
In 2007 Radyne/Comstream bought Tiernan and using the DVB expertise built a new ABR called the ABR202A. They continued with this until Comtech EF Data bought Radyne in 2008. Shortly after, in mid 2009, Comtech stopped supporting ABR20* series receivers and sold Tiernan (and the audio broadcast systems division) to the Canadian International Datacasting Corporation.
Now (as we enter 2010) only the ABR202A is supported by the new manufacturer.
S+AS Limited intends to keep on supporting ABR20* networks as long as spares are available. The new 202A is compatible with the older 200 and 202 networks. S+AS Limited can supply the new ABR202A if needed, please contact firstname.lastname@example.org for pricing and delivery.
S+AS Limited has a number of refurbished ABR's, DAC's and CM701 modems in stock
Call: (+44) 1555 666313 (extension 220) or send an eMail to: email@example.com
Last Revised: 2/December/2009
Copyright © 1999/2009 S+AS Limited. All rights reserved.
We hope you found this page informative. S+AS Limited (was) an authorised re-seller of Radyne/Comstream
equipment. If you have any questions, which you would like answered, please Email the the sales desk at S+AS Limited see our contact page for more detail. If you require a quotation for any Radyne/Comstream product please EMail
Compiled by Mike Bartlett