# USB command: correction

**Correction table**

There are two user controllable level correction mechanisms in the tinySA:

First is the leveloffset which is frequency independent and set by either doing a level calibration or using the ACTUAL POWER menu.

The second mechanism is the frequency dependent correction table. This table with 10 entries for frequency dependent level corrections. The default table for the V0.3 HW contains these values.

align=center cellspacing=2 width=20% slot frequency value

- 10000 6.0
- 100000 2.8
- 200000 1.6
- 500000 -0.4
- 30000000 0.0
- 140000000 -0.4
- 200000000 0.4
- 300000000 3.0
- 330000000 4.0
- 350000000 8.1

The current content of the table is shown by entering **correction** without any arguments. The data in the table can be modified by specifying the slot number and the new values.

Example: ** correction 5 10000000 -0.5**.

This command will set slot 5 to 10MHz and a correction of -0.5dB. The frequencies specified in the table must be sorted in increasing frequency. Make sure you do a **saveconfig** after updating to save the new values to flash memory so they will survive reset.

There MUST be one entry for 30MHz and the correction for that frequency MUST be zero. You are free to choose which entry as long as the table is sorted in increasing frequency.

**Use of the correction table**

All level measurements will use the frequency of the measurement to find the applicable correction.

- Any frequency below the frequency in slot 0 will use the correction from slot 0
- Any frequency above the frequency in slot 9 will use the correction from slot 9
- Any in between frequency will use a frequency based linear interpolation to calculate the applicable correction

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