Hi,
I was trying to find the insertion loss value for the tsw4100 board, but couldn't find it, therefore my question are as follows:
* What is the min/max insertion loss for tsw4100 design.
* What is the min/max gain we can set using tsw4100 design (analog/adc/ddc/duc/dac/analog).
Thanks
Jacob
Hello,
There is not a simple answer to your question. There is no direct Insertion loss term for the TSW4100. It is a series of attenuation and gain terms.
IF input filter insertion loss
The ADC can have a loss depending on the peak operating level. This is typically done with the analog input peak of ~-2 to -3dbc. , this is compensated for later at the DDC output.
Real tuning - real signal loses one sideband
Filtering and decimation does not normally cause insertion loss for the passband
The CIC shift, PFIR filtering, PFIR shift normally are adjusted within the cmd5016 tool to provide for 0 to -6db gain, this loss is made-up with the DDC baseband gain.
The DDC baseband gain is typically set so that a subband input power, measured by the baseband power meter is adjusted for 1:1 gain, this removes the real tuning loss and filtering loss..
The DUC baseband gain, and sumshift gain are adjusted to balance the number of transmit subbands. Typically the baseband gain is set to 1/number carriers transmitted
initially
The interpolation, PFIR filtering, CIC shift are typically adjusted with each channels DUC baseband gain.
The sumchain can provide a gain or loss, normally the initial value is -6db, then we adjust the BBgain for each channel so that each subcarrier has good signal quality, and is adjusted for 6db lower power. After each channel is tested, the sumshift value is raised by one value (this prevents DAC input saturation affects).
The complex output to the DAC has a coarse gain, the power output can be calibrated with the DUC BBgain,, DUC sumshift gain, and DAC Coarse gain and current to voltage conversion. In most cases we aren't as concerned with gain, but not saturating in any stage.
There is not a specific number, more a procedure to get each channel (repeater band) to have appropriate gain within the 2,3, or 4 sub bands transmitted.
Most customers build a spreadsheet to account for the gain and loss terms, and compare the spreadsheet and lab test results.
Regards,
Radio Joe