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MOTOROLA Technical Developments
RELIABLE VOICE MESSAGE TRANSMISSION
by Volker Martschink and Klaus Pai
INTRODUCTION
is done by comparison of the lengths of the transmitted and the received message.
c) Finally, the receiver checks if the squelch lcir- cuitry was enabled during receive time to have an indication for signal interruptions, e.g. caused by temporary loss of the received signal.
If all these three indicators have been rated OK, the receiver will send an acknowledgement to the transmitter.
Since the receiver is able to detect interruptions or lower signal quality by evaluation of the signal strength and squelch status, the following scenarios are possible if the whole message or parts of the message have been corrupted during transmission:
a) Whole message unuseable: Receiver forces transmitter to try again later.
b) Parts of the message lost or corrupted: Receiver might force the transmitter to send the whole or parts of the message again, dependent on the overall quality. This would help to save channel capacity. If the transmitter does not receive any acknowledgement during a specified time after transmission of the message, it may wait some time and try again once or several times, which may be selectable by the operator and may be dependent on the importance of the message. Nevertheless, the transmitter will be able to defi- nitely report a status of the transmission (full acknowledgement, transmitted message cormpt- ed or no connection to the receiver). ABSTRACT
Radio communication system for reliable trans- mission of spoken words.
This paper deals with the improvement of voice transmission in analogue radio systems. It will help to improve the reliability of the transmission of spo- ken words and provide an acknowledgement. PROBLEMS TO BE SOLVED
Information transmission is very dependent on the quality of the transmit-receive line. Sometimes messages get lost due to poor transmission quality,
e.g. caused by fading and other negative influences on the communication line.
PROPOSED SOLUTION TO THE PROBLEM
The described system should make sur...
