Software notes: SpecLab

Externally triggered screen capture

(v2.70 b20) This is straightforward, but there may be a delay of several seconds before the capture happens.

Capture using preset options:

speclab /si /capture

Capture to a windoze bitmap with the time in the filename:

speclab /si /capture("capt"+str("YYYYMMDDhhmm",now)+".bmp")

Crontab line:

52 1 2 12 * c:\spectrum\speclab /si /capture("capt"+str("YYYYMMDDhhmm",now)+".bmp")

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Configuration for recording LEO spectra

(v2.71 b4)

These are the essential settings I use for recording RS-15's beacon from an HF receiver tuned to the beacon's nominal frequency in CW mode. The frequency offset matches that of the receiver in CW mode (and should be 0Hz in SSB mode). The frequency extrema encompass the beacon's doppler of +-500Hz with a little to spare to allow for this particular beacon's tendency to drift. A higher frequency beacon in a similar orbit will require a wider bandwidth. Each RS-15 pass is audible for around 30 minutes; the scroll rate ensures that all of a pass can be captured on one screen without wasting too much space. This could be increased for satellites in lower orbits. The settings for displayed amplitude range will depend on the aerial system, receiver and soundcard.

Intrepreter command equivalents

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Stuck watch window

Problem (v2.5 b12): if the watch window is enabled, the program hangs when you try to close it.

Solution: before restarting the program edit the settings.ini file and ensure that under

[WatchWindow]

it says

Visible=0

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Default capture caption

(v2.70 b15)

"Date="+str("YYYY-MM-DD",now)+" Time="+str("hh:mm",now)
"Freq= "+str("###0.#",water.f_min)+"..."+str("###0.#",water.f_max)+" Hz"

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Multiple-strip waterfall

(v2.71 b4)

Spectrum (1): check "vertical frequency axis" (for horizontal strips), "multi strip WF" and enter an appropriate strip width in pixels. Speclab inserts a small gutter between the strips.

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Stereo

(v2.71 b4)

Audio I/O (Options... Audio settings)): check "stereo processing". Use the circuit window (View/windows... Spectrum lab components) to direct the channels via filters and mixers (if required) and to the appropriate analyser/s. The waterfall display in stereo mode sometimes goes haywire for no readily apparent reason, producing solid blocks of colour which bear no relation to the input signal. The only "cure" I've found so far is to click "apply" in the configuration window); this restores normal behaviour.

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Document history