Which of the following is included in packet radio transmissions?

Packet radio transmissions utilize several key features to ensure reliable communication over radio frequencies.

One important element is the inclusion of a check sum. This is a numerical value calculated from the data being transmitted, which allows the receiving station to verify the integrity of the received information. If discrepancies are found between the calculated check sum and the one received, it indicates an error in transmission, prompting the need for retransmission.

Another critical aspect in packet radio is the automatic repeat request (ARQ) system. If an error is detected (through the check sum, for example), the receiving station can send a request back to the transmitting station to resend the particular data packet. This mechanism helps maintain data integrity, ensuring that messages are transmitted accurately.

Additionally, packet radio transmissions typically include a header that identifies the destination station, often containing the call sign of the intended recipient. This is vital for directing packets to the correct receiver in the network, distinguishing it from other simultaneous transmissions.

The combination of these features—error detection via check sums, retransmission through ARQ, and identification through headers—contributes to the effectiveness of packet radio communication. Therefore, all these elements working together affirm that the correct answer encompasses all choices provided.