Comtech EF Data LTT1450G - Manual (Page 31)

LTT1450G Ku-Band Loop Test Translator Serial Interface Protocol
TM063 - Rev. 1 Page 5-3
1 Ku-25 MHz loop voltage
2 Spare
3 Spare
4 Spare
5 Spare
6 Spare
7 D/A attenuation control voltage
The translator will return the following string:
[1]{cr}
Where Byte 1 is the hexadecimal 8-bit value read from the ADC.
5.3.2 Return DAC Value
Often it would be good to know what the current DAC value is before issuing any commands to change
that value. The Return DAC Value command is useful for either double checking the DAC value prior to
storage or simply determining what the value is prior to issuing a new value. To request the current DAC
value enter:
MMV{cr}
The translator will return the following string:
[1][2]{cr}
Where bytes 1 and 2 are the hexadecimal 16-bit value of the right justified 12-bit DAC value.
5.4 Calibration Commands
The calibration shell resident in the test translator firmware is used to load calibration data into the
EEPROM for the purpose of linearizing the PIN diode attenuator. This calibration was performed at the
factory and should not be needed to be performed in the field. However, there are situations where the
user may want to re-calibrate the attenuator on the translator. One reason may be to eliminate
interconnect cable frequency response variations in gain. In this situation, a user may want to calibrate
the gain to some port other than the one’s on the translator itself.
Note that calibration of the translator is only as accurate as the equipment used in making the calibration.
Normally, the calibration requires that a test signal be input to the translator at a known level and then
the translator output power be measured with a spectrum analyzer. Few power meters have the required
dynamic range and selectivity.