Q1- Original Pactor or Pactor III- Which has the higher maximum 'baud rate'
Answer- Original Pactor. It has two symbol rates- 100 and 200 baud (or bauds if you prefer). Pactor III has a fixed symbol rate of 100.
Q2- True or False?- The 31 in PSK31 represents the 31 Hz bandwidth.
Answer- False - The 31 represents the 31.25 data rate. The real bandwidth for PSK31 transmitting data is 63 Hz at 30 db down.
Q3- Pactor and PSK31 have encoding schemes that make common letters quicker to send than those less common. What older mode has the same property?
Answer- Morse Code
Q4. True or False? - Sneezing while sending a Winlink file could slow the uplink
Answer- True. If the Pactor controller is connected through the transceiver's ACC port, it is probable that the mic is live when the controller transmits a frame. Any sound picked up could corrupt the Pactor modulation and cause a retry. Gesundheit !
Q5. Pactor II or Pactor III - Which is the more spectrum efficient?
Answer- Pactor II by a small margin. Using the metric of maximum uncompressed data transfer rate per unit of occupied bandwidth, both do very well at better than one bit per second per hertz.
Q6. True or False? – You have to be careful to use the correct sideband (USB/LSB) with HF Packet, PSK31 (in common BPSK mode), and Pactor.
Answer- False except for Pactor III. The others will work in either USB or LSB or even crossed if the frequency setup is correct. SCS recommends USB for Pactor III.
Q7. True or False?- If you receive reports of distorted voice audio when your Pactor modem is connected, unplugging it while using SSB to clear the distortion only ignores a problem.
Answer- True. The voice distortion is the probable result of rectified RF in the Pactor controller. When it is reconnected for digital use the distortion will still be present and cause problems.
Q8. True or False ? – Pactor II and III use FSK (Frequency Shift Keying).
Answer- True. FSK is used for the initial connection and then the link steps to PSK (Phase Shift Keying).
Q9. True or False? - If you have an up-to-date frequency list, a correctly configured Pactor controller, and carefully set your HF transceiver to the frequency calculated by Airmail, you will be ‘spot on’ with the Winlink station.
Answer- False. There are several errors that could put you off frequency enough to compromise performance or even prevent connection. The most probable is the dial calibration of your transceiver. The arithmetic sum of all frequency errors (yours and the Winlink station’s) has to be less than 80 Hz or so in the FSK initial acquire phase.
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