Rangecast FAQ
[FAQ-1063] RCX Severe Audio Distortion Problem

Page Type: SYMPTOM


In rare installations using Rangecast RCX USB interface boxes there has been severe audio distortion that renders transmissions unintelligible. The cause is unknown but may be due to the PC's unique USB hardware and/or the Windows operating system. Over 99% of installations operate normally. However there is a limited workaround.


This URL contains a short sample: http://rangecast.com/resource/hnp.mp4


The functional symptom, when this problem is present, is that some transmissions are distorted into unintelligible harsh sizzling.

--The problem has never occurred if there are 3, or fewer, active sound channels.
--The problem can be triggered by accessing a 4th, previously idle, sound channel. The 4th channel did not cause trouble while idle, only upon being accessed.

Other observations may later help to find a solution:
--The distortion problem is often limited to one or two senders.
--The problem seems to be linked to specific Windows PCs, and travels with them when replaced.
--Seemingly identical PCs may not exhibit the problem.
--It seems to occur more often with Dell PCs, but has happened with Microcenter PCs.
--The problem can be triggered by accessing an idle 4th sound channel.
--Replacing RCX units has not fixed the problem.


(1) The problem is evident upon hearing an instance. Listen to the URL listed above.

(2) The problem can be easily seen on the Status Page. When the audio is malfunctioning, the audio levels from a Sender (normally between 5 to 20) become much higher (often 50 to 150.) A second indication is that numbers begin appearing in the "BG" column, which is normally clear.


There are currently only TWO POSSIBLE SOLUTIONS to the noise problem.

(1) ENABLE NO MORE THAN 3 SOUND CHANNELS. This has always been effective in systems with the problem. In cases where only 3 Senders are adequate for the job, it may be an acceptable solution. Otherwise it is only a workaround since it places an unnecessary limit on system capacity, because a normal Rangecast installation can handle 6 or more Senders per PC.

(2) REPLACE THE PC. This may be an actual solution because the trouble is caused in the PC. It has been effective but extreme and has only been done a few times. It did cure the problem in those cases.




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