Rangecast FAQ
[FAQ-1068] Error Message: QUIET TRANSMISSIONS (Code 21)

Page Type: SYMPTOM

OVERVIEW

Quiet Transmissions means that, during a significant fraction of the time, the scanner is recording content that is rejected due to abnormally low audio levels. There are two possible reasons - either the audio input is running low (and can be raised through the Windows Sound user interface), or the designated programming for the scanner includes channels that are producing non-voice content (such as periods of silence.)

BACKGROUND

In the normal default software configuration, transmissions with extremely low audio levels are rejected by the software (never sent into Rangecast). This is to screen out silent transmissions with no meaningful content (for example, mic clicks, or total silence.) If the audio level from the scanner is abnormally low, then real transmissions may be screen out by this filter, resulting in missing content on channels received by that scanner.

SYMPTOMS

If the rejected transmissions carried voice content that were too quiet due to level settings, then this error may result in missing content. Even if other scanners in the cluster were operating normally, since Multisync makes scanners collaborate on reception, so that each transmission is captured by only a single radio, transmissions rejected due to audio level settings are lost to the system.

If the rejected transmissions did not carry viable audio content, then including the broadcast channel in the programming may result in missed content on other channels, because when the scanner is locked onto the channel without meaningful content, it cannot detect or record content from other channels.

METHOD

There are two possible causes for the Loud Transmissions error message.

1) If this error is due to audio levels:

Raise the audio levels in Windows Sound for the audio input from the scanner.

[FAQ-1067] Adjusting Windows audio input levels

The Rangecast audio recording process compresses audio to support a wide dynamic range, but if the levels are too high or low, quality is compromised (and some transmissions may even be discarded). Also, if the level is too low, the Rangecast software may not reliably detect the audio port. A level control is available in Windows Sound to adjust the input levels from each scanner, and Rangecast provides information about observed levels to help determine when adjustments are needed.



It is recommended that the audio levels be checked on all scanners connected to this PC. When one scanner shows a "Quiet Transmissions" error, it is not uncommon for other scanners to have marginal quality audio levels (low, but not low enough to raise an alarm) that would benefit from adjustment. It is easy to check and correct the audio levels on all scanners connected to a single PC at the same time.

2) If this error is due to the scanner locking onto transmissions that do not carry voice, but instead produce nearly silent audio:

Determine which channels are producing this content, and remove them from the programming for the system.

(Note that rejected content will not appear in the Rangecast player, or on the status page, so these resources are not a reliable indicator of what channels may be responsible for these transmissions. It is recommended that the scanner or sender be observed directly, at the feed site PC. Immediately after the end of a transmission, if the transmission is rejected due to being too quiet, the word "Quiet" will appear on the "Last File" line of the sender status report.)

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