Timewave DSP-59+ - Page 15

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The mark-space frequencies of the modem, receiver and DSP-59+ must match.
Default mark-space frequency shifts and center frequencies vary among modem and radio
manufacturers, and in different parts of the world. Some modems have default HF Packet
mark-space center frequencies different from their RTTY, AMTOR, and PACTOR mark-
space center frequencies. The DSP-59+ standard mark-space center frequency is 2210 Hz.
for RTTY, AMTOR, and PACTOR data modes (use the 2.21k (red letters) position of the
Center Freq. control). The DSP-59+ Option mark-space center frequency factory setting is
1700 Hz. for HF Packet mode. Use the Option (red letters) position of the Center Freq.
control.
The mark-space center frequencies of the modem, receiver and DSP-59+ must
match.
Some modems and radios have programmable mark-space frequencies. If your
modem and radio default to different mark-space center frequencies, you must change the
modem or radio mark-space center frequencies to match the DSP-59+ or change the DSP-
59+ mark-space center frequencies to match the modem and radio mark-space center
frequencies. See your radio or modem instruction manual, and the DSP-59+ Back Panel
Jumper table on page 16 of this manual.
Note that some receivers do not have specific provisions to use their narrow (200 - 600 Hz
wide) filters for data. Operate these radios in their SSB voice filter bandwidth. Other
receivers may have fixed or variable mark-space frequencies - check your operating
instructions carefully!
The Kantronics KAM+ usually has the HF Packet mark-space center frequency set to 1700
Hz. (1600-1800 Hz. mark-space frequencies). See the KAM+ manual for the procedure to
change the KAM+ mark-space center frequency setting via software.
See the Back Panel Jumper Function Table on page 16 for DSP-59+ filters and settings.
Jumpers 7 and 8 set the mark-space center frequencies.
Data Operating Hint
Choosing the correct bandwidth for the baud rate and shift of a data signal is critical to reject
QRM while minimizing the bit error rate from noise. If there is no QRM, wide bandwidths may
be acceptable on a strong signal, but could cause increased bit errors on a weak signal. Use the
following settings for the best trade-off between bit error rate and QRM rejection.
Mode Shift Speed DSP-59+
Bandwidth
RTTY 170 Hz. 45.5 baud 250 Hz.
AMTOR 200 Hz. 100 baud 350 Hz.
PACTOR 200 Hz. 100/200 baud 450 Hz.
G-TOR 200 Hz. 100/200/300 baud 550 Hz.
HF Packet 200 Hz. 300 baud 550 Hz.