Yesterday we performed some RFC scans in order to check the modulation depth for the F6MHz F8MHz F56MHz and F81MHz sidebands.
Each scan is performed setting the power (on the LNFS) to 12dBm for one frequency and all the others to -30 dBm, 500s per scan, 500µm.
The results are the folllowing:
| m | gps (UTC) | |
| F6MHz | 0.18 | 16.11.00 |
| F8MHz | 0.13 | 16.37.10 |
| F56MHz | 0.14 | 16.24.30 |
| F81MHz | 0.07 | 16.48.50 |
If these measurements were made with a -3dB attenuator in front of each EOM, removing it will result in a free sqrt(2) increase in modulation depth.
Here are the new theoretical values:
| new "m" value | |
| F6MHz | 0.25 |
| F8MHz | 0.18 |
| F56MHz | 0.20 |
| F81MHz | 0.10 |
A further sqrt(2) increase could be achieved by using +15dBm for the LNFS output value, but in some cases this could lead to nonlinearity of the last RF power amplifiers. To be verified.