Spectrum DSP M2 User Manual page 25

Using the Spectrum DSP with computer "Sound Card" (e.g. digital) modes
via the Line-Input and Line-Output connections:
The Spectrum DSP may be connected to a computer, tablet or smart phone via audio cables
and the PTT line on the Microphone cable to allow modes such as SSTV, PSK31, WSPR or
other digital "Sound Card" mode. To do this, configure the transceiver as follows:
Using the mode button select USB mode: All digital modes are operated using USB,
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regardless of band. In this way the audio frequency of the digital signal may be
added to the frequency display to calculate the actual transmit/receive frequency.
Set RIT to zero by swiping up/dwn in the right region with the DSP menu showing
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(which activates swiping changes): Press the RIT box as necessary until RIT is
highlighted to allow adjustment. When using a digital mode the RIT MUST be disabled
or else you will have difficulty making contacts!
Set CMP to zero by swiping in the left-side of the LCD with the DSP menu active:
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Press the AFG box as necessary to highlight CMP to allow adjustment by swiping in
the left-side of the LCD. When using a digital mode, the audio compressor must be set
to MINIMUM (0) or else it may degrade the digital signal!
Before connecting the external device (Computer, tablet, phone) set the audio output
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level to mid-scale. Also set the audio input gain to approximately mid-scale as well.
For receive, one may use any of the available receive audio filters, but it is
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recommended that the Wide filter not be used! If narrow (300Hz, 500Hz or 1.8 kHz)
filters are used, one may shift the center frequency of that filter in the menu to suit the
passband for that mode, but be aware that it is possible to run too narrow a filter for
some of the "wider" digital modes! In the vast majority of cases the 2.3kHz filter will be
adequate.
Be certain that DSP filtering is turned off! The DSP noise reduction or notching on
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any radio necessarily alters signals and doing so can degrade them, making them
difficult for the attached computer/device to decode!
Connect the Line-Input jack (optional port) of the Spectrum DSP to the audio output of the
device you are using to generate the audio and connect the Headphones jack of the
Spectrum DSP to the audio input of that same device.
To key the transceiver, you will need also to connect a cable to the EXT to trigger TX mode by
grounding the line: Typical rig-computer interfaces will easily accommodate this connection.
Preferably, connect the transmitter to a 50 ohm dummy load capable of handling at
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least 10 watts. Alternatively, you may tune to a clear frequency while connected to an
antenna with a known-good 50 ohm match.
Press the RIT box to select LIN mode. You may need to press-and-hold this button to
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change from MIC to LIN. Press the RIT box as necessary to highlight LIN.
Press the AGC box to select the AUDIO meter.
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Using the program running on the external device, key the computer using the selected
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mode. If the program has a "test" mode, use it for this.
Adjust the LIN setting by swiping up/dwn in the right-region for a reading on the AUDIO
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meter of +2 to +4.
Make sure that you have set "CMP" to 0 as noted above!
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Un-key the transceiver.
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Spectrum DSP M2 User Manual V1.1
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