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Section 2 13 scanning
Open SCAN (System module) to work through channels and stop where somebody is transmitting. Two kinds:
- MEM — the stored memory channels, each in its own mode and filter. Mark any of them SKIP to pass it over; a channel that is always busy with something you do not want to hear is what that is for.
- RANGE — a slice of a band on a channel grid. Give it a From and a to in MHz, a Step (5 / 6.25 / 8.33 / 10 / 12.5 / 25 kHz) and a mode.
A range scan is fast, and not in the way a handheld scanner is. A scanner has one receiver and has to visit each channel in turn, which is why sweeping 2 m takes minutes. Here the FFT that already draws the panadapter sees over a megahertz at once, so the radio moves one span at a time and reads every channel in that span together — the whole of 2 m in well under a second. A CAT rig feeding demodulated audio has no such span, so it falls back to visiting channels one at a time, and behaves like the handheld.
A memory scan stops on each channel in its own set-up. Stopping on a channel sets the mode, the filter and the DUPLEX and TONE stored with it, so a scan across a mixed list leaves you on a repeater channel with its shift and tone on and on a simplex one with both off. That matters more here than on a recall, because a scan hands you whichever channel called and you answer it by reaching straight for the PTT — a shift left standing from the last stop would put the over 600 kHz away from the station calling you. A channel stored before the set-up existed counts as plain simplex with no tone, exactly as a recall reads it (2.12). The antenna is the one thing a stop does not touch, unlike a recall: a scan is not worth a relay per channel.
A memory scan can be pointed at chosen folders. With folders in use (2.12) a Folders row appears above the channel list: ALL, then one button per folder with the number of channels in it, and Unfiled for the top level. Pick one or several and the scan runs over those alone — the marine channels while you are on the water, the local repeaters while you are not — and the list below narrows to the channels it will actually visit, so what you are looking at is what the scan will do. ALL is not every button lit: it means no selection, which is also where a folder you make tomorrow lands, so a new folder is scanned rather than silently left out. A folder you delete drops out of the selection with it, since its channels are back at the top level by then. The row is not drawn at all until there is a folder to choose.
FAST reads the list off the spectrum. A memory scan normally does what a handheld does: tune to each channel, listen, move on — a settling time apiece, so a hundred channels is fifteen seconds a lap. Press FAST and a receiver with I/Q of its own instead puts every channel that falls inside one window on the same transform the panadapter is already made from, and only tunes to the ones something is on. A list that fits in one window then costs one tune a lap however long it is, and a list spread over four bands costs four. The scan still listens on each candidate before it stops, so what makes it stop is unchanged.
It is off by default and worth knowing why. The sweep measures a channel through the FFT rather than through the receiver's own filter and AGC, so a Stops at level that was right for the slow scan is not automatically right for this one — if a fast scan stops on nothing, raise it; if it stops everywhere, lower it. Two kinds of channel are never judged from the sweep at all and always get a listen: one out at the edge of the window, where the anti-alias filter makes everything read low, and one sitting exactly on the receiver's centre, where a zero-IF front end's own local oscillator is. A CAT rig feeding demodulated audio has no spectrum to read, so the button is greyed there and its memory scan visits every channel as before.
Stops at is how loud a channel has to be. Either give a level directly, or
press SQL to use the receiver's own squelch, which makes the scan stop
exactly where the audio would have opened — one control instead of two. Note
that with the squelch slider at off the scan will stop on the first channel it
looks at, since every channel then counts as busy. The squelch is one of the
per-mode settings (see Per-mode settings (the reset chip)), so SQL uses
the squelch of the mode being scanned: a frequency scan in NFM started from
SSB stops at NFM's squelch, which is open until you set one there, and a memory
scan judges each channel by the squelch of the mode it was stored in. Set it
once while the scan is running in that mode and it is remembered for next time.
Listens for is how long it stays on a candidate before judging it. Below about a tenth of a second the level meter has not settled and weak signals get missed; the default 150 ms is a reasonable balance.
Resumes decides what ends a stop:
- CARRIER — carry on once the signal drops, plus a grace period. The grace is what keeps you on a conversation through the gaps between overs; two seconds is a good starting point.
- TIMED — carry on after a fixed time whether or not the signal is still there. Useful on a channel somebody is sitting on.
- MANUAL — stay until you press NEXT.
While a scan is running, NEXT moves on now and SKIP moves on and adds the channel to the skip list. Touching the dial, changing band, recalling a memory or transmitting all stop the scan where it is — as on any scanner, and so that the radio is not fighting you for the VFO.
SKIP works in a range scan too, and it is remembered. There is no stored channel to mark, so the frequency itself goes on a skip list shown under the range — a row of buttons, one per channel, with CLEAR to empty it. The list is saved with the rest of the settings, so a data channel, a pager or a birdie dismissed once stays dismissed for the rest of the evening and for every later run over the same range, instead of costing a stop every pass. Click a button to put its channel back into the scan.
The list belongs to the range it was taken in: change the From, the to or the Step and it is emptied, because a channel dismissed on 2 m says nothing about 70 cm — and a scanner quietly refusing to stop somewhere you do not remember dismissing is worse than one that stops too often.
The SCAN button in the System module lights while a scan is running, in cyan
while it is sweeping and green while it is stopped on something, so you can
close the window and still see what it is doing. Settings are remembered in
scanner.json.
From the User Manual. Home.