TX Preamble Duration

Setting the TX Preamble Duration to a value greater than zero causes the radio to insert a string of bits in front of a data or control message (e.g. Text Messaging, Location Messaging, Registration, Radio Check, Private Call, etc.). This preamble prolongs the message in order to reduce the chances of the message being missed by a receiving radio. 

This duration may need to be increased if the radios on the system use scan and there are a number of channels in the scan list. This value can be increased in all the transmitting radios if scanning radios are often missing data messages. However, a larger preamble occupies the channel longer. Therefore, increasing the TX Preamble Duration will increase the success rate of data received while other radios are scanning, but will decrease the amount of data that can be transmitted on the channel (channel loading).

For nearly all applications, the default value of 960 ms is sufficient. Further details about TX Preamble Duration and scan can be found in the MOTOTRBO System Planner.

8 comments:

  1. Hello Wayne,

    I tried to scan a channel for text messages but that does n't work.Any sugggestions?

    Regards
    Philip

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    Replies
    1. Have you tried turning up the TX preamble time on the 'sending' radio? I seem to think that an incoming text message doesn't count as valid channel activity for scan - will need to check that though. Good question!

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    2. Per §2.5 of the (Rev. M) EMEA System Planner "While scanning, the radio can accept data (e.g., text message, location, telemetry, or terminal (PC) data). However this is only applicable if the data is received on its selected (home) channel."

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  2. Hello Sir, i have been facing "NO VOICE TRANSMISSION while PTT is engaged" problem either on one, two, some or all recipient walkie talkie sets randomly while operating on 2 repeaters capacity plus mode connected through Ethernet cable. kindly guide me in this regard please. Regards

    ReplyDelete
    Replies
    1. See my reply to your comment on the MOTOTRBO and IP post http://bit.ly/1C4IUmN. The symptom you describe here is difference but the cause is probably the same.

      Are you using a RF combiner on this system?

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    2. Sorry, replace the word "difference" with DIFFERENT. (The price one pays for responding on an iPad :-( )

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