Miscellaneous - microHAM SMORF Manual

MISCELLANEOUS menu allows to set two operating parameters.
First is an ability to suppress ALC overshoots. Virtually every transceiver
generates overshoots at the beginning of transmission until ALC loop
stabilizes (hundreds μs up to several ms). Exact time and amplitude of
overshoots can be easily measured on the Oscilloscope screen.
SMΩRF has very fast measurement and reliably captures every
overshoot with multiple samples. Once you are aware that this happens, it can be annoying to see "bumped"
peak and peak hold values on regular screens every time ALC loop timeouts and transceiver generates new
overshoot. To help with this problem, SMΩRF allows to turn on filter to SUPPRESS OVERSHOOTS.
Second parameter helps to deal with false triggering. Those who are operating at multi transmitter sites are
probably familiar with effect of "magic SWR needle" on analog power meters. This effect is caused by RF
energy coupled from the antenna radiating power to the closely spaced antenna which is at the moment used at
another position for receiving. Coupled power is high enough to be detected by sensor and since power is
generated from the opposite side of the coupler, it has impact to level of reflected sample. On U/I couplers,
where U and I samples are equal in amplitude under matched conditions, it causes false triggering. To avoid this
issue in multi TX setups, SMΩRF provides adjustable POWER THRESHOLD, which sets minimal power
necessary to initiate measurements.
For FWD/REF sensors power coming from opposite direction is easy recognizable (reflected sample is larger
than forward) and false triggering is eliminated by software.
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CONTROLS:
1. SUPPRESS OVERSHOOT
YES enables overshoot suppressing filter. This function is not generally applicable to all screens when
enabled. Advanced metering screens like the Oscilloscope or the Spectrum screens intentionally do not
suppress overshoots. Also please note, that suppression time larger than 2-3ms will have impact to peak
reading amplitude of SSB signals, where peaks of such duration are normal.
TIME
2.
Sets time used by overshoot suppressing filter. Exact value is specific to every transceiver and can be
measured on the Oscilloscope screen. Good value to start with is 2ms.
POWER THRESHOLD
3.
Sets minimal power to initiate measurements. If you are not operating in multi transmitter environment, it
is good to set it for minimal, 10mW level.
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SENSOR 1 MENU – MISCELLANEOUS
Oscilloscope screen showing ALC overshot on initial
dot of CW signal ("bump" on leading edge).
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