Rangecast FAQ
[FAQ-1259] Blocked Channels


Page Type: REFERENCE


OVERVIEW

If recordings on a single scanner from a broadcast channel consistently produce no meaningful audio content (defined as more than two-thirds of audio being silent, extremely loud such as digital data, or broken into recordings of nearly zero duration), the channel will be temporarily blocked from that scanner. If all scanners in a cluster independently determine that the channel meets these criteria, the channel may be temporarily excluded from Rangecast. Temporary blocks are cleared daily, but the block will be regularly restored for channels with consistently bad quality.


BACKGROUND

An individual transmission is rejected (recorded at the radio, but not delivered into Rangecast) if the audio level is either (a) nearly silent, or (b) extremely loud, or (c) the total duration of the transmission is under one-third of a second.

Extremely quiet signals are usually fully silent, tying up the scanner for no beneficial purpose. Typical examples are birdies or stuck carriers. Extremely loud signals are usually digital data, or sometimes unintelligible audio produced by a flaw in the PCs audio processing system. Extremely brief signals are not uncommon, but if seen continuously may indicate a problem with the agencies radio transmission system.

A channel is temporarily blocked from a single scanner if more than 2/3 of total recording time is rejected from Rangecast due to one of the conditions listed above, with a minimum of at least 4 rejected transmissions containing a cumulative 30 seconds of rejected audio. This is done to keep a scanner from locking up on channels that are producing no meaningful content, and the process is an automated system to lock out data channels, birdies, or other worthless content.

Such temporary blocks are limited to a single scanner (as sometimes the conditions that lock up a scanner relate to that one scanner's antenna or audio path). A channel will not be blocked entirely from reception via Rangecast unless every radio in the cluster independently determines that the channel should be blocked.

Temporary blocks are cleared daily, and whenever the Rangecast software is closed and relaunched, so if the block is caused by some temporary condition the loss of the channel will not be permanent.


METHOD

To prevent a channel from being blocked, you can apply a command like this in Special Settings (replacing the channel ID with the specific ID of the channel you wish to prevent from being blocked):

noblockcid=C123456

Multiple channels can be unblocked by using a DASH (not comma) between CIDs. (The comma is used to separate commands. For example:

noblockcid=CX10244-CX10243-CX10242

If the channel is silent much of the time, and is unblocked, the Rangecast system may interpret the abnormally low audio levels as an indication of a possible problem with the audio system, and frequently recalibrate and compare audio ports. If this happens, you can also limit these retests to daily with this command:

recalinterval=86400000

Use caution in permanently unblocking channels, because it is possible this may tie up the scanners on content that cannot be processed into Rangecast. (Individual transmissions will still be rejected if they fail the silent/load/brief tests, so this kind of problem may not be apparent to the user, but will result in the failure of the scanners to record other content. However, the status page reports the percentage of time the scanner spends recording rejected content in the Debris column.)

If you wish to have all recorded content on a channel submitted to Rangecast (bypassing the rejection tests for individual transmissions), use the "continuous" command instead of "noblockcid", for example:

continuous=CX10739-CX10770-CX10771


REFERENCE

To see if a channel is blocked, view the status page - Blocked tab.




The "Hours Ago" column reports how recently the block was in effect. Current blocks show as 0, higher numbers indicate the block was previously in effect but has been released.

This report includes, in the left column, the CID of each channel (may be useful if choosing to permanently unblock channels via Special Settings)


CITATIONS

INDEX


Rangecast FAQ - ID 1259 - last updated 08 March 2019     Images shown - [block]