TMM-2800自動調制度測試儀 Frequency Range 1.5MHz- 1.2 GHz useful indications to 2GHz. AM and FM measurement over full
range LED indication of lock, level low and high Analog...
Frequency Range 1.5MHz- 1.2 GHz useful indications to 2GHz. AM and FM measurement over full
range LED indication of lock, level low and high Analogue display CCIT Filter De-emphasis network
very low noise
Description:
The Automatic Modulation Meter TMM2800 has been designed to simplify the task of measuring
amplitude and frequency modulation on signals in the range 1.5MHz to 1.2GHz. By emliinating
the need to tune a local oscillator and make level adjustments the TMM2800 speeds up
measurements and reduces errors.
AM and FM measurements can be made at full accurancy over the frequency range 1.5MHz to
1.2GHz and with reduced accuracy and sensitivity to 2 GHz. On FM, five ranges are provided with
full scale readings of 1KHz, 3KHz, 10kHz, 30KHz and 100Khz deviation can be displayed. On AM
five ranges five full scale readings of 1%, 3%, 10%, 30% and 99%. Peak, through or mean of
percentage modulation can be displayed.
For ease of measurement, three bandpass filters with nominal upper cut-off frequency of 60KHz,
15Hz and 3.5Hz, a CCITT psophomatric filter or a 750us de-emphasis network can be selected to
filter or the recovered modulation.
The different ranged and functions are selected by front panel push buttons with lED's providing
indication of function.
Specification:
RF INPUT
Frequency Range
1.5MHz to 2.8MHz, 3.2MHz to 1.2 GHz with a useful response, with reduced sensitivity, to at least 2 GHz.
Tuning Automatic tuning selects the largest available signal.
Correct operation requires spurious signals to be > 10dB below the wanted signal.
Acquisition Time
Typically less than 100ms to locate and lock to the carrier signal. Setting time for the
demodulation and AF circuits is additional and istypically 1 second.
Lock and Level Indicator
A LED indicates that the instrument is locked to an input signal and that the level is within range.
Input impedance
50 Ohms nominal
Input Level
The unit will lock and measurement modulation for input carrier levels in the range 2mV to 1V. Full
specification for noise, accuracy etc. only applies over the input range 10mV to1V.
Maximum Safe Input level
0.5W continuous
Local oscillator Feed-out
Typically <-60dBm.
FM MEASURMENT
FM Ranges
Five ranges with full scale deviations of1KHz, 3KHz, 10KHz, 30KHz and 100KHz.
Accuracy
2% of full scale. See Audio filter specification for additional error due to AF response Residual FM is additional.
Residual FM < 20 Hz at 100MHz, < 100Hz at 500MHz, <200Hz at 1000MHz.
Distortion
<1% at 50KHz deviation with a 1 KHz tone.
FM Measurement Modes
Peak +Ve, Peak and Mean deviation
AM MEASURMENT
AM Ranges
Five ranges with full-scale indications of 1%, 3%, 10%, 30% and 99%.
Accuracy
2% of full scale. See Audio filter specification for additional error due to audio response. Residual
Am is additional.
Residual AM Less than 0.5% with a 15KHz bandwidth selected
Distortion
<1% for 50 5 AM with a 1 KHz tone
AM Measurement Modes
Peak, through and Mean of peak and through
AUDIO FILTERS
60KHz bandpass Filter 25Hz-60KHz 1dB, typically 12 Hz-72KHz 3 dB with roll off at 80dB / decade.
15KHz Bandpass Filter
25Hz-15KHz 1db, typically 12 Hz-19.5KHz 3db with HF roll off at 60dB /decade
3.5 KHz Bandpass Filter
25Hz-3.5KHz 1db, typically 12Hz-4.0KHz 3dB with HF roll off at 100dB /decade
CCITT filter
Complies with CCITT Volume VP 53
De-emphasis network
750 us de-emphasis, 3dB bandwidth
Typically 12 Hz to 212 Hz.
HF roll off 20dB/ decade
AF OUTPUT
Demodulated AF Output
Front panel BNC
AF Output Level
0dBm corresponding to full scale deflection
AF Output impedencd
600 ohms
IF OUTPUT
IF Output
Front Panel BNC
If Output Level
Typically 100mV
Display
Type moving coil meter with 0-3,0-10 and 20dB scale with % and KHz notation
Overload
The meter is fully protected
Power Requirements
Mains 220V or 110V selectable
Frequency 50/60Hz
Power Approx. 6VA
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