Spectrum DSP M2 User Manual V1.1
Initial set-up of the Spectrum DSP:
There are a number of set-ups that can be optionally performed/checked, including:
• Carefully observe the start-up screen: If you see warnings – typically in red – pay
close attention to and resolve them – some of which are detailed in this section.
• Turn on the “Frequency Translate” mode [TUNE/O shows green] for best receive
quality if noise interference is detected. .
• Frequency Calibration: (for Spectrum with the RF/IF receiver module installed)
▪ A known-accurate frequency source. This could be a precision oscillator/test
equipment or an off-air signal from a time station such as WWV.
▪ A means of accurately determining an audio frequency. This could be a
frequency counter or a computer with sound card with a known-accurate sample
rate running an audio analysis program.
◦ Set the receiver to USB mode.
◦ If the signal source is available on multiple frequencies, pick the highest frequency
available.
◦ Tune the receiver 1 kHz below the frequency of the selected reference frequency.
◦ Set the tuning step size to 1 Hz.
◦ Couple the output of the receiver to the audio frequency measuring device so that
you get a reading.
◦ Go to the calibration menu item “Freq. Calibrate” and adjust it to obtain a precise 1
kHz audio frequency.
▪ Note: It is possible that the Si570 may be off frequency by hundreds of Hz – or
even several kHz. You may change the frequency step size to facilitate this
adjustment.
• TX and RX I/Q Phase/Balance adjustments:
◦ The procedures for adjusting TX and RX I/Q Phase and balance are detailed in
later sections of this manual and should be reviewed.
Additional settings:
The following settings should be known to the Spectrum DSP operator. Please refer to the
previous sections containing the menu items for more details on their use.
• Voltmeter Cal. - This calibrates the on-screen voltmeter: Only a known-accurate
voltmeter should be used as a reference. Note that the voltmeter display updates only
once every second or so.
• Max Volume – This puts a limit in the maximum volume setting – particularly useful if
one primarily uses headphones where loud sounds may cause hearing damage.
P 60
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