On what band do amateurs share channels with the unlicensed Wi-Fi service?
- 432 MHz
- 902 MHz
- 2.4 GHz
- 10.7 GHz
Which digital mode is used as a low-power beacon for assessing HF propagation?
What part of a packet radio frame contains the routing and handling information?
Which of the following describes Baudot code?
- A 7-bit code with start, stop, and parity bits
- A code using error detection and correction
- A 5-bit code with additional start and stop bits
- A code using SELCAL and LISTEN
In the PACTOR protocol, what is meant by a NAK response to a transmitted packet?
- The receiver is requesting the packet be retransmitted
- The receiver is reporting the packet was received without error
- The receiver is busy decoding the packet
- The entire file has been received correctly
What action results from a failure to exchange information due to excessive transmission attempts when using PACTOR or WINMOR?
- The checksum overflows
- The connection is dropped
- Packets will be routed incorrectly
- Encoding reverts to the default character set
How does the receiving station respond to an ARQ data mode packet containing errors?
- It terminates the contact
- It requests the packet be retransmitted
- It sends the packet back to the transmitting station
- It requests a change in transmitting protocol
Which of the following statements is true about PSK31?
- Upper case letters are sent with more power
- Upper case letters use longer Varicode bit sequences and thus slow down transmission
- Error correction is used to ensure accurate message reception
- Higher power is needed as compared to RTTY for similar error rates
What does the number 31 represent in "PSK31"?
- The approximate transmitted symbol rate
- The version of the PSK protocol
- The year in which PSK31 was invented
- The number of characters that can be represented by PSK31
How does forward error correction (FEC) allow the receiver to correct errors in received data packets?
- By controlling transmitter output power for optimum signal strength
- By using the Varicode character set
- By transmitting redundant information with the data
- By using a parity bit with each character
How are the two separate frequencies of a Frequency Shift Keyed (FSK) signal identified?
- Dot and dash
- On and off
- High and low
- Mark and space
Which type of code is used for sending characters in a PSK31 signal?
What is indicated on a waterfall display by one or more vertical lines on either side of a digital signal?
- Long path propagation
- Backscatter propagation
- Insufficient modulation
Which of the following describes a waterfall display?
- Frequency is horizontal, signal strength is vertical, time is intensity
- Frequency is vertical, signal strength is intensity, time is horizontal
- Frequency is horizontal, signal strength is intensity, time is vertical
- Frequency is vertical, signal strength is horizontal, time is intensity