DaySequerra M2A-FM - Manual (Page 13)

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M2A-FM User Manual
DEMODULATION LEVEL SELECT – Front panel control permits user to select Left or L+R demodulated
audio level to be displayed on top Demodulation Level meter, and Right or L–R demodulated audio level to
be displayed on bottom Demodulation Level meter. Green LEDs indicate the user selection of display
mode.
DEMODULATION LEVEL METERS – 58-segment multi-colored LED meters display demodulated analog
audio levels; either de-emphasized or pre-emphasized audio can be displayed; select pre-emphasized audio
by shorting internal Pre-Emphasis Jumper JP15 (left channel) and JP16 (right channel). Your M2A-FM
was shipped with JP15 and JP16 open to display de-emphasized audio. A Torx
TM T-8 L-key
(included) or driver is required to remove the M2A-FM’s cover.
The meters levels are peak responding between +10dB and –30dB, and average responding between –
30dB and –64dB.
CARRIER MODULATION SELECT – Front panel control permits user to select positive, negative or both
deviations, or pilot and SCA injection levels to be displayed on the carrier modulation meter. Green LEDs
indicate the user selection of display mode.
CARRIER MODULATION METER – 58-segment multi-colored LED meter displays the FM carrier level, as
described below. The meter has a quasi-peak response with a floating peak-hold and displays positive or
negative peaks or both simultaneously from 46% to 125% with user programmable measurement integration
times of 100, 200, 500 and 1000µSec. The measurement integration times can be changed using internal
Time Integration Jumper JP1. Your M2A-FM was shipped from the factory preset for 100uSec
integration time.
RF SIGNAL LEVEL – 8-segment green LED display indicates relative RF signal level received at the
antenna connector on the M2A-FM rear panel. A minimum of 5 RF signal strength segments must be
illuminated (indicating >65dBf) for accurate demodulation and carrier level measurements.
Headphones. Recessed screwdriver control adjusts headphone output level on recessed ¼” TRS jack.
Default set at the factory is -7.0dBm (0.1VAC Pk-Pk).
SCA and AM Measurements
Overview. The M2A-FM provides for peak-type measurements of the injection level for 19kHz pilot, and
57kHz, 67kHz and 92 kHz sub-carriers using the Carrier Modulation LED display with a 0.2% resolution
between 4.4% and 10.4%. A rear panel MPX Output for external sub-carrier decoding is also included. The
M2A-FM also provides a relative indication of the incidental AM noise component of the FM carrier using the
top Demodulation Level LED display. During the AM noise and Sub-Pilot measurements, all other M2A-FM
functions are disabled.
AM Noise Level. A relative measurement of the incidental AM noise component of the FM carrier can be
made by first tuning to the FM station of interest and then selecting AMN mode by pressing the
Demodulation Level Select switch until the green AMN LED illuminates. The top Demodulation Level LED
meter will indicate the relative level of the incidental AM noise component present in the FM carrier. The
0dB indication is referenced to –50dB.
Pilot and SCA Injection Level. The injection level for 19kHz pilot as well as 57kHz SCA, 67kHz SCA and
92kHz SCA of an analog FM signal can be accurately measured using the Carrier Modulation LED display
by first tuning to the FM station of interest and then selecting the Sub-Pilot mode by pressing the Carrier
Modulation Select switch until the green Sub-Pilot LED illuminates. The received RF signal level of the
analog FM signal must be at least 65dBf for the Sub-Pilot mode to be active.